The development of green-based nanomaterials as antimicrobial agents offers a sustainable and safe alternative to conventional antibiotics, aligning with both environmental and public health priorities. The paper wasp (Parapolybia escalerae) is a novel species known for its unique honey, which has not been previously explored for its potential in green nanotechnology and biomedical applications. In this study, paper wasp honey was used to prepare silver nanoparticles (H-Ag NPs), which serves a dual role as both the reducing and stabilizing agent. The structural, morphological, and optical characteristics of the biosynthesized nanoparticles were assessed using UV-Vis double beam spectroscopy, X-ray diffraction (XRD) pattern, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). Additionally, the antibacterial potential of the synthesized H-Ag NPs was evaluated against gram-positive bacteria Staphylococcus aureus (ATCC 6538), Staphylococcus aureus MRSA, and multidrug-resistant gram-negative bacteria Acinetobacter baumannii by determining their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using the broth microdilution method. Notably, MIC and MBC of this nanoparticle against S. aureus (ATCC 6538) and S. aureus MRSA strains were found to be 17.5 µg/mL. Additionally, at lesser doses (8.5 µg/mL), these nanoparticles can inhibit the growth of the Gram-negative bacteria A. baumannii. The novel feature of this method lies in its environmentally friendly and sustainable approach, as it avoids the use of hazardous chemicals typically employed in conventional synthesis methods.

Triple-color emission ratiometric fluorescence sensing has emerged as a powerful tool in biochemical analysis, enabling a shift from semi-quantitative to fully quantitative and highly precise measurements. This review presents a comprehensive overview of the design principles, fabrication strategies, and practical applications of triple-color emission probes excited under single-wavelength excitation. By incorporating three distinct emission channels, these probes offer self-calibrating, interference-resistant, and sensitive detection with enhanced color discrimination. We categorize the fabrication strategies into one-, two-, and three-emitter designs, discussing the mode of action for each and how they ensure spectral stability, tunability, and robustness in multiplexed sensing. Special attention is given to how these systems outperform conventional binary systems in terms of sensitivity, dynamic range, and color hue variation. Recent advancements span metal ion detection, pH sensing, enzyme assays, antibiotic and biomarker analysis, explosives, and others. This review provides key insights and guidance for advancing next-generation quantitative biochemical sensing technologies.

Real-time sensing applications demand dual-emitting materials with built-in self-referencing capabilities to minimize background interference and enhance detection accuracy. Despite their significant potential to improve sensor reliability, sensitivity, and longevity, the fabrication of metal-organic frameworks (Eu-MOFs) with both dual-emission characteristics and dual-state behavior remains rare and technically challenging. The intricate design and precise control required for such structures make their successful synthesis an ongoing challenge in materials science. In this work, we report the synthesis of a new Eu-based MOF that displays dual fluorescence, emitting both blue and red light in liquid and solid states. The blue emission arises from coordination-induced ligand luminescence upon integration into the MOF framework. Notably, the red emission is selectively quenched in the presence of diclofenac (DCF), while the blue emission remains stable. This dual-emission property enables the construction of a ratiometric sensing platform, where the unaffected blue fluorescence acts as an internal reference and the quenched red fluorescence provides the detection signal for DCF. The developed method achieves a Linear detection range of 0–231 µM with a detection Limit of 0.2 µM. In addition, a smartphone-based visual sensing strategy was applied through RGB analysis, enabling convenient and on-site quantification. Since the Eu-MOF functions as an intrinsic sensor without the need for encapsulation or surface modification, it demonstrates excellent stability, recyclability, and selectivity, highlighting its strong potential for practical analytical applications.

Point-of-care testing demands ultra-sensitive, real-time, and rapid detection of nitrite to address critical challenges in environmental monitoring, food safety assurance, and on-site health diagnostics, owing to the widespread presence and high toxicity of nitrite across ecological and biological systems. In this study, a novel and stable silver-based metal-organic framework (Ag-MOF) was synthesized and utilized for the selective detection of nitrite. The fabricated Ag-MOF functioned as a potent oxidase mimic, catalyzing the transformation of 3,3′,5,5′-tetramethylbenzidine (TMB) into its oxidized derivative (oxTMB+.), which manifested visually as a vivid blue coloration. Upon the introduction of nitrite ions, a diazotization reaction was triggered, converting oxTMB+. into its dicationic form (oxTMB2+), resulting in a distinct color transition from blue to green-yellow. Capitalizing on this visually perceptible shift, a dual-mode detection strategy was successfully implemented, enabling nitrite quantification through two distinct approaches: (i) smartphone-assisted visual and RGB-based analysis, and (ii) conventional instrument-based fluorescence measurements using a spectrofluorometer. The oxidase-mimicking Ag-MOF exhibited a Michaelis–Menten constant (Km) of 33.4 μM, reflecting its high affinity for the substrate and enhanced catalytic efficiency, particularly at low substrate concentrations. Notably, this nanozyme is both cold- and heat-adapted, maintaining its oxidase-like activity across a broad temperature range from 5 °C to 100 °C without any loss of performance. To enable precise detection, we designed a ratiometric colorimetric platform that allows both conventional and smartphone-based analysis, utilizing color tonality changes for quantification. The traditional colorimetric approach exhibited a linear detection range for nitrite from 0.0 to 66.0 μM, achieving a low detection limit of 0.011 μM. In comparison, the smartphone-integrated method demonstrated linearity between 0.0 and 60.0 μM, with a corresponding detection limit of 0.12 μM. The Ag-MOF platform enabled smartphone-based nitrite detection in water, showing practicality, sensitivity, and promise for rapid environmental monitoring.

A novel zinc-based metal–organic framework was successfully employed as a catalyst in the Claisen–Schmidt condensation reaction for the synthesis of azo-chalcone. The catalyst demonstrated excellent recyclability and maintained high activity after the reaction without loss of effectiveness. The synthetic protocol allows for simple product isolation, easy workup, and efficient purification, supporting potential scale-up for industrial applications. Quantum chemical calculations provided insights into the electronic and structural properties of the synthesized azo-chalcone. Molecular docking studies revealed strong binding affinity of the chalcone to Escherichia coli DNA gyrase, with a docking score of − 10.794 kcal/mol. Key interactions involved hydrogen bonding and van der Waals forces, particularly with the amino acid Asn46, which is critical in ATP hydrolysis inhibition. The compound also displayed favorable drug-like properties according to Lipinski’s rule and absorption, distribution, metabolism, elimination, and toxicity profiles.

Microfluidic technology has seen remarkable advancements in recent years, drawing significant attention in the field of pharmaceutical sciences under the term “Pharm-Lab-on-a-Chip.” Its appeal lies in numerous advantages, including high throughput, rapid detection, minimal reagent usage, efficient analysis, and compact design. Accordingly, the microfluidic platform is a promising pharmaceutical analysis tool. This review covers the advancements and utilization of microfluidic chip technology in pharmaceutical and pharmacological analysis. Firstly, the basic structure of a microfluidic chip was introduced, along with the fabrication of microfluidic chips. Subsequently, the use of the microfluidic chip in pharmaceutical analysis was discussed, with particular attention paid to the separation and analysis of drug molecules on the chip and integrating a microfluidic chip with other techniques. Furthermore, the role of microfluidic chips in pharmacological analysis was explored, mainly focusing on applying chip-based models for assessing the effectiveness and safety of drugs.

The development of a dual-emitting fluorophore with strong fluorescence intensity and long-term stability is essential for innovative, efficient, and user-friendly sensing platforms in bioanalysis, enabling precise detection and broad applicability in real-world scenarios. In this study, a dual-antenna effect was successfully integrated into a single dual-ligand europium-based metal-organic framework (BiL-MOF), which was both designed and systematically investigated. Upon excitation at 250 nm, the BiL-MOF exhibited two distinct emissions: a blue emission at 365 nm and the characteristic red emission peaks of Eu3+ ions. The use of two different ligands enabled efficient energy transfer from the excited states of the ligands to the 5D₀ state of Eu3+ ions, facilitating the dual-antenna effect. This phenomenon, along with the sensitization of Eu3+, was confirmed through both experimental studies and theoretical analysis. The dual-antenna design significantly improved the fluorescence quantum yield, from 2 % and 10 % in mono-ligand MOFs, to 42 % in the BiL-MOF, while also enhancing structural stability. Additionally, a red shift in absorption and an associated hyperchromic effect were observed, contributing to its potential utility in a variety of sensing applications. Interestingly, folic acid (FA) simultaneously quenched both emission peaks, a behavior attributed to the inner filter effect. This dual-response mechanism enabled the development of a highly sensitive and reliable ratiometric probe for FA detection using both conventional fluorometry and smartphone-based visual readouts. The fluorometric method achieved a detection limit of approximately 0.12 μM, with a linear response range from 5.0 to 165.0 μM. The smartphone-based visual approach also demonstrated excellent performance in analyzing pharmaceutical samples, delivering recovery rates between 98.1 % and 102.2 %, with outstanding reproducibility (RSD < 1 %, n = 4), underscoring its promise for real-world applications.

Metal-organic frameworks (MOFs)-derived heterogeneous catalysis has gained significant attention for their catalytic efficacy and unique structural features, making them valuable in various organic syntheses by enhancing reaction efficiency, selectivity, and sustainability. MOFs are highly effective catalysts in organic synthesis due to their catalytically active sites, significant surface areas, tunable pore structures, and a wide range of chemical characteristics that enhance selectivity and accelerate reactions. This study introduces the application of a novel MOF (called UoZ-2) as a heterogeneous catalyst for synthesizing a novel azo-chalcone product through the Claisen-Schmidt condensation process. The UoZ-2 acid catalyst is esteemed for its many benefits, such as operating under mild conditions, achieving rapid reaction rates, facilitating straightforward recovery and isolation without diminishing catalytic efficiency after multiple uses, enabling easy product purification, and offering scalability and lower cost for industrial applications. Furthermore, azo-chalcone product synthesis under microwave irradiation conditions achieves a high yield, saving energy and time, which was compared with the traditional reflux method. Ultimately, these outcomes confirm the use of a friendly environmental method. Moreover, the reusable studies exhibited that the catalysts were found to be stable and reusable for up to three cycles without substantial loss of catalytic activity. The synthesized azo-chalcone was thoroughly characterized using spectroscopic techniques, and its biological potential was assessed through molecular docking studies with the HER2 protein. Computational studies, including density functional theory and ADMET analysis, further revealed the synthesized compound’s electronic properties and pharmacokinetic potential. The findings highlight the potential of UoZ-2 as an efficient and sustainable catalyst for the scalable synthesis of biologically relevant chalcones, offering an environmentally friendly alternative to traditional homogeneous catalytic systems.

Designing metal-organic frameworks (MOFs) with dual-state dual-emission properties is both rare and technically demanding. Despite this challenge, such materials hold immense potential for real-time sensing applications, offer exceptional stability, and provide intrinsic self-referencing mechanisms that effectively minimize background interference and enhance detection reliability. In this study, a novel Eu-based (Eu-MOF) is synthesized, demonstrating both liquid-phase and solid-state fluorescence. The as-prepared Eu-MOF exhibits a nano-spherical morphology and displays distinct dual emissions, blue (425 nm) and red (617 nm), under 250 nm excitation. A ratiometric sensing platform is established, leveraging the selective quenching of red fluorescence by Dexamethasone (DEX) while the blue emission remains nearly unaffected. This method enables a linear detection range of 8.0–222 µM with an impressive limit of detection of 0.34 µM. Furthermore, a smartphone-assisted visual detection approach is developed using RGB analysis via the Color Grab App, facilitating portable and on-site quantification. This intrinsic dual-emitting MOF eliminates the need for additional encapsulation or surface modifications, making it a highly stable, recyclable, and selective sensor with broad potential for real-world applications.

The development of dual-emission metal-organic frameworks (MOFs) is essential for advancing luminescence-based applications. In this study, a highly fluorescent bi-ligand Eu-based MOF (BiL-Eu-MOF) was synthesized exploiting coordination-induced emission (CIE) and dual-antenna effect phenomena. Upon excitation, the BiL-Eu-MOF emits both blue (CIE effect) and intense red (dual-antenna effect) fluorescence, enabling ratiometric detection. Amoxicillin (AMX) selectively quenches the red emission via the inner filter effect, while the blue emission remains stable, serving as an internal reference. This property facilitates AMX detection using two methods: conventional spectrofluorometric and a smartphone-assisted visual approach. The spectrofluorometric method achieved a detection range of 5.0–250 μM with a detection limit of 0.34 μM, while the smartphone-based approach reached a detection limit of 3.3 μM. The BiL-Eu-MOF demonstrated high accuracy (98.1–102.7 %) and precision (RSD < 2 %) in milk and pharmaceutical samples, highlighting its potential as a simple, effective, and modification-free sensing platform.

Dual-emitting combined with dual-mode detection holds great importance in variety of luminescence-based applications. The dual-emitting property of a single metal-organic framework (MOF) is highly attractive due to its stability and the ability to achieve dual emission without requiring additional fluorophores. In this study, a novel dual-emitting dual-state bi-ligand Eu-based MOF (BiL-Eu-MOF) was synthesized exploiting dual-antenna effect. The dual-antenna effect, achieved through precise tuning of the ligands' energy levels in alignment with the empty 5D0 orbitals of Eu3+ ions, significantly enhances charge transfer from the ligands to the metal center, resulting in intensified emission. In this regard, dexamethasone (DX) quenches the red emission, while the blue emission remained slightly affected. This phenomenon, led us to design ratiometric-tonality platform for detection of DX using conventional fluorometry and fluorescence tonality visual-based mode. The intrinsic dual-emitting properties of BiL-Eu-MOF enable stable, recyclable, and selective on-site detection DX without the need for encapsulation or functionalization.

Integrating multiple phenomena in one metal–organic frameworks (MOFs) is essential to construct intense and dual-emitting MOF for diverse luminescence-based applications. By leveraging the antenna effect and coordination-induced emission (CIE), we developed fluorescent bi-ligand Eu-MOFs capable of simultaneously producing red and blue emissions under a single-wavelength excitation. The CIE mechanism induces ligand emission by restricting intramolecular rotation within the MOF structure, while the antenna and dual-antenna enhances the characteristic red-emission of Eu3+ ions. The prepared bi-ligand Eu-MOFs emits in solid and liquid form enlarged the zone of applications. The addition of diclofenac (DCF) quenches most of red emission via an inner filter effect mechanism while leaving the blue emission less affected. This property enabled the development of precise ratiometric-based detection method using traditional spectrofluorometric and smartphone-based visual analysis. The spectrofluorometric analysis measured DCF concentrations between 6.0 and 305 µM with a detection limit as low as 0.077 µM. Smartphone-assisted color tonality analysis was conducted, shifting from red to blue, with linear range from 10 to 280 µM and detection limit down to 0.87 µM. These probes were successfully applied to quantify DCF in pharmaceutical formulations with high accuracy (98 to 101 % recovery) and precision (less than 2 % RSD). With its unique dual-emission capabilities and robust detection potential, this MOF demonstrates promise for broad-ranging applications in luminescence-based sensing.

Detection of mercury ions in environmental samples using accurate and precise methods is highly essential due to their toxicity and potential adverse effects on ecosystems and human health. Metal-organic frameworks (MOFs) have garnered considerable attention in recent years due to their unique structural and physicochemical properties. MOFs exhibit an enzyme-mimic properties due to their structural diversity, allowing them to imitate the catalytic functions of natural enzymes. These features enable MOFs to catalyze a range of reactions efficiently and selectively, offering opportunities for applications in diverse fields, especially in environmental analysis. This review outlines using of MOFs as nanozymes for the detection of mercury ions in environmental samples. The remarkable catalytic activity exhibited by MOFs, combined with their high surface area and tunable pore structures, presents a promising platform for sensitive and selective detection of mercury ions (Hg2+). It also discusses using pristine and/or modified MOFs for enzyme-based assays, highlighting the advantages and disadvantages of each type. A critical analysis is made of the specific details and figures of merit of the developed assays. Furthermore, challenges and future perspectives in the development of MOF-based nanozymes for mercury ion detection are discussed, offering insights into potential strategies for enhancing sensitivity, selectivity, and practical applicability in environmental monitoring and remediation efforts.

In biochemical sensing, substantial progress has been achieved in the design, development, and application of metallic nanoclusters (NCs) and metal–organic frameworks (MOFs) as distinct entities. Integration of these two nanostructured materials is a promising strategy to form innovative composites with improved properties. Some improvements include (i) supporting platform to minimize the aggregation of NCs and enhance the emission efficiency; (ii) dual-emitting NCs@MOFs from the fluorescent/non-fluorescent MOFs and/or fluorescent NCs; and (iii) stability enhancement. These improvements increase the sensitivity, signal-to-noise ratio, and color tonality, lower the limit of detection, and improve other analytical figures of merits. In this review, we outline the preparation methods of NCs@MOF composites with the improvements offered by them in the field of biochemical analysis. Analytical applications in different fields, such as bioanalysis, environmental monitoring and food safety, are presented. Finally, we address the challenges that remain in the development and application of these composites, such as ensuring stability, enhancing the fluorescence intensity, and improving selectivity and scalability. Furthermore, perspectives on future research directions in this rapidly evolving field are offered.

Nanozymes, engineered catalysts exhibiting catalytic properties, have emerged as key players at the interface of nanotechnology and biology, holding great promise in diverse food applications. Notably, nanoscale metal-organic frameworks (MOFs) have gained widespread recognition as flexible platforms for developing potent nanozymes. This review explores the design, development, and applications of MOF-based nanozymes, with a focus on their potential in detecting antioxidants and total antioxidant capacity (TAC), two critical parameters in the assessment of oxidative stress and related diseases. A comprehensive classification of these MOF-based nanozymes is presented, based on their catalytic activities, and recent advancements in their application to antioxidants and TAC detection are discussed. The review further delves into the challenges faced by MOF nanozymes in these areas, including issues related to stability, reproducibility, and selectivity. By addressing these challenges and proposing potential solutions, the review offers future perspectives on advancing the use of MOF nanozymes in sensing applications.

Manganese nanoparticles (Mn NPs) were successfully synthesized using a cost-effective and eco-friendly biogenic approach, with pinus brutia pine needles. The produced Mn NPs were thoroughly characterized using common spectroscopic and microscopic techniques. The Mn NPs exhibited remarkable oxidase-like activity, effectively catalyzing the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to its oxidized form (oxTMB) over a broad temperature range. This robust catalytic performance highlights their versatility and stability under varying thermal conditions, making them suitable for diverse applications. Nitrite forms orange-yellow color via diazotization of the blue oxTMB. An image processing algorithm analyzes the image changes induced by addition of nitrite. Under optimized conditions, the visual-based platform demonstrated a broad linear response for NO₂⁻ detection, spanning 0.0–58.0 uM and the detection limit was 0.11 μM. The visual method demonstrated exceptional sensitivity and recovery for nitrite detection in food samples. Combining simplicity, cost-effectiveness, and eco-friendliness, this instrument-free approach ensures accurate, portable, and point-of-care nitrite detection, ideal for real-world food testing applications.

The development is shown of rod-shaped manganese-based metal–organic frameworks (Mn-MOFs) as hot- and cold-adapted oxidase-like nanozymes, with strong magnetic properties. These Mn-MOFs enable highly sensitive detection of nitrite ions, utilizing both convenient colorimetric ratio analysis and a visual instrument-free-based approach compatible with smartphone-based detection. The Mn-MOF showed multi-functional activity, such as cold/hot-adapted and magnetic oxidase-like activity, catalyzing the oxidation of chromogenic substrates 3,3′,5,5′-tetramethylbenzidine (TMB) to blue oxidized TMB (oxTMB). Mn-MOF shows high oxidase activity with Vmax of 1.39 × 10−8 M/s and Km of 0.068 mM for TMB oxidation. Nitrite ions further react with oxTMB to form a yellow color via diazotization resulting in the ratiometric change in absorbance (A652/A461). The color ratio is also quantified through the naked eye and/or smartphone app by analyzing RGB values, providing a rapid, portable, and cost-effective method for on-site detection. When applying Mn-MOF for smartphone-based nitrite detection, it performs excellent detection, with a linear range of 5.0–55.0 µM and a limit of detection of 0.18 µM, superior to most of the oxidase nanozyme-based nitrite sensing platforms. The detection platforms develop sensing probes using a reusable nanozyme that enables highly sensitive and selective detection of nitrite, featuring a broad linear range and a low limit of detection.

This study presents the synthesis of novel flower-like silver-based zeolitic imidazolate frameworks (Ag-ZIFs) with petal-like nanosheet structures, exhibiting robust oxidase-like activity. These nanozymes catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) effectively across a wide temperature range (5 °C to 80 °C), making them suitable for thermophilic and cryogenic applications. Leveraging this strong oxidase activity, Ag-ZIFs@TMB system was used to design a conventional ratiometric colorimetric method for nitrite detection in water and food samples, alongside a color tonality-based visual detection mode. Nitrite concentrations ranging from 1.0 to 54.0 μM were quantified, achieving a detection limit of 0.06 μM. The ratiometric approach demonstrated enhanced sensitivity, lower detection limits, and superior resistance to interference compared to traditional single-absorbance methods. Furthermore, the smartphone-assisted or naked-eye detection mode enabled rapid, portable, and accurate analysis, offering practical applications in environmental monitoring and food safety. These results highlight the multifunctional potential of Ag-ZIFs in advanced sensing technologies.

Sustainable and natural-based materials with high stability and efficiency for water pollutant removal are vital for advancing sustainable water treatment technologies. This study investigates the use of chalcopyrite mineral nanoparticles (CP NPs), derived from natural and sustainable sources, as efficient, recyclable, and scalable adsorbents for the removal of organic dyes from aqueous solutions. The CP nanoparticles have been thoroughly characterized using spectroscopic and microscopic techniques to determine their size, shape, elemental composition, and the oxidation states of the constituent elements. Due to their high surface area, unique electronic properties, and structural stability, chalcopyrite nanoparticles demonstrate promising potential in capturing and eliminating various dye pollutants from water. The BET analysis of CP NPs reveals a high surface area of 4.5 m2 g−1 with mesoporous structures and varying pore sizes (1.57–112.58 nm). We explored adsorption efficiencies using methylene blue dye, concentrations, and environmental conditions, showing that CP NPs offer high dye removal rates and rapid adsorption kinetics. Under the optimized conditions, a maximum removal efficiency of 99% was achieved using a pH of 8, a contact time of 40 minutes, a dye concentration of 10 mg L−1, and an adsorbent dosage of 0.05 g/100 mL. The experimental data aligned most closely with the Freundlich isotherm model (R2 = 0.991), suggesting that the adsorption occurred on a non-uniform, multilayered surface. The mechanism of the adsorption was elaborated. This work highlights the natural-based nanoparticles' applicability as cost-effective and sustainable adsorbents for water purification, advancing solutions to manage industrial dye pollutants and improve water quality in environmental systems.

Chemically-synthesized Nanozymes that are widely used as alternatives to enzymes face challenges such as high precursor costs, complex preparation processes, and limited catalytic efficiency. To overcome these drawbacks, we introduce naturally derived nanozymes, nanomineralzymes, as a promising alternative, offering benefits like affordability, cost-effectiveness, and scalability. Chalcopyrite (CP, CuFeS2) was sourced from a mineral deposit, and CP nanoparticles were produced by milling. These nanoparticles exhibited strong peroxidase-like activity, achieving a low Michaelis-Menten constant using 3,3′,5,5′-tetramethylbenzidine as a substrate. Characterizations revealed the presence of cuprous, cupric, ferrous, and ferric ions in the CP mineral. The proposed mechanism involves an enhanced Fenton and Fenton-like process due to the metal ions' multi-valence states. CP nanozyme activity was inhibited to produce radicals due to hydrogen atom transfer and single electron transfer with ascorbic acid, glutathione and cysteine. The CP mineralzyme-based total antioxidant capacity probe was successfully used for detection of TAC in citrus fruits.

Antioxidants are vital components in various food, plant, and pharmacological products, making their quantitative, selective, and straightforward assessment essential for evaluating product quality and health benefits. Nanozymes, such as metal–organic frameworks (MOFs) with enzyme-like catalytic activity, hold significant potential for developing highly efficient antioxidant sensing platforms. This is due to their large specific surface area, low density, high porosity, structural diversity, and adjustable pore size. In this study, we synthesized a silver-based MOF exhibiting effective oxidase-like activity and modified it with molecularly imprinted polymer (MIP) using radical polymerization. The developed system (Ag-MOF@MIP) was successfully applied for the colorimetric detection of quercetin, achieving a limit of detection of 0.43 μM and a limit of quantification of 1 μM within a detection range of 1 to 132 μM. This combination exhibited improved selectivity and sensitivity towards quercetin and demonstrated high stability after one month of storage. This detection strategy can also be used to detect other analytes using TMB as a probe.

An efficient dual-state blue-emitting zinc-based metal–organic frameworks (MOFs), designated as UoZ-8 has been developed. Coordination-induced emission causes the UoZ-8 to give the blue emission in both solid and dispersed form in liquid. Upon the addition of tetracycline (TC), a noticeable shift from blue emission to greenish-yellow emission occurred, with a marked increase in intensity, which was attributed to the inner filter effect accompanied by aggregation-induced emission (IFE-AIE). Consequently, ratiometric-based fluorometry (in solution) and color tonality visual detection platform (on paper) were developed, exploiting the dual-state property of UoZ-8 alone and UoZ-8:TC. The detection limit using the ratiometric-based fluorescence method was 3.8 nM, while on paper it was 3.5 µM. Paper-based visual mode was used for the detection of TC in tap and river water samples showing satisfactory accuracy and precision.

This study presents a novel approach for the on-site quantitative visual detection probe of ferric ions (Fe3+) in real samples using a fluorescent zinc-based metal–organic frameworks (denoted as UoZ-8). The novel UoZ-8 produces strong blue emission at 390 nm when excited at 330 nm. The UoZ-8-based probe utilizes the unique fluorescent properties of MOFs when it quenches in the presence of Fe3+ ions via inner filter effect. By exploiting the high sensitivity and selectivity of these MOFs, the probe provides a simple, instrument-free, cost-effective, and reliable method for Fe3+ detection. On–Off mode was used for detection of Fe3+ ions using conventional fluorometry and smartphone assisted visual detection. By analyzing the blue intensity changes of blue channels with the assistance of smartphone, the quantitative detection was realized within the range of 10.0–125.0 µM with limit of detection 0.23 µM. Real water sample analyses validate the effectiveness of the probe in various matrices, showing its potential for environmental monitoring and industrial applications. The results highlight the ability of MOF to deliver accurate and rapid measurements, making it a valuable tool for on-site ferric ion detection.

Metal–organic frameworks (MOFs) have emerged as innovative nanozyme mimics, particularly in the area of oxidase catalysis, outperforming traditional MOF-based peroxidase and other nanomaterial-based oxidase systems. This review explores the various advantages that MOFs offer in terms of catalytic activity, low-cost, stability, and structural versatility. With a primary focus on their application in biochemical sensing, MOF-based oxidases have demonstrated remarkable utility, prompting a thorough exploration of their design and modification strategies. Moreover, the review aims to provide a comprehensive analysis of the strategies employed in the rational design and modification of MOF structures to optimize key parameters such as sensitivity, selectivity, and stability in the context of biochemical sensors. Through an exhaustive examination of recent research and developments, this article seeks to offer insights into the nuanced interplay between MOF structures and their catalytic performance, shedding light on the mechanisms that underpin their effectiveness as nanozyme mimics. Finally, this review addresses challenges and opportunities associated with MOF-based oxidase mimics, aiming to drive further advancements in MOF structure design and the development of highly effective biochemical sensors for diverse applications.

Repurposing expired drugs is highly significant as it prevents the accumulation of pharmaceutical wastes, optimizes resource usage, and reduces environmental harm. Metformin, used for type II diabetes, lowers blood sugar via decreasing liver glucose production and increasing muscle insulin sensitivity. However, the growing number of expired tablets annually necessitates a strategic approach for repurposing or reusing these tablets. Herein, we develop a simple hydrothermal approach for converting expired metformin to valuable fluorescent carbon quantum dots (m-CQDs) with sizes smaller than 10 nm. The m-CQDs displayed a blue emission at 420 nm when excited at 350 nm. Interestingly, when tetracycline (TC) was added, the blue emission diminished, and a greenish-yellow emission emerged at 530 nm. This emission tunning was the resulting of combination of inner filter effect and aggregation induced emission. Leveraging this dynamic emission tunning, we developed both ratiometric-based fluorescence and color tonality-based visual detection methods for detecting TC in pharmaceuticals and wastewater. More importantly, three assessment tools, ComplexMoGAPI, AGREE, and BAGI were used to evaluate the environmental sustainability of the proposed analytical method. The evaluation confirmed the sustainability of the method and the alignment with the greenness guidelines for analytical methods.

Red-emitting metal–organic frameworks (MOFs) are still mostly based on the use of lanthanides or functionalization with red fluorophores. However, production of transition-metal-based MOFs with red-emitting is scarce. This work reports on the synthesis of a novel dual-state red-emitting Zn-based MOF (denoted as UoZ-7) with the capability to detect target molecules in dual state, in solution, and as solid on paper. UoZ-7 gives strong red emission when excited in the solution and in the solid state with 365 nm ultraviolet (UV) lamp irradiation. Coordination-induced emission is the mechanism for the red emission enhancement in the MOF as a restriction of intramolecular rotation occurred to the ligand within the framework structure. UoZ-7 was successfully used for tetracycline (TC) using dual-mode detection, fluorescence-based ratiometry, and color tonality, in the dual state, in solution, and on the paper. TC molecules adsorb on the red-emitting UoZ-7 surface, and a yellow-greenish color emerges due to aggregation-induced emission between TC and UoZ-7. Concurrently, the inner filter effect diminishes the red emission of UoZ-7. The dual-mode or dual-state detection platform provides a simple and reliable fast method for the detection of TC on-site in various environmental and biomedical applications. Moreover, red-emitting UoZ-7 will have further luminescence-based biomedical applications.

The conventional notion is that enzymes, natural and nanozymes, exhibit peak activity solely within defined psychrophilic or thermophilic conditions. This work challenges the notion by preparing a highly efficient oxidase-mimic of Ag-based metal–organic frameworks (MOFs) (referred to as UoZ-3; UoZ stands for University of Zakho), which work effectively in a wide-range of temperatures. This breakthrough not only widens the working temperature range but also overcomes the instability problem of hydrogen peroxide which limited the use of peroxidase-based applications. UoZ-3 showed lower Michaelis–Menten constants compared to silver nanoparticles and silver ions. Surprisingly, the cold/hot adapted UoZ-3 nanozyme exhibited sensitivity to both hydrogen-atom transfer and single-electron transfer reactions with reducing agents, effectively encompassing all of the antioxidant species that are relevant in physiological contexts. Furthermore, the visual-based platform integrated with a smartphone was established and successfully applied for total antioxidant capacity detection in various temperatures in breast cancer patients. The cold/hot adapted oxidase-mimic nanozyme will open an avenue of nanozyme research and applications.

In the present work, intrinsic fluorescent zinc-based metal–organic framework (FMOF-5) was prepared and used for folic acid (FA) detection. The intrinsic emission of zinc-based MOFs without encapsulation and/or functionalization of the ligand and/or the MOF is not very common. Here, the intrinsic emission of FMOF-5 is triggered by the coordination-induced emission of weakly fluorescent organic ligand in the framework structure. FMOF-5 showed fluorescence emission at 440 nm when excited at 300 nm. Common characterization techniques were used to investigate the size, morphology, and optical properties of the FMOF-5. The fluorescence emission of the prepared MOF was quenched by the internal filter effect, which gives us an opportunity to design a novel on-off mode sensor for the detection of FA. The conventional fluorometric-based assay and the smartphone-assisted visual detection mode were developed and validated. The visual-mode linearity was from 30 to 270 µM with limit of detection about 4.3 µM. The on-off sensor was successfully applied for detection of FA in pharmaceutical formulations with excellent recovery and reproducibility. The visual on-off mode using intrinsic fluorescent MOFs is highly appealing for pint of care testing applications.

Nanozymes, synthetic nano-scale materials with enzyme-like behavior, have shown remarkable advancements and widespread utilization across various applications. However, the majority of nanozymes require precursor of synthetic-chemicals, which are sometimes expensive and undergo complicated preparations and tedious purification procedures. Therefore, it is of utmost significance to find an enzyme mimic that is affordable, abundant, highly efficient, and sustainable for various applications in biomedicine, environmental sciences, and the food industry. We prove the efficient peroxidase-like activities of the earthly available mineral, barunite-II. The braunite-II mineral micro-nanoparticles (NB) were prepared via physical milling. The enzyme mimetic activity of mineral nanoparticles, referred to as “mineralzyme,” could oxidize the chromogenic blue color of TMB (3,3′,5,5′-tetramethylbenzidine) to oxTMB (3,3′,5,5′-tetramethylbenzidine oxide). Michaelis-Menten constant (Km) and maximum velocity (Vmax) were 135 mM and 62.73 mM min−1 for TMB as a substrate, 139.2 mM, and 2.69 mM min−1 for H2O2 as a substrate. The Km values are much lower than those for HRP. We accurately quantified the total antioxidant capacity in seminal fluid samples from infertile patients using the peroxidase activity of the mineral nanoparticles. This investigation will open new avenues to explore the realm of mineralzyme, revealing its significant potential for a wide range of applications involving diverse enzymatic behaviors.

Integrating multiple functionalities into a single entity is highly important, especially when a broad spectrum of application is required. In the present work, we synthesized a novel manganese-based MOF (denoted as UoZ-6) that functions as a cold/hot-adapted and recyclable oxidase nanozyme (Km 0.085 mM) further developed for ratiometric-based colorimetric and color tonality visual-mode detection of nitrite in water and food. Nitrite ions promote the diazotization process of the oxTMB product, resulting in a decay in the absorbance signal at 652 nm and the emergence of a new signal at 461 nm. The dual-absorbance ratiometric platform for nitrite ion detection functions effectively across a wide temperature range (0 °C to 100 °C), offering a linear detection range of 5–45 μM with a detection limit of 0.15 μM using visual-mode. This approach is sensitive, reliable, and selective, making it effective for detecting nitrite ions in processed meat and water.

On-site, robust, and quantitative detection of diclofenac (DCF) is highly significant in bioanalysis and quality control. Fluorescence-based metal–organic frameworks (MOFs) play a pivotal role in biochemical sensing, offering a versatile platform for detecting various biomolecules. However, conventional fluorescent MOF sensors often rely on lanthanide metals, which can pose challenges in terms of cost, accessibility, and environmental impact. Herein, an intrinsic blue fluorescent zinc-based metal–organic framework (FMOF-5) was prepared free from lanthanide metals. Coordination-induced emission as an effective strategy was followed wherein a non-fluorescent ligand is converted to a fluorescent one after insertion in a framework. Conventional fluorometry and smartphone-assisted visual methods were employed for the detection of DCF. The fluorescence emission of the FMOF-5 was effectively quenched upon the addition of the DCF, endowing it an “off” condition, which permits the construction of a calibration curve with a wide linear range of 30 – 670 µM and a detection limit of about 4.1 µM. Other analytical figures of merit, such as linearity, sensitivity, selectivity, accuracy, and precision were studied and calculated. Furthermore, the proposed sensor was successfully applied to quantify DCF in pharmaceutical tablets with reliable recovery and precision. Importantly, the elimination of lanthanide metals from the fluorescence detection system enhances its practicality and sustainability, making it a promising alternative for DCF detection in pharmaceutical analysis applications.

Metal-organic frameworks (MOFs) are crystalline materials whose synthesis depends on the association between organic linkers and metal ions and/or metal clusters. MOFs have unique properties, including impressive porosity and easy modification of their surface structure. Owing to these distinctive characteristics, MOFs are extensively used in sensing and extraction applications. Polyphenolic molecules, which have distinct and potent antioxidant properties, can operate as efficient radical scavengers, reducing their harmful effects on the body. This explains the growing interest in polyphenolic compounds of natural origin and the need for sensitive analytical methods to determine these antioxidants in cosmetics, dyes, pesticides, food, beverages, and pharmaceutical matrices. In this review, the synthesis and characterization of MOFs for the application in chemical sensing and the analysis of polyphenolic antioxidants in different matrices are discussed in more details. Challenges and limitations associated with the use of MOFs for chemical sensing and the analysis of polyphenolic antioxidants such as sensitivity, selectivity, sample preparation, and scalability are discussed as well.

Three phenomena, namely coordination-induced emission (CIE), aggregation-induced emission (AIE), and inner filter effect (IFE), were incorporated into the design of a ratiometric and color tonality-based biosensor. Blue fluorescent Al-based metal–organic frameworks (FMIL-96) were prepared from non-emissive ligand and aluminum ions via CIE. Interestingly, the addition of tetracycline (TC) led to ratiometric detection and color tonality, as the blue emission at 380 nm was quenched (when excited at 350 nm) due to IFE, while the green-yellowish emission at 525 nm was enhanced due to AIE. Based on that, an ultra-sensitive visual-based color tonality mode with smartphone assistance was developed for detection of TC. The sensor exhibited a linear relationship within a broad range of 2.0 to 85.0 μM TC with a detection limit of 68.0 nM. TC in milk samples was quantified with high accuracy and precision. This integration of smartphone and visual fluorescence in solution is accurate, reliable, cost-effective, and time-saving, providing an alternative strategy for the semi-quantitative determination of TC on-site.

The growth and spread of multidrug-resistant bacterial species, such as Klebsiella pneumoniae, pose a serious threat to human health and require the development of innovative antibacterial agents. The search for an acceptable, safe, and efficient antibacterial is a matter of significant concern. In the present work, silver-based metal–organic frameworks (Ag-MOFs) showed efficient antibacterial activity against multidrug-resistant K. pneumoniae (KBP 11) with a minimum inhibitory concentration and minimum bactericidal concentration of 10 μg mL−1. Moreover, the Ag-MOF showed enhanced antibacterial activity compared to silver ions and silver nanoparticles. Our experimental investigation showed that the antibacterial efficacy is attributed to the production of reactive oxygen species and the release of cellular constituents, such as K+ ions and proteins. The MOF scaffold enhances the stability and controlled release of silver ions, enabling sustained antibacterial activity and minimizing the risk of bacterial resistance development. Additionally, the MOF class, due to the high surface area and porous nature, enhances the transfer of bacteria into and on the surface of the MOF.

Bimetallic-metal organic frameworks (BiM-MOFs) or bimetallic organic frameworks represent an innovative and promising class of porous materials, distinguished from traditional monometallic MOFs by their incorporation of two metal ions alongside organic linkers. BiM-MOFs, with their unique crystal structure, physicochemical properties, and composition, demonstrate distinct advantages in the realm of biochemical sensing applications, displaying improvements in optical properties, stability, selectivity, and sensitivity. This comprehensive review explores into recent advancements in leveraging BiM-MOFs for fluorescence-based biochemical sensing, providing insights into their design, synthesis, and practical applications in both chemical and biological sensing. Emphasizing fluorescence emission as a transduction mechanism, the review aims to guide researchers in maximizing the potential of BiM-MOFs across a broader spectrum of investigations. Furthermore, it explores prospective research directions and addresses challenges, offering valuable perspectives on the evolving landscape of fluorescence-based probes rooted in BiM-MOFs.

The construction of a highly luminescent, stable, and target-insensitive internal reference signal is highly significant in ratiometric and color tonality applications. Improvement of the antenna effect, the efficient mechanism that enhances luminescence emission via sensitization, is an effective route to obtain bright luminescence. Additionally, manipulation of the crystal structure and morphology is the key issue to control the reactivity, especially in metal–organic frameworks (MOFs). In the present work, a novel internal reference red emitter of Eu/Zn bimetal biligand MOF (UoZ-5) was synthesized and used as an internal reference signal. A dual-antenna effect, from triplet states (T1) of the ligands to 5Do of the Eu3+ ion, was observed and explained on the basis of the energy levels. With UoZ-5 serving as the internal reference, blue-emitting carbon quantum dots (CQDs) selective for Ag+ ions and a nonfluorescent composite, CQDs@Ag+, serving as a selective probe for vitamin B1, a color tonality-based platform and ratiometric analysis were developed.

The regular and on-site monitoring of ions in drinking water is essential for safeguarding public health, ensuring high water quality, and preserving the ecological balance of aquatic ecosystems. Thus, developing a portable analytical device for the rapid, cost-effective, and visual on-site detection of multiple environmental pollutants is notably significant. In the present work, a novel ratiometric microfluidic paper-based analytical device (μPAD) was designed and developed for the simultaneous detection of Fe3+ and Cu2+ ions in water samples taking advantages from built-in masking zone. The μPAD was functionalized with a greenish-yellow fluorescent Zn-based metal–organic framework@tetracycline (FMOF-5@TC) nanocomposite, and the ratiometric design was based on the change in emission color from greenish yellow (FMOF-5@TC) to blue (FMOF-5). The μPAD consisted of one sample zone linked to two detection zones via two channels: the first channel was for the detection of both ions, while the second was intended for detecting only Cu2+ ions and comprised a built-in masking zone to remove Fe3+ ions prior to reaching the detection zone. The corresponding color changes were recorded with the aid of a smartphone and RGB calculations. The linear ranges were 0.1–80 μM for Cu2+ and 0.2–160 μM for Fe3+, with limits of detection of 0.027 and 0.019 μM, respectively. The simple μPAD design enabled the simultaneous detection of Cu2+ and Fe3+ ions in drinking water samples with excellent accuracy and precision, with spike recoveries of 81.28–96.36% and 83.01–102.33% for Cu2+ and Fe3+, respectively.

Current nanozyme applications rely heavily on peroxidase-like nanozymes and are limited to a specific temperature range, despite notable advancements in nanozyme development. In this work, we designed novel Mn-based metal organic frameworks (UoZ-4), with excellent oxidase mimic activity towards common substrates. UoZ-4 showed excellent oxidase-like activity (with Km 0.072 mM) in a wide range of temperature, from 10 °C to 100 °C with almost no activity loss, making it a very strong candidate for psychrophilic and thermophilic applications. Ascorbic acid, cysteine, and glutathione could quench the appearance of the blue color of oxTMB, led us to design a visual-based sensing platform for detection of total antioxidant capacity (TAC) in cold, mild and hot conditions. The visual mode successfully assessed TAC in citrus fruits with satisfactory recovery and precisions. Cold/hot adapted and magnetic property will broaden the horizon of nanozyme applications and breaks the notion of the temperature limitation of enzymes.

Synthesis of dual-state dual emitting metal–organic frameworks (DSDE-MOFs) is uncommon and challenging. Additionally, DSDE-MOFs can fulfil the expanding need for on-site detection due to their stability and self-reference for a variety of non-analyte variables. In the present work, a novel intrinsic DSDE of chemically engineered bi-ligand Eu-based MOF (UoZ-1) was designed. The prepared UoZ-1 spherical particles were small-sized around 10–12 nm and displayed blue (425 nm) and red fluorescence (620 nm) at both states, dispersed in liquid and in solid state, when excited at 250 nm. A ratiometry platform was developed since the red emission was quenched by the addition of folic acid and the blue emission was almost remained unaffected. In the fluorometric ratiometric-mode, a dynamic linear range was recorded from 10 to 200 µM with LOD about 0.4 µM. Visual-based detection with assistance of smartphone was developed for quantification based on RGB analysis using Color Grab App. In the visual-mode, LOD as small as 2.3 µM was recorded. By utilizing the intrinsic dual-emitting UoZ-1, highly stable, recyclable, sensitive, and selective on-site visual detection of folic acid can be achieved. UoZ-1, a DSDE-MOF with no encapsulation or functionalization requirements, exhibits great potential for diverse applications.

Dual-state emitters (DSEs) are entities that exhibit fluorescence in both the solution and solid state, which open up a wide range of possibilities for their utilization in various fields. The development of detection platforms using intrinsic luminescent metal–organic frameworks (LMOFs) is highly desirable for a variety of applications. DSE MOFs as a subclass of intrinsic LMOFs are highly attractive due to no need for encapsulation/functionalization by fluorophores and/or using luminescent linkers. Herein, a highly stable intrinsic dual-state blue emission (λem = 425 nm) zinc-based MOF with rodlike nanostructures (denoted as UoZ-2) was synthesized and characterized. To the best of our knowledge, intrinsic DSE of Zn-MOFs with blue emission in the dispersed form in solution and solid-state fluorescence have not been reported yet. When tetracycline (TC) was added, a continuous color evolution from blue to greenish-yellow with dramatic enhancement was observed due to aggregation induced emission (AIE). Thus, a sensitive ratiometry-based visual detection platform, in solution and on paper independently, was designed for detection of TC exploiting the DSE and AIE properties of UoZ-2 alone and UoZ-2:TC. The detection limit was estimated to be 4.5 nM, which is considered to be one of the most sensitive ratiometric fluorescent probes for TC sensing. The ratiometry paper-based UoZ-2 sensor displays a reliable TC quantitative analysis by recognizing RGB values in the on-site TC detection with satisfactory recoveries.

Color tonality by intrinsic fluorescent metal-organic frameworks (MOFs) is highly desirable in bioanalytical applications due to its stability, low-cost and robustness with no need for functionalization and/or encapsulation of fluorophores. In the present work, ultra-small and higly fluorescent zinc-based MOFs (FMOF-5) were synthesized. The prepared FMOFs were around 5 nm in size, and gave strong blue emission at 440 nm when excited at 350 nm. Interestingly, tetracycline (TC) selectively tuned the blue emission of FMOF-5 to greenish-yellow emission (520 nm) with dramatic enhancement through aggregation induced emission (AIE). The fluorimetric analysis of TC was carried out through the ratiometric peak intensities of F520/F440, with detection limit (LOD) of 5 nM. To realize quantitative point-of-care based on color tonality, a smartphone integrated with the ratiometric visual platform was thereby design. Hence, TC was visually detected with LOD of 10 nM. The prepared FMOF-5-based probe showed high stability (3 months) and reusability (∼10 times). The developed visual-based platform presents great promise for practical point of care testing due to its low-cost, robustness, ruggedness, simple operation, and excellent selectivity and repeatability.

Multicolor visual sensing approach significantly improves accuracy, reproducibility and detection rate of targets. Herein, a novel red emitter bi-ligand Eu-based metal organic framework (BiL-Eu-MOF) was successfully synthesized using a one step solvothermal method and was evaluated as a reference signal for multicolor visual-based ratiometry detection. The synergistic effects offered by the double ligand and Eu significantly showed red shift excitation towards many cations and anions and fluorescence stability at least for 6 months. As a fluorescent multicolor-visual probe, selective blue emitter carbon dots to Ag+ ions were encapsulated into the pores of the red emissive of BiL-Eu-MOF to form blue-purple color. Addition of Ag+ ions changed emission color from blue-purple to red, while addition of cysteine (Cys) restored the original blue-purple color. Employing RGB analysis using smartphone, the detection mode showed good linearity of Ag+ and Cys in the range of 0–660 and 0–405 μM with limit of detection of 2.1 and 0.15 μM, respectively. Ultimately, our probe was applied for the quantification of silver ions in water samples and Cys in human serum samples showing excellent accuracy and precision.