The convenient and reliable detection of glutathione is beneficial to the human body. The colorimetric detection method based on nanozyme is accurate and easy to operate. However, there are still ...problems with the improvement in the activity and stability of nanozyme, as well as the rational construction of colorimetric platform. Herein, daptomycin templated PdPt3 nanoparticles (PdPt3-Dap NPs) were prepared with a size of 2.46±0.11 nm. PdPt3-Dap NPs were demonstrated to possess peroxidase-like and oxidase-like activities and the dual-enzymatic activities were improved through the regulation of Pd and Pt ratio. Besides, the unique amphipathic structure of Dap conferred the stability to PdPt3-Dap NPs in detection applications. The peroxidase-like mechanism of PdPt3-Dap NPs was to catalyze the generation of •OH from H2O2. The oxidase-like mechanism was to catalyze the generation of superoxide anions(•O2-) and singlet oxygen(1O2) from dissolved oxygen. Because oxidase activity reduces interference from additional hydrogen peroxide, a colorimetric detecting method for glutathione was established based on the oxidase-like activity of PdPt3-Dap NPs. The linear range of the proposed detecting method for glutathione was 0–400 μM and the low limit of detection was 2.56 μM. The detecting method had been successfully applied in detecting glutathione in food samples with a recovery range between 92.20 % and 107.27 %. which showed a good prospect for detecting glutathione in practical applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The pathogenic bacteria induced foodborne disease has been detrimental to public health worldwide. Herein, the peroxidase (POD)-like Fe3O4/MWCNTs@Mo-CDs (FMMC) nanozyme was applied for the detection ...of Escherichia coli (E. coli). The E. coli aptamer was conjugated with the surface of the FMMC, which effectively enhanced the POD-like activity attributing to the higher affinity to the substrate, and then specific capture of E. coli in food matrices, leading to the reduction of POD-like activity. Therefore, a robust and facile colorimetric aptasensor was developed for detecting E. coli with a wide linear range of 101–106 CFU/mL, low LOQ of 101 CFU/mL and LOD of 0.978 CFU/mL. The aptasensor demonstrated the satisfied selectivity for E. coli compared to the other strains. This method possessed the potential application for fast in situ screening of foodborne pathogens in food products.
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•Fe3O4/MWCNTs@Mo-CDs nanozyme was facilely synthesized via hydrothermal method.•The POD-like activity of Fe3O4/MWCNTs@Mo-CDs was enhanced combined with aptamer.•The colorimetric biosensor was developed for E. coli detection.•The method has successfully detected E. coli in real food matrix.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Changes in recognition of sensor TQB for Ag+ can be observed with the naked eye in ambient or ultraviolet light.•The detection limit of sensor TQB is 0.65 μM to Ag+.•Sensor TQB can ...be applied for recognition of Ag+ in test strips.
In this study, a novel, highly sensitive fluorescent sensor (E)-2-((2-(benzod thiazol-2-yl) quinolin-8-yl) oxy)-N’-(4-(5, 5-difluoro-1, 3, 7, 9-tetramethyl-5H-4λ4, 5λ4-dipyrrolo 1, 2-c:2’, 1’-f 1, 3, 2 diazaborinin-10-yl) benzylidene) acetohydrazide (TQB) was developed for dual mode of Ag+ detection (colorimetric/fluorescence), and its structural and spectral properties were characterized by 1H NMR, ESI-MS, X-ray, ultraviolet and fluorescence photometry. It is found that TQB could specifically and efficiently identify Ag+ among many other metal ions in CH3OH/H2O (7:3 v/v, pH = 7.23) buffer. The maximum absorption wavelength of TQB is red-shifted while its fluorescence is quenched with a quenching rate of 88.7%. The energy difference between TQB and TQB-Ag+ complex was calculated by DFT, and the applicability of TQB was verified by paper strip test. In addition, TQB has been successfully applied to the determination of Ag+ in real water samples with good reversibility and recoveries.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Colorimetric techniques have been developed and used in routine analyses for over a century and apparently all their potentialities have been exhaustively explored. However, colorimetric techniques ...have gained high visibility in the last two decades mainly because of the development of the miniaturization concept, for example, paper-based analytical devices that mostly employ colorimetric reactions, and by the advances and popularity of image capture instruments. The impressive increase in the use of these devices was followed by the development and enhancement of different modes of color detection to meet the demands of making qualitative, semi-quantitative, and fully quantitative analyses of multiple analytes. Cameras, scanners, and smartphones are now being used for this purpose and have become suitable alternatives for different approaches to colorimetric analysis; this, in addition to advancements in miniaturized devices. On the other hand, recent developments in optoelectronics technologies have launched more powerful, more stable and cheaper light-emitting diodes (LEDs), which once again have become an interesting tool for the design of portable and miniaturized devices based on colored reactions. Here, we present a critical review of recent developments and challenges of colorimetric detection in modern analytical chemistry in the last five years, and present thoughts and insights towards future perspectives in the area to improve the use of colorimetric detection in different application approaches.
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•We review the contributions of colorimetric detection in analytical chemistry over the past 5 years.•The use of light-emitting diodes in colorimetric detectors.•The contribution of computer vision to colorimetric analysis.•The use of different colorimetric detection modes in distinct analytical devices are highlighted.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Smartphones' ubiquitous distribution and international connectivity is changing the concept of mobile health.•Smartphones are exploited as both portable detectors and instrumental ...interfaces.•Smartphone-based devices have great potential as point-of-care platforms for healthcare, food safety, environmental monitoring, and biosecurity.
The ubiquitous distribution and international connectivity of smartphones is changing the concept of mobile health and promising to reshape the biosensor market. Smartphone-based biosensors have been explored using different approaches, either using the smartphone as detector or as instrumental interface. Smartphone-based biosensors have great potential as point-of-care and point-of-need platforms for healthcare, food safety, environmental monitoring, and biosecurity, especially in remote and rural areas. Here, we critically review the most recent papers on the use of smartphones as analytical devices and biosensors. We focus on analytical performance and on prospects for commercialization.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•The frustule sourced from Nitzschia sp of a sediment sample was used as catalytic support.•Diatom frustule-supported Fe3O4 NPs show enhanced and robust oxidoreductase ...activity.•Direct colorimetric detection of Cr(VI) without the H2O2 is achieved.•Selective colorimetric detection Cr(VI) down to 0.21 µM is achieved .
Given Cr(VI) is a ubiquitous water pollutant posing significant public health risks, there is a need for an inexpensive and easy-to-use detection tool. Herein, a diatom frustule-supported Fe3O4 (DF-Fe3O4) with enhanced oxidoreductase mimetic activity is reported for direct colorimetric detection of Cr(VI). Unlike the peroxidase nanozymes which are often reported for colorimetric detection, DF-Fe3O4 triggered a chromogenic redox reaction between TMB and Cr(VI) without requiring H2O2. This enables direct redox reactions while circumventing potential interferences associated with the use of H2O2. DF-Fe3O4 was synthesized with a coprecipitation method and subsequently characterized by SEM, XRD, and XPS techniques, revealing the distribution of Fe3O4 NPs on the frustule matrix. The frustule obtained from Nitzschia sp. of a sediment sample rendered a robust catalytic support enhancing the oxidoreductase activity of pristine Fe3O4 NPs by 20.8 %. Further, the nanozyme maintains 73 % of its activity even at 95 °C while losing only 33 % of its activity after one month of storage. The oxidoreductase mimetic activity was evaluated using the chromogenic redox reaction between TMB and Cr(VI) which rapidly forms a blue color (λmax= 654 nm), where its intensity forms the basis of the colorimetric detection. With a Km value of 0.058 mM, the nanozyme was able to selectively detect Cr(VI) down to 0.21 µM with a linear range between 0.1–500 µM. Recoveries from spiked wastewater samples were between 91.14–102.20 %. The obtained analytical figures of merits demonstrated the applicability of the developed sensor for Cr (VI) analysis devoid of complex instrumentation in the established analytical methods.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Detection of heavy metal ions has drawn significant attention in environmental and food area due to their threats to the human health and ecosystem. Colorimetry is one of the most frequently-used ...methods for the detection of heavy metal ions owing to its simplicity, easy operation and rapid on-site detection. The development of chromogenic materials and their sensing mechanisms are the key research direction in the area of colorimetric method. Since each chromogenic material has their unique optical and chemical properties, they have totally different colorimetric sensing mechanisms. This review focuses on the chromogenic materials and their sensing strategies for the colorimetric detection of heavy metal ions. We divide the chromogenic materials into three types, including organic materials, inorganic materials, and other materials. As for each type of chromogenic material, we discuss their detailed sensing strategies, sensing performance, and real sample applications. Moreover, current challenges and perspectives related to the colorimetry of heavy metal ions are also discussed in this review. The aim of this review is to help readers to better understand the principles of colorimetric methods for heavy metal ions and push the development of rapid detection of heavy metal ions.
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•Different chromogenic materials for the colorimetric detection of heavy metal ions.•Detailed sensing strategies and applications for each chromogenic material.•Current challenges and perspectives related to the colorimetry of heavy metal ions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, novel biogenic silver (AgNPs) and gold nanoparticles (AuNPs) were developed using a green approach with Ganoderma lucidum (GL) extract. The optimization of synthesis conditions for the ...best outcomes was conducted. The prepared materials were characterized and their applicability in catalysis, antibacterial and chemical sensing was comprehensively evaluated. The GL-AgNPs crystals were formed in a spherical shape with an average diameter of 50 nm, while GL-AuNPs exhibited multi-shaped structures with sizes ranging from 15 to 40 nm. As a catalyst, the synthesized nanoparticles showed excellent catalytic activity (>98% in 9 min) and reusability (>95% after five recycles) in converting 4-nitrophenol to 4-aminophenol. As an antimicrobial agent, GL-AuNPs were low effective in inhibiting the growth of bacteria, while GL-AgNPs expressed strong antibacterial activity against all the tested strains. The highest growth inhibition activity of GL-AgNPs was observed against B. subtilis (14.58 ± 0.35 mm), followed by B. cereus (13.8 ± 0.52 mm), P. aeruginosa (12.38 ± 0.64 mm), E. coli (11.3 ± 0.72 mm), and S. aureus (10.41 ± 0.31 mm). Besides, GL-AgNPs also demonstrated high selectivity and sensitivity in the colorimetric detection of Fe3+ in aqueous solution with a detection limit of 1.85 nM. Due to the suitable thickness of the protective organic layer and the appropriate particle size, GL-AgNPs validated the triple role as a high-performance catalyst, antimicrobial agent, and nanosensor for environmental monitoring and remediation.
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•Biogenic AgNPs and AuNPs were prepared using Ganoderma lucidum extract.•Both MNPs possessed excellent catalytic activity for the reduction of 4-nitrophenol.•AgNPs showed strong antibacterial activity against several bacterial strains.•The AgNPs-based probe can accurately determine Fe3+ in water with LOD of 1.85 nM.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Tetracycline antibiotics (TCs) are one kind of broad spectrum bacteriostatic agents. However, excessive use of TCs will have a threat to the environment and human health. Therefore, it is necessary ...to develop a simple method for direct detection of TCs. Based on intrinsic peroxidase-like activity of gold nanoclusters (AuNCs), we used TC-specific aptamers (Apt) to improve the catalytic activity of AuNCs toward the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation by H2O2, and established a colorimetric sensing platform for TCs. The catalytic enhancement by Apt allows for sensitive colorimetric detection of TCs, and Apt as molecular recognition elements can specifically combine with TCs leading to high selectivity. This developed sensing platform can quantitatively detect TCs in the concentration range of 1–16 μM with a limit of detection (LOD) as low as 46 nM. Interestingly, the naked-eye detection capability of this method is estimated to be 0.5 μM. Finally, the detection of TCs in real samples like drugs and milk was validated.
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•A gold nanoclusters-based colorimetric aptasensor for tetracycline was presented.•Specificity and sensitivity of gold nanoclusters were greatly improved by aptamer.•The aptamer-enhanced peroxidase-like activity of gold nanoclusters was validated.•The sensor can accurately and reproducibly detect tetracycline in drugs and milk.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Manganese (Mn) is a versatile transition element with diverse oxidation states and significant biological importance. Mn-based nanozymes have emerged as promising catalysts in various applications. ...However, the direct use of manganese oxides as oxidase mimics remains limited and requires further improvement. In this study, we focus on hydroxylated manganese (MnOOH), specifically the layered form β-MnOOH which exhibits unique electronic and structural characteristics. The two-dimensional β-MnOOH nanosheets were synthesized through a hydrothermal approach and showed remarkable oxidase-like activity. These nanosheets effectively converted the oxidase substrate, 3,3′,5,5′-tetramethylbenzidine (TMB), into its oxidized form by initiating the conversion of dissolved oxygen into ·O2−, 1O2 and ·OH. However, in the presence of L-cysteine (L-Cys), the catalytic activity of β-MnOOH was significantly inhibited, enabling highly sensitive detection of L-Cys. This sensing strategy was successfully applied for smartphone-based L-Cys assay, offering potential utility in the diagnosis of Cys-related diseases. The exploration of layered β-MnOOH nanosheets as highly active oxidase mimics opens up new possibilities for catalytic and biomedical applications.
•Two-dimensional β-MnOOH hexagonal nanosheets are synthesized in a controlled way.•The β-MnOOH have high oxidase-like activity and affinity for catalytic substrate.•L-cysteine can effectively inhibit the oxidase-mimetic activity of β-MnOOH.•Spectrophotometer or smartphone as a colorimetric signal readout for L-cysteine.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
