Search

[Display omitted] • A novel competitive strategy using oxidase nanozyme for glucose detection was proposed. • The strategy shows high detection efficiency with convenience, rapidness, sensitivity all promised. • The strategy can be applied into human serums with good accuracy. Nanozyme-based sensing strategy for glucose generally involves a two-step H 2 O 2 -bridged cascade reaction. However, this two-step cascade reaction always shows a limited detection efficiency for glucose, which hardly makes simply operation, rapid detection, and sensitivity all promised. Herein, a novel strategy for one-step glucose detection was proposed based on the efficiently competitive relationship between glucose oxidase catalyzed glucose oxidation and oxidase nanozyme catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB) colorimetric oxidation. As a proof of concept, Co-Nx sites on porous carbon (Co-Nx/PC) derived from ZIF-67 was selected as the oxidase nanozyme with O 2 -sensitive nature, which can activate O 2 to produce 1O 2 for TMB colorimetric oxidation. In the presence of glucose, the competitive reaction of glucose oxidase catalyzed glucose oxidation occurs, which will obviously inhibit the Co-Nx/PC catalyzed TMB colorimetric oxidation to construct method for glucose detection. The usage of the same reactant O 2 and the production of suppressive H 2 O 2 cause a dual effect to this inhibition. In addition, the available pH range of Co-Nx/PC overlaps with that of glucose oxidase, promising a one pot reaction. The proposed method with Co-Nx/PC as oxidase nanozyme based on one-step competitive strategy for glucose detection possesses high detection efficiency with convenience (one-pot), rapidness (total reaction time of 10 min) and sensitivity (LOD of 0.31 μM) all promised, which is superior among the methods based on two-step one-pot or two-pot cascade strategy. The strategy can be successfully applied into the blood glucose detection in human serums with satisfactory results. Also, the strategy can be scalable to other oxidase nanozyme like Mn 3 O 4. [ABSTRACT FROM AUTHOR]

Fe-MIM/ZIF-8 with rich biomimetic iron-imidazole groups was prepared and investigated as superior peroxidase mimic for colorimetric analysis of H 2 O 2 and glucose. [Display omitted] • Biomimetic Fe-MIM/ZIF-8 nanoflower was fabricated and firstly explored as nanozyme. • Fe-MIM/ZIF-8 with rich biomimetic Fe-MIM exhibits superior peroxidase-like activity. • Fe-MIM/ZIF-8 owns a strong affinity for H 2 O 2 with a low K m of 0.028 mM. • The colorimetric biosensor for H 2 O 2 and glucose promises high sensitivity. • The biosensor can detect glucose content in biological samples with high accuracy. The active site of natural horseradish peroxidase (HRP) comprises iron coordinated equatorially by a porphyrin ring and axially by the imidazole group of His170. The low water solubility of porphyrin rings inspired us to investigate the potential of the iron-imidazole group as peroxidase mimic. Herein, iron-imidazole (Fe-MIM) was one-pot constructed using ascorbic acid stabilized Fe2+ and 2-methylimidazole in the presence of zinc acetate at room temperature in aqueous medium, along with the formation of ZIF-8 framework around Fe-MIM sites. Fe-MIM/ZIF-8 was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller surface measurements. Fe-MIM/ZIF-8 exhibits high peroxidase-like activity, efficiently catalyzing the redox reaction between H 2 O 2 and 3, 3′, 5, 5′-tetramethylbenzidine, as made evident by the appearance of a UV–Vis signal at 652 nm. Fe-MIM/ZIF-8 displays higher catalytic activity than the material (Fe + MIM) prepared by ascorbic acid stabilized Fe2+ and MIM, due to its rich biomimetic architecture and large BET surface area. The K m of Fe-MIM/ZIF-8 for H 2 O 2 was 28 μM, which is 132 and 98 times lower than those of HRP and hemin (ironIII porphyrin), respectively. This low K m value indicates the strong affinity of Fe-MIM/ZIF-8 for H 2 O 2 , which proves the superiority of biomimetic Fe-MIM sites and suggests Fe-MIM/ZIF-8′s potential for H 2 O 2 -related biosensing. The highly sensitive colorimetric methods for H 2 O 2 and H 2 O 2 -related glucose detection has been proposed. The applicability of this method to glucose detection in serum samples was tested with satisfactory results. [ABSTRACT FROM AUTHOR]

Lanthanum-modified mesoporous graphite nitride carbon composites (La-g-C3N4) were synthesized using a thermal shrinkage polymerization method. The samples underwent characterization through X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmet–Teller (BET) analysis. The results revealed that the La30-g-C3N4 sample displayed a more porous layered morphology with a uniform pore structure. The BET surface area of the sample was found to be 38.6 m2 g−1, which is 5.8 times higher than that of the undoped sample g-C3N4. The sample exhibited a type IV isotherm, indicating its mesoporous nature with a pore size distribution ranging from 3 to 20 nm. The application of these materials was investigated for the degradation of tetracycline (TC) and acidic fuchsin (AF) in simulated wastewater. The results demonstrated that the La30-g-C3N4 sample exhibited rapid and efficient degradation, along with excellent adsorption capacity for both TC and AF. Within 5 minutes, the degradation efficiency of the La30-g-C3N4 sample for TC and AF was measured to be 83.1% and 74.1%, respectively, with corresponding adsorption capacities of 63.9 mg g−1 and 129.4 mg g−1. The kinetic and thermodynamic analysis of the adsorption process revealed that the adsorption of TC and AF by La30-g-C3N4 followed the quasi-second-order kinetics and Langmuir adsorption isotherm model, indicating a predominantly single-layer chemical adsorption process. Furthermore, the composite material exhibited good cycling stability and maintained excellent adsorption performance even after six repeated uses. [ABSTRACT FROM AUTHOR]

Nowadays, bacterial infections are attracting great attention for the research and development of new antimicrobial agents. As one of the quinolones, ciprofloxacin (CI) has a broad-spectrum, strong antibacterial effect. However, the clinical use of ciprofloxacin is limited by drug resistance. Ciprofloxacin carbon dots (CCDs) with enhanced antibacterial activity and copper-doped ciprofloxacin carbon dots (Cu-CCDs) were synthesized by a simple hydrothermal method. The results of structural analysis and antibacterial experiments show that CCDs and Cu-CCDs have effective antibacterial properties by retaining the active groups of ciprofloxacin (-COOH, C-N, and C-F), and Cu-CCDs doped with copper have a better antibacterial effect. In addition, experiments have shown that Cu-CCDs show excellent antibacterial activity against E. coli and S. aureus and have good biocompatibility, which indicates that they have great prospects in clinical applications. Therefore, novel modified copper CCDs with broad-spectrum antibacterial activity, which can be used as antibacterial nanomaterials for potential applications in the field of antibacterial drugs, were synthesized in this study. [ABSTRACT FROM AUTHOR]

Exosomes derived from cancer cells have been recognized as a promising biomarker for minimally invasive liquid biopsy. Herein, a novel sandwich-type biosensor was fabricated for highly sensitive detection of exosomes. Amino-functionalized Fe3O4 nanoparticles were synthesized as a sensing interface with a large surface area and rapid enrichment capacity, while two-dimensional MXene nanosheets were used as signal amplifiers with excellent electrical properties. Specifically, CD63 aptamer attached Fe3O4 nanoprobes capture the target exosomes. MXene nanosheets modified with epithelial cell adhesion molecule (EpCAM) aptamer were tethered on the electrode surface to enhance the quantification of exosomes captured with the detection of remaining protein sites. With such a design, the proposed biosensor showed a wide linear range from 102 particles μL−1 to 107 particles μL−1 for sensing 4T1 exosomes, with a low detection limit of 43 particles μL−1. In addition, this sensing platform can determine four different tumor cell types (4T1, Hela, HepG2, and A549) using surface proteins corresponding to aptamers 1 and 2 (CD63 and EpCAM) and showcases good specificity in serum samples. These preliminary results demonstrate the feasibility of establishing a sensitive, accurate, and inexpensive electrochemical sensor for detecting exosome concentrations and species. Moreover, they provide a significant reference for exosome applications in clinical settings, such as liquid biopsy and early cancer diagnosis. [ABSTRACT FROM AUTHOR]

Room-temperature phosphorescent (RTP) carbon dots (CDs) have promising applications in bioimaging, anticounterfeiting, and information encryption owing to their long lifetimes and wide Stokes shifts. Numerous researchers are interested in developing highly bright RTP CDs using environmentally friendly and safe synthesis processes (e.g., natural raw materials and zero-pollution production pathways). In this study, we successfully synthesized RTP CDs using a hydrothermal process employing natural vitamins as a raw material, ethylenediamine as a passivator, and boric acid as a phosphorescent enhancer, which is referred to as phosphorescent CD (PCD). The PCDs exhibit both bright blue fluorescence emission and green RTP emission, with a phosphorescence lifetime as long as 293 ms and an excellent green afterglow visible to the naked eye for up to 7.0 s. The total quantum yield is 12.69%. The phosphorescence quantum yield (PQY) is up to 5.15%. Based on the RTP performance, PCDs have been successfully employed for anticounterfeiting and information protection applications. The results of this study provide a green strategy for the scalable synthesis of RTP materials, which is a practical method for the fabrication of RTP materials with high efficiency and long afterglow lifetimes. [ABSTRACT FROM AUTHOR]

Copper nanoclusters (Cu NCs) have attracted a surge of interest in fluorescent sensors as their outstanding physicochemical and optical properties. However, most of the reports have focused on single-signal fluorescent sensors, which are susceptible to background interferences and affect accuracy of the results. Herein, we constructed a facile ratiometric fluorescent sensor for monitoring ethanol based on Cu NCs with tunable dual emission. Polyvinylpyrrolidone (PVP)-modified Cu NCs were simply prepared in water, which exhibit ratiometric dual emission, including a strong green emission at 520 nm and a weak blue emission at 450 nm. The PVP-Cu NCs in water with strong green emission display monodisperse state due to the formation of hydration shell around Cu NCs. In ethanol where the hydration shell is destructed, Cu NCs tend to aggregate and show strong blue emission. This emission shift might attribute to the enhancement of Cu–Cu metallophilic interaction with the aggregation of Cu NCs, which induces the excited-state level increasing. Thus, a ratiometric fluorescent probe for ethanol based on the PVP-Cu NCs is fabricated, which possesses rapid response (<1 min), and realize full-range detection from 0 to 100%. In addition, this ratiometric probe is successfully applied to determine the alcohol strength of alcohol beverages, demonstrating the great potential in practical application. A facile and label-free ratiometric fluorescent probe for sensing ethanol contents in water was proposed based on the PVP-Cu NCs with unique ethanol-induced blue shift of emission property. [Display omitted] • The PVP-Cu NCs were prepared with ratiometric dual emission. • A facile ratiometric fluorescent probe was designed for sensing ethanol in water. • This probe has rapid response rate (<1 min) and full detection range from 0 to 100%. • This probe has great anti-interference capacity, and was successfully used in real sample. [ABSTRACT FROM AUTHOR]

The development of immobilization method of a chemoprobe on solid support without sacrificing its good original performance in homogeneous solution is a tricky problem. Herein, we make use of the transparent agarose hydrogel with semi-wet property which provided appropriate microenvironment to immobilize the chemoprobe and maintained its original performance to develop an excellent smartphone-enabled colorimetric platform. As a proof of concept, the sensing platform was fabricated with agarose hydrogel that captured diethylaminoethyldextran chloride (DEAE-dextran) and dithiothreitol modified copper nanoclusters (Cu NCs) as a fluorescence probe. Benefiting from the aggregation-induced emission (AIE) effect and confinement effect of hydrogel, the fluorescence quantum yield (QY) of Cu NCs hydrogel is three times higher than that of Cu NCs. Moreover, sensitively detection of Cr(VI) can be realized in the concentration range of 0.07–38.00 μM based on the amplified fluorescence probe. The outstanding analysis performance for Cr(VI) is also achieved when Cu NCs hydrogel was directly immobilized on paper as a smartphone-enabled colorimetric platform, indicating that our strategy can promote the further development of the application of hydrogel materials. [Display omitted] • An AIE-active copper nanoclusters (Cu NCs) functionalized hydrogel was prepared. • The amplified fluorescent detection of Cr(VI) by Cu NCs hydrogel was achieved. • Cu NCs hydrogel as a smartphone-enabled colorimetric platform showed an outstanding performance of detecting Cr(VI). • Smartphone-enabled colorimetric platform can realize instrument-free, portable and on-site detection of Cr(VI). [ABSTRACT FROM AUTHOR]

[Display omitted] • A three-in-one signal sensing probe is designed for the determination of PMS. • The multisignal output guarantees more accurate monitoring of the PMS. • A conventional chromogenic substrate realizes the output of multiple signals. • Such a strategy improves the probe's reliability, sensitivity and adaptability. The extensive applications of peroxymonosulfate (PMS) in the field of environmental pollutant treatment based on advanced oxidation processes (AOPs) have prompted a high demand for advances in the probe ranging from improving their performances to strengthening their practicalities. Here, a multisignal-output probe of PMS was achieved by the unconventional application of traditional chromogenic system, 3,3′,5,5′-tetramethylbenzidine with Co2+ ions (Co2+-TMB). It works on the trace Co2+-catalyzed specific conversion of a colorless TMB into a blue oxidation product (oxTMB) with PMS as the oxidizing agent, accompanied by the enhanced absorption value of oxTMB at 652 nm and decreased fluorescence intensity of TMB at 405 nm. The change of color was directly observed. The combination of a hydrogel with a colorimetric platform favors the real-time and convenient sensing of PMS in the concentration range of 0.98 to 130.29 μM. A good linear relationship between the PMS concentration and both the absorption and fluorescence intensity was obtained with an r 2 value of 0.999, and a detection limit of 0.03 μM for fluorescence and 0.11 μM for spectrometry. Such a multisignal output probe with the advantages of simplicity, convenience, high sensitivity and stability improves the reliability and practical adaptability. This study successfully applied a valuable strategy for sensing PMS, and verified its availability in detecting the residual quantity of PMS in pollutant water treated by AOPs and PMS concentrations in actual water samples with peroxydisulfate (PDS). [ABSTRACT FROM AUTHOR]

Carbon dots without heteroatoms-doping and surface modifications were designed to be a novel chemosensing strategy on the quantitative detection of uric acid (UA) with the aid of uricase-induced enzymatic reaction and Fenton reaction. In this work, ascorbic acid (AA)-derived carbon dots (A-CDs) were prepared in the mixture of ethanol and water via one-step hydrothermal synthesis at a relatively low temperature (120 °C) for 10 h. The resultant A-CDs were proved to be excitation-independent. When excited at the wavelength of 420 nm, the nanodots displayed green fluorescence (535 nm) which was then linearly quenched as UA concentration increased in the range of 0–56 μM, according to which the detection limit was calculated to be 0.49 μM. With regards to the excellent sensitivity and selectivity to UA, real sample assay was performed on the A-CDs detection system, which provided relatively reliable recoveries of UA contained in human serum/urine. Besides, in view of the high quantum yield, the A-CDs were applied to live-cell imaging assay and were considered to become an alternative tracer tool in biomedical imaging. [Display omitted] • Carbon dots are prepared at a relatively low temperature without heteroatoms doping and surface modification. • The sensing system based on the carbon dots has a low detection limit to uric acid. • The system not only allows for quantifying uric acid and H 2 O 2 , but also possesses the imaging ability to living cells. [ABSTRACT FROM AUTHOR]

• Carbon dots were made from nitrogen-rich adenine via simple hydrothermal strategy. • The sensing mechanism of carbon dots was based on aggregation-induced enhanced emission (AIEE). • Carbon dots can efficiently detect and quantify ClO− in real water samples. A novel fluorescent chemosensing strategy on the detection and determination of hypochlorite (ClO−) based on fluorescence enhancement was reported. In this work, nitrogen-doped carbon dots (N-CDs) were prepared via one-step hydrothermal conversion of nitrogen-rich adenine and ethylenediamine. The N-CDs solution showed excitation-dependent characteristic and displayed green fluorescence (535 nm) when excited by blue light (480 nm). The fluorescence intensity was linearly enhanced with the concentration of ClO− increasing in the range of 0.01–1 mM, and the limit of detection was calculated to be 0.82 μM. Other than the common oxidation of the N-CDs surface by ClO−, spectra change stemmed mainly from aggregation-induced enhanced emission (AIEE), including π-π staking and J-aggregation, which together induced red-shift absorption band and effective fluorescence enhancement. Based on the good sensitivity to ClO−, the N-CDs probe also underwent real sample assay and gave relatively reliable recoveries of ClO− contained in various water samples. In addition, the N-CDs showed excellent anti-interference in the selectivity test and exhibited good stability in complex solution environment with different pH values or ion strengths. In view of the results, the N-CDs sensing probe has impressive sensitivity and selectivity on ClO− determination and possesses good potential on bioimaging applications. [ABSTRACT FROM AUTHOR]