Boron carbon oxyphosphide heterostructured nanodots with phosphate tunable emission for switchable dual detection channels of 6-mercaptopurine assay.

The preparation of boron-carbon-oxygen (BCO)-based heterostructure needs commonly high temperature, high pressure and/or auxiliary strong oxidant. And the BCO-based probe for the sensing application is still rare owing to their few active groups, low quantum yield or missing specificity. Exploring BCO-based heterostructured probe via simple routes and application in sensing, therefore, is highly challenging. Herein, we proposed a novel boron-carbon-phosphorus-oxygen (BCPO) nanodot with phosphate tunable near-ultraviolet emission performance and narrow full width at half maximum by a facile, green and gentle synthesis process. The BCPO not only exhibits a distinctive colorimetric response to 6-mercaptopurine (6-MP), but also displays 6-MP-sensitive photoluminescence quenching. Thus, dual detection channels for 6-MP based on BCPO probe have been developed, and the mechanism has been speculated. Enrichment-electron of the 6-MP can be adsorbed at the boron vacancy orbits of the BCPO by the chemical action. The formation of 6-MP/BCPO complexes trigger the efficient photoluminescence quenching and light-absorbing enhancing of the BCPO, owing to the synergistic effect of the acceptor-excited photo-induced electron/energy transfer, inner filter effect and p/π-π conjugated stacking. Furthermore, the presence of ClO- anion efficaciously sparks the release of the 6-MP molecule from the 6-MP/BCPO complexes, thereby a rapid photo-switch of the BCPO for the 6-MP has been developed. Thus, this study can not only guide the further rational design of the BCPO probe, but also inspire the in-depth application of the BCPO and other nanomaterial-based probes.

Platinum group element-based nanozymes for biomedical applications: an overview.

With a rapid advancement of nanotechnology and the close integration of disciplines, research on nanozymes (nanomaterials with enzyme-like activities), is becoming an expeditiously developing field. In recent years, platinum group element (PGE)-based (Pt, Pd, Ru, Rh, Ir, and Os) nanozymes developed successively, have not only promoted the research of nanozymes but also expanded the biomedical applications of nanomaterials. Generally speaking, PGE-based nanozymes process high catalytic efficiency, specific surface area, stability, and other physical/chemical properties, which benefit for their applications in biosensing, biological medicine, biomedical imaging, and environmental protection. This paper will introduce the research progress of PGE-based nanozymes including their synthesis, characterization, enzyme-like activities, stability, biocompatibility, toxicity, and applications for biological detection and clinical relevance. Our emphasis is put on unfolding the roles of PGE-based nanozymes in biomedical applications and how they overcome the limitations. Last but not least, trends and future perspectives of PGE-based nanozymes in biomedical applications are also provided.

Solid-state thiolate-stabilized copper nanoclusters with ultrahigh photoluminescence quantum yield for white light-emitting devices.

As a new emerging candidate for solid-state phosphors, copper nanoclusters (CuNCs) have gained tremendous interest in the field of white light-emitting devices (WLEDs). However, their further applications are impeded by the low photoluminescence quantum yield (PLQY) and poor emission color tunability of CuNCs. This work demonstrates the synthesis of cyan and orange emitting CuNCs, and their combination as color conversion phosphors in WLEDs. The cyan and orange emitting CuNCs were prepared employing 2-mercapto-1-methylimidazole (MMI) and N-acetyl-l-cysteine (NAC), respectively, as stabilizing-cum-reducing agents. The dispersions of MMI-CuNCs and NAC-CuNCs are weakly emissive. However, after processing into powders, they both possess ultrahigh PLQYs (45.2% for MMI-CuNCs, and 64.6% for NAC-CuNCs) owing to the effect of aggregation-induced emission (AIE). All-CuNC based WLEDs are then designed and developed using powdered MMI-CuNC and NAC-CuNC samples on commercially available 365 nm GaN LED chips. They display acceptable white light characteristics with a Commission Internationale de l'Eclairage coordinate value and color rendering index of (0.26, 0.30) and 83, respectively. We believe that these cost-effective and eco-friendly CuNCs with interesting AIE properties will vigorously promote the development of high-quality WLEDs for commercial applications.

Protein-Supported RuO2 Nanoparticles with Improved Catalytic Activity, In Vitro Salt Resistance, and Biocompatibility: Colorimetric and Electrochemical Biosensing of Cellular H2O2.

Protein-supported nanoparticles have a great significance in scientific and nanotechnology research because of their "green" process, low cost-in-use, good biocompatibility, and some interesting properties. Ruthenium oxide nanoparticles (RuO2NPs) have been considered to be an important member in nanotechnology research. However, the biosynthetic approach of RuO2NPs is relatively few compared to those of other nanoparticles. To address this challenge, this work presented a new way for RuO2NP synthesis (BSA-RuO2NPs) supported by bovine serum albumin (BSA). BSA-RuO2NPs are confirmed to exert peroxidase-like activity, electrocatalytic activity, in vitro salt resistance (2 M NaCl), and biocompatibility. Results indicate that BSA-RuO2NPs have higher affinity binding for 3,3',5,5'-tetramethylbenzidine or H2O2 than bare RuO2NPs. Moreover, BSA turns out to be a crucial factor in promoting the stability of RuO2NPs. Taking the advantages of these improved properties, we established colorimetric (linear range from 2 to 800 µM, a limit of detection of 1.8 µM) and electrochemical (linear range from 0.4 to 3850 µM, a limit of detection of 0.18 µM) biosensors for monitoring in situ H2O2 secretion from living MCF-7 cells. Herein, this work offers a new biosynthesis strategy to obtain BSA-RuO2NPs and sheds light on the sensitive biosensors to monitor the H2O2 secreted from living cells for promising applications in the fields of nanotechnology, biology, biosensors, and medicine.

6-Aza-2-Thio-Thymine Stabilized Gold Nanoclusters as Photoluminescent Probe for Protein Detection.

This study puts forward an efficient method for protein detection in virtue of the tremendous fluorescence enhancement property of 6-aza-2-thio-thymine protected gold nanoclusters (ATT-AuNCs). In-depth studies of the protein-induced photoluminescence enhancement mechanism illustrate the mechanism of the interaction between ATT-AuNCs and protein. This new-established probe enables feasible and sensitive quantification of the concentrations of total protein in real samples, such as human serum, human plasma, milk, and cell extracts. The results of this proposed method are in good agreement with those determined by the classical bicinchoninic acid method (BCA method).

Enzyme-free electrocatalytic sensing of hydrogen peroxide using a glassy carbon electrode modified with cobalt nanoparticle-decorated tungsten carbide.

An efficient non-enzymatic electrochemical sensor for hydrogen peroxide (H2O2) was constructed by modifying a glassy carbon electrode (GCE) with a nanocomposite prepared from cobalt nanoparticle (CoNP) and tungsten carbide (WC). The nanocomposite was prepared at low temperature through a simple technique. Its crystal structure, surface morphology and elemental composition were investigated via X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The results showed the composite to be uniformly distributed and that the CoNP are well attached to the surface of the flake-like WC. Electrochemical studies show that the modified GCE has an improved electrocatalytic activity toward the reduction of H2O2. H2O2 can be selectively detected, best at a working voltage of -0.4 V (vs. Ag/AgCl), with a 6.3 nM detection limit over the wide linear range from 50 nM to 1.0 mM. This surpasses previously reported non-enzymatic H2O2 sensors. The sensor was successfully applied to the determination of H2O2 in contact lens solutions and in spiked serum samples. Graphical abstract Schematic presentation of a method for electrochemical sensing of hydrogen peroxide in real samples using cobalt nanoparticle decorated tungsten carbide (WCC) modified glassy carbon electrode (GCE).

Facile synthesis of hierarchically nanostructured bismuth vanadate: An efficient photocatalyst for degradation and detection of hexavalent chromium.

Heterostructured nanomaterials can paid more significant attention in environmental safety for the detection and degradation/removal of hazardous toxic chemicals over a decay. Here, we report the preparation of hierarchically nanostructured shuriken like bismuth vanadate (BiVO4) as a bifunctional catalyst for photocatalytic degradation and electrochemical detection of highly toxic hexavalent chromium (Cr(VI)) using the green deep eutectic solvent reline, which allows morphology control in one of the less energy-intensive routes. The SEM results showed a good dispersion of BiVO4 catalyst and the HR-TEM revealed an average particle size of ca. 5-10 nm. As a result, the BiVO4 exhibited good photocatalytic activity under UV-light about 95% reduction of Cr(VI) to Cr(III) was observed in 160 min. The recyclability of BiVO4 catalyst exhibited an appreciable reusability and stability of the catalyst towards the photocatalytic reduction of Cr(VI). Also, the BiVO4-modified screen printed carbon electrode (BiVO4/SPCE) displayed an excellent electrochemical performance towards the electrochemical detection of Cr(VI). Besides, the BiVO4/SPCE demonstrated tremendous electrocatalytic activity, lower linear range (0.01-264.5 µM), detection limit (0.0035 µM) and good storage stability towards the detection of Cr(VI). Importantly, the BiVO4 modified electrode was also found to be a good recovery in water samples for practical applications.

Sonochemical synthesis of molybdenum oxide (MoO3) microspheres anchored graphitic carbon nitride (g-C3N4) ultrathin sheets for enhanced electrochemical sensing of Furazolidone.

Present strategy introduce the sonochemical synthesis of molybdenum oxide (MoO3) microspheres anchored graphitic carbon nitride (g-C3N4) ultrathin sheets as a novel electrocatalyst for the detection of Furazolidone (FU). TEM results revealed that MoO3 are microspheres with an average size of 2 µM and the g-C3N4 seems like ultrathin sheets. Owing to their peculiar morphological structure, g-C3N4/MoO3 composite modified electrode provided an enriched electroactive surface area (0.3788 cm2) and higher heterogeneous electron transfer kinetics (K°eff = 4.91×10-2 cm s-1) than the other controlled electrodes. It is obviously observed from the voltammetric studies that the proposed sensor based on g-C3N4/MoO3 composite can significantly improve the electrocatalytic efficiency towards the sensing of FU. Due to the excellent synergic effect of g-C3N4/MoO3 composite, can detect the ultra-level FU with a limit of detection of 1.4 nM and a broad dynamic range of 0.01-228 µM, which surpassed the many previously reported FU sensors. Hence, the proposed sensor was successfully applied to sensing the FU in human blood serum, urine and pharmaceutical samples, gained an agreeable recoveries.

Simplistic synthesis of ultrafine CoMnO3 nanosheets: An excellent electrocatalyst for highly sensitive detection of toxic 4-nitrophenol in environmental water samples.

Design and fabrication of cost effective analytical tools to monitor toxic organic emissions in eco system is of a great necessity. Nitrophenols are a class of widespread toxic organic pollutant lead to serious adverse effects in biosphere on its consumption. This article reports a high sensitive, cost effective, robust electrochemical sensor for 4-nitrophenol (4-NP) in environmental water samples. A novel sheet like CoMnO3 (CMO Ns) nanocatalyst was synthesized via oxalic acid assisted co-precipitation technique and employed as electrocatalyst for the high sensitive detection of 4-NP. The physiochemical properties of CMO Ns are studied in detail via XRD, FTIR, TEM, TGA, and XPS. TEM results reviled the protocol is an excellent way for synthesis of a uniformly distributed CMO Ns with lathery surface. Evident to the surface and other physiochemical studies the CMO Ns based sensor holds superior electrocatalytic activity towards 4-NP detection with excellent sensitivity (2.458 µA µM-1 cm-2) coupled with nanomolar detection (10 nm) limits. Moreover, the constructed sensor holds reliable long-term durability, good reproducibility, and excellent working stability. The practical applicability of the developed sensor was evaluated by determination of 4-NP in samples acquired from water resources with RSD ± 3.3%.

Ultrasonic energy-assisted preparation of ß-cyclodextrin-carbon nanofiber composite: Application for electrochemical sensing of nitrofurantoin.

A simple ultrasonic energy assisted synthesis of ß-cyclodextrin (ß-CD) supported carbon nanofiber composite (CNF) and its potential application in electrochemical sensing of antibiotic nitrofurantoin (NFT) is reported. The elemental composition and surface morphology of the ß-CD/CNF composite was validated through Field emission scanning electron microscopy, energy dispersive X-ray microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The uniform enfolding of hydrophilic ß-CD over CNF enhance the aqueous dispersion and offer abundant active surface to the ß-CD/CNF composite. Further, the electrocatalytic efficacy of the ß-CD/CNF composite is utilized to fabricate an electrochemical sensor for the high sensitive quantitative detection of NFT. Under optimized analytical conditions, the sensor displays a broad working range of 0.004-308 µM and calculated detection limit of 1.8 nM, respectively. In addition, the sensor showcased a good selectivity, storage, and working stability, with amiable reproducibility. The point-of-care applicability of the sensor was demonstrated with NFT spiked human blood serum and urine sample with reliable analytical performance. The simple, cost-effective NFT sensor based on ß-CD/CNF offered outstanding analytical performance in real-world samples with higher reliability.

Amperometric sensing of nitrite at nanomolar concentrations by using carboxylated multiwalled carbon nanotubes modified with titanium nitride nanoparticles.

A glassy carbon electrode (GCE) was modified with a nanocomposite prepared from carboxylated multiwalled carbon nanotubes (c-MWCNT) and titanium nitride (TiN) nanoparticles to obtain a sensor for nitrite. The nanocomposite was characterized by transmission electron microscopy, elemental mapping, X-ray diffraction, and Raman spectroscopy. Electrochemical studies results show the modified GCE to possess a low electrochemical resistance (Rct = 7 Ω) and a large electroactive surface (A = 0.112 cm2). The heterogeneous electron transfer rate (ks) is found to be 1.26 × 10-2 cm s-1. Due to the excellent synergistic effect of c-MWCNT and TiN, the GCE displays and excellent performance in terms of nitrite sensing. At a typical working voltage of +0.8 V (vs. Ag/AgCl), the limit of detection (LOD) is as low as 4 nM, and the useful analytical range extends from 6 nM to 950 µM. This is much better than the LODs of previously reported nitrite sensors. The sensor is fast (response time 4 s), selective, and long-term stable. It was applied to the determination of nitrite in spiked water and meat samples and gave good recoveries. Graphical abstract Schematic presentation of electrochemical determination of nitrite using carboxylated multiwalled carbon nanotubes modified with titanium nitride nanoparticles modified electrode.

Facile Solvothermal Preparation of Mn2CuO4 Microspheres: Excellent Electrocatalyst for Real-Time Detection of H2O2 Released from Live Cells.

Hydrogen peroxide (H2O2) is an eminent biomarker in pathogenesis; a selective, highly sensitive real-time detection of H2O2 released from live cells has drawn a significant research interest in bioanalytical chemistry. Binary transition-metal oxides (BTMOs) displayed a recognizable benefit in enhancing the sensitivity of H2O2 detection; although the reported BTMO-based H2O2 sensor's detection limit is still insufficient, it is not appropriate for in situ profiling of trace amounts of cellular H2O2. In this paper, we describe an efficient, reliable electrochemical biosensor based on Mn2CuO4 (MCO) microspheres to assay cellular H2O2. The Mn2CuO4 microspheres were prepared through a superficial solvothermal method. It is obvious from impedance studies, introduction of manganese into copper oxide lattice significantly improved the ionic conductivity, which is beneficial for the electrochemical sensing process. Thanks to the distinct microsphere structure and excellent synergy, MCO-modified electrode exhibited excellent nonenzymatic electrochemical behavior toward H2O2 sensing. The MCO-modified electrode delivered a broad working range (36 nM to 9.3 mM) and an appreciable detection limit (13 nM), with high selectivity toward H2O2. To prove its practicality, the developed sensor was applied in the detection of cellular H2O2 released by RAW 264.7 cells in presence of CHAPS. These results label the possible appliance of the sensor in clinical analysis and pathophysiology. Thus, BTMOs are evolving as a promising candidate in designing catalytic matrices for biosensor applications.

Voltammetric sensing of sulfamethoxazole using a glassy carbon electrode modified with a graphitic carbon nitride and zinc oxide nanocomposite.

A voltammetric sensor is described for the determination the antibiotic sulfamethoxazole (SMZ). It is based on the use of a glassy carbon electrode (GCE) modified with a nanocomposite prepared from graphitic carbon nitride and zinc oxide (g-C3N4/ZnO). The nanorod-like ZnO nanostructure were synthesized sonochemically. The g-C3N4/ZnO nanocomposite was then prepared by mixing g-C3N4 with ZnO, followed by ultrasonication. The morphology and structure of the nanocomposite were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy and transmission electron microscopy. Under the optimal conditions, the response of the electrode, typically measured between 0.8 and 0.9 V (vs. Ag/AgCl), increases linearly in the 20 nM to 1.1 mM SMZ concentration range, and the lower detection limit is 6.6 nM. This is better than that of many previously reported sensors for SMZ. The modified electrode is highly selective, well reproducible and maintains its activity for at least 4 weeks. It was applied to the determination of SMZ in spiked human blood serum samples in with satisfactory results. Graphical abstract Schematic presentation of the voltammetric sensor for sulfamethoxazole. It consists of a glassy carbon electrode modified with a nanocomposite prepared from graphitic carbon nitride (g-C3N4/ZnO) that was supported with zinc oxide nanorods.

A new electrochemical sensor for highly sensitive and selective detection of nitrite in food samples based on sonochemical synthesized Calcium Ferrite (CaFe2O4) clusters modified screen printed carbon electrode.

Herein, we report a novel, disposable electrochemical sensor for the detection of nitrite ions in food samples based on the sonochemical synthesized orthorhombic CaFe2O4 (CFO) clusters modified screen printed electrode. As synthesized CFO clusters were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformer infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and amperometry (i-t). Under optimal condition, the CFO modified electrode displayed a rapid current response to nitrite, a linear response range from 0.016 to 1921 µM associated with a low detection limit 6.6 nM. The suggested sensor also showed the excellent sensitivity of 3.712 µA µM-1 cm-2. Furthermore, a good reproducibility, long-term stability and excellent selectivity were also attained on the proposed sensor. In addition, the practical applicability of the sensor was investigated via meat samples, tap water and drinking water, and showed desirable recovery rate, representing its possibilities for practical application.