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Abstract: ZnO coated multiwalled carbon nanotubes (ZnO-MWCNTs) nano-composite was synthesized by the hydrothermal method and expected to offer a promising template for biosensor fabrication due to satisfying biocompatibility and improved properties. The ZnO-MWCNTs nano-composite was mixed with Nafion solution to form a composite matrix for the fabrication of hemoglobin (Hb) biosensor. This composite matrix combined the advantages of inorganic composite (ZnO-MWCNTs) and organic polymer (Nafion) and could promote the direct electron transfer of Hb. The Hb/ZnO-MWCNTs/Nafion film exhibited a pair of well-defined, quasi-reversible redox peaks with a formal potential of −0.353V (vs. SCE), characteristic of heme redox couple (Fe(III)/Fe(II)) of Hb. Hb retained its near-native conformation in the composite film. The immobilized Hb showed fast and excellent electrocatalytic activity to H2O2 with a linear range from 2×10−7 to 1.2×10−5 M, and the detection limit was 8.4×10−8 M. The sensitivity and apparent Michaelis–Menten constant were 1.31A/(M·cm2) and 82.8μM, respectively, which indicated that Hb had a high affinity to H2O2. This biosensor also showed excellent electrocatalytic activity towards trichloroacetic acid. [Copyright &y& Elsevier]

Owing to the importance of α‐amylase in industry, it is necessary to develop a more simple and practical approach to measure α‐amylase activity. Herein, a fluorescence method was established for the detection of α‐amylase activity based on hydroxyproply‐β‐cyclodextrin‐curcumin inclusion complex (HP‐β‐CDs‐Cur). Curcumin was utilized as a signal probe, while hydroxyproply‐β‐cyclodextrin (HP‐β‐CDs) was employed both as a substrate of α‐amylase and the carrier of curcumin. α‐amylase is capable to hydrolyse α‐1,4‐glycosidic bond on the HP‐β‐CDs ring, facilitating the detection of its activity through the measurement of the decrease of fluorescence intensity caused by the release of curcumin into the aqueous. The results showed that there was a good linear relationship between fluorescence intensity and α‐amylase concentration in the range of 0.065~1.365 U mL−1, and the detection limit was 0.0065 U mL−1. The successful application of this method to evaluate the activities of multiple commercial α‐amylases underscores its robustness and reliability. [ABSTRACT FROM AUTHOR]

A modified screen‐printed electrode based on zeolite imidazole framework‐8 (ZIF‐8), silver nanoparticles (Ag NPs) and electrochemically reduced graphene oxide (ErGO) were developed to detect dopamine. The morphology and electrochemical performance were investigated, and the results showed that ErGO/Ag‐ZIF‐8 composites were successfully synthesized without destruction of the ZIF‐8 structure. In addition, the peak current of dopamine (DA) oxidation increased linearly in the range of 0.1–200 μM, and the detection limit was 0.03 μM (S/N=3). Furthermore, the sensor showed good reproducibility and selectivity, and was successfully applied to the detection of DA in goat serum with a satisfactory recovery range. [ABSTRACT FROM AUTHOR]

[Display omitted] • The probe HBT-LDC was synthesized by the acylation of ESIPT fluorophore AIEgen 2-(2-hydroxyphenyl)benzothiazole (HBT) and dodecyl chloride. • A fluorescent probe HBT-LDC with AIE + ESIPT characteristic was reported for the first time to detect lipase activity. • The specific catalysis of lipase in homogeneous system was realized by HBT-LDC probe. • The probe HBT-LDC has been successfully applied to the evaluation of commercial lipase and the in vivo bioimaging sensing exogenous lipase activity in HeLa cells. • The probe HBT-LDC could serve as a potential tool in lipase related drug discovery and disease diagnostics, as well as the functional study of drug metabolism and disease pathology. Lipases are acyl hydrolases that play a key role in fat digestion and monitoring of acute pancreatitis by cleaving long-chain triglycerides into polar lipids. Due to an opposite polarity between the hydrophilic enzyme and their lipophilic substrates, lipase reaction occurs at the interface between the aqueous and the oil phases. It is quite challenging to develop a specific probe to detect lipase activity, especially in homogeneous systems. Herein we designed a blue fluorescent probe HBT-LDC for specific detection of lipase activity based on both aggregation induced emission (AIE) and excited-state intramolecular proton transfer (ESIPT) effect. The probe shows significant advantages, such as high selectivity and excellent sensitivity, no self-quenching at high concentration, large Stokes shift, low cytotoxicity, and good biocompatibility. The linear range for in vitro quantification of lipase is 0.2–1.3 mg/mL with a detection limit of 0.01 mg/mL. The probe has been successfully applied to the evaluation of commercial lipase and the in vivo bioimaging sensing exogenous lipase activity in HeLa cells. The results revealed that the probe could serve as a potential tool in lipase related drug discovery and disease diagnostics. [ABSTRACT FROM AUTHOR]

By coating polydimethylsiloxane (PDMS) relief structures with a layer of opaque metal such as gold, the incident light is strictly allowed to pass through the nanoscopic apertures at the sidewalls of PDMS reliefs to expose underlying photoresist at nanoscale regions, thus producing subwavelength nanopatterns covering centimeter-scale areas. It was found that the sidewalls were a little oblique, which was the key to form the nanoscale apertures. Two-sided and one-sided subwavelength apertures can be constructed by employing vertical and oblique metal evaporation directions, respectively. Consequently, two-line and one-line subwavelength nanopatterns with programmable feature shapes, sizes, and periodicities could be produced using the obtained photomasks. The smallest aperture size and line width of 80 nm were achieved. In contrast to the generation of raised positive photoresist nanopatterns in phase shifting photolithography, the recessed positive photoresist nanopatterns produced in this study provide a convenient route to transfer the resist nanopatterns to metal nanopatterns. This nanolithography methodology possesses the distinctive advantages of simplicity, low cost, high throughput, and nanoscale feature size and shape controllability, making it a potent nanofabrication technique to enable functional nanostructures for various potential applications. [ABSTRACT FROM AUTHOR]

A quantitative colorimetric sensing strategy utilizing cysteamine modified gold nanoparticles (CA–AuNPs) as reporters for Hg2+ and melamine was demonstrated. Cysteamine is a cheap and commercially available aminothiol and is also the most important chelating ligand in coordination chemistry possessing the ability to coordinate to Hg2+ and melamine. The terminal thiol group in cysteamine is used to bind to AuNPs and another terminal amine group is used as a colorimetric probe either for Hg2+ or melamine. By adjusting the pH, protonation of cysteamine's terminal amine groups allows for tuning of the surface charge on the cysteamine-modified gold nanoparticles. At acidic pH, the CA–AuNPs are positively charged due to the protonated amine groups, which may electrostatically bind melamine resulting in aggregation of CA–AuNPs, while at alkaline pH, the amine groups are deprotonated, and if Hg2+ is present, they may form an N–Hg2+–N structure to induce the aggregation of CA–AuNPs. The detection limits (S/N = 3) of Hg2+ and melamine were 30 nM and 80 nM respectively, which were comparable with or even lower than those of other single analyte methods. The proposed sensing mechanisms, which are based on electrostatic attraction for melamine and the N–Hg2+–N structure for Hg2+, were validated by zeta potential measurements. The facile one-step surface modification strategy for AuNPs is suitable for the effective analysis of large numbers of samples, which would open new opportunities for development of miniaturized Hg2+ and melamine sensors. [ABSTRACT FROM AUTHOR]

A dispersible graphene/gold nanoclusters hybrid in aqueous solution was fabricated in situbased on the bilayer graphene template, and its electrogenerated chemiluminescence (ECL) behavior was studied. [ABSTRACT FROM AUTHOR]