Detection of Arsenic(V) by Fluorescence Sensing Based on Chlorin e6-Copper Ion.

The high toxicity of arsenic (As) can cause irreversible harm to the environment and human health. In this study, the chlorin e6 (Ce6), which emits fluorescence in the infrared region, was introduced as the luminescence center, and the addition of copper ion (Cu2+) and As(V) provoked a regular change in fluorescence at 652 nm, whereas that of As(III) was 665 nm, which was used to optionally detect Cu2+, arsenic (As(III), and As(V)). The limit of detection (LOD) values were 0.212 µM, 0.089 ppm, and 1.375 ppb for Cu2+, As(III), and As(V), respectively. The developed method can be used to determine Cu2+ and arsenic in water and soil with good sensitivity and selectivity. The 1:1 stoichiometry of Ce6 with Cu2+ was obtained from the Job plot that was developed from UV-visible spectra. The binding constants for Cu2+ and As(V) were established to be 1.248 × 105 M-1 and 2.35 × 1012 M-2, respectively, using B-H (Benesi-Hildebrand) plots. Fluorescence lifetimes, B-H plots, FT-IR, and 1H-NMR were used to postulate the mechanism of Cu2+ fluorescence quenching and As(V) fluorescence restoration and the interactions of the two ions with the Ce6 molecule.

Rapid and sensitive detection of alkaline phosphatase and glucose oxidase activity through fluorescence and colorimetric dual-mode analysis based on CuO NPs@ZIF-8 mediated enzyme-cascade reactions.

The combined application of nanozymes and natural enzymes has received widespread attention in recent years. In this work, a simple and efficient method was used to synthesize a composite material of CuO nanoparticle-modified zeolitic imidazolate framework-8 (CuO NPs@ZIF-8) with multiple enzyme activities (glucose oxidase-like and hydrolase-like activities) to detect the activity of natural enzymes through fluorescence and colorimetric (UV-vis) dual-mode detection. The hydrolase- and oxidase-like activities of CuO NPs@ZIF-8 show an acceptable affinity with l-ascorbic acid 2-phosphate trisodium (AAP) and o-phenylenediamine (OPD). Using the developed sensor, highly sensitive detection of natural enzymes glucose oxidase (GOX) and alkaline phosphatase (ALP) was achieved through both fluorescent and colorimetric analyses with a wide linear range (fluorescence for GOX: 0.86-1.23 × 105 mU mL-1, UV-vis for GOX: 0.081-1.62 × 105 mU mL-1; fluorescence for ALP: 0.042-1.20 × 104 mU mL-1, UV-vis for ALP: 0.0046-1.23 × 104 mU mL-1) and low LOQs (fluorescence for GOX: 0.86 mU mL-1, UV-vis for GOX: 0.081 mU mL-1; fluorescence for ALP: 0.042 mU mL-1, UV-vis for ALP: 0.0046 mU mL-1). Compared to the other fluorescent and colorimetric sensors, this sensor has better catalytic activity due to the addition of GOX and ALP, which can amplify the detection signal and improve the sensitivity. This is the first time that composite material CuO NPs@ZIF-8 with "tandem enzyme" activity was synthesized and applied in the detection of enzyme activity. Additionally, the proposed fluorescent and UV-vis platforms exhibit the capability to detect GOX and ALP in serum samples with satisfactory recovery, indicating potential application prospects in biochemical analysis.

Preparation of Alcohol Dehydrogenase-Zinc Phosphate Hybrid Nanoflowers through Biomimetic Mineralization and Its Application in the Inhibitor Screening.

A biomimetic mineralization method was used in the facile and rapid preparation of nanoflowers for immobilizing alcohol dehydrogenase (ADH). The method mainly uses ADH as an organic component and zinc phosphate as an inorganic component to prepare flower-like ADH/Zn3(PO4)2 organic-inorganic hybrid nanoflowers (HNFs) with the high specific surface area through a self-assembly process. The synthesis conditions of the ADH HNFs were optimized and its morphology was characterized. Under the optimum enzymatic reaction conditions, the Michaelis-Menten constant (Km) of ADH HNFs (ß-NAD+ as substrate) was measured to be 3.54 mM, and the half-maximal inhibitory concentration (IC50) of the positive control ranitidine (0.2-0.8 mM) was determined to be 0.49 mM. Subsequently, the inhibitory activity of natural medicine Penthorum chinense Pursh and nine small-molecule compounds on ADH was evaluated using ADH HNFs. The inhibition percentage of the aqueous extract of P. chinense is 57.9%. The vanillic acid, protocatechuic acid, gallic acid, and naringenin have obvious inhibitory effects on ADH, and their percentages of inhibition are 55.1%, 68.3%, 61.9%, and 75.5%, respectively. Moreover, molecular docking analysis was applied to explore the binding modes and sites of the four most active small-molecule compounds to ADH. The results of this study can broaden the application of immobilized enzymes through biomimetic mineralization, and provide a reference for the discovery of ADH inhibitors from natural products.

Dual tumor-targeted poly(lactic-co-glycolic acid)-polyethylene glycol-folic acid nanoparticles: a novel biodegradable nanocarrier for secure and efficient antitumor drug delivery.

Further specific target-ability development of biodegradable nanocarriers is extremely important to promote their security and efficiency in antitumor drug-delivery applications. In this study, a facilely prepared poly(lactic-co-glycolic acid) (PLGA)-polyethylene glycol (PEG)-folic acid (FA) copolymer was able to self-assemble into nanoparticles with favorable hydrodynamic diameters of around 100 nm and negative surface charge in aqueous solution, which was expected to enhance intracellular antitumor drug delivery by advanced dual tumor-target effects, ie, enhanced permeability and retention induced the passive target, and FA mediated the positive target. Fluorescence-activated cell-sorting and confocal laser-scanning microscopy results confirmed that doxorubicin (model drug) loaded into PLGA-PEG-FA nanoparticles was able to be delivered efficiently into tumor cells and accumulated at nuclei. In addition, all hemolysis, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, and zebrafish-development experiments demonstrated that PLGA-PEG-FA nanoparticles were biocompatible and secure for biomedical applications, even at high polymer concentration (0.1 mg/mL), both in vitro and in vivo. Therefore, PLGA-PEG-FA nanoparticles provide a feasible controlled-release platform for secure and efficient antitumor drug delivery.