A simplified and miniaturized glucometer-based assay for the detection of β-glucosidase activity / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

β-Glucosidase activity assays constitute an important indicator for the early diagnosis of neonatal necrotizing enterocolitis and qualitative changes in medicinal plants. The drawbacks of the existing methods are high consumption of both time and reagents, complexity in operation, and requirement of expensive instruments and highly trained personnel. The present study provides a simplified, highly selective, and miniaturized glucometer-based strategy for the detection of β-glucosidase activity. Single-factor experiments showed that optimum β-glucosidase activity was exhibited at 50 °C and pH 5.0 in a citric acid-sodium citrate buffer when reacting with 0.03 g/mL salicin for 30 min. The procedure for detection was simplified without the need of a chromogenic reaction. Validation of the analytical method demonstrated that the accuracy, precision, repeatability, stability, and durability were good. The linear ranges of β-glucosidase in a buffer solution and rat serum were 0.0873-1.5498 U/mL and 0.4076-2.9019 U/mL, respectively. The proposed method was free from interference from β-dextranase, snailase, β-galactosidase, hemicellulase, and glucuronic acid released by baicalin. This demonstrated that the proposed assay had a higher selectivity than the conventional dinitrosalicylic acid (DNS) assay because of the specificity for salicin and unique recognition of glucose by a personal glucose meter. Miniaturization of the method resulted in a microassay for β-glucosidase activity. The easy-to-operate method was successfully used to detect a series of β-glucosidases extracted from bitter almonds and cultured by Aspergillus niger. In addition, the simplified and miniaturized glucometer-based assay has potential application in the point-of-care testing of β-glucosidase in many fields, including medical diagnostics, food safety, and environmental monitoring.

Vascular endothelial cells targeted Tyr-RGD-PEG-PEI nano-drug synthesis and its biological activity / 药学学报

The study is designed to synthesize nano-carrier Tyr-RGD (cyclo-[Arg-Gly-Asp-d-Tyr-Lys]) and poly(ethylene glycol) modified polyethylenimine (Tyr-RGD-PEG-PEI) targeting vascular endothelial cells, then analyze its nanoparticle properties and the characteristics of drug carrying and targeting properties in vivo / in vitro tumor. The nano-carrier Tyr-RGD-PEG-PEI was synthesized with the method of chemical synthesis and the properties of this nanoparticle and drug carrying characteristics were identified. Its effect of targeting vascular endothelial cells in vitro was studied with the method of competitive binding assay. The fluorescent labeled nano-drug was injected into tumor-bearing nude mice to observe its tumor-targeting. The mean size of nano-carrier Tyr-RGD-PEG-PE was about 145 nm, good in encapsulation efficiency of siRNA. After incubation in plasma for half an hour, only about 3 percent of siRNA out. It was confirmed that it was a single spot with TLC analysis, the R(f) value was 0.65. Receptor competition experiments showed that the nano could effectively compete with RGD in binding the receptors on endothelial cells. Tumor-bearing nude mice experiments showed that when containing a fluorescent-labeled siRNA of Tyr-RGD-PEG-PEI nano-drug was injected into mice, after 24 hours this nano-drug mainly distributed within the tumor tissue. However, nano-drug without Tyr-RGD appeared in tumor tissue as well as other organs such as livers, lungs, etc. The Tyr-RGD-targeted gene vector Tyr-RGD-PEG-PEI synthesized in this study has good nanoparticle properties and high efficiency of gene-drug encapsulation. Study of nude mice shows that the ability of its tumor-targeting is significantly better than nano-drug without Tyr-RGD.