Search

Developing low-cost, portable and simple analysis tools is of vital importance for food safety point-of-care testing. Therefore, herein, a new low-cost, simple to fabricate, disposable, electrochemical mast cell-based paper sensor is proposed and developed to sensitively determine the major milk allergen casein. Then, a graphene (GN)/carbon nanofiber (CN)/ Gelatin methacryloyl (GelMA) composite material with high conductivity and good biocompatibility was modified on the cell-based paper sensor to improve the electrical conductivity and provide a sensing recognition interface for the immobilization of rat basophilic leukemia (RBL-2H3) mast cells. The cyclic voltammetry and differential pulse voltammetry measurement of the mast cells in the paper sensor revealed an irreversible anodic peak, whose peak current is proportional to the number of cells in the range from 1 × 102 to 1 × 108 cells/mL. For the milk allergen detection tests, mast cells exposed to the casein caused a significant reduction in the current signal, displaying an inverse dose-dependent relationship. The developed cell sensor exhibited a range of linearity between 1 × 10−7 and 1 × 10−6 g/mL of casein with a detection limit of 3.2 × 10−8 g/mL and a great reproducibility and selectivity. The electrochemical responses obtained using the cell-based paper sensor were well consistent with the conventional detection assay, with good stability and reproducibility. Therefore, a simple and novel electrochemical method for food allergens detection was developed, demonstrating its potential application in the food safety determination and evaluation.

According to the different point of zero charge (PZC) of MoO3 and carbon black (XC72R), an efficient method for preparing highly dispersed carbon-supported Pd/Mo bimetallic nanoparticles is described. The charge enhanced dry impregnation (CEDI) technique is developed for the preparation of Pd/Mo/C electrocatalysts by selectively driving the [Pd(NH3)4]2+ cations onto MoO3 phase instead of carbon support. The CEDI method could minimize the migration of Pd away from the MoO3 phase to carbon support during reduction up to 400 °C. Oxygen reduction measurements by linear sweep voltammetry indicate the carbon-supported Pd/Mo catalyst prepared by the CEDI method has better catalytic activity than that prepared with the dry impregnation method as the CEDI method gives strong interactions between Pd and Mo.

Analyzed the anti-proliferative activities (EC50 values) and cytotoxicities (CC50 values) of adlay extracts with adlay (Coix lacryma-jobi L.) varieties grains, Guizhou Heigu (hard hull, black), Liaoning 5 (soft hull, black) and Longyi 1 (hard hull, brown) to be the materials, normal human MCF-10a breast epithelial cells, human MDA breast cancer cells and human MCF-7 breast cancer cells to be the research subjects. After being processed by free or bound phenolic extracts of adlay, detected the expression levels of proteins such as PCNA, p21 and CDK4, which were related to cell proliferation and cell cycle in cells, by using western-blot test to preliminary obtain the mechanism of inhibition of tumor cells proliferation of adlay extracts. The results showed that the adlay extracts by different varieties had obvious anti-proliferative effects to tumor cells, and adlay samples themselves had no cytotoxicity in the tested experimental concentration range. Besides, adlay extracts inhibited the proliferation of HepG2 cells by regulating the cell cycle mediated by DNA polymerase adjustment factors such as PCNA and p21.