Paper-based platforms with coulometric readout for ascorbic acid determination in fruit juices

Paper-based electrochemical platforms with coulometric readout are employed for fast and low cost determination of ascorbic acid in commercial juice samples.

One-Step Synthesis of Anisotropic Gold Nanoparticles with the Aid Extract from Wuluh Starfruit (Averrhoa Bilimbi) Fruit as Reducing and Morphology Controlling Agent

The synthesis of anisotropic gold nanoparticles have been successfully conducted using one-step experimental procedures, with the aid of extract from wuluh starfruit (Averrhoa bilimbi) as reducing agent. The synthesis was carried out in the microwave oven at certain power of irradiation. The as-formed nanoparticles were characterized by UV-Vis spectrophotometry and transmission electron microscopy (TEM). The phytochemical assay and ascorbic acid determination was done to support the prediction about the contribution of those compounds in the synthesis. The antimicrobial activity was assayed toward some bacteria. The results confirmed that the amount of phytochemicals and ascorbic acid in the extracts may contribute largely to the effectivity of the synthesis. The morphology of these nanoparticles was greatly affected by both the Au precursor concentration and volume ratio of precursor : extract. The as-formed nanoparticles have medium antibacterial activity, toward Escherichia coli and Bacillus, in which the magnitude of antibacterial activity depends on the ratio of precursor : extract.