Enhanced Sporicidal Activity of Alcohol and Epigallocatechin-Palmitate-Based Hand Hygiene Formulations Comprised of Plant-Derived Compounds

Pathogenic spore-forming bacteria pose high risks to healthcare settings, as well as in the food and beverage industries. We reported recently that novel alcohol-based formulations containing plant-derived compounds, including epigallocatechin-3-gallate-palmitate (EGCG-P), a green tea polyphenol ester, provide > 99.99% inactivation of bacterial spores within 60 sec. Based on recently published data from our group and others, we hypothesize that a combination of EGCG-P and alcohol formulated with other plant-derived ingredients would achieve high sporicidal efficacy against a wide spectrum of bacterial spores and can provide novel hand hygiene methods against bacterial spores without toxicity. The objectives of the current study were to optimize two novel formulations with combinations of glycerol, citric acid, and EGCG-P to increase sporicidal activity and explore the rapid inactivation mechanisms and suitability for sporicidal products with broad-spectrum activities against aerobic and anaerobic bacterial spores. Methods included suspension testing of two formulations against spores from Bacillus cereus and Clostridium sporogenes, quantification of spore germination, and scanning electron microscopy. The results demonstrated that these novel formulations were able to reduce spore germination by >99.999% after 30 sec exposure in suspension tests, and rapidly caused physical damage to the spores. Additional studies are warranted to determine the suitability of the novel formulations for future hand hygiene use.

Anthrax Biomarker:a Fluorescent Probe for Dipicolinic Acid Using Eu(Ⅲ)-doped Nanosheets

A novel two-dimensional nanosheet fluorescent probe embedded with rare earth Eu(Ⅲ)was developed to detect dipicolinic acid(DPA),a biomarker of Bacillus anthracis bacterial spores.DPA,a major component of Bacillus anthracis spores which were highly toxic to humans,was not found in other common bacteria.The ability to detect ultra-low concentrations of DPA would therefore be of great significance.Eu(Ⅲ)-doped ytterbium hydroxide nanosheets were obtained by mechanical exfoliation from layered rare-earth hydroxide(LRH)materials.The crystallinities,layered structure and morphology of the as-synthesized nanosheets were studied by power X-ray diffraction,transmission electron microscopy and atomic force microscopy.Eu(Ⅲ)emission increased linearly with DPA addition in the range of 0.1~30μmol/L.Based on the antenna effect,the detection limit of DPA was 0.078μmol/L and much lower than the infective dose of Bacillus anthracis in humans of 60μmol/L.The nanosheet fluorescent probe exhibited good specificity toward DPA,and the interferences with selected aromatic ligands and amino acids were observed to be negligibly small in comparison with that of DPA.Our findings provide a basis for the application of Eu(Ⅲ)-doped nanosheets for accurate,sensitive,and selective monitoring of DPA as a biomarker of anthrax.