(545m) Microencapsulated Fluorescent Gold for Ppb-Level Chromium(VI) Sensing
AIChE Annual Meeting
2018 AIChE Annual Meeting
Poster Session: Environmental Division
Wednesday, October 31, 2018 - 3:30pm to 5:00pm
Fluorescent gold nanoclusters (Au NC) are a promising probe material for selective chemical sensing. However, low fluorescence intensity and an incomplete understanding of the mechanistic origin of the fluorescence limit their practical implementation. We induced glutathione-capped Au NCs to aggregate within silica-coated microcapsular structures using polymer-salt aggregate (PSA) self-assembly chemistry. The encapsulated NCs can detect Cr(VI) at concentrations as low as 5.8 ppb (= 0.05 ÂµM CrO42-) through fluorescence quenching, compared to free Au NCs which have a QY of ~15% and a limit of detection (LOD) of 116 ppb (= 1 Î¼M CrO42-). This LOD is 15Ã lower than the US EPA maximum contaminant level for total chromium (Cr(III) and Cr(VI), 100 ppb) in drinking water. No pH adjustment is needed using the encapsulated Au NCs, unlike the case for free Au NCs. This material may serve as a basis for a practical Cr(VI)-sensitive sensor at parts-per-billion concentration levels.