(545m) Microencapsulated Fluorescent Gold for Ppb-Level Chromium(VI) Sensing | AIChE

(545m) Microencapsulated Fluorescent Gold for Ppb-Level Chromium(VI) Sensing


Yin, Y. - Presenter, Rice University
Coonrod, C. L., Rice University
Heck, K. N., Rice University
Wong, M. S., Rice University
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 µM 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 μM CrO42-). This LOD is 15× 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.