Microencapsulated Photoluminescent Gold for ppb-Level Chromium(VI) Sensing

Abstract

Luminescent gold nanoclusters (Au NCs) are a promising probe material for selective chemical sensing. However, low luminescent intensity and an incomplete understanding of the mechanistic origin of the luminescence limit their practical implementation. We induced glutathione-capped Au NCs to aggregate within silica-coated microcapsular structures using polymer−salt aggregate self-assembly chemistry. The encapsulated NCs have a 5× luminescence enhancement compared to free Au NCs and can detect Cr(VI) at concentrations as low as 6 ppb (=0.12 μM CrO 4 2− ) through luminescence quenching, compared to free Au NCs, which have a limit of detection (LOD) of 52 ppb (=1 μM CrO 4 2− ). The LOD is 16× lower than the United States Environmental Protection Agency maximum contaminant level for total chromium (Cr(III) + Cr(VI), 100 ppb) in drinking water. No pH adjustment is needed using the encapsulated Au NCs, unlike the case for free Au NCs. The luminescent microcapsule material can sense Cr(VI) in simulated drinking water with a ∼20−30 ppb LOD, serving as a possible basis for a practical Cr(VI) sensor.

Ultrasensitive point-of-care biochemical sensor based on metal-AIEgen frameworks

“…A calculated limit of detection (LOD) value is about 0.1 nM (3 per slope), which is more sensitive than current MOF sensors and other sensors (Fig. 4D and table S2) (51)(52)(53)(54)(55)(56)(57)(58)(59)(60)(61)(62)(63). Cr 3+ -incubated MAF-4 has a slight increase of hydrodynamic diameter (Fig.…”

Self‐Assembly of Precision Noble Metal Nanoclusters: Hierarchical Structural Complexity, Colloidal Superstructures, and Applications

“…modified the polyamine‐based assembly by introducing a salt of polyvalent anions. [ 275 ] Here, the polymer‐salt aggregates helped to entrap charged NCs to produce Au NC containing microcapsules. The multilayered and semipermeable matrix of microcapsules was further stabilized with SiO 2 NPs.…”

A water-soluble conjugated polyelectrolyte for selective and sensitive detection of carcinogenic chromium(vi)

“…Furthermore, the low cost of analysis and multiple portable platforms make fluorescence-based detection systems a better choice among sensors. Thus, recently various advanced materials such as polymers, 12,13 small organic compounds, 14 nanocomposites, [15][16][17][18][19] gold nanoclusters, 20 metal-organic frameworks (MOFs), [21][22][23][24][25] carbon dots, etc. [26][27][28][29][30][31] have been developed as fluorescent probes for Cr(VI) detection.…”