Using gold nanorod-based colorimetric sensor for determining for chromium in biological samples

Hexavalent chromium can inflict several health issues in comparison to other oxidation states of chromium. An-isotropic gold nanorods (AuNRs) have size-tunable optical properties, and hence, the spectral shift noted with increasing Cr6+ concentrations can be employed for the development of a Cr6+ sensor. The present work involves the usage of BSA-coated AuNRs for Cr6+ detection in biological samples by utilizing hydrobromic acid. AuNRs, upon interaction with Cr6+, can exhibit decreased aspect ratio and transform to nanospheres for higher Cr6+ concentration, for which the color changes from violet to red can be visualized by bare eyes as well be characterized using transmission electron microscopy, UV-visible spectroscopy, and zeta potential analyzer. Cr6+ solutions prepared in phosphate buffer were acid digested to oxidize total chromium to Cr6+. A good linear calibration was noted for longitudinal surface plasmon peak shift (Delta lambda(max)) plotted against Cr6+ concentrations with a detection limit of 0.32 mu M (R-2 = 0.979; Range: 1-100 mu M). The method was applied for Cr6+ spiked in artificial gastric and intestinal fluids and simulated blood plasma with good recovery percentages. Their applicability to test chromium internalized in Cr-tolerant bacterial cells and Cr bound to cell walls and chromium internalized in human cells was determined. Hence, the present method can be used as an alternative for Cr6+ analysis in biological matrices. (C) 2018 Elsevier B.V. All rights reserved.