Gold-Modified Micellar Composites as Colorimetric Probes for the Determination of Low Molecular Weight Thiols in Biological Fluids Using Consumer Electronic Devices

This work describes a new, low-cost and simple-to-use method for the determination of free biothiols in biological fluids. The developed utilizes interaction with gold ions, previously anchored on micellar assemblies through electrostatic interactions hydrophilic headgroup cationic surfactant micelles. Specifically, reaction AuCl4− cetyltrimethyl ammonium bromide (CTAB) produces an intense orange coloration, due to ligand substitution Br− Cl− anions, followed by coordination AuBr4− anions micelle surface interactions. When are added solution, they complex ions disrupt AuBr4−–CTAB complex, quenching initial coloration inducing decrease light absorbance solution. Biothiols assessed monitoring their color RGB model, using flatbed scanner operating transmittance mode as inexpensive microtiter plate photometer. was applied determine biothiol content urine blood plasma samples, satisfactory recoveries (i.e., >67.3–123% external calibration 103.8–115% standard addition calibration) good reproducibility (RSD < 8.4%, n = 3).