Metal oxide surfaces for enhanced colorimetric response in bioassays

Abstract

Physical stability of metal nanoparticle films on planar surfaces can be increased by employing surface modification techniques and/or type of metal nanoparticles. Subsequently, the enzymatic response of colorimetric bioassays can be increased for improved dynamic range for the detection of biomolecules. Using a model bioassay b-BSA, three planar platforms (1) poly (methyl methacrylate) (PMMA) with silver thin films (STFs) (2) silver nanowires (Ag NWs) on paper and (3) indium tin oxide (ITO) on polyethylene terephthalate (PET) were evaluated to investigate the extent of increase in the colorimetric signal. Bioassays for b-BSA and Ki-67 antigen (a real-life bioassay) in buffer were performed using microwave heating (total assay time is 25–30 min) and at room temperature (a control experiment, total assay time is 3 hours). Model bioassays showed that STFs were removed from the surface during washing steps and the extent of ITO remained unchanged. The lowest level of detection (LLOD) for b-BSA bioassays were: 10−10 M for 10 nm STFs on PMMA and Ag NWs on paper and 10−11 M for ITO. Bioassays for Ki-67 antigen yielded a LLOD of <10−9 M on ITO platforms, while STFs platforms were deemed unusable due to significant loss of STFs from the surfaces.

Rapid Sensing of Biological and Environmental Analytes Using Microwave-Accelerated Bioassays and a MATLAB Application

“…5(b) shows results for MC-LR assay completed under microwave heating (total assay time = 15 mins) with the estimated concentration for sample 1 and sample 2 being ~ 0.5 and ~ 0.7 mg/L, respectively. The difference in the results can be attributed to the MABs technique which is well detailed in the previously published work [12, 13, 15, 16].…”

“…Protein assay, b-BSA (a model protein) was carried out as described in our previous work [12, 13]. The colorimetric detection method was used to report the magnitude of the enzymatic signal.…”