A facile electrophoresis sensor with capacitively coupled contactless conductivity for detection of protein content in biosamples

Abstract

To address the issue of the dependence electrophoresis titration (ET) visualization technique on indicators and achieve rapid quantitative detection of protein content, an electrophoresis titration sensor with capacitively coupled contactless conductivity detection (ET-C4D) model and theory were proposed. First, the relevant numerical simulation was developed to validate the developed ET-C4D model and theory. Second, a detection device has been built and a software has been developed that could capture the conductivity changes of substances in the detection channel in real time. Herein, two systems, the polyacrylamide gel (PAG) and the agarose gel, were used to verify the validity of the ET-C4D model, theory and numerical simulation. The experiments showed that the detection results of ET-C4D using two gel systems were in agreement with the simulation results, validating the numerical simulation, theory, and model of ET-C4D. Finally, the ET-C4D was applied to the protein content analysis of Yili skim milk samples and the detection data of ET-C4D were in agreement with actual data, further validating the model and theory. The ET-C4D had the following merits: (i) facile and rapid quantitative detection avoiding complex image processing via optical detection device and process of adding indicators to color the moving boundary, (ii) fair linear range of 0.5–3 mg/mL in PAG and 2.5–10 mg/mL in agarose gel and (iii) good sensitivity of 0.05 mg/mL limit of detection (LOD). All these results proved that the developed model, theory and device have good applicability to the analysis of the dairy product content and the quantitative analysis of biosamples.