Enhanced capture efficiencies of antigens in immunosensors

• Higher capture efficiency is an important performance parameter for immunosensors.
• Experiments were conducted to understand the effect of the process parameters.
• Models were used to extract the dependencies of the transport and reaction parameters.
• Simulations were used to find the optimal conditions for the highest antigen capture.
• Effects of pH and the underlying mechanisms of antigen capture were explained.

Higher capture efficiencies with faster response times are important performance benchmarks for heterogeneous immunosensors which are utilized in recognitions of analytes for disease detection. As the capture involves transport of antigens from the bulk solution to the surface immobilized antibodies and the subsequent binding, the transport and reaction parameters play a critical role. While there are reports on the effect of individual process parameters (temperature, extent of mixing, pH) on the antigen/antibody interaction, we are not aware of any studies on the combined effect of these process parameters, and moreover, there are limited studies on the effect of these process parameters on the reaction and transport parameters. Knowledge of the effect of the process parameters on the transport and reaction parameters is necessary to understand their relative contributions to and the mechanism involved in the capture of the antigens. In this work, we have made an attempt to quantify the transport and reaction parameters and studied their dependencies on the process parameters. Experiments were conducted with three systems – BSA/anti-BSA, PSA/anti-PSA and CRP/anti-CRP, to quantify the captured antigen. The dependencies of the process parameters on the transport and reaction parameters were obtained from the experimental data using a diffusion–convection–electromigration–reaction model. Utilizing these dependency functions, the process parameters were modeled to find the optimal conditions for the highest capture efficiencies. Specifically, the influence of pH on maximizing the antigen capture and the underlying mechanism of the electrostatic interactions based on the surface charges and zeta potentials were elucidated.

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