Hindered diffusion in lateral flow nitrocellulose membrane: Experimental and modeling studies

Lateral flow systems in nitrocellulose (NC) membranes are widely used for transport media applications related to immunoassays. The most important aspect of membranes is their ability to control the diffusion rate of the medium. This study investigated the effects of membrane pore size on lateral diffusion of protein molecules in a NC membrane. Both experimental work and mathematical modeling were carried out in this study. In modeling, the driving force for transportation of the diffusing molecule was the concentration gradient in lateral diffusion cell under unsteady diffusion. Diffusion experiments for Lysozyme and BSA were carried out by using different pore sizes of NC membranes. Good agreement was observed between the developed model and experimental results with correlation coefficients of more than 0.98. Effects of diffusion length and different diffusing molecules toward the lateral diffusion performance in NC membranes were also discussed extensively. The good fit between the model and experimental results has proven the reliability and flexibility of the lateral diffusion model developed in this study. The understanding of the diffusion phenomenon would be a useful tool for membrane properties design and customization of specific membrane applications in immunoassay.