Thermal Mechanical Stretching to Imprint Pores Morphology of Nitrocellulose Membrane for Immuno-sensing Application

Abstract

Performance of membrane such as the lateral flow wicking time and protein binding ability are important to generate consistent results for diagnostics purposes. Different diagnostic kit need different surface properties of membrane, structures and dimension. This work evaluates the feasibility of controlling membrane pores morphology through thermal-mechanical stretching. Results shows that membrane fabricated using longer nitrocellulose (NC) polymer chain length produced smaller pores with lower porosity (56%). Thus, it took longer time of 32s to migrate the testing liquid along the membrane strip. By having higher membrane’s porosity (72.3%), the membrane synthesized using shorter NC chain length exhibited faster wicking time, which is 3 times faster (wicking time of 8s) than that of the membrane produced with longer NC chain length. In terms of the thermal-mechanical stretching effects, the stretched membranes (both uniaxial and biaxial directions) had demonstrated improved immunoassay performances compared to the unstretched membrane. Specifically, uniaxial stretching is preferable than biaxial stretching configuration, due to the great improvement of lateral wicking time (22% faster) without jeopardize the membrane protein binding capacity (only 1.7% decrement), in relative to the unstretched membrane. This study provides some interesting insight on the physical membrane modification to provide better performance in immunoassay applications.