Analytical and Biomedical Applications of Porous Membranes

Abstract

<p>Membrane filtration is widely used to biomedical and analytical applications. Compared to other techniques available membrane filtration provides fast processing time, easy availability, robust performance and relatively low cost. These advantages make ultrafiltration and microfiltration well integrated into bioseparation, purification of biomedical materials and downstream polishing. Apart from the advatanges, there are certain drawbacks with microfiltration and ultrafiltration. While perceived negative in many scenarios, the effects does not necessarily counteract the purpose of the process and could find some useful applications if treated from a different perspective.</p> <p>By the virtue of fast processing of membrane filtrations, applications were made in processing biomedical materials and developing analytical methods. Poly(<em>N</em>-isopropylacrylamide) microgels are of potential in many biomedical applications. Microfiltration and ultrafiltration of such microgels for fast purification were explored. Meanwhile, the environmental responsive behaviours of such microgels bring about opportunity and challenge. Investigations were made on the salt-responsive transmission behaviours of microgels in microfiltrations. A hypothesis was raised and verified. Implications of applications <em>in vivo</em> were drawn based on experimental results. Many techniques for analysis of protein-drug binding have been under development. A new alternative utilizing pulsed tangential flow ultrafiltration was developed in this study and used to obtain binding data between aspirin and BSA under different conditions. The performance of the systems was assessed under different parameter settings. Possibility of further automation was discussed. On account of the fouling and concentration polarization, a new perspective was taken with the effort of developing such effects into potential applications. Patterned fouling was introduced and the fouled membrane was used to filter coloured feed to reveal the patterns transferred. Concentration polarization in ultrafiltrations with different levels of fixation of membranes was visualized by dyed particles. The possible flow modes under these conditions were suggested. A hypothesis was attempted from a fluidics point of view.</p>