Title : Excimer laser processing of ph and glucose sensing membranes for controlled drug delivery
pH and glucose responsive membranes can be used in controlled drug delivery applications. Controlled drug flow across the membrane is very important for such applications. It is therefore of the foremost importance to obtain membranes with uniform pore morphology. We developed a two-step membrane fabrication technique using 248 nm KrF excimer laser. In the first step uniform, ordered and well-defined porous structure is developed on polyimide (PI) film with the help of metal mask. In this step, laser fluence (energy/area), number of pulses and mesh size can be adjusted and optimized tocontrol the pore dimensions. In the second step, PI pores are further grafted with polyacrylic acid (PAAc) using the same 248 nm KrF excimer laser. Grafted membranes respond to the change in pH. The fabrication technique proves the versatility of laser as a tool to develop stimuli responsive polymeric membrane. Membrane fabrication time also reduces significantly to the order of minutes, or even, seconds. Grafting density, responsiveness and fabrication time can be tuned by appropriate selection of laser parameters and solution parameters. Two separate studies focusing on the effect of laser parameters and solution parameters on responsiveness of the membrane were carried out. Our work showed that PAAc hydrogel network remains intact inside PI pores under applied pressure. Diffusion transport studies across the membrane proved their potential application in drug delivery application. These membranes were further characterized using ATR-FTIR, fluorocense microscope and SEM. TGA was used to do the quantitative analysis of grafted membranes. We further immobilized these membranes with glucose oxidase. Diffusion studies across these immobilized membranes were carried out using caffeine as a model drug. These membranes not only detect the presence of glucose but can also respond corresponding to the amount of glucose present in the system. This opens a whole new window for potential application of the process for diabetes treatment.