Adsorption and release of caffeine from smart PVDF polyampholyte membrane

Abstract

pH sensitivity, load, and release of caffeine from polyampholyte, acrylic acid (AAc), and 2-N,N-dimethylamino ethyl methacrylate (DMAEMA) grafted onto DURAPORE® PVDF membrane were studied. Polyampholyte was previously “grafted-from” on membranes by gamma irradiation technique in two steps: (1) PVDF-g-DMAEMA using direct method and (2) grafted AAc by pre-irradiation method, to obtain (PVDF-g-DMAEMA)-g-AAc. The results showed that binary copolymer grafted onto PVDF membrane PVDF-g-DMAEMA-g-AAc acts as responsive porous polymer membrane to control drug delivery. For this project, caffeine was used as a model drug. Drug adsorption was enhanced by the dissociation of grafting chains (PAAc and PDMAEMA) and by drug charge. The adsorption results showed that caffeine was loaded and released by the modified membrane and due to the nature of binary copolymer and the drug adsorption. Additional analysis as mechanical testing, scanning electron microscopy, and contact angle measurements was done to characterize the polyampholyte. This work designates the role of pH-sensitive acid, alkaline, and polyampholyte monomers in the improvement of no functionalized fluoropolymer membranes imparting its pH sensitivity and specific interaction with charged molecules as some drugs, proteins, or metals among others. The present results show that the load and release of caffeine adsorbed onto the pH-sensitive membrane and its strong dependence on pH and grafting degree. The membrane may be suitable for separating drugs from protein aqueous substances for subsequent monitoring and evaluation process.