Preparation and investigation of poly [N-isopropylacrylamide-acrylamide] membranes in temperature responsive drug delivery

Physiological changes in the body may be utilized as potential triggers for controlled drug delivery. Based on these mechanisms, stimulus-responsive drug delivery has been developed. In this study, a kind of poly [N-isopropylacrylamide-acrylamide] membrane was prepared by radical copolymerization. Changes in swelling ratios and diameters of the membrane were investigated in terms of temperature. On-off regulation of drug permeation through the membrane was then studied at temperatures below and above the phase transition temperature of the membrane. Two drugs, vitamin B[12] and acetaminophen were chosen as models of high and low molecular weights here, respectively. It was indicated that at temperatures below the phase transition temperature of the membrane, copolymer was in a swollen state. Above the phase transition temperature, water was partially expelled from the functional groups of the copolymer. Permeation of high molecular weight drug models such as vitamin B[12] was shown to be much more distinct at temperatures below the phase transition temperature when the copolymer was in a swollen state. At higher temperatures when the copolymer was shrunken, drug permeation through the membrane was substantially decreased. However for acetaminophen, such a big change in drug permeation around the phase transition temperature of the membrane was not observed. According to the pore mechanism of drug transport through hydrogels, permeability of solutes decreased with increasing molecular size. As a result, the relative permeability, around the phase transition temperature of the copolymer, was higher for solutes of high molecular weight

novel composite membrane for ph responsive permeation

In this study, a kind of pH sensitive composite membrane was prepared and drug permeation through it was investigated in terms of pH. Rationale of this study originated from the fact that a pH change which may be a result of a disease state in the body can trigger drug release. Here, a kind of pH sensitive composite membrane containing different nanoparticle [1: 1 n-isopropyl acrylamide [Nipam]: metacrylic acid [Maa]] contents in ethylcellulose was prepared by a casting method. Swelling ratios of these nanoparticles and composite membranes with different particle loadings were determined. Permeation of two different drug models with different hydrophilicity and molecular weights, vitamin B12 [vit B12] and paracetamol, through these membranes was studied in terms of pH. It was seen that swelling ratios of nanoparticles and the composite membranes went up as the particle content increased at each pH. Vit B12 and paracetamol permeation through the membranes in pH value below the pKa was much higher than that at pHs above it, but this difference was much more pronounced for vit B12 compared to paracetamol. Permeation through these membranes showed a sharp sensitivity to pH changes. Nanoparticles in the composite membranes could act as nanovalves due to their sharp swelling/shrinkage around the pKa of Maa. These membranes could be considered as an ideal stimuli-sensitive barrier for modulating drug release with a small change in pH