Investigation on the morphology and the permeability of biomimetic cellulose triacetate (CTA) impregnated membranes (IM): In-situ synchrotron imaging, experimental and computational studies

Abstract

The goal of the present study is to ascertain the controlled permeability of the biomimetic cellulose triacetate (CTA) membranes at different temperatures and salt concentrations by investigating the electrical oscillatory behaviour across the impregnated membranes (IM). The novel biomimetic CTA membranes were infused with a capric fatty acid to induce the electrical oscillatory behavior, and hence, to ensure the controlled permeability. In-situ synchrotron-based X-ray tomography (SR-μCT) at BioMedical Imaging and Therapy (BMIT) Beamline at the Canadian Light Source (CLS) was used to evaluate the main impregnated membrane morphology compared to neat CTA to ensure the fatty acid penetration inside membrane pores along membrane matrices. This study has revealed changes in phase transition temperatures of the impregnated CTA membrane at the melting temperature of the fatty acid. The pulsations of measured voltages were observed to be related to changes in the KCl concentration in the vicinity of the Ag/AgCl electrode. In this study, amplitudes and frequencies of voltage pulsations were dependent on the temperature and concentration of the KCl solution to control the permeability of the biomimetic membrane membranes. Increasing the KCl concentration led to a higher frequency of oscillation which reflects a higher permeability. In addition, no mechanical stirring or disturbance of the system was required for the electrical oscillatory phenomenon to occur. Nevertheless, for the average waveforms, the peak-to-peak value obtained was doubled when stirring was performed, while for the higher amplitude waveforms, the amplitude increased by 5 times. In addition, interactions at the molecular level between water molecules and the fragments of infused membranes at different temperatures and their effect on controlling permeability was investigated using pair interaction energy decomposition analysis (PIEDA) as part of the fragment molecular orbital (FMO) method's framework. Those results opened new frontiers for facilitation and regulation of active transport and permeability through biomimetic smart membranes for a variety of biomedical and drug delivery applications.