Controlled Release of Metformin Hydrochloride from Core-Shell Nanofibers with Fish Sarcoplasmic Protein.

Background and Objectives: A coaxial electrospinning technique was used to produce core/shell nanofibers of a polylactic acid (PLA) as a shell and a polyvinyl alcohol (PVA) containing metformin hydrochloride (MH) as a core. Materials and Methods: Fish sarcoplasmic protein (FSP) was extracted from fresh bonito and incorporated into nanofiber at various concentrations to investigate the influence on properties of the coaxial nanofibers. The morphology, chemical structure and thermal properties of the nanofibers were studied. Results: The results show that uniform and bead-free structured nanofibers with diameters ranging from 621 nm to 681 nm were obtained. A differential scanning calorimetry (DSC) analysis shows that FSP had a reducing effect on the crystallinity of the nanofibers. Furthermore, the drug release profile of electrospun fibers was analyzed using the spectrophotometric method. Conclusions: The nanofibers showed prolonged and sustained release and the first order kinetic seems to be more suitable to describe the release. MTT assay suggests that the produced drug and protein loaded coaxial nanofibers are non-toxic and enhance cell attachment. Thus, these results demonstrate that the produced nanofibers had the potential to be used for diabetic wound healing applications.

Applications of mesoporous silica in biosensing and controlled release of insulin.

The development of new oral insulin delivery systems could bring significant benefits to insulin-dependent patients due to the simplicity of the method, avoidance of pain caused by parenteral administration and maintenance of optimal therapeutic levels for a longer period. However, administration of such therapeutic proteins orally remains a challenge because insulin (Ins) is a very sensitive molecule and can be easily degraded under the existing pH conditions in the stomach and intestines. Moreover, due to the large size of insulin, intestinal epithelium permeability is very low. This could be improved by immobilizing insulin in the mesoporous silica pores (MSN), acting as a shield to protect the molecule integrity from the proteolytic degradation existing in the stomach and upper part of the small intestine. Due to the high adsorption capacity of insulin, biocompatibility, ease of functionalization with various organic and/or inorganic groups, high mechanical and chemical resistance, adjustable pore size and volume, MSN is considered an ideal candidate for the development of controlled release systems that are sensitive to various stimuli (pH, temperature) as well as to glucose. Modifying MSN surfaces by coating with various mucoadhesive polymers (chitosan, alginate, etc.) will also facilitate interaction with the intestinal mucus and improve intestinal retention time. Moreover, the development of glucose-responsive systems for achieving MSN-based self-regulated insulin delivery, decorated with various components serving as sensors - glucose oxidase (GODx) and phenylboronic acid (PBA) that can control the insulin dosage, avoiding overdose leading to serious hypoglycemia. MSN have also been tested for application as biosensors for glucose monitoring.