A novel injectable pH-temperature sensitive hydrogel containing chitosan-insulin electrosprayed nanosphere composite for an insulin delivery system in type I diabetes treatment.

A novel insulin composite delivery system was prepared and characterized. The composite consisted of a pH- and temperature-sensitive hydrogel, which is an oligomer serine-b-poly(lactide)-b-poly(ethylene glycol)-b-poly(lactide)-b-oligomer serine (OS-PLA-PEG-PLA-OS) pentablock copolymer, as matrix and chitosan-insulin electrosprayed nanospheres (CIN) as constituent materials. The properties of the OS-PLA-PEG-PLA-OS pentablock copolymer and the chitosan-insulin nanoparticles were characterized. The chitosan-insulin nanospheres uniformly distributed in the matrix had a reinforcing effect on the mechanical properties and prolonged the degradation time of the hydrogel depot under body conditions. The composite solutions accommodating different concentrations of the chitosan-insulin nanospheres were subcutaneously injected into induced diabetic BALB/c mice to study the in vivo insulin-release profile. The result showed that insulin concentrations in blood plasma were maintained at a steady-state level. Furthermore, the bio-properties of the insulin were retained and it showed a blood glucose level reducing effect for more than 60 hours after injection to a streptozotocin (STZ)-induced diabetic mouse model. The results suggested that this injectable pH-temperature sensitive hydrogel containing chitosan-insulin electrosprayed nanosphere composites has promising potential applications for type 1 diabetes treatment.

Facile and Scalable Fabrication of Porous Polystyrene Fibers for Oil Removal by Centrifugal Spinning.

The demand for an efficient oil sorbent with high sorption capacity, low cost, scalable fabrication, and high selectivity for the cleanup of spreading oil on water is increasingly urgent due to the frequent occurrence of oil spill accidents in seawater all over the world. In this study, porous polystyrene (PS) fibers with high hydrophobicity and superoleophilicity were directly fabricated by a centrifugal spinning method (CS). The effect of solvents, tetrahydrofuran (THF), and dimethylformamide (DMF) on the morphology and porous structure of the polystyrene fibers was evaluated by using scanning electron microscopy and nitrogen adsorption-desorption experiments. The formation mechanism for the porous structure on the fibers was also evaluated. The oil sorption capacities of the PS fibers for silicon oil, pump oil, and vegetable oil were investigated. The highest oil sorption capacity was found in PS fibers fabricated from PS solution with a THF/DMF weight ratio of 1/3, which exhibited the highest specific surface area, pore volume, and porosity. The high productivity and highly porous structure of PS fibers indicate that CS is a promising method to fabricate porous fibers for the cleanup of oil spills.

pH-Sensitive pentablock copolymer nanocapsules as nontoxic and efficient gene carriers.

A biodegradable amphiphilic pentablock copolymer PAE-PCL-PEG-PCL-PAE with a pH-sensitive unit was synthesized for use as a nontoxic, biodegradable carrier for gene delivery by forming nanocapsules entrapping nucleic acid drugs. The PAE block can interact with plasmid DNA to form polyelectrolyte complexes in an acidic environment. At physiological pH, the PAE blocks are deprotonated and form an insoluble skin, resulting in the formation of nanocapsules that encapsulate plasmid DNA. The surface charges of the nanocapsules became almost neutral at pH = 7.4, and their size ranged from 210 to 280 nm. The nanocapsule maintained most of its transfection efficiency even in the presence of serum. These nanocapsules are therefore potential carriers for systemic gene therapy.