Electrospun gelatin biopapers as substrate for in vitro bilayer models of blood-brain barrier tissue.

Gaining a greater understanding of the blood-brain barrier (BBB) is critical for improvement in drug delivery, understanding pathologies that compromise the BBB, and developing therapies to protect the BBB. In vitro human tissue models are valuable tools for studying these issues. The standard in vitro BBB models use commercially available cell culture inserts to generate bilayer co-cultures of astrocytes and endothelial cells (EC). Electrospinning can be used to produce customized cell culture substrates with optimized material composition and mechanical properties with advantages over off-the-shelf materials. Electrospun gelatin is an ideal cell culture substrate because it is a natural polymer that can aid cell attachment and be modified and degraded by cells. Here, we have developed a method to produce cell culture inserts with electrospun gelatin "biopaper" membranes. The electrospun fiber diameter and cross-linking method were optimized for the growth of primary human endothelial cell and primary human astrocyte bilayer co-cultures to model human BBB tissue. BBB co-cultures on biopaper were characterized via cell morphology, trans-endothelial electrical resistance (TEER), and permeability to FITC-labeled dextran and compared to BBB co-cultures on standard cell culture inserts. Over longer culture periods (up to 21 days), cultures on the optimized electrospun gelatin biopapers were found to have improved TEER, decreased permeability, and permitted a smaller separation between co-cultured cells when compared to standard PET inserts.

Molecular orientation evolution and solvent evaporation during electrospinning of atactic polystyrene using real-time Raman spectroscopy.

Real-time Raman spectroscopy was successfully utilized to monitor solvent evaporation and molecular orientation during electrospinning of atactic polystyrene (a-PS). The use of a binary solvent system of N,N-dimethyl formamide (DMF) and tetrahydrofuran (THF) provided a stable, straight jet during the experiment. The prominent Raman bands centered at 866 cm(-1), 914 cm(-1), and 1004 cm(-1), unique to DMF, THF, and a-PS, respectively, were used to monitor solvent concentration changes along the electrospinning jet for two different a-PS solutions. In addition, the changes in relative intensity for the radial skeletal ring vibration of the aromatic group of a-PS at 623 cm(-1) in two different polarization geometries, ZZ and YY, were monitored for orientation information. This study reports the first quantitative vibrational spectroscopic measurement during the electrospinning process. A significant change in concentration and orientation was observed during the process. The changes are explained in relation to the electrospinning process.