Crystallization Control of N,N'-Dioctyl Perylene Diimide by Amphiphilic Block Copolymers Containing poly(3-Hexylthiophene) and Polyethylene Glycol.

The preparation of micron- to nanometer-sized functional materials with well-defined shapes and packing is a key process to their applications. There are many ways to control the crystal growth of organic semiconductors. Adding polymer additives has been proven a robust strategy to optimize semiconductor crystal structure and the corresponding optoelectronic properties. We have found that poly(3-hexylthiophene) (P3HT) can effectively regulate the crystallization behavior of N,N'-dioctyl perylene diimide (C8PDI). In this study, we combined P3HT and polyethylene glycol (PEG) to amphiphilic block copolymers and studied the crystallization modification effect of these block copolymers. It is found that the crystallization modification effect of the block copolymers is retained and gradually enhanced with P3HT content. The length of C8PDI crystals were well controlled from 2 to 0.4 µm, and the width from 210 to 35 nm. On the other hand, due to the water solubility of PEG block, crystalline PEG-b-P3HT/C8PDI micelles in water were successfully prepared, and this water phase colloid could be stable for more than 2 weeks, which provides a new way to prepare pollution-free aqueous organic semiconductor inks for printing electronic devices.

Effects of surface condition of conductive electrospun nanofiber mats on cell behavior for nerve tissue engineering.

Electrospun nanofibrous scaffold is a promising implant for peripheral nerve regeneration. Herein, to investigate the effect of surface morphological features and electrical properties of scaffolds on nerve cell behavior, we modified electrospun cellulose (EC) fibrous mats with four kind of soluble conductive polymers derivates (poly (N-(methacryl ethyl) pyrrole) (PMAEPy), poly (N-(2-hydroxyethyl) pyrrole) (PHEPy), poly (3-(Ethoxycarbonyl) thiophene) (P3ECT) and poly (3-thiophenethanol) (P3TE)) by an in-situ polymerization method. The morphological characterization showed that conductive polymers formed aggregated nanoparticles and coatings on the EC nanofibers with the increased fiber diameter further affected the surface properties. Compared with pure EC scaffold, more PC12 cells were adhered and grown on modified mats, with more integral and clearer cell morphology. The results of protein adsorption study indicated that modified EC mats could provide more protein adsorption site due to their characteristic surface morphology, which is beneficial to cell adhesion and growth. The results in this study suggested that these conductive polymers modified scaffolds with special surface morphology have potential applications in neural tissue engineering.

Electrospun cellulose-based conductive polymer nanofibrous mats: composite scaffolds and their influence on cell behavior with electrical stimulation for nerve tissue engineering.

The fabrication of scaffolds with suitable chemical, physical, and electrical properties is critical for nerve cell adhesion and proliferation. Recently, electrical stimulation on conductive polymers has been applied to construct functional nerve cell scaffolds. Herein, we prepared natural polymer (cellulose)/conductive polymer nanofibrous mats, i.e., electrospun cellulose (EC)/poly N-vinylpyrrole (PNVPY) and EC/poly(3-hexylthiophene) (P3HT) through an efficient in situ polymerization method. The surface immobilization was characterized by optical microscopy (OM), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, hydrophilicity, porosity, and cyclic voltammetry. The OM and SEM images showed that PNVPY formed polymer coatings and aggregated nanoparticles on the EC nanofibers, while P3HT only produced polymer coatings. Compared with pure EC mats, both the composite mats had increased thickness, higher porosity, and higher conductivity. Also, an increase in hydrophilicity was found for EC/P3HT. In vivo cytocompatibility of the undifferentiated PC12 cells showed that the EC/PNVPY and EC/P3HT scaffolds exhibited favorable cell activity, adhesion, and proliferation. Furthermore, the results of electrical stimulation experiments indicated that the EC/P3HT mats could effectively promote the proliferation of the PC12 cells more than the EC and EC/PNVPY mats. The findings suggest a positive outcome regarding the conductive polymer-modified EC/PNVPY and EC/P3HT nanofibrous mats in neural tissue engineering.

Electrospun natural polymer and its composite nanofibrous scaffolds for nerve tissue engineering.

Attributed to the excellent biocompatibility and desirable mechanical properties to natural tissue, natural polymer-based electrospun nanofibers have drawn extensive research interests in tissue engineering. Electrospun nanofibers have been explored as scaffolds in tissue engineering to modulate cellular behavior. Also, electrospun nanofiber matrices have morphological similarities to the natural extra-cellular matrix (ECM). Natural polymer and its composite nanofiber mats are the promising candidates in governing nerve cells growth and nerve regeneration due to their unique characteristics such as high permeability, stability, porosity, suitable mechanical performance and excellent biocompatibility. In this review, the progress in electrospun natural polymers and its composite nanofibers scaffold for neural tissue engineering are presented. The influences of fiber orientation and electrical stimulation on the nerve cell behavior and neurite growth are systematically summarized. Furthermore, the current application of natural polymer composite scaffold as in vivo implantable device for nerve regeneration is also discussed (see Figure 1).