Fabricating an electroactive injectable hydrogel based on pluronic-chitosan/aniline-pentamer containing angiogenic factor for functional repair of the hippocampus ischemia rat model.

The hippocampus, a critical cerebral region involved in learning and memory formation, is especially vulnerable to ischemic defect. Here, we developed an injectable electroactive hydrogel based on pluronic-chitosan/aniline-pentamer with proper conductivity around 10-4 S/cm to achieve the functional repair of the hippocampus following the ischemic defect. FTIR, DSC, and TGA measurements were performed to assess the chemical structure and thermal stability of the synthesized hydrogel. Aniline pentamer decreased the swelling capacity, degradation, and drug release rate. Further, contact angle, melting point, and gelation time of hydrogels were enhanced by addition of aniline oligomer. Moreover, it endowed the on-demand electro-responsive drug release. Injectability of hydrogel was evaluated by rheometry, exhibiting proper gelling time at the body temperature. The ionic/electrical conductivity and desired in vitro biocompatibility with PC12 cells were also achieved. Injection of VEGF-loaded electroactive hydrogel in the hippocampal ischemic animal model resulted in decreased infarction volume, improved hippocampal dependent learning, and memory performance. Taken all together, the results confirmed that fabricated injectable hydrogel would be a suitable candidate for ischemic defect treatment and can lead to new horizons to treat neurological disorders.

Chitosan in Biomedical Engineering: A Critical Review.

Biomedical engineering seeks to enhance the quality of life by developing advanced materials and technologies. Chitosan-based biomaterials have attracted significant attention because of having unique chemical structures with desired biocompatibility and biodegradability, which play different roles in membranes, sponges and scaffolds, along with promising biological properties such as biocompatibility, biodegradability and non-toxicity. Therefore, chitosan derivatives have been widely used in a vast variety of uses, chiefly pharmaceuticals and biomedical engineering. It is attempted here to draw a comprehensive overview of chitosan emerging applications in medicine, tissue engineering, drug delivery, gene therapy, cancer therapy, ophthalmology, dentistry, bio-imaging, bio-sensing and diagnosis. The use of Stem Cells (SCs) has given an interesting feature to the use of chitosan so that regenerative medicine and therapeutic methods have benefited from chitosan-based platforms. Plenty of the most recent discussions with stimulating ideas in this field are covered that could hopefully serve as hints for more developed works in biomedical engineering.

A facile route to the synthesis of anilinic electroactive colloidal hydrogels for neural tissue engineering applications.

An innovative drug-loaded colloidal hydrogel was synthesized for applications in neural interfaces in tissue engineering by reacting carboxyl capped aniline dimer and gelatin molecules. Dexamethasone was loaded into the gelatin-aniline dimer solution as a model drug to form an in situ drug-loaded colloidal hydrogel. The conductivity of the hydrogel samples fluctuated around 10-5 S/cm which appeared suitable for cellular activities. Cyclic voltammetry was used for electroactivity determination, in which 2 redox states were observed, suggesting that the short chain length and steric hindrance prevented the gel from achieving a fully oxidized state. Rheological data depicted the modulus decreasing with aniline dimer increment due to limited hydrogen bonds accessibility. Though the swelling ratio of pristine gelatin (600%) decreased by the introduction and increasing the concentration of aniline dimer because of its hydrophobic nature, it took the value of 300% at worst, which still seems promising for drug delivery uses. Degradation rate of hydrogel was similarly decreased by adding aniline dimer. Drug release was evaluated in passive and stimulated patterns demonstrating tendency of aniline dimer to form a vesicle that controls the drug release behavior. The optimal cell viability, proper cell attachment and neurite extension was achieved in the case of hydrogel containing 10 wt% aniline dimer. Based on tissue/organ behavior, it was promisingly possible to adjust the characteristics of the hydrogels for an optimal drug release. The outcome of this simple and effective approach can potentially offer additional tunable characteristics for recording and stimulating purposes in neural interfaces.