Enhanced mechanical properties and electrical conductivity of Chitosan/Polyvinyl Alcohol electrospun nanofibers by incorporation of graphene nanoplatelets

The subject of this paper is to develop a highly conductive Graphene nanoplatelets (GNPs)-Chitosan (CS)/Polyvinyl Alcohol (PVA) (GNPs-CP) nanofibers with excellent mechanical properties. An experimental study was designed to produce nanofibers based on CP nanofibers as matrix and GNPs as reinforcement materials. The microstructure and the surface morphology of the electrospun nanofibers along with their electrical and mechanical properties were examined to study the effect of GNPs content. The SEM results showed that the gradual increase in GNPs content led to a porous web like morphology with no bead. There is a decrease in the diameter of nanofibers by increasing the concentration of GNPs to 1 wt% GNPs from 370 ± 40 nm for CP blend to 144 ± 18 nm for 1 wt% GNPs. Transmission electron microscopy results depicted that GNPs were dispersed uniformly confirmed by the absence of characteristic peak of graphite at 2θ = 26.5°. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy results indicate the occurrence of a few interactions between GNPs and CP matrix. Nitrogen adsorption/desorption measurement demonstrated that increasing GNPs content increased the specific surface area of nanofibers from 238.377 to 386.708 m²/g for 0 and 1 wt% GNPs content. The test results also show that the presence of GNPs considerably enhances tensile strength, elastic modulus and electrical conductivity. Furthermore, the toughness of GNPs-CP nanofibers including 1 wt% GNPs significantly improved (12-fold) compared to the one for CP nanofibers. So, the proposed composite provides a decent functionality for nanofibers as scaffolds in tissue engineering applications.

Synthesis and Nanomechanical Properties of Polystyrene/Silica Core/Shell Particles Via Atomic Force Microscopy

Due to the unique properties of core/shell particles, these structures have been considered in various applications. Employing core/shell particles consisting of a polymer core and a ceramic shell as an abrasive in a chemical mechanical planarization (CMP) process enhanced the quality of processed wafers. In the present study, polystyrene/silica core/shell particles were synthesized and the elastic modulus was examined via atomic force microscopy (AFM). The impact of the indentation depth and contact mechanics models on the elastic modulus was studied. Also, the plastic properties of particles were examined for the first time. Using the Hertz model and a diamond-like carbon (DLC) probe, the elastic moduli of the polymer and core/shell particles were measured at 2.82 ± 0.03 and 6.53 ± 0.05 GPa, respectively.

In Vitro Assessment of Synthetic Nano Engineered Graft Designed for Further Clinical Study in Nerve Regeneration

Background: Electrospun nanofibrous scaffolds are considered as promising candidates in neural tissue regeneration due to their ability to support neural cell attachment, spreading and proliferation. Methods: In this paper, various type of nanofibers scaffold based on polycaprolactone) (PCL) were fabricated using electrospinning. The main drawback of PCL scaffolds is their low bioactivity of scaffold surface. To overcome this surface and composition modification was used to enhanced hydrophilicity and bioactivity of scaffold. Results: The scanning electron microscopy (SEM) results indicate that fiber diameter entirely depends on the solvent system and added component of gelatin and chitosan which by adding gelatin and chitosan fiber diameter decreased. In vitro studies using PC12 cells revealed that the plasma surface modified and blended scaffold with chitosan and gelatin nanofibrous scaffold supports cell attachment, spreading and indicate a significant increase in proliferation of PC12 in the presence of chitosan. The results demonstrated that gelatin and chitosan caused a significant enhancement in the bioactivity of the scaffold, which confirmed by MTT assay and improved the cell spreading and proliferation of neural cell on the scaffolds. Conclusion: Based on the experimental results, the PCL/chitosan/PPy conductive substrate could be used as a potential scaffold for clinical research in the field of neural regeneration and healing.