In this study, we have prepared a series of novel biodegradable polymer [Polylactide (PLA)]-based nanocomposites using graphite nanosheets (GNs) and multi-walled carbon nanotubes (MWCNTs) by solution-blending technique and investigated their morphologies, structures, thermal stabilities, mechanical and dielectric properties, and electrical and thermal conductivities. Before preparation of the PLA/GNs/MWCNTs nanocomposites, the raw GNs used were endured a rapid expansion by thermal treatment. Temperature of this treatment had some obvious impacts on morphological changes of graphite nanosheets which were verified by means of scanning electron microscope (SEM) and X-ray diffraction (XRD) techniques. Resultant nanocomposites were characterized and evaluated by means of SEM, XRD, thermal conductivity measurements, tensile and impact tests, thermogravimetric analysis and dielectric measurements. Results obtained in this study indicated that thermal-expanded GNs in the presence of MWCNTs facilitate the formation of an appropriate conductive network in PLA matrix which resulted in a relatively low percolation threshold for thermal and electrical conductions of PLA/GNs/MWCNTs nanocomposites. Significant improvements in thermal and electrical conductivities, thermal stability and mechanical properties of PLA/GNs/MWCNTs nanocomposites obtained through the presence of both nanoparticles in PLA matrix were associated with their good co-dispersion and co-reinforcement effects. The macroscopic properties of nanocomposites were found to be strongly dependent on their components, concentrations, dispersion, and the resulted morphological structures.

Introduction: The venom of Jellyfish venom contains a variety of bioactive proteins that can be studied for vaccine application. Poly-Lactic Acid is a biodegradable polymer that is used in vaccine systems. The aim of this study was to encapsulate the C-CfTX1-STxB protein into PLA-PEG-PLA three-block copolymer and its immunogenicity study in mice. Materials and Methods: After purification, the protein was confirmed by Western Blot. Then, the antigen was loaded in the three-block copolymer using the solvent evaporated method and prepared nanoparticles characteristics by SEM electron microscopy and DLS. Following encapsulated and free antigen with complete and incomplete adjuvant, PBS and PLA_PEG-PLA nano were injected subcutaneously into the mice four times. In the end, the amount of antibody produced was measured by indirect ELISA and the survival of immunized animals against challenges by jellyfish venom was studied. Results: The results showed that the prepared nanoparticles have good quality and quantity. The size of the nanoparticles was 176. 1 nm and the protein encapsulation efficiency was 71%. In the end, it was shown that immunized mice survived the challenge with the venom and the production of antibody titers was directly related to laboratory animal resistance. Conclusion: Regarding the lack of cardiotoxicity and neurotoxicity of the recombinant C-CfTX1-STxB protein, as well as the results, PLA-PEG-PLA nanoparticles could be suggested as suitable carriers for the preparation of a vaccine against jellyfish venom for further investigation.

In this study, chitosan/Polylactide scaffolds reinforced with nano-calcium phosphate (average crystallite size of 16.5 nm) (CP) were fabricated to create a material with excellent properties for bone tissue engineering applications via freeze-casting method. The structural and mechanical properties of nano composite scaffolds were studied by increasing amount of chitosan/poly lactide ratio and nano-CP content in both dry and hydrate states, which reflected the exact status of scaffolds in a real biomechanical environment. The morphologies of the nano composite scaffolds were viewed using scanning electron microscopy (SEM) and all the scaffolds exhibited a high porosity (up to 92 %) with open pores of 38–387 μm average diameters, which decreased with increased chitosan/Polylactide ratio and nano-CP content. Also, SEM photograph of the cross-sectional area of the scaffold showed nano-CP was dispersed all over the polymer matrix thoroughly. The results of mechanical tests showed that the compressive modulus (E) and compressive stress (s) enhanced, when chitosan and nano-CP increased. X-ray diffraction analysis indicated typical chitosan, polylactic acid and nano-CP peaks and showed that the increase in nano-CP weight percentage increased its peak intensities. In addition, the effect of pore-size distributions of the scaffolds with the same composition was studied in relation to mechanical properties. The results showed substantial differences in the pore-size distributions of scaffolds with the same composition prepared, which have no effect on their dry states.