Synthesis and characterization of poly(L-lactic acid-co-ethylene oxide-co-aspartic acid) and its interaction with cells

Multiblock terpolymer of poly(L-lactic acid)/ poly(ethylene oxide)/poly(L-aspartic acid), (PLLA/PEO/ PAsp) was synthesized by ring opening polymerization of β -benzyl L-aspartate N-carboxyanhydride, Asp(OBzl)-NCA with α-ω -hydroxy terminated triblock PLLA/PEO/PLLA copolymer. The resulting multiblock terpolymer was characterized by several techniques including Fourier transform infrared spectroscopy and differential scanning calorimetry.¹H nuclear magnetic resonance spectra indicated the molar ratio of PLLA/PEO/PAsp (OBzl) to be 86/10/4. Thermal gravimetric analysis and environmental scanning electron microscopy data showed that PLLA/PEO/PAsp had crystalline and brittle structure. In order to improve its mechanical and physical properties, the terpolymer was blended with high molecular weight poly(L-lactic-co-glycolic acid) copolymer, PLGA(85/15) (M_w: 95000 gmol^{− 1}) in 25/75 and 50/50 mole ratios. The hydrolytical degradation properties of these polymers were studied. Degradation experiments were performed during a 48-day period in pH:7.4 phosphate-buffered saline (PBS) at 37^∘C. The observed molecular weight losses were 91% and 67% for the 25/75 and 50/50 mixtures, respectively. In vitro attachment and growth of L929 mouse fibroblasts on these biopolymers were also investigated. Cell growth experiments indicated that the copolymer blend allowed the attachment and growth of cells.     

Sponge-like chitosan-based nanostructured antibacterial material as a topical hemostat

In this study, chitosan/alginic acid/zinc oxide (CHI/AA/ZnO) nanostructured hydrogel sponges were fabricated by incorporating ZnO nanoparticles (<100 nm) into polymer matrix to develop a new potential biomaterial for hemorrhage control. For this purpose, the crosslinked CHI/AA/ZnO nanostructured sponges were synthesized by freeze-drying technique. Genipin was used as a crosslinker. The prepared chitosan-based sponges were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy—energy-dispersive spectroscopy analysis. The effects of ZnO content on the physicochemical characteristics of sponge-like nanostructured hydrogels were evaluated by swelling ratio in two different pH values. Physical immobilization of dexamethasone as a model drug in hydrogel matrix resulted sustained release of drug more than 3 days. Antibacterial activity of hydrogel sponges was assessed against Staphylococcus aureus. The cytotoxicity and hemostatic efficacy of crosslinked CHI/AA/ZnO sponge like-nanostructured hydrogels was evaluated in vitro and in vivo, respectively. The results of this study demonstrated that the prepared CHI/AA/ZnO nanostructured sponge had the potential to be an antibacterial topical hemostat. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47522.     

Characterization of key aroma compounds in a representative aromatic extracts from citrus and astragalus honeys based on aroma extract dilution analyses

The aroma and aroma-active compounds of astragalus and citrus honeys were determined by GC-MS-olfactometry (GC-MS-O). The honey extracts were obtained by two different extraction techniques including liquid–liquid extraction (LLE) and solid phase extraction (SPE), and compared to determine the more representative odour aromatic honey extract. According to sensory analysis, the aromatic extract (40 g honey with 22 mL water) obtained by LLE was the most similar of honey odour. The amount of aroma compounds of citrus honey (14391.6 µg kg^?1) was higher than astragalus honey (4270.1 µg kg^?1). Terpenes and acids in citrus honey and esters and aldehydes in astragalus honey were the most dominant aroma compounds. Aroma extract dilution analysis (AEDA) was used to determine the aroma-active compounds of honey samples. By application of AEDA on the aromatic extracts isolated by LLE, 12 aroma-active compounds in astragalus honey and 23 in citrus honey could be detected within a flavour dilution (FD) factor range of 8–128. On the basis of the FD factor, phenylethyl alcohol in both honeys was the most powerful key compound and was described as the flowery odour.     

Controlled release of imatinib mesylate from PLGA microspheres inhibit craniopharyngioma mediated angiogenesis

Poly(lactic-co-glycolic acid) microspheres loaded with imatinib mesylate has been developed as a new therapeutic strategy to prevent craniopharyngioma recurrence. Microspheres composed of different lactic/glycolic acid ratios, molecular weights and drug compositions were synthesized and loaded with imatinib mesylate by modified double-emulsion/solvent evaporation technique and subsequently characterized by particle-size distribution, scanning electron microscopy, encapsulation efficiency and in vitro drug release. Inhibitory potential of imatinib containing microspheres on tumor neovascularization was investigated on craniopharyngioma tumor samples by rat cornea angiogenesis assay. Results showed that microspheres in different LA:GA ratios [LA:GA 50:50 (G50), 75:25 (G25), 85:15 (G15)] considerably reduced neovascularization induced by recurrent tumor samples in an in vivo angiogenesis assay (P < 0.01). Our data indicate that local delivery of imatinib mesylate to the post-surgical tumoral cavity using biodegradable microspheres may be a promising biologically selective approach to prevent the recurrence of craniopharyngiomas, via inhibition of neovascularization.