Abstract We report on the preparation and characterization of nanocomposite chitosan hydrogels with embedded poly (lactic-co-glycolic acid) (PLGA) nanoparticles employed for encapsulation of an enriched flavonoid fraction of Cecropia glaziovii Snethl. As a first step, the experimental conditions to obtain homogeneous chitosan hydrogels at 37 °C through gelation with NaHCO3 were optimized. Then, nanocomposite chitosan hydrogels were prepared through direct incorporation of nanoparticlesat different concentrations ranging from 1 to 10% w/w to gelling aqueous chitosan solutions. The resulting hydrogels were characterized through Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), oscillatory rheological experiments and cytotoxicity tests. FT-IR spectra confirmed the PLGA nanoparticles presence within the chitosan matrix through the absorption peak located at 1750 cm−1. The presence of the PLGA nanoparticles decreased the thermal stability of the nanocomposite chitosan hydrogels compared to the pure chitosan hydrogel. SEM images allowed observing porous matrixes where nanoparticles appeared to be homogeneously dispersed. The elastic moduli found for nanocomposite chitosan hydrogels varied with the PLGA nanoparticles concentration with a maximum at 3% nanoparticles concentration. Cytotoxicity tests revealed that after 48 h, neither thepure hydrogel nor the nanocomposite chitosan hydrogels with 10% nanoparticles concentration showed toxicity on VERO cells.

中文翻译：

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基于PLGA纳米粒子的纳米复合壳聚糖水凝胶作为潜在的生物医学材料

摘要我们报告了纳米复合壳聚糖水凝胶的制备和表征，其中嵌入了聚（乳酸 - 共 - 乙醇酸）（PLGA）纳米颗粒，用于封装 Cecropia glaziovii Snethl 的富含类黄酮部分。作为第一步，优化了通过与 NaHCO3 凝胶化在 37°C 下获得均质壳聚糖水凝胶的实验条件。然后，纳米复合壳聚糖水凝胶是通过直接掺入不同浓度的纳米颗粒来制备的，纳米颗粒的浓度范围从 1% 到 10% w/w，以胶凝壳聚糖水溶液。通过傅里叶变换红外光谱 (FT-IR)、热重分析 (TGA)、扫描电子显微镜 (SEM)、振荡流变实验和细胞毒性测试对所得水凝胶进行表征。FT-IR 光谱通过位于 1750 cm-1 的吸收峰证实壳聚糖基质中存在 PLGA 纳米颗粒。与纯壳聚糖水凝胶相比，PLGA 纳米颗粒的存在降低了纳米复合壳聚糖水凝胶的热稳定性。SEM 图像允许观察多孔基质，其中纳米颗粒似乎均匀分散。纳米复合壳聚糖水凝胶的弹性模量随 PLGA 纳米颗粒浓度而变化，最大纳米颗粒浓度为 3%。细胞毒性试验表明，48 小时后，无论是纯水凝胶还是 10% 纳米颗粒浓度的纳米复合壳聚糖水凝胶，均未显示出对 VERO 细胞的毒性。与纯壳聚糖水凝胶相比，PLGA 纳米颗粒的存在降低了纳米复合壳聚糖水凝胶的热稳定性。SEM 图像允许观察多孔基质，其中纳米颗粒似乎均匀分散。纳米复合壳聚糖水凝胶的弹性模量随 PLGA 纳米颗粒浓度而变化，最大纳米颗粒浓度为 3%。细胞毒性试验表明，48 小时后，无论是纯水凝胶还是 10% 纳米颗粒浓度的纳米复合壳聚糖水凝胶，均未显示出对 VERO 细胞的毒性。与纯壳聚糖水凝胶相比，PLGA 纳米颗粒的存在降低了纳米复合壳聚糖水凝胶的热稳定性。SEM 图像允许观察多孔基质，其中纳米颗粒似乎均匀分散。纳米复合壳聚糖水凝胶的弹性模量随 PLGA 纳米颗粒浓度而变化，最大纳米颗粒浓度为 3%。细胞毒性试验表明，48 小时后，无论是纯水凝胶还是 10% 纳米颗粒浓度的纳米复合壳聚糖水凝胶，均未显示出对 VERO 细胞的毒性。纳米复合壳聚糖水凝胶的弹性模量随 PLGA 纳米颗粒浓度而变化，最大纳米颗粒浓度为 3%。细胞毒性试验表明，48 小时后，无论是纯水凝胶还是 10% 纳米颗粒浓度的纳米复合壳聚糖水凝胶，均未显示出对 VERO 细胞的毒性。纳米复合壳聚糖水凝胶的弹性模量随 PLGA 纳米颗粒浓度而变化，最大纳米颗粒浓度为 3%。细胞毒性试验表明，48 小时后，无论是纯水凝胶还是 10% 纳米颗粒浓度的纳米复合壳聚糖水凝胶，均未显示出对 VERO 细胞的毒性。