Synthesis, Characterization, and Cytotoxicity Analysis of a Biodegradable Polyurethane

A polyester urethane was synthesized for use in a biodegradable scaffold. The polyurethane was synthesized in a two-step process: first, ester diol was synthesized from lactic acid and polyethylene glycol 400 (PEG 400), then it was polymerized with toluene diisocyanate using dibutyl tin dilaurate (DBTDL) as a catalyst to form a polyester urethane. Polyester urethane has tensile strength of 51-59 MPa and elongation at fracture of 369-439%. FTIR and XRD were used to confirm the formation and structure of the polymer. Hydrolytic degradation was studied in different alkali solutions and in saline water. In order to assess the cellular response of this material, cytotoxicity analysis was carried out against the cell line.     

Cancer preventive effect of Thai rat-tailed radish (Raphanus sativus L. var. caudatus Alef)

The cancer preventive effect of Raphanus sativus L. var. caudatus Alef (Thai rat-tailed radish) extract was evaluated against the HCT116 colon cancer cell line. HPLC and GC–MS were used to identify the phytoconstituents in Thai rat-tailed radish extract. Thai rat-tailed radish extract showed high cytotoxicity against HCT116 with an IC₅₀ at 9.42 ± 0.46 μg/ml. Apoptosis induced by Thai rat-tailed radish extract was confirmed (a) by DAPI staining which demonstrated nuclei morphological changes, chromatin condensation and nuclear fragmentation and (b) by Annexin V/PI flow cytometry. GC–MS analysis of Thai rat-tailed radish extract revealed two isothiocyanates; sulforaphane and sulforaphene, whose cytotoxicity and apoptosis induction effect were evident, giving Thai rat-tailed radish extract its anticancer attributes. This is the first report on the cancer preventive effect of Thai rat-tailed radish extract against HCT116 colon cancer cell line, through apoptosis induction.     

Reprint of: Improved cytotoxicity testing of magnesium materials

Metallic magnesium (Mg) and its alloys are highly suitable for medical applications as biocompatible and biodegradable implant materials. Magnesium has mechanical properties similar to bone, stimulates bone regeneration, is an essential non-toxic element for the human body and degrades completely within the body environment. In consequence, magnesium is a promising candidate as implant material for orthopaedic applications. Protocols using the guideline of current ISO standards should be carefully evaluated when applying them for the characterization of the cytotoxic potential of degradable magnesium materials. For as-cast material we recommend using 10 times more extraction medium than recommended by the ISO standards to obtain reasonable results for reliable cytotoxicity rankings of degradable materials in vitro. In addition primary isolated human osteoblasts or mesenchymal stem cells should be used to test magnesium materials.     

Improved cytotoxicity testing of magnesium materials

Metallic magnesium (Mg) and its alloys are highly suitable for medical applications as biocompatible and biodegradable implant materials. Magnesium has mechanical properties similar to bone, stimulates bone regeneration, is an essential non-toxic element for the human body and degrades completely within the body environment. In consequence, magnesium is a promising candidate as implant material for orthopaedic applications. Protocols using the guideline of current ISO standards should be carefully evaluated when applying them for the characterization of the cytotoxic potential of degradable magnesium materials. For as-cast material we recommend using 10 times more extraction medium than recommended by the ISO standards to obtain reasonable results for reliable cytotoxicity rankings of degradable materials in vitro. In addition primary isolated human osteoblasts or mesenchymal stem cells should be used to test magnesium materials.     

Cytotoxicity induced by nanobacteria and nanohydroxyapatites in human choriocarcinoma cells

We explored the cytotoxic effects of nanobacteria (NB) and nanohydroxyapatites (nHAPs) against human choriocarcinoma cells (JAR) and the mechanisms of action underlying their cytotoxicity. JAR cells were co-cultured with NB and nHAPs for 48 h, and ultrastructural changes were more readily induced by NB than nHAPs. Autophagy in the plasma of JAR cells were observed in the NB group. The rate of apoptosis induced by NB was higher than that for nHAPs. The expression of Bax and FasR proteins in the NB group was stronger than that for the nHAP group. NB probably resulted in autophagic formation. Apoptosis was possibly activated via FasL binding to the FasR signaling pathway.     

Synthesis of gold nanoparticles using aqueous extract of Calotropis procera latex

This is an account of the use of aqueous extract of the latex of Calotropis procera for the synthesis of gold nanoparticles. UV-Vis spectroscopic studies of the products resulting from reaction between the aqueous latex extract and chlorauric acid indicated the successful synthesis of gold nanoparticles. Reaction parameters viz. concentration of latex extract and reaction time were optimized for maximum yield of gold nanoparticles. Effect of reaction temperature on the synthesis rate of the particles and their optical properties was also studied. Transmission electron microscopic (TEM) studies of the particles revealed the dominance of spherical particles. Mean particle size distribution was found to be 22 ± 10 nm. Crystalline nature of the particles was confirmed from X-ray diffractrograms. FT-IR analysis and protein coagulation test of the gold nanoparticles confirmed capping behaviour of the latex proteins that contributed to their long term stability (6 months) in aqueous medium. Toxicity of the particles was tested on three cell lines, HeLa, A549 and BHK21. The method exploits a cheap and easily available biomaterial not explored so far for the synthesis of metallic nanoparticles.     

Preliminary evaluation of the in vitro cytotoxicity of PMMA-co-EHA bone cement

This work reports a preliminary in vitro cytotoxicity assessment of new poly (methyl methacrylate)-co-ethyl hexylacrylate (PMMA-co-EHA) bone cement by evaluating the effect of its leachables on the viability of human osteoblast-like cells (MG63 line) and their progression through the cell cycle. MG63 cells were exposed to 72 h-extract dilutions of PMMA-co-EHA and their viability was tested using the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. Also, putative changes in the progression of cells through the cell cycle were monitored using flow cytometry. For that the relative nuclear DNA content and the ratio of cells at G₁:S:G₂ stages of the cell cycle were measured after three exposure periods (24, 48 and 72 h). The obtained results revealed a dose-dependent influence of the cement extract in MG63 cell metabolism when compared to cells cultivated in a culture medium only. The MTT assay showed that a moderate number of cells died after exposure to the most concentrated extract. The cell cycle analysis revealed that leachables of PMMA-co-EHA led to significant changes in cellular proliferation, with cells exposed for 48 h to the most concentrated extract being arrested in the S phase of the cell cycle. However, despite the initial period of cytotoxicity, the obtained results suggest that after 72 h of exposure, the surviving cells are able to recover from this arresting condition and continue to proliferate. Therefore, this preliminary study indicates that, at the biological level, PMMA-co-EHA may have potential of being used as a bone cement matrix. However, a more detailed research work is needed to fully understand the factors responsible for the initial cytotoxicity observed.     

A study of the mechanism of in vitro cytotoxicity of metal oxide nanoparticles using catfish primary hepatocytes and human HepG2 cells

Nanoparticles (NPs), including nanometal oxides, are being used in diverse applications such as medicine, clothing, cosmetics and food. In order to promote the safe development of nanotechnology, it is essential to assess the potential adverse health consequences associated with human exposure. The liver is a target site for NP toxicity, due to NP accumulation within it after ingestion, inhalation or absorption. The toxicity of nano-ZnO, TiO₂, CuO and Co₃O₄ was investigated using a primary culture of channel catfish hepatocytes and human HepG2 cells as in vitro model systems for assessing the impact of metal oxide NPs on human and environmental health. Some mechanisms of nanotoxicity were determined by using phase contrast inverted microscopy, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, reactive oxygen species (ROS) assays, and flow cytometric assays. Nano-CuO and ZnO showed significant toxicity in both HepG2 cells and catfish primary hepatocytes. The results demonstrate that HepG2 cells are more sensitive than catfish primary hepatocytes to the toxicity of metal oxide NPs. The overall ranking of the toxicity of metal oxides to the test cells is as follows: TiO₂ < Co₃O₄ < ZnO < CuO. The toxicity is due not only to ROS-induced cell death, but also to damages to cell and mitochondrial membranes.     

米糠纳米纤维素的制备表征及其细胞毒性

研究以提取的米糠纤维素（纤维素含量90.22%）为原料,采用不同体积分数硫酸水解（60%、64%和68%）制备获得米糠纳米纤维素（Rice Bran Nanocellulose,RBNC）,对其表面形貌、尺寸、电位、化学结构、热稳定性及晶体结构进行了表征,并进一步评价了其细胞毒性。透射电镜和原子力显微镜结果显示,制备得到的RBNC是长度在196.45 ~ 257.26 nm、直径为8.46 ~ 16.34 nm、长径比为17.06 ~ 24.34范围内的针状粒子;Zeta电位值在-32.9 ~ -35.2 mV范围内;红外光谱和X-射线衍射分析表明得到的RBNC化学结构未发生变化,仍保留纤维素Ⅰ型晶体结构。体积分数为64%的硫酸水解得到的RBNC长径比最优（24.34±3.63）、结晶度最高（81.32%）、Zeta电位绝对值最大（-35.2±0.85 mV）。进一步的细胞毒性评价表明,RBNC分别在≤ 2000 μg/mL和≤ 500 μg/mL浓度范围内,对Caco-2和HepG-2细胞无显著毒性,表现出良好的生物相容性。研究结果可为RBNC做为一种新型纳米材料在食品领域的应用提供理论基础,为米糠的高值化利用提供新途径。