Injectable and moldable hydrogels for use in sensitive and wide range strain sensing applications

Recently, the use of hybrid double network (DN) hydrogels has become prominent due to their enhanced mechanical properties, which has opened the door for new applications of these soft materials. Only a few of these gels have demonstrated both injectable and moldable capabilities. In this work, we report the mechanical properties, gauge factor (GF) values and demonstrate both the injectability and moldability of a gelatin/polyacrylamide DN hydrogel. We optimized several parameters, such as, gelatin to polyacrylamide ratio, reactant concentrations and metal ion concentration, to produce a gelatin/polyacrylamide hydrogel with superior mechanical properties. The highest water content gel was capable of withstanding strains of 5000% before failure. These gels were facilely injected into molds where they effectively changed shape and maintained similar properties prior to remolding. When 20 mM calcium was doped into a similar gel, a tensile strength of 1.71 MPa was achieved. Aside from improving the mechanical properties of the gels, both Ca²⁺ and Mg²⁺ also improved their conductivity, so they were tested for use as strain sensors. The sensitivity of the hydrogel strain sensors were measured using the GF. For the 20 mM Ca²⁺ hydrogel, these GF values ranged from 1.63 to 6.85 for strains of 100% to 2100% respectively. Additionally, the sensors showed good stability over continuous cyclic stretching, demonstrating their long term reliability for strain sensing.     

MiR-34a inhibits the proliferation,migration, and invasion of oral squamous cell carcinoma by directly targeting SATB2

In various kinds of carcinomas, the special AT-rich sequence-binding protein 2 (SATB2) with its atypical expression promotes the metastasis and progression of the tumor, though in the oral squamous cell carcinoma (OSCC) its inherent mechanism and the status of SATB2 remain unclear. The role played by the SATB2 expression in the OSCC cell lines and tissue samples in the target of miR-34a downstream is the intended endeavor of this study. In te OSCCs the miR-34a expression was determined by quantitative real-time polymerase chain reaction (q-PCR), while the SATB2 expression in the cell lines and tissue samples in OSCC was analyzed with the q-PCR and the western blot. Studies in both in vitro and in vivo of the effects of miR-34a on the initiation of OSCC were conducted. As a direct target of the miR-34a the SATB2 was verified with the luciferase reporter assay. In cases where the miR-34a levels were low, the SATB2 in OSCCs seemed to be overexpressed. Besides, both in the in vitro and in vivo a suppression of migration, invasion, and cell growth was caused by miR-34a by down regulating the SATB2 expression. The SATB2 being a direct target of miR-34a was confirmed by the cotransfection of miR-34a mimics specifically the decrease in the expression of luciferase of SATB2–3′UTR-wt reporter. As a whole, our study confirmed the inhibition of miR-34a in the invasion, proliferation, and migration of the OSCCs, playing a potential tumor suppressor role with SATB2 as its downstream target.     

Umbilical cord-derived mesenchymal stromal/stem cells expressing IL-24 induce apoptosis in gliomas

Although much progress has been made in the treatment of gliomas, the prognosis for patients with gliomas is still very poor. Stem cell-based therapies may be promising options for glioma treatment. Recently, many studies have reported that umbilical cord-derived mesenchymal stromal/stem cells (UC-MSCs) are ideal gene vehicles for tumor gene therapy. Interleukin 24 (IL-24) is a pleiotropic immunoregulatory cytokine that has an apoptotic effect on many kinds of tumor cells and can inhibit the growth of tumors specifically without damaging normal cells. In this study, we investigated UC-MSCs as a vehicle for the targeted delivery of IL-24 to tumor sites. UC-MSCs were transduced with lentiviral vectors carrying green fluorescent protein (GFP) or IL-24 complementary DNA. The results indicated that UC-MSCs could selectively migrate to glioma cells in vitro and in vivo. Injection of IL-24-UC-MSCs significantly suppressed tumor growth of glioma xenografts. The restrictive efficacy of IL-24-UC-MSCs was associated with the inhibition of proliferation as well as the induction of apoptosis in tumor cells. These findings indicate that UC-MSC-based IL-24 gene therapy may be able to suppress the growth of glioma xenografts, thereby suggesting possible future therapeutic use in the treatment of gliomas.     

Epigenetic modifier trichostatin A enhanced osteogenic differentiation of mesenchymal stem cells by inhibiting NF-κB (p65) DNA binding and promoted periodontal repair in rats

We wished to evaluate whether epigenetic modifiers have a beneficial effect on treating experimental periodontitis and mechanisms for regulating the cell fate of mesenchymal stem cells (MSCs) in inflammatory microenvironments. We isolated MSCs from healthy and inflamed gingival tissues to investigate whether trichostatin A (TSA) could improve osteogenic differentiation and resolve inflammation in vitro. The tissue regenerative potentials were evaluated when treated with a temperature-dependent, chitosan-scaffold-encapsulated TSA, in a rat model of periodontitis. After induction with the conditioned medium, TSA treatment increased the osteogenic differentiation potential of inflamed MSCs and healthy MSCs. In addition, interleukin-6 and interleukin-8 levels in supernatants were significantly decreased after TSA treatment. Moreover, TSA promoted osteogenic differentiation by inhibiting nuclear factor-κB (p65) DNA binding in MSCs. In rats with experimental periodontitis, 7 weeks after local injections of chitosan-scaffold-encapsulated TSA, histology and microcomputed tomography showed a significant increase in alveolar bone volume and less inflammatory infiltration compared with vehicle-treated rats. The concentrations of interferon-γ and interleukin-6 were significantly decreased in the gingival crevicular fluid after TSA treatment. This study demonstrated that TSA had anti-inflammatory properties and could promote periodontal tissue repair, which indicated that epigenetic modifiers hold promise as a potential therapeutic option for periodontal tissue repair.     

p120-catenin suppresses proliferation and tumor growth of oral squamous cell carcinoma via inhibiting nuclear phospholipase C-γ1 signaling

p120-catenin (p120) serves as a stabilizer of the calcium-dependent cadherin-catenin complex and loss of p120 expression has been observed in several types of human cancers. The p120-dependent E-cadherin-β-catenin complex has been shown to mediate calcium-induced keratinocyte differentiation via inducing activation of plasma membrane phospholipase C-γ1 (PLC-γ1). On the other hand, PLC-γ1 has been shown to interact with phosphatidylinositol 3-kinase enhancer in the nucleus and plays a critical role in epidermal growth factor-induced proliferation of oral squamous cell carcinoma (OSCC) cells. To determine whether p120 suppresses OSCC proliferation and tumor growth via inhibiting PLC-γ1, we examined effects of p120 knockdown or p120 and PLC-γ1 double knockdown on proliferation of cultured OSCC cells and tumor growth in xenograft OSCC in mice. The results showed that knockdown of p120 reduced levels of PLC-γ1 in the plasma membrane and increased levels of PLC-γ1 and its signaling in the nucleus in OSCC cells and OSCC cell proliferation as well as xenograft OSCC tumor growth. However, double knockdown of p120 and PLC-γ1 or knockdown of PLC-γ1 alone did not have any effect. Immunohistochemical analysis of OSCC tissue from patients showed a lower expression level of p120 and a higher expression level of PLC-γ1 compared with that of adjacent noncancerous tissue. These data indicate that p120 suppresses OSCC cell proliferation and tumor growth by inhibiting signaling mediated by nuclear PLC-γ1.     

荧光银纳米团簇的生物合成及其在痕量六价铬检测中的应用

【目的】利用季也蒙毕赤酵母ZJC-1合成银纳米团簇并用于痕量Cr(Ⅵ)的检测。【方法】使用经耐银驯化的季也蒙毕赤酵母ZJC-1生物合成荧光银纳米团簇,并对其结构和荧光性能进行了表征,探究Cr(Ⅵ)对银纳米团簇荧光的选择性猝灭作用,建立了银纳米团簇荧光强度与Cr(Ⅵ)浓度的线性关系。同时还考察了体系p H和其他金属离子对Cr(Ⅵ)检测的影响。【结果】Cr(Ⅵ)浓度在一定的范围内(1–80μmol/L)与银纳米团簇荧光强度(F_0–F)/F_0有着良好的线性关系(R~2=0.9821),线性方程为(F_0–F)/F_0=0.0054×C_cr(Ⅵ)+0.1876,检测限为184 nmol/L(信噪比为3)。利用该方法检测实际水样(松花江、马家沟河)中的Cr(Ⅵ),回收率介于97.73%–102.88%之间。【结论】以季也蒙毕赤酵母ZJC-1为还原剂和稳定剂,制备了具有较好荧光性能的水溶性银纳米团簇,基于Cr(Ⅵ)对银纳米团簇荧光的选择性猝灭作用,建立了一种快速且灵敏检测痕量Cr(Ⅵ)的新方法,并成功地应用于松花江、马家沟河水样中Cr(Ⅵ)的测定,在分析检测领域中具有良好的应用前景。     

基于环介导等温扩增技术的微流控芯片在病原菌检测方面的研究进展

环介导等温扩增(LAMP)技术是一种新兴的核酸恒温扩增技术,与微流控芯片技术相结合,可实现对病原菌的快速检测,具有特异性强、灵敏度高、操作简单等优点。本文根据不同终产物的检测方法对目前检测病原菌的相关微流控LAMP芯片进行了分类与介绍,并对技术的改进和存在的问题进行了分析,以期为后续的相关研究提供参考。     

长江口外低氧区及其邻近海域表层沉积物反硝化微生物多样性和分布特征

【目的】微生物参与的反硝化是河口区氮损失的主要途径。【方法】本研究采用Illumina MiSeq测序方法,研究了长江口外低氧区及其邻近海域表层沉积物中nirS型和nirK型反硝化微生物群落的多样性和分布特征。【结果】样品共检测到346个nirS Operational Taxonomic Units和267个nirK Operational TaxonomicUnits,根据采样地的环境特征及nirS型和nirK型反硝化微生物群落聚类分析结果将所有OperationalTaxonomicUnits划分为低氧区、南部区域及外部深水区,其中外部深水区的样品nirS功能基因的多样性最高。各实验样地优势Operational Taxonomic Units在系统进化关系上可分为多个不同的簇。此次发现的所有优势OperationalTaxonomicUnits均属于未被培养的菌群,其中部分Operational Taxonomic Units还是首次被发现。此外还发现nirS功能基因对低氧区的环境适应性更好。【结论】我们的研究结果表明广泛存在的反硝化微生物在河口沉积物的氮循环中发挥重要作用。     

锡林河流域不同植被带土壤绿菌门微生物群落的空间分布特征

[目的] 为了探究锡林河流域中游不同植被带土壤绿菌门（Chlorobi）成员的空间分布特征及驱动因子。[方法] 本文选择典型河滨带环境为研究对象,沿河流中心至河流阶地（陆向）方向,在无植被带（BC）、水莎草沼泽（BS）、灯芯草沼泽化草甸（LF）、鹅绒委陵菜草甸（HF）、河流阶地羊草草原（LT）、丘陵坡地大针茅典型草原（HT）中分别采集0-10 cm土壤样品。基于16S rRNA基因高通量测序分析土壤绿菌门微生物群落的组成、丰度及空间分布特征;结合土壤理化因子分析绿菌门微生物群落空间异质性的驱动因子。[结果] 在属水平上共检测到来自绿菌目（Chlorobiales）和Ignavibacteriales目的9个类群。Chlorobiales1、2、6及Ignavibacteriales7、9类群的最高相对丰度低于0.40%;Ignavibacteriales3、4、5、8类群的最高相对丰度介于0.54%-1.06%。Chlorobiales1、2类群在HF、LT和HT的相对丰度显著高于BS（P<0.05）,Chlorobiales1类群的相对丰度与pH和总有机碳含量呈极显著正相关（P<0.01）;Chlorobiales2类群的相对丰度与粉黏粒含量呈极显著正相关（P<0.01）;Ignavibacteriales3、5、7、9和Ignavibacterium4类群在LF的相对丰度显著高于BC（P<0.05）,与含水量呈极显著正相关（P<0.01）;Chlorobiales6和Ignavibacteriales8类群在BS的相对丰度显著高于其他植被带（P<0.05）,与氨态氮含量呈极显著正相关（P<0.01）。变异权重分析表明,土壤含水量解释了绿菌门微生物群落空间变异的65.7%。[结论] 锡林河流域不同植被带土壤绿菌门微生物群落存在明显的空间异质性;土壤含水量是不同植被带绿菌门微生物群落空间异质性的主要驱动因子。     

蓝藻挥发物α-紫罗酮诱导莱茵衣藻细胞程序性死亡

【目的】蓝藻挥发性有机化合物(VOCs)对其他藻类的化感作用可促进蓝藻成为富营养化水体优势种群,本研究旨在以VOCs主要成分α-紫罗酮为例揭示其化感致死机制。【方法】采用α-紫罗酮处理莱茵衣藻,测定藻细胞生长以及致死浓度下藻细胞光合性能、caspase-likes活性和DNA ladders。【结果】采用0.05和0.1mmol/Lα-紫罗酮处理24h后,莱茵衣藻细胞生长均受到明显抑制,其中0.1 mmol/L处理时部分藻细胞发生死亡,死亡率为38.3%。采用0.2 mmol/Lα-紫罗酮处理时,藻细胞全部死亡,同时光合色素逐渐降解、Fv/Fm逐渐降低并消失,这表明藻细胞死亡并非坏死。在藻细胞死亡过程中,caspase-9-like和caspase-3-like活性明显增强;DNA在处理1h时出现ladders,并逐渐降解为100–250 bp片段。【结论】这表明蓝藻VOCs可通过诱导细胞程序性死亡以发挥化感作用。