Effects of synchronous intermissive multi-ultrasound and esterification dual modification on functionalities of starch and its emulsion stabilization ability.

Dodecenylsuccinic anhydride (DDSA) has been widely used to obtain amphiphilic starches. In this study, we investigated the functionalities of synchronous intermissive multi-ultrasound-assisted esterified starch. Compared to native starch (NS), it was deduced that multi-ultrasound-modified starch (US), esterified starch (ES), and multi-ultrasound-assisted esterified starch (UES) exhibited increased viscosities but reduced gelatinization temperatures and thermal stabilities. The viscoelastic moduli, retrogradation behaviors and hydrophobicity of the ES and UES species significantly altered. Moreover, the results of structural characterization suggested that esterification reduced the molecular weight and structural order of starch, whereas the intermissive ultrasonication treatment did not aggravate the structural disruption of ES. Additionally, compared with NS and US, the emulsification abilities of the ES and UES specimens were improved, leading to the desirable effect of stabilizing astaxanthin. Overall, this study provides a method for preparing amphiphilic starch, which can be exploited as a potential emulsifier and emulsion stabilizer for bioactive compounds.

Designable microfluidic ladder networks from backstepping microflow analysis for mass production of monodisperse microdroplets.

Controllable mass production of monodisperse droplets plays a key role in numerous fields ranging from scientific research to industrial application. Microfluidic ladder networks show great potential in mass production of monodisperse droplets, but their design with uniform microflow distribution remains challenging due to the lack of a rational design strategy. Here an effective design strategy based on backstepping microflow analysis (BMA) is proposed for the rational development of microfluidic ladder networks for mass production of controllable monodisperse microdroplets. The performance of our BMA rule for rational microfluidic ladder network design is demonstrated by using an existing analogism-derived rule that is widely used for the design of microfluidic ladder networks as the control group. The microfluidic ladder network designed by the BMA rule shows a more uniform flow distribution in each branch microchannel than that designed by the existing rule, as confirmed by single-phase flow simulation. Meanwhile, the microfluidic ladder network designed by the BMA rule allows mass production of droplets with higher size monodispersity in a wider window of flow rates and mass production of polymeric microspheres from such highly monodisperse droplet templates. The proposed BMA rule provides new insights into the microflow distribution behaviors in microfluidic ladder networks based on backstepping microflow analysis and provides a rational guideline for the efficient development of microfluidic ladder networks with uniform flow distribution for mass production of highly monodisperse droplets. Moreover, the BMA method provides a general analysis strategy for microfluidic networks with parallel multiple microchannels for rational scale-up.

Magnetic hierarchical porous SiO2 microparticles from droplet microfluidics for water decontamination.

A simple and flexible strategy based on droplet microfluidics is developed for controllable fabrication of uniform magnetic SiO2 microparticles with highly-interconnected hierarchical porous structures for enhanced water decontamination. Uniform precursor water droplets containing surfactants and homogenized fine oil droplets with a relatively high volume ratio are generated from microfluidics as templates for microparticle synthesis via hydrolysis/condensation reaction. The SiO2 microparticles possess hierarchical porous structures, containing both mesopores with size of several nanometers, and well-controlled and highly-interconnected macropores with size of hundreds of nanometers. The SiO2 microparticles synergistically integrate fast mass transfer and large functional surface area for enhanced adsorption. To demonstrate the enhanced adsorption performances for organic dyes and toxic heavy metal ions, the microparticles are respectively used for removal of methylene blue in water, and modified with thiol-groups for removal of Pb2+ ions in water. Meanwhile, the microparticles can be easily recycled by magnetic field for reuse.

Promoter methylation status of MGMT, hMSH2, and hMLH1 and its relationship to corresponding protein expression and TP53 mutations in human esophageal squamous cell carcinoma.

To determine the relevance of O-6-methylguanine-DNA methyltransferase (MGMT), human mutS homolog 2 (hMSH2), and human mutL homolog 1 (hMLH1) in TP53 mutations in esophageal squamous cell carcinoma, we employed methylation-sensitive high-resolution melting technology and methylation-specific polymerase chain reaction (PCR) to analyze promoter hypermethylation of MGMT, hMSH2, and hMLH1, respectively, in 51 paired tumors and their adjacent normal tissues. The protein expression of the three proteins was also evaluated by Western blot analysis, and the PCR products of TP53, from exon 5 to exon 8, were directly sequenced to measure the mutation spectrum. Esophageal tumor tissues embraced statistically higher MGMT and hMSH2 promoter methylation level than normal tissue. The promoter methylation status of MGMT and hMSH2 corresponds positively with the protein expression level of MGMT and hMSH2. However, such relevance was not found for hMLH1. Furthermore, TP53 mutation status was well associated with MGMT and hMSH2 promoter methylation status, indicating that silencing of the two genes could lead to TP53 mutation in ESCC.

Malignant progression in O6-methylguanine-DNA methyltransferase-deficient esophageal cancer cells is associated with Ezrin protein.

The abnormal function of O(6)-methylguanine-DNA methyltransferase (MGMT) is reported to be associated with the occurrence of various tumors and malignant tumor progression. However, little evidence is available to describe its role in esophageal carcinogenesis. To address this issue, we constructed a stable MGMT-silenced esophageal cancer cell line by RNA interference, and exposed the cells to N-methyl-N-nitro-N-nitrosoguanidine (MNNG) to investigate the role that MGMT plays in toxicity. During this time, we also observed the malignant behavior of cells in vitro and in vivo. In addition, two-dimensional electrophoresis and mass spectrometry were used to detect and confirm the proteins that were differentially expressed in the MGMT-deficient and MGMT-proficient cells, which might be responsible for the malignant alteration of cells. Results showed that the IC(50) of MGMT-deficient and MGMT-proficient cells exposed to MNNG was 30 µM and 65 µM, respectively, and MGMT-deficient cells had more aggressive motility and invasive abilities compared with MGMT-proficient cells. Nineteen differentially expressed proteins were detected between the MGMT-deficient and MGMT-proficient cells, 14 of which were identified, including the membrane-cytoskeleton linker protein, Ezrin, which was confirmed by both mass spectrometry and western blot analysis. The correlation between MGMT, Ezrin expression, and the malignant behavior of one normal epithelial esophageal cell line and seven esophageal cancer lines is discussed. In conclusion, loss of MGMT expression leads EC109 esophageal cancer cells to have increased malignant behavior, which may correlate with its high Ezrin protein expression.

Influence of different sizes of titanium dioxide nanoparticles on hepatic and renal functions in rats with correlation to oxidative stress.

As titanium dioxide (TiO(2)) nanoparticles are widely used commercially, the potential effects of TiO(2) nanoparticles on humans are a concern. To evaluate the effects of TiO(2) nanoparticles on hepatic and renal functions and correlate changes to oxidative stress, Sprague-Dawley rats were treated with TiO(2) particles of two different specific surface areas (TiO(2-S50): 50 m(2)/g, and TiO(2-S210): 210 m(2)/g) at 0.5, 5, or 50 mg/kg body weight by intratracheal instillation. After 7 d, TiO(2) nanoparticles produced no obvious acute toxicity on hepatic and renal functions. However, superoxide dismutase (SOD) activity of plasma and glutathione peroxidase (GSH-PX) activity of kidney in the low-dose TiO(2-S210) group were significantly decreased. After TiO(2-S210) exposure, malondialdehyde (MDA) levels of liver and kidney in intermediate and high-dose groups were significantly increased. This change only appeared in liver after TiO(2-S50) exposure. Furthermore, SOD activity in liver and kidney and GSH-PX activity in kidney with low TiO(2-S210) exposure group were significantly less than with low TiO(2-S50). No apparent pathological changes in liver and kidney were observed. Intratracheal exposure to TiO(2) nanoparticles may induce oxidative stress in liver and kidney, but does not influence hepatic or renal functions. There was no apparent evidence that TiO(2-S210) was more toxic than TiO(2-S50). In general, intratracheal exposure to TiO(2) did not markedly affect extrapulmonary tissue functions.