In vitro effects of chitosan nanoparticles on proliferation of human gastric carcinoma cell line MGC803 cells

AIM： To investigate the effects of chitosan nanoparticles on proliferation of human gastric carcinoma cell line MGC803 in vitro and the possible mechanisms involved. METHODS： Chitosan nanoparticles were characterized by particle size, zeta potential, and morphology. After treatment with various concentrations of chitosan nanoparticles （25, 50, 75, 100 μg/mL） at various time intervals, cell proliferation, ultrastructural changes, DNA fragmentation, mitochondrial membrane potential （MMP）, cell cycle phase distribution and apoptotic peaks of MGC803 cells were analyzed by MTT assay, electron microscopy, DNA agarose gel electrophoresis, and flow cytometry. RESULTS： Chitosan nanoparticles exhibited a small particle size as 65 nm and a high surface charge as 52 mV. Chitosan nanoparticles markedly inhibited cell proliferation of MGC803 cells with an ICso value of 5.3 μg/mL 48 h after treatment. After treatment with chitosan nanoparticles, the typical necrotic cell morphology was observed by electron microscopy, a typical DNA degradation associated with necrosis was determined by DNA agarose electrophoresis. Flow cytometry showed the loss of MMP and occurrence of apoptosis in chitosan nanoparticles-treated cells. CONCLUSION： Chitosan nanoparticles effectively inhibit the proliferation of human gastric carcinoma cell line MGC803 in vitro through multiple mechanisms, and may be a beneficial agent against human carcinoma.

Effect of temperature on the morphology of nanobubbles at mica/water interface

The great implication of nanobubbles at a solid/water interface has drawn wide attention of the scientific community and industries. However, the fundamental properties of nanobubbles remain unknown as yet. In this paper, the temperature effects on the morphology of nanobubbles at the mica/water interface are explored through the combination of AFM direct image with the temperature control. The results demonstrate that the apparent height of nanobubbles in AFM images is kept almost constant with the increase of temperature, whilst the lateral size of nanobubbles changes significantly. As the temperature increases from 28℃ to 42℃, the lateral size of nanobubbles increases, reaching a maximum at about 37℃, and then decreases at a higher temperature. The possible explanation for the size change of nanobubbles with temperature is suggested.

Association of TCF7L2 mutation and atypical diabetes in a Uruguayan population

AIM To investigate if mutations in TCF7 L2 are associated with "atypical diabetes" in the Uruguayan population.METHODS Healthy, nondiabetic controls(n = 133) and patients with type 2 diabetes(n = 177) were selected from among the presenting population at level-3 referral healthcare centers in Uruguay. Patients with type 2 diabetes were subgrouped according to "atypical diabetes"(n = 92) and "classical diabetes"(n = 85). Genotyping for the rs12255372 and rs7903146 single nucleotide polymorphisms(SNPs) in the TCFTL2 gene was carried out with Taq Man? probes. Random samples were sequenced by Macrogen Ltd.(South Korea). Statistical analysis of the SNP data was carried out with the SNPStats online tool(http://bioinfo.iconcologia.net/SNPstats). The best inheritance model was chosen according to the lowest values of Akaike's information criterion and Bayesian information criterion. Differences between groups were determined by unpaired t-tests after checking the normal distribution or were converted to normalize the data. The association of SNPs was tested for matched case-control samples by using χ2 analysis and calculation of odds ratios(ORs) with 95% confidence intervals(CIs). All statistical tests were performed using SPSS v10.0 and EpiI nfo7 statistical packages. Significant statistical differences were assumed in all cases showing adjusted P < 0.05.RESULTS We genotyped two TCF7 L2 SNPs(rs7903146 and rs12255372) in a population-based sample of 310 Uruguayan subjects, including 133 healthy control subjects and 177 clinical diagnosed with type 2 diabetes. For both SNPs analyzed, the best model was the dominant type: rs12255372 = G/G vs G/T+T/T, OR = 0.63, 95%CI: 0.40-0.98, P < 0.05 and rs7903146 = C/C vs C/T+T/T, OR = 0.79, 95%CI: 0.41-1.55, P = 0.3. The rs12255372 SNP showed high association with the type 2 diabetes cases(OR = 1.60, 95%CI: 1.20-2.51, P < 0.05). However, when the type 2 diabetics group was analyzed according to the atypical and classical subgroupings, the association with diabetes existed only for rs12255372 and the classical subgroup(vs controls: OR = 2.1, 95%CI: 1.21-3.75, P < 0.05); no significant differences were found for either SNP or atypical diabetes.CONCLUSION This is the first time SNPs_TCF7 L2 were genotyped in a diabetic population stratified by genotype instead of phenotype. Classical and atypical patients showed statistical differences.

Gold nanoflowers for 3D volumetric molecular imaging of tumors by photoacoustic tomography

By binding molecular probes that target tumor cells, gold nanoparticles （AuNPs） with superior characteristics have shown great potential in tumor molecular imaging studies. The non-invasive, high-resolution, and three-dimensional imaging of the targeted AuNPs within the tumor is desirable for both diagnosis and therapy. In this study, gold nanoflowers （AuNFs） are presented as a novel contrast agent for photoacoustic tomography （PAT）. By binding to folic acid, the molecular probe, the tail-vein injected AuNFs concentrated within the tumor site in mice; this was clearly visualized by three-dimensional （3D） PAT imaging. In addition, toxicity assay proved that AuNFs were harmless to living cells and animals. Our results demonstrate that AuNFs have great potential in tumor molecular imaging.

In situ AFM observation of BSA adsorption on HOPG with nanobubble

Nanobubbles have been proven existent at the liquid/solid interface, and become a focus of research on varied interfacial processes. In the present work, by observing in situ with atomic force microscope (AFM), we found that nanobubbles could influence the adsorption process of bovine serum albumin (BSA) on hydrophobic surface of highly ordered pyrolytic graphite (HOPG). BSA could adsorb evenly, and coexist with nanobubbles at water/HOPG interface. After removing nanobubbles by injecting ethanol, some hollows were found in the BSA layers at the same positions of nanobubbles existing previously. These hollows were about 8 nm in depth and dozens of nanometers in diameter. The correlation coefficient between the areas of nanobubbles and that of the corresponding hollows reached 0.88―0.94, which strongly supported the assumption that the hollows were indeed caused by the nanobubbles. Moreover, the BSA molecules formed rings around the nanobubbles, suggesting the preference of BSA adsorption onto the contact line at water/HOPG interface.

Separation and analysis of the soluble trimer of Aβ_(1-40) and its effects on the rise in intracellular calcium

The oligomers of Aβ1-40 peptide in PBS buffer solution were analyzed by SEC and native PAGE, and the trimer of Aβ1-40 was also isolated by SEC. In addition, the effects of the soluble Aβ1-40 trimer on intracellular free calcium (Ca2+) balance of hippocampal neurons of postnatal rats were investi- gated by fluorescence microscopy. The experimental results indicated that Aβ1-40 peptide existed in the form of low molecular weight oligomers in 0.231 mmol/L fresh Aβ1-40 solution (20 mmol/L sodium phosphate buffer, pH 7.4, 0.02% sodium azide) within 24 h and the soluble trimer was the most abundant species. Both the trimeric and the fibrillar Aβ1-40 were able to increase the intracellular Ca2+ concentration, but the Aβ1-40 trimer caused a gradual rise and the potential was also stronger than that of the fibrils at the same concentration. In addition there were dif- ferent response modes for trimeric and fibrillar Aβ1-40, meaning that there are different mechanisms of in- crease in intracellular Ca2+ caused by Aβ1-40.

Erratum to： Gold nanoflowers for 3D volumetric molecular imaging of tumors by photoacoustic tomography

The original version of this article unfortunately missed acknowledgements part. The acknowledgements are as below.