量子点荧光微球免疫层析试纸条定量检测恶性疟原虫

以羧基化Cd Te/Zn Se量子点荧光微球为荧光标记物,采用1-乙基-（3-二甲基氨基丙基）碳酰二亚胺（EDC）法偶联抗恶性疟原虫富组氨酸蛋白（Pf）单克隆抗体制备荧光探针;以羊抗恶性疟原虫组氨酸多克隆抗体和驴抗鼠二抗分别喷涂硝酸纤维膜,形成试纸条检测线和质控线,建立了免疫层析试纸条定量检测血清中恶性疟原虫的方法。所使用的羧基化量子点荧光微球的荧光强度为单个量子点的2800倍。实验结果表明,该荧光试纸条定量检测血清中恶性疟原虫线性范围为5.8-8010 Parasite/μL,最低灵敏度达到5.8 Parasite/μL,单个样品检测时间只需15 min。加标回收实验显示,试纸条批内回收率为93.0%-111.8%,批间回收率为98.3%-115.1%,且批内、批间的相对标准偏差均小于5%。

IN SITU IMAGING OF BREAST CANCER CELLS USING GREEN SEMICONDUCTOR QUANTUM DOTS

The breast cancer is the most common cause of cancer death in women. To establish an early stage in situ imaging of breast cancer cells, green quantum dots （QDs） are used as a fluorescent signal generator. The QDs based imaging of breast cancer cells involves anti-HER2/neu antibody for labeling the over expressed HER2 on the surface of breast cancer cells. The complete assay involves breast cancer cells, biotin labeled antibody and streptavidin conjugated QDs. The breast cancer cells are grown in culture plates and exposed to the biotin labeled antibodies, and then exposed to streptavidin labeled QDs to utilize the strong and stable biotin-streptavidin interaction. Fluorescent images of the complete assay for breast cancer cells are evaluated on a microscope with a UV light source. Results show that the breast cancer cells in the complete assay are used as fluorescent cells with brighter signals compared with those labeled by the organic dye using similar parameters and the same number of cells.

量子点荧光微球免疫层析试纸条定量检测玉米中赭曲霉毒素A

采用1-乙基-(3-二甲基氨基丙基)碳二亚胺(EDC)法将抗赭曲霉毒素A(OTA)腹水与量子点荧光微球偶联制备荧光探针,以牛血清白蛋白-OTA偶联物及驴抗鼠二抗喷涂硝酸纤维膜形成试纸条检测线(T线)和质控线(C线),建立了基于T/C荧光强度(FI_T/FI_C)比值法免疫层析试纸条高灵敏度、快速定量检测玉米中OTA的新方法。量子点荧光微球试纸条定量检测OTA线性范围为0.05~1.0ng/mL(Y=0.259lnX+0.897,R^2=0.995),半数抑制浓度(IC_(50))为(0.215±0.023)ng/mL(n=5),玉米提取液中OTA的检出限为0.05 ng/mL,单个样品检测时间10min。加标回收实验表明,3个OTA加标浓度的平均回收率为107.2%-125.5%,相对标准偏差均小于10%。40个实际玉米样品检测结果表明,量子点荧光微球试纸条与酶联免疫吸附分析方法检测OTA的结果具有良好的相关性(R^2=0.975)。

Expression and Characterization of ArgR, An Arginine Regulatory Protein in Corynebacterium crenatum

Objective Corynebacterium crenatum MT, a mutant from C. crenatum AS 1.542 with a lethal argR gene, exhibits high arginine production. To confirm the effect of ArgR on arginine biosynthesis in C. crenatum, an intact argR gene from wild-type AS 1.542 was introduced into C. crenatum MT, resulting in C. crenatum MT. sp, and the changes of transcriptional levels of the arginine biosynthetic genes and arginine production were compared between the mutant strain and the recombinant strain. Methods Quantitative real-time polymerase chain reaction was employed to analyze the changes of the related genes at the transcriptional level, electrophoretic mobility shift assays were used to determine ArgR binding with the argCJBDF, argGH, and carAB promoter regions, and arginine production was determined with an automated amino acid analyzer. Results Arginine production assays showed a 69.9% reduction in arginine from 9.01±0.22 mg/mL in C. crenatum MT to 2.71±0.13 mg/mL （P〈0.05） in C. crenatum MT. sp. The argC, argB, argD, argF, argJ, argG, and carA genes were down-regulated significantly in C. crenatum MT. sp compared with those in its parental C. crenatum MT strain. The electrophoretic mobility shift assays showed that the promoter regions were directly bound to the ArgR protein. Conclusion The arginine biosynthetic genes in C crenatum are clearly controlled by the regulator ArgR, and intact ArgR in C. crenatum MT results in a significant descrease in production. negative arginine production.

Quantum-Confined Stark Effect in Ensemble of Colloidal Semiconductor Quantum Dots

The presence of a strong, changing, randomly-oriented, local electric field, which is induced by the photo-ionization that occurs universally in colloidal semiconductor quantum dots （QDs）, makes it difficult to observe the quantum-confined Stark effect in ensemble of colloidal QDs. We propose a way to inhibit such a random electric field, and a clear quantum-confined Stark shift is observed directly in close-packed colloidal QDs. Besides the applications in optical switches and modulators, our experimental results indicate how the oscillator strengths of the optical transitions axe changed under external electric fields.

Superhydrophobic Surfaces Produced by Applying a Self- Assembled Monolayer to Silicon Micro/Nano-Textured Surfaces

A novel way of producing superhydrophobic surfaces by applying a self-assembled monolayer(SAM)to silicon micro/nano-textured surfaces is presented in this paper.The micro/nano-textured surfaces on silicon substrates were generated by the aluminum-induced crystallization(AIC)of amorphous silicon(a-Si)technique.Octadecyltrichlorosilane(OTS)SAMs were then applied to the textured surfaces by dip coating.The topography and wetting properties of the resulting surfaces were characterized using scanning electron microscopy(SEM)and a video-based contact angle measurement system.The results show that by introducing OTS SAMs on the silicon micro/nano-textured surfaces,superhydrophobic surfaces with water contact angles(WCAs)of 155°were obtained,as compared to the WCAs of OTS-modified smooth silicon surfaces of about 112°.Surface topography was found to directly influence the WCA as predicted by the Cassie-Baxter model.

In vitro cytotoxicity of CdSe/ZnS quantum dots with different surface coatings to human keratinocytes HaCaT cells

Quantum dots （QD） nanoparticles have been widely used in biomedical and electronics fields, because of their novel optical properties. Consequently it confers enormous potential for human exposure and environmental release. To increase the biocompatibility of QDs, a variety of surface coatings or functional groups are added to increase their bioactivity and water solubility. Human adult low calcium high temperature （HaCaT） cells are the epithelial cells derived from adult human skin that exhibits normal differentiation capacity and a DNA fingerprint pattern that is unaffected by long-term cultivation, transformation, or the presence of multiple chromosomal alternations. Human keratinocytes, HaCaT cells were used to systematically evaluate the cytotoxicity of biocompatible QD made of CdSe metal core and ZnS shell with three different coatings and at three different wavelengths （530, 580 and 620 nm）. In terms of half- maximal inhibitory concentration, QSA-QDs with amine-polyethyleneglycol coating and QSH-QDs with amphiphilic polymer coating were not cytotoxic, while QEI-QDs with polyethylenimine coating were highly toxic to the HaCaT cells in comparison to a reference CulnS2/ZnS. QEI-QDs led to significant increase in reactive oxygen species, decrease in mitochondrial membrane potential and DNA damage in HaCaT cells. The mechanisms of toxicity of QEI-530 and QEI-580 can be attributed to the combination of intracellular reactive oxygen species production and loss of MMP. The QDs toxicity can be attributed to the polyethylemimine surface coating which was highly toxic to cells in comparison with amine-polyethyleneglycol, but not due to the release of cadmium ions.

Preparation and Control of the Formation of Single Core and Clustered Nanoparticles for Biomedical Applications Using a Versatile Amphiphilic Diblock Copolymer

We report the application of a versatile diblock copolymer,poly(ethylene oxide)-b-poly(γ-methacryloxypropyl trimethoxysilane)(PEO-b-PγMPS),to prepare nanocrystals such as iron oxide nanoparticles or quantum dots,with either a single core or multi-core cluster,for biomedical applications.This amphiphilic copolymer comprises both a hydrophilic PEO segment and a hydrophobic segment with a“surface anchoring moiety”(the silane group)which can interact effectively with the hydrophobic nanocrystals through ligand exchange.One of the unique features of this work is that we can control the formation of either single core nanoparticles or multi-core nanoclusters by simply varying the conditions of ligand exchange and aging of the mixture of block copolymer and nanoparticles without needing to change the copolymer.The morphologies of the resulting single core nanoparticles or multi-core nanoclusters were confirmed by dynamic light scattering and transmission electron microscopy.The clustered nanoparticles exhibit enhanced physicochemical properties that are beyond those expected from a simple accumulation of individual nanoparticles.Additionally,the hybrid nanoparticles containing both magnetic iron oxide nanoparticles and optical quantum dots obtained using our strategy provide have combined magnetic and optical functionalities that allow for potential new and expanded biomedical applications,as demonstrated by their use for magnetic resonance imaging and biomarker-targeted cell imaging.