Electrochemiluminescence of CdSe quantum dots for immunosensing of human prealbumin

We describe a non-labeled electrochemiluminescence (ECL) immunosensor based on CdSe quantum dots (QDs) for the detection of human prealbumin (PAB, antigen). The immunosensor was fabricated by layer by layer coupled with nanoparticle-amplification techniques. After two gold nanoparticle layers were self-assembled onto the gold electrode surface through cysteamine, anti-PAB (antibody) were conjugated with -COOH groups of both the CdSe QDs and cysteine, which were linked to the gold nanoparticle-modified electrode. The principle of ECL detection was that the immunocomplex inhibited the ECL reaction between CdSe QDs and K(2)S(2)O(8), which resulted in the decrease of ECL intensity. On the one hand, the immunocomplex increased the steric hindrance. On the other hand, the immunocomplex maybe inhibit the transfer of K(2)S(2)O(8) to the surface of the CdSe QD-electrode. The PAB concentration was determined in the range of 5.0 x 10(-10) to 1.0 x 10(-6) g mL(-1), and the detection limit was 1.0 x 10(-11) g mL(-1). The developed CdSe QD-based ECL immunosensor provides a rapid, simple, and sensitive immunoassay protocol for protein detection, which could be applied in more bioanalytical systems.     

量子点生物传感体系用于胆碱酯酶抑制剂检测的研究进展

量子点是一种具有独特性质的纳米材料,近年来被广泛应用于传感领域。对高毒性胆碱酯酶抑制剂类化合物进行灵敏检测一直是传感领域的一个研究热点。我们就偶联标记型和非标记型两种传感策略,对量子点生物传感体系用于胆碱酯酶抑制剂检测的研究工作进行了综述。     

CdSe量子点荧光猝灭法测定尿嘧啶

以CdSe量子点为荧光探针,基于荧光猝灭法对碱基尿嘧啶进行了定量检测,考察了缓冲液体系、反应时间、量子点浓度等多种因素的影响. 实验结果表明,在pH 7.4的0.2 mol/L Na₂HPO₄-NaH₂PO₄缓冲液中,反应时间为60 min,尿嘧啶浓度为10^-6～10^-4mol/L范围时,其线性回归方程为F₀/F =0.992+3.35×10⁴Q (mol/L),检测限为3.23×10^-6 mol/L(即0.36μg/ml). 该方法检测范围宽,灵敏度高,为尿嘧啶的测定提供了新的方法.     

CdSe/ZnS-SA量子点细胞毒性的初步研究

目的：探讨链亲和素修饰的CdSe/ZnS核壳结构量子点（CdSe/ZnS-SA）对稳定转染pcDNA3.1/APP595/596质粒的人胚肾（HEK293）细胞的短期毒性作用.方法：将CdSe/ZnS-SA量子点与稳定转染pcD-NA3.1/APP595/596质粒的HEK293细胞共培育,在倒置荧光显微镜下观察细胞形态学变化;MTT法测定细胞活性;流式细胞术检测细胞凋亡率.结果：终浓度为2.5 nmol/L-20 nmol/L的CdSe/ZnS-SA量子点与HEK293细胞分别共育8h、16h、24 h后,细胞的形态无明显改变;终浓度为2.5 nmol/L-25 nmol/L的CdSe/ZnS-SA量子点与HEK293细胞分别共育8h、16 h、24 h,各处理组与对照组间,各处理组间的吸光度值、细胞凋亡率差异均无统计学意义（P＞0.05）.结论：一定浓度范围的CdSe/ZnS-SA量子点在短期内对稳定转染pcDNA3.1/APP595/596质粒的HEK293细胞无明显的毒性作用,具有较好的生物相容性.     

CdSe量子点与蛋白质的作用研究

以油酸为稳定剂,石蜡为还原剂,采用有机相法合成了尺寸均匀的CdSe量子点,并通过巯基乙酸将合成的量子点转移至水相。考查了CdSe量子点与几种结构不同的蛋白质(酶)之间的作用规律。研究发现,经巯基乙酸修饰后的量子点与牛血清白蛋白和胰凝乳蛋白酶作用后,荧光强度明显增大。而铜/锌-超氧化物歧化酶对量子点的荧光有明显的淬灭作用,牛血红蛋白对量子点的影响是随着时间的增加荧光强度先增大后减小,体现出一般蛋白质使荧光增强和部分金属离子使荧光淬灭两者的协同效应。     

Can earthworms biosynthesize highly luminescent quantum dots?

Band gap tunable cadmium selenide (CdSe) quantum dots (QDs) were synthesized within earthworms that emit in the middle of the visible spectrum. We demonstrated that this luminescence emission is a combination of the earthworm's protein and QD luminescence, such that the contribution of QDs in the luminescence was negligible. Eisenia fetida earthworms were used for QD biosynthesis and were exposed to different concentrations of CdCl₂ and Na₂SeO₃ in standard soil for an adequate exposure time. The size of the CdSe QDs based on the effective mass model was in agreement with the size measured from the transmission electron microscopy analysis, with an average diameter of 7 nm. Ultraviolet–visible and photoluminescence analyses confirmed the synthesis of CdSe QDs with unique absorption and luminescence at 430 nm and 605 nm, respectively.     

量子点荧光光谱学与生命科学

近年来,量子点(半导体纳米微晶体)的研究引起国内外研究者的广泛兴趣,其研究内容涉及物理学、化学、材料等多学科,已成为一门新兴的交叉学科。虽然量子点在生物学中的应用才刚刚起步,但是已经取得了有意义的进展,成为人们极为关注的一个热点。现就量子点的光学特性、制备方法,以及在生物学中的研究进展和应用前景作一简要综述。     

Aqueous synthesis of highly stable CdTe/ZnS Core/Shell quantum dots for bioimaging

In this work, we report the synthesis, characterization and biological application of highly stable CdTe/ZnS (cadmium tellurite/zinc sulphide) Core/Shell (CS) quantum dots (QDs) capped with mercaptosuccinic acid (MSA). The CS QDs were synthesized using a simple one‐pot aqueous method. The synthesized CdTe/ZnS CS QDs were found to exhibit excellent stability even 100 days after preparation and also showed better photoluminescence quantum yield (PLQY) of about 50% compared with that of only CdTe QDs which was nearly 12%. The formation of the CdTe/ZnS CS was confirmed by high‐resolution transmission electron microscopy (HR‐TEM), and Fourier transform infra‐red (FTIR) and X‐ray diffraction (XRD) analyses. Further, on extending our study towards bioimaging of E. coli cells using the QDs samples, we found that CdTe/ZnS CS QDs showed better results compared with CdTe QDs.     

水溶性纳米量子点在玉米幼根中运输的可视化

在纳米生物学效应研究中,纳米颗粒能否自由进入植物体内是一个亟待考证的关键问题。本文尝试采用一定浓度的水溶性纳米量子点溶液培养玉米幼根,然后徒手切片,用荧光显微镜直接观察发光量子点在根内的运输和分布。结果表明,量子点能够自由进入玉米根且在多种类型的细胞内都有分布;尤其是在导管内也观察到量子点,说明这种纳米材料能够穿透极厚的细胞壁输送到胞内。本文也讨论了该实验设计的优缺点。     

Atomic force microscopy-based cell nanostructure for ligand-conjugated quantum dot endocytosis

While it has been well demonstrated that quantum dots (QDs) play an important role inbiological labeling both in vitro and in vivo,there is no report describing the cellular nanostructure basis ofreceptor-mediated endocytosis.Here,nanostructure evolution responses to the endocytosis of transferrin(Tf)-conjugated QDs were characterized by atomic force microscopy (AFM).AFM-based nanostructureanalysis demonstrated that the Tf-conjugated QDs were specifically and tightly bound to the cell receptorsand the nanostructure evolution is highly correlated with the cell membrane receptor-mediated transduction.Consistently,confocal microscopic and flow cytometry results have demonstrated the specificity anddynamic property of Tf-QD binding and internalization.We found that the internalization of Tf-QD is linearlyrelated to time.Moreover,while the nanoparticles on the cell membrane increased,the endocytosis was stillvery active,suggesting that QD nanoparticles did not interfere sterically with the binding and function ofreceptors.Therefore,ligand-conjugated QDs are potentially useful in biological labeling of cells at a nanometerscale.