Protease-activated quantum dot probes based on fluorescence resonance energy transfer

A novel sensing system based on fluorescence resonance energy transfer (FRET) between CdTe quantum dots (QDs) and Rhoda-mine B (RB) was established for the detection of matrix metalloproteinases (MMOL/LPs). In this system, 535-nm-emitting quantum dots (QDs) were bound to Rhodamine B (RB) via a MMOL/LP-specific peptide. A 76% reduction in luminescence was achieved because of FRET. Release of RBs by peptide cleavage restores radiative QD photoluminescence. Initial studies observed a 73% rise in luminescence over 60 min. The design platform of the nanosensor is flexible and can be fine-tuned for a wide array of applications such as the detection of biomarkers, early diagnosis of disease, and monitoring therapeutic efficacy simply by changing the sequence of the peptide linker.     

CdSe量子点修饰物DSPE-PAA对其荧光增强效应的研究

采用有机热溶剂法制备出荧光量子效率高、单分散性良好的油溶性CdSe半导体量子点,将其用水溶性低分子量两性聚合物DSPE-PAA[poly（acylicacid）-1,2-distearoyl-sn-glycero-3-phosphoethanolamine,聚丙烯酸-1,2-二硬脂酰-sn-丙三醇-3-磷脂酰乙醇胺]进行修饰,得到水溶性和生物相容性良好的量子点。用透射电子显微镜（TEM）和荧光光谱等方法对CdSe纳米微粒的结构、形貌和光学特性分别进行了表征。并探讨和研究了在修饰过程中发生的DSPE-PAA对量子点由于荧光共振能量转移（FRET）作用产生的量子点荧光增强的现象。     

Fluorescent immunosensor based on fluorescence resonance energy transfer between CdSe/ZnS quantum dots and Au nanorods for PRRSV detection

An ultrasensitive and selective sandwich-type fluorescent immunosensor based on fluorescence resonance energy transfer (FRET) between CdSe/ZnS quantum dots (QDs) and Au nanorods (AuNRs) was developed for the rapid detection of porcine reproductive and respiratory syndrome virus (PRRSV). Modified CdSe/ZnS QDs and AuNRs were bioconjugated with primary antibodies M and GP5, respectively. When the target antigen was present, a well-known sandwich-type form CdSe/ZnS QDs-M antibody-antigen-GP5 antibody-AuNRs was produced, and thus reducing the distance between the QDs and NRs. As a result, FRET occurred and the fluorescence intensity of CdSe/ZnS QDs decreased, and this decrease was used to determine the antigen concentration. Ultrasensitive detection of PRRSV at low concentrations in swine serum was achieved with a limit of detection of 0.55 TCID₅₀/mL and a linear detection range of 10¹–3.5 ?× ?10⁴ TCID₅₀/mL. Therefore, the fluorescent immunosensor is selective and highly sensitive; specifically, it can detect PRRSV at low concentrations in swine serum over a large concentration range. This proposed detection method can facilitate the development of high-performance fluorescent immunosensors for the detection of PRRSV and other antigens.     

Effect of serum on PEGylated quantum dots: Cellular uptake and intracellular distribution

Protein adsorption is closely related with the interactions between nanoparticles and physiological systems,and further influences the cellular uptake and distribution of nanoparticles in cells.Although polyethylene glycol(PEG)ylation can largely reduce specific protein adsorption,some protein components in whole serum still interact with nanoparticles.In this work,PEGylated quantum dots(QDs) were used for investigating the quantitative and qualitative relationships of fetal bovine serum(FBS) and the cellular uptake/intracellular distribution in human hepatoma(HepG2) cell line.Nondenaturing polyacrylamide gel electrophoresis and two dimensional electrophoresis were used to analyze the adsorption of protein by PEGylated QDs.Quantitative cellular uptake of PEGylated QDs was determined by fluorescence activated cell sorting(FACS) with different FBS concentrations and incubating durations.The intracellular location of PEGylated QDs in HepG2 cells was observed using a confocal laser scanning microscope(CLSM) and a transmission electron microscope(TEM).This work will be helpful to understand the interaction between nanoparticles and cells with serum.     

Effect of protein molecules on the photoluminescence properties and stability of water-soluble CdSe/ZnS core-shell quantum dots

The fact that the photoluminescence properties of quantum dots are always strongly influenced by the environment limits the scope of further progress in the field of QD’ bio-applications. In this paper, the effects of immunoglobulin G (IgG) on the photo-luminescence properties and stability of water-soluble CdSe/ZnS core-shell quantum dots coated with amphiphilic poly (acrylic acid) (PAA) are studied. Photoluminescence (PL) spectra, UV-vis spectra and excited state lifetime measurements are used to characterize the influence of different protein molecules, such as IgG (goat anti-human IgG, rabbit anti-human IgG, human IgG, and goat anti-human IgG-human IgG conjugates), avidin and bovine serum albumin (BSA) on the PL properties of QDs. The PL intensity and stability of CdSe/ZnS are largely enhanced compared to that of pure CdSe/ZnS QDs when the IgG molecules are added into the QD solution. The PL intensity increases with increasing the IgG concentration, but there appears no influence on the PL peak and a full width at half maximum (FWHM). The PL evolution of QDs as a function of different protein molecules depends on the structure of protein molecules, which is used as a sensor to recognize human IgG. It is inferred that the interaction between PAA coating layer and IgG molecules results in the enhancement of PL intensity. The study of the effect of pH and ion strength on optical properties of QD-IgG mixed solution, compared with the pure QD solution, suggests that pH value and ion strength do not destroy the interaction between the PAA coating layer and IgG. Excited state lifetime analysis indicates that the PL enhancement comes from the passivation of surface of the QDs with the PAA coating layer. IgG molecules have no effects on the properties of the biological system but can increase the stability and PL intensity of CdSe/ZnS QDs, which will enlarge the application of QDs in biomedicine and other fields.     

基于VTK的鼻咽部组织三维重建的应用研究

放射治疗是鼻咽癌治疗的主要手段.为了提高放射治疗的成功率,本文采用可视化工具包(VTK)分别实现了鼻咽部组织的表面重建和体重建.表面重建用移动立方体法和轮廓拼接法实现,体重建则用光线投射法实现.利用一种改进的高斯拉普拉斯核进行平滑和锐化处理,并通过调整光照参数和透明度值使重建效果达到最佳.在此基础上,比较了两种重建方法的优缺点.实验结果表明,利用VTK可实现复杂组织结构的多彩色三维重建和三维图像的优化处理.     

N-苄基-N-正丁基丙烯酰胺三元共聚物与SDS的相互作用

两亲聚合物与表面活性剂在溶液中能形成聚合物/表面活性剂复合物从而引起溶液性质发生重大变化。通过自由基胶束共聚法制备疏水单体为N-苄基-N-正丁基丙烯酰胺(BBAM)的三元共聚两亲聚合物P(AM-NaA-BBAM),并采用FT-IR进行结构表征。采用荧光探针法、黏度法、流变法研究P(AM-NaA-BBAM)与十二烷基磺酸钠(SDS)的相互作用,分析二者的相互作用机制。结果表明:SDS质量浓度较低时,P(AM-NaA-BBAM)与SDS通过形成混合胶束提高P(AM-NaA-BBAM)/SDS混合体系中疏水基团的缔合强度以及混合溶液的表观黏度和弹性;SDS质量浓度较高时,部分疏水基团单独增溶于表面活性剂胶束中从而破坏溶液的空间网络结构,疏水基团的缔合强度降低,混合溶液表观黏度及弹性降低。     

聚合物微珠与量子点复合物的制备及性能

在有机体系中通过软化学方法制备出荧光量子点,该方法简单、新颖,且原料成本低;利用种子乳液聚合法合成了粒径为60～70nm的具有特殊功能团的聚合物微珠,该微珠具有水溶性,具备一些与生物分子偶联的基团,相对μm级的聚合物微球有很大优势;通过物理溶胀的方法将量子点嵌入带有特殊功能团的聚合物微珠,为制备量子点与生物分子连接中的荧光探针奠定基础．通过紫外吸收光谱（UV—Vis）、荧光发射光谱（PL）、透射电子显微镜（TEM）、红外光谱（FTIR）、激光扫描共聚焦显微镜（CLSM）、电导滴定等手段对制备的样品进行了表征．实验结果表明,成功地将荧光量子点嵌入聚合物微珠,打破了只有水相合成的量子点才能与生物分子相连的限制．     

CdSe/巯基-β-环糊精量子点的纯化及应用

以单-(6-巯基)-β-环糊精作为修饰剂,在水溶液中合成了稳定的CdSe量子点(CdSe/CD QDs),并系统考察了溶剂的种类及加入量对量子点纯化效果的影响.同时研究了该量子点在2种细菌标记及分子识别的应用.结果表明:2倍体积的乙腈完全沉淀CdSe/CD QDs所用的时间最短,纯化后荧光强度略有增强.CdSe/CD ...     

PAA-DSPE修饰的CdSe量子点的制备及其对蛋白的标记检测应用

本文采用有机溶剂热法合成了量子效率高的油溶性CdSe QDs（quantum dots）,利用自制的水溶性生物相容性良好的两性PAA-DSPE（聚丙烯酸-1,2-二硬脂酰-sn-丙三醇-3-磷脂酰乙醇胺）低分子聚合物对其表面进行修饰,得到稳定性高、水溶性良好的半导体纳米荧光标记物,并对其进行了TEM,紫外-可见光吸收光谱和荧光光谱的表征。还利用制备的水溶性QDs对NFkB蛋白及其抗体蛋白进行标记,利用荧光显微镜对标记后的结构进行观察,探索标记后量子点对蛋白免疫结合性质的影响。实验结果表明,CdSe/PAA-DSPE的标记对抗原、抗体蛋白的免疫性质未产生明显的影响。     

包被试剂对CdS量子点化学发光特性的影响

分别以半胱胺(CA)、半胱氨酸(L-cys)、谷胱甘肽(GSH)为包被试剂,制备出了3种粒径相同的水溶性CdS量子点,考察了这些CdS量子点在不同氧化剂体系下的化学发光行为.结果表明,CdS量子点化学发光性能与氧化体系密切相关,而且包被试剂对CdS量子点化学发光性能影响很大.此研究为提高量子点的化学发光效率提出了一种新的途径,即通过优化其包被试剂来提高量子点的化学发光效率.     

两亲性羟乙基纤维素的合成及溶液性质

选择羟乙基纤维素(HEC)作为两亲性聚合物主体,合成具有两亲性的活性单体二甲基十四烷基环氧丙烷氯化铵(M EQ),采用大分子反应法,制备出具有不同增粘性能和表面活性的羟乙基纤维素(M EQHEC)。系统地对M EQHEC的溶液性质进行了研究,包括增粘性、盐敏性、温敏性、流变性、表面活性等,并采用荧光光谱和原子力显微镜(AFM)分析对聚合物在溶液中超分子聚集形态进行了探索研究。     

两亲性聚乳酸嵌段共聚物的制备及性能研究

以端羟基聚乳酸和α-溴代丙酰溴为原料，制备了溴端基的聚乳酸；再以其为大分子引发剂，以溴化亚铜/2,2’-联吡啶为催化体系进行N-乙烯基吡咯烷酮的原子转移自由基聚合，制得了两亲性聚乳酸嵌段共聚物。用IR、GPC对聚合物进行了表征，用接触角测定仪测定了聚合物薄膜的水接触角，并考察了不同反应时间对共聚物的特性粘度和吸水率的影响。结果表明，该聚乳酸共聚物的亲水性较聚乳酸均聚物明显增大，TEM证实共聚物在水相中可形成一壳多核球状胶束，进一步佐证了该共聚物具有明显的两亲性。     

III族氮化物量子点中类氢施主杂质位置对束缚激子结合能的影响

在有效质量近似下,运用变分方法,考虑内建电场效应和量子点(QD)的三维约束效应的情况下,研究了类氢施主杂质在量子点中的位置对III族氮化物量子点中束缚激子结合能的影响。结果表明:当类氢施主杂质位于量子点中心时,对于InxGa1-xN/GaN量子点,量子点高度和In含量存在临界值,当参数大于临界值时,约束在QD中束缚激子的结合能升高,激子态的稳定性增强,提高了激子的离解温度,使人们能在较高的温度条件下观察到半导体量子点吸收谱中的激子峰。而类氢施主杂质总是使束缚在GaN/A lxGa1-xN量子点中激子的结合能升高,载流子被更强的约束在量子点中。说明对GaN/A lxGa1-xN量子点,杂质使人们能在更高温度下观察到量子点中的激子。类氢施主杂质位于量子点上界面时,束缚激子的结合能最大,系统最稳定;随着施主杂质下移,激子结合能减小,激子的离解温度下降。     

氟硼二吡咯类共轭聚合物均相检测miRNA研究

基于水溶性氟硼二吡咯类共轭聚合物PBF可与长波长区(> 600 nm)荧光染料产生荧光共振能量转移(FRET),结合引物延伸反应,发展了一种均相检测miRNA的新方法.方法首先通过引物延伸反应在目标miRNA分子上引入荧光染料Cy5,形成miRNA-Cy5. 然后,PBF与miRNA-Cy5/DNA杂合体通过静电力结合并发生从PBF到Cy5的有效FRET,实现了基于阳离子共轭聚合物(CCP)的长波长区miRNA的均相检测,方法灵敏度高、特异性好,测定miR-221的线性为15~6 000 pmol/L,检出限(3σ)为8.4 pmol/L.方法拓展了CCP的应用,为基于CCP的生物传感和生化分析提供了新的均相检测平台.     

Self-assembling Characteristics of Amphiphilic Star Block Copolymers with a Polyelectrolyte Shell

1 Results Amphiphilic block copolymers are capable of forming supramolecular assemblies resembling those observed in nature,such as spherical micelles,worm micelles,and vesicles.Changing the solvent composition,ionic strength or pH of the polymer solution may induce the self-assembly of block copolymers or trigger the transition between the geometries of noncovalent assemblies.In the current work,we have synthesised starlike amphiphilic block copolymers having hydrophobic poly(methyl methacrylate),PMMA,...     

由十二烷基苯磺酰氯制备两亲性聚合物

以十二烷基苯磺酰氯为引发剂、氯化亚铜（CuCl）/2,2'-联吡啶为催化剂进行了甲基丙烯酸甲酯（MMA）的原子转移自由基聚合,结果表明聚合为活性自由基聚合过程。在此基础上,进行了甲基丙烯酸叔丁酯（t-BMA）的原子转移自由基聚合,得到了窄分子量分布的聚合物,并且引发剂的引发效率较高。将所得聚甲基丙烯酸叔丁酯水解,得到了以十二烷基苯基为疏水端、甲基丙烯酸链段为亲水端的两亲性聚合物。该聚合物具有表面活性,可以明显降低水的表面张力。     

Nanoengineered polypeptides from tetraphenylethylene-functionalized N-carboxyanhydride: Synthesis,self-assembly and intrinsic aggregation-induced emission

Ring-opening polymerization of N-carboxyanhydrides (NCAs) bearing pendant groups creates functional polypeptides. In this paper, we report the design, synthesis and polymerization of tetraphenylethylene (TPE)-modified NCA, which is used to incorporate aggregation-induced emission (AIE)-active segments into polypeptides. Specifically, we attempted the synthesis of amphiphilic methoxy poly(ethyleneglycol)-block-poly(γ-benzyl-_l-glutamate)-block-poly(γ-4-(1,2,2-triphenylvinyl)benzyl-_l-glutamate) (PEG-PBLG-PTPELG), which had well-controlled molecular weight and narrow polydispersity. The hydrophilic PEG and hydrophobic PBLG-PTPELG assembled into micelles in aqueous solution with diameter around 70 ​nm, displaying AIE at 480 ​nm. Our work demonstrates that the TPE-modified NCA is applicable for the preparation of the AIE-active polypeptides, integrating the AIE luminogens into the polypeptides which may offer unique opportunities for tuning AIE properties by adjusting the composition and conformation of polypeptides. We preliminarily explored the use of the amphiphilic polypeptides for the formulation of doxorubicin-containing micelles that can potentially be used for real-time monitoring of the nanomedicine distribution.     

驱油两亲聚合物及其分离组分的乳化规律研究

利用稳定性分析仪、光学显微镜、激光粒度分析仪、界面张力仪及流变仪研究驱油两亲聚合物及其分离组分的乳化规律及机制。结果表明:驱油两亲聚合物及其分离组分的分子结构相似,但疏水基团含量不同;大分子组分相比小分子组分界面活性较弱,形成乳化液的粒径较大,但其体系黏弹性更高,致使乳化液液滴迁移速率降低,稳定性增强;驱油两亲聚合物在不同组分的协同作用下,界面活性较高,形成乳化液的粒径最小,体系黏弹性适中且稳定,因此乳化液液滴的迁移速率最低,稳定性最高。     

Optical detection of acetylcholine esterase based on CdTe quantum dots

In this study, we have constructed a simple, sensitive and rapid biosensor for detection of acetylcholine esterase (AChE) based on CdTe quantum dots (QDs). The detection limit of AChE by one-step enzyme reaction based on the thiolglycolic acid (TGA) stabilized QDs (TGA-QDs) was 10 U/L and the linear range was 10-100 and 100-1200 U/L, respectively. The detection limit of AChE by two-step enzyme reaction based on the 3-mercaptopropionic acid (MGA) stabilized QDs (MGA-QDs) was found to be 20 U/L and the linear range was 100-2500 U/L. The experimental conditions of biosensors were optimized, and the detection mechanism was studied. We also detected AChE in serum samples based on TGA-QDs or MGA-QDs. The linear range was 10-140 and 50-1000 U/L, respectively. The excellent performance of this novel biosensor demonstrated that this strategy has prodigious potential to be applied in practice detection of AChE.