ZnS∶Cu-罗丹明B的荧光共振能量转移性质

为了解决现有的基于量子点荧光共振能量转移体系的生物毒性问题,选用无毒的ZnS∶Cu量子点与罗丹明B构建新型荧光共振能量转移体系。通过共沉淀法成功制备了形貌均一的ZnS∶Cu纳米晶量子点。在此基础上,测试了不同掺杂浓度的ZnS∶Cu量子点及罗丹明B的荧光光谱。然后,通过对ZnS∶Cu量子点的表面修饰构建了以ZnS∶Cu量子点为供体、罗丹明B为受体的荧光共振能量转移体系。实验结果表明:ZnS∶2%Cu量子点的发光光谱与罗丹明B的吸收光谱在481 nm处有较大重合,说明构建荧光共振能量转移的最佳铜掺杂摩尔分数为2%。通过计算发现以ZnS∶2%Cu量子点为供体、罗丹明B为受体的荧光共振能量转移体系的能量转移效率为25.8%。进一步实验结果表明,罗丹明B浓度也能够影响能量转移。     

CdTe量子点-铜酞菁复合体系荧光共振能量转移的研究

以波长为780 nm、重复频率为76 MHz、脉宽为130 fs的飞秒激光作为激发光源, 采用超快时间分辨光谱技术研究了CdTe量子点-铜酞菁复合体系的荧光共振能量转移. 实验结果表明, 在780 nm的双光子激发条件下, 复合体系中CdTe量子点的荧光寿命随着铜酞菁溶液浓度的增加而减少, 荧光共振能量转移效率增加. 同时也研究了激发功率对荧光共振能量转移效率的影响. 结果表明, 随着激发光功率的增加, 复合体系溶液中CdTe量子点的荧光寿命增加, 荧光共振能量转移效率减小, 其物理机理是因为高激发功率下的热效应和由双光子诱导的高阶激发态的跃迁. 当激发光功率为200 mW时, 双光子荧光共振能量转移效率为43.8%. 研究表明CdTe量子点-铜酞菁复合体系是非常有潜力的第三代光敏剂.     

CdTe量子点-罗丹明B荧光共振能量转移猝灭法测定金银花中的微量铜

研究CdTe量子点(供体)和罗丹明B(受体)之间荧光共振能量转移的最佳条件,建立了荧光共振能量转移猝灭法测定金银花中微量铜的新方法.采用十六烷基三甲基溴化铵,在pH 6.00的Tris-HCl缓冲液中,Cu2+能对能量转移体系中罗丹明B荧光峰强猝灭从而测定铜的含量.Cu2+浓度在1.3×10-4～3.1×10-2 μg...     

CdTe量子点-罗丹明B荧光共振能量转移法测定溶菌酶

合成了以硫代乙醇酸为稳定剂的CdTe量子点,以发射波长为530 nm的量子点为供体,罗丹明B为受体,建立一种以十六烷基三甲基溴化铵为介质的荧光共振能量体系检测溶菌酶含片中溶菌酶含量的方法。结果表明:在pH=5.0时,溶菌酶的浓度与共振能量转移效率降低值在2×10^-7~ 8×10^-6 mol·L^-1范围内呈线性关系,其线性方程为Y=306.07-13.85X,相关系数为0.991 0,检出限为2×10^-8 mol·L^-1,RSD为5.8%,平均回收率为101%(n=5)。     

由供体受体对的发射谱直接拟合计算荧光共振能量转移效率

荧光共振能量转移(FRET)广泛用于研究分子间的距离以及相互作用,但是由于光谱的串扰和荧光强度对浓度依赖的复杂性,很难定量测量FRET效率.本文提出了一种利用供体、受体和供体受体对的发射谱通过计算机拟合计算FRET效率的理论和方法.该方法适用于选择性地激发供体和受体与供体的浓度比已知的情况,因而适合基于绿色荧光蛋白(GFP)供体-受体对.本文利用该方法拟合计算了Cameleon分别在零钙和饱和钙时的FRET效率.     

基于四甲基联苯胺和吖啶橙间荧光共振能量转移的比率型荧光测定左氧氟沙星

基于3,3’,5,5’(四甲基联苯胺(3,3’,5,5’-tetramethylbenzidine, TMB)和吖啶橙(AO)之间荧光共振能量转移(FRET),建立了一种快速、低背景干扰、高灵敏度测定盐酸左氧氟沙星(LVF)的新型比率型荧光探针。在pH 5.0 NaAc-HCl缓冲溶液中,在310 nm的光激发下,TMB在350～500 nm处的荧光光谱和AO的吸收光谱重叠。以TMB作为能量供体,AO作为能量受体,构建了FRET体系。根据能量转移理论,该体系的荧光共振能量转移效率为62.5%,供体-受体间距离为2.17 nm,进一步说明TMB和AO之间发生了FRET。当在体系中加入LVF后,TMB将荧光能量转移给LVF, LVF又作为供体将能量转移给AO。LVF在TMB和AO之间起到桥梁作用,LVF将吸收的TMB荧光能量转移给AO,使得TMB荧光强度明显降低,AO的荧光强度则显著增加,从而提高了体系的FRET效率。在最优实验条件下,F_{546 nm}与F_{402 nm}之比与LVF浓度(2～80μmol·L^-1)之间存在良好的线...     

荧光共振能量转移增敏法测定锌

以巯基乙酸为稳定剂合成了CdTe量子点,并利用其与牛血清白蛋白(BSA)组成了荧光共振能量转移体系,考察BSA(供体)和CdTe量子点(受体)之间的荧光共振能量转移的最佳条件,建立了荧光共振能量转移增敏法测定Zn2+的新方法.在pH 7.4的Tris-HCl缓冲溶液中,Zn2+能对能量转移体系中CdTe量子点增敏从而测定锌的含量.Zn2+浓度在0.49-4.88μg/mL浓度范围内与CdTe量子点荧光强度呈现良好线性关系(r=0.9996),检出限为0.13μg/mL,RSD为3.2％,平均回收率为99.5％(n=5).方法适用于果汁饮料中微量锌的测定.     

碳量子点/罗丹明B分子复合体系中的能量和电子转移过程研究（英文）

本文采用荧光光谱结合稳态和瞬态吸收光谱技术,研究了碳量子点(CQDs)/罗丹明B(RhB)分子复合体系o-CQDs/RhB和mCQDs/RhB中的能量转移和电子转移过程以及它们之间的关系.研究发现在能量转移效率为73.2%的o-CQDs/RhB体系中,电子转移过程可以忽略;而在能量转移效率低于33.5%的m-CQDs/RhB体系中,电子转移过程则较为显著.在这个由碳量子点和染料分子组成的典型复合体系中所揭示的能量转移与电子转移过程之间的内联关系,将为与激子猝灭相关的应用提供有用的视角.     

Er3+离子掺杂钡镓锗玻璃上转换发光机理研究

研究了Er³⁺离子掺杂钡镓锗玻璃的吸收光谱、拉曼光谱和上转换光谱.分析了Er³⁺离子在钡镓锗玻璃中的上转换发光机理.结果表明：玻璃的最大声子能量为828cm^-1，紫外截止波长为275nm.采用800nm和980nmLD激发玻璃样品，在室温下观察到强烈的上转换绿光和红光发射.随着Er³⁺离子浓度的增加，绿光发光强度先增加后减小，而红光发光强度呈单调递增趋势.能量分析表明：800nmLD激发产生的绿光主要源于Er³⁺离子4I_13/2能级的激发态吸收过程；红光发射主要源于Er³⁺离子4I_13/2能级与4I_11/2能级之间的能量转移过程.980nmLD激发产生的绿光主要源于Er³⁺离子4I_11/2能级之间的能量转移过程；而红光发射主要源于Er³⁺离子4I_13/2能级与4I_11/2能级之间的能量转移过程和4I_13/2能级的激发态吸收过程.通过量子效率分析，发现采用800nmLD激发Er³⁺离子掺杂浓度为1mol% 的样品时，上转换绿光发光效率最高. 关键词： 上转换发光机理 3+离子掺杂')" href="#">Er³⁺离子掺杂 钡镓锗玻璃     

表面增强的分子间能量转移效应的机理研究

对吸附于粗糙金属银表面的分子间能量转移效应的机理进行了研究.采用电磁理论,讨论了金属银表面对分子间能量转移速率的影响.结果表明,当能量供体(D)分子的辐射频率和能量受体(A)分子的吸收频率同时与银表面等离子体激发频率共振时,分子间非辐射的能量转移速率被增强10~3—10~4倍.采用表面增强喇曼散射(SERS)活性表面-银胶,测量了吸附的2,2菁染料单体分子和J聚集体分子的荧光光谱,观察到的J聚集体分子增强的592.4nm的荧光带是通过被加速的分子间能量转移过程而产生的,从而证实了表面增强的分子间能量转移效 关键词：     

聚二甲基硅氧烷微流道中光流控荧光共振能量转移激光

将单一折射率的石英裸光纤植入由聚二甲基硅氧烷构成的基片微流道中,以低折射率的罗丹明B(RhB)和吡啶821(LDS821)乙醇溶液构成的供体和受体对作为激光增益介质.采用沿光纤轴向消逝波抽运方式,首先以波长为532nm的连续波激光器作为激励光,对荧光共振能量转移特性参数进行了研究.然后以波长为532nm的脉冲激光器作为抽运光,通过直接激励供体分子RhB,并将其能量转移给临近的受体分子LDS821,在不改变抽运光波长的条件下,实现了较低阈值(1.26μJ/mm~2)的受体LDS821激光辐射.     

Photobleaching-Based Quantitative Analysis of Fluorescence Resonance Energy Transfer inside Single Living Cell

The current advances of fluorescence microscopy and new fluorescent probes make fluorescence resonance energy transfer (FRET) a powerful technique for studying protein-protein interactions inside living cells. It is very hard to quantitatively analyze FRET efficiency using intensity-based FRET imaging microscopy due to the presence of autofluorescence and spectral crosstalks. In this study, we for the first time developed a novel photobleaching-based method to quantitatively detect FRET efficiency (Pb-FRET) by selectively photobleaching acceptor. The Pb-FRET method requires two fluorescence detection channels: a donor channel (CH ₁ ) to selectively detect the fluorescence from donor, and a FRET channel (CH ₂ ) which normally includes the fluorescence from both acceptor and donor due to emission spectral crosstalk. We used the Pb-FRET method to quantitatively measure the FRET efficiency of SCAT3, a caspase-3 indicator based on FRET, inside single living cells stably expressing SCAT3 during STS-induced apoptosis. At 0, 6 and 12 h after STS treatment, the FRET efficiency of SCAT3 obtained by Pb-FRET inside living cells was verified by two-photon excitation (TPE) fluorescence lifetime imaging microscopy (FLIM). The temporal resolution of Pb-FRET method is in second time-scale for ROI photobleaching, even in microsecond time-scale for spot photobleaching. Our results demonstrate that the Pb-FRET method is independent of photobleaching degree, and is very useful for quantitatively monitoring protein-protein interactions inside single living cell.     

Förster resonant energy transfer in quantum dot layers

Förster resonant energy transfer (FRET) in quantum dot (QD) layer structures has been analyzed. Small and large colloidal CdTe QDs were used as donors and acceptors, respectively. A FRET theory for random donor/acceptor distributions in two dimensions, taking into account exclusion zones around the donors, was applied to characterize FRET in a mixed monolayer. The exclusion zones provide a possibility to include the QD size in the FRET analysis and to determine its impact on the FRET efficiency. The acceptor concentration dependence of the FRET efficiency can also be described within this theory. In a separate donor/acceptor layer structure the distance dependence of the FRET efficiency as well as the acceptor enhancement was investigated. Both were found to agree well with the model of FRET between donor and acceptor layers.     

Two-Photon Excited Fluorescence Energy Transfer: A Study Based on Oligonucleotide Rulers

The use of two-photon excitation of fluorescence for detection of fluorescence resonance energy transfer (FRET) was studied for a selected fluorescent donor–acceptor pair. A method based on labeled DNA was developed for controlling the distance between the donor and the acceptor molecules. The method consists of hybridization of fluorescent oligonucleotides to a complementary single-stranded target DNA. As the efficiency of FRET is strongly distance dependent, energy transfer does not occur unless the fluorescent oligonucleotides and the target DNA are hybridized. A high degree of DNA hybridization and an excellent FRET efficiency were verified with one-photon excited fluorescence studies. Excitation spectra of fluorophores are usually wider in case of two-photon excitation than in the case of one-photon excitation [1]. This makes the selective excitation of donor difficult and might cause errors in detection of FRET with two-photon excited fluorescence. Different techniques to analyze the FRET efficiency from two-photon excited fluorescence data are discussed. The quenching of the donor fluorescence intensity turned to be the most consistent way to detect the FRET efficiency. The two-photon excited FRET is shown to give a good response to the distance between the donor and the acceptor molecules.     

Energy transfer between fluorescent dyes in photonic crystals

Energy transfer from fluorescein (Fl) to Rhodamine B (RhB) in the opal photonic crystals has been investigated by photoluminescence. The results show that the energy transfer can be enhanced effectively by photonic bandgaps. When the fluorescence emission wavelength of donor Fl overlaps the photonic bandgap the fluorescence intensity of the donor is suppressed, while the fluorescence intensity of acceptor RhB is obviously enhanced. This enhancement can be attributed to the inhibition of radiative emission of the donor in the photonic crystals.     

庆大霉素与水溶性CdTe量子点的荧光共振能量转移作用

以巯基丙酸(mercaptopropionic acid,MPA)为稳定剂合成水溶性CdTe最子点(quantum dots,QDs),以CdTe QDs作为能量供体.庆大霉素(Gentamycin,GT)作为能垦受体,建立了荧光共振能量转移(fluorescence resonance energy transfer,FRET)体系.在690 nm处可见发射峰,半峰宽约10 nm,在一定范围内荧光强度与GT的含量旱线性关系,线性范围为2～20 mg·L-1,相关系数r=0.986 7.优化了不同的激发波长、pH、离子强度、时间和温度等凼素对反应的影响,并应用傅里叶变换红外光谱(Fourier transform infrared spectroscopy,FTIR)和高效液相色谱(high-performance liquid chromatography,HPLC)分别表征了化学结构和相对专一性.结果表明巯基丙酸的巯基中S原子和羧基中氧原子与纳米微粒表面的富Cd离子发生了配位作用,CdTe QDs与GT的耦合主要是通过量子点周围巯基丙酸羧基(-COOH)中的氧原子与GT的胺基(-NH2)形成分子问氧键实现的;GT与CdTe QDs的结合率为0.35:1.研究表明GT可以作为检测CdTe QDs标记牛血清白蛋白(bovine serum albumin,BSA)的荧光增敏剂,荧光强度值增强6倍,应用前景广阔.     

Quantitative analysis of caspase-3 activation by fitting fluorescence emission spectra in living cells

Confocal fluorescence imaging and fluorescence resonance energy transfer (FRET) technology have been widely used to study protein–protein interactions in living cells. However, it is very difficult to quantitatively analyze FRET efficiency due to the excitation spectral crosstalk and emission spectral crosstalk between donor and acceptor. In this study, we developed a novel method to quantitatively obtain the FRET efficiency by fitting the emission spectra (FES) of donor–acceptor pair, and this method is free from both excitation and emission spectral crosstalk. We used the FES method to quantitatively monitor the FRET efficiency of SCAT3, a caspase-3 indicator based on FRET, inside living cells stably expressing SCAT3 during STS-induced apoptosis. At 0, 6 and 12 h after STS treatment, the FRET efficiency of SCAT3 obtained by FES are consistent with that by two-photon excitation (TPE) fluorescence lifetime imaging microscopy (FLIM) in living cells stably expressing SCAT3. In this study, the FES was also used to analyze the caspase-3 activation in living cells during anti-cancer drug such as taxol, Artesunate (ART) or Dihydroartemisinin (DHA) treatment. Our results showed that ART or DHA induced apoptosis by a caspase-3-dependent manner, while caspase-3 was not involved in taxol-induced cell death.     

基于银纳米三角片与罗丹明6G的荧光共振能量转移法检测钴离子

以罗丹明6G和牛血清白蛋白的复合物为荧光探针,银纳米三角片为猝灭剂,研究了银纳米三角片与荧光复合物的荧光共振能量转移现象,建立了测定钴离子的荧光分析法。研究发现,一定浓度的荧光复合物与银纳米三角片混合后,由于荧光复合物在银纳米三角片上吸附而发生荧光共振能量转移,荧光猝灭达到80%左右。当钴离子存在时,银纳米三角片与罗丹明6G荧光共振能量转移被破坏,荧光逐渐恢复。随着钴离子浓度的增加,体系荧光值的恢复率(I/I₀)与钴离子的浓度(c_Co2+)有良好的线性关系,线性回归方程为I/I₀=1.054+21.72 c_Co2+,相关系数r2为0.996 2。通过对自然水样进行加标回收检测,实现了钴离子的定量检测,回收率在90.4%～115.1%之间。建立了一种可靠的选择性检测钴离子的荧光分析方法。