红外荧光染料发色机理的探讨

本文根据现代量子理论分析了红外荧光染料的发色机理,探讨了激发能量与光谱反射之间的关系。研究表明,红外荧光染料的伪装性能受分子结构、取代基、纤维基质和上染率等的影响。     

Ultrabright Fluorescent Silica Mesoporous Silica Nanoparticles: Control of Particle Size and Dye Loading

The synthesis of ultrabright fluorescent mesoporous silica nanoparticles (UFSNPs) of various sizes loaded with different amounts of fluorescent dye (Rhodamine 6G) is reported here. The dye is physically entrapped inside the nanochannels of the silica matrix created during templated sol–gel self assembly. Due to the specific nanoenvironment, the fluorescence of the encapsulated dye molecules remains unquenched up to very high concentrations, which results in relatively high fluorescence. The particle size (ranging from 20–50 nm) and dye loading (0.8–9.3 mg dye per g particles) are controlled by the timing of the synthesis and the concentration of several organotriethoxysilanes, which are coprecursors of silica. The quantum yields of the encapsulated dye range from 0.65 to 1.0. The relative brightness of a single particle is equivalent to the fluorescence of 30–770 free nondimerized R6G dye molecules in water, or to that of 1.5–39 CdSe/ZnS quantum dots. Despite the presence of some hydrophobic groups on the particles' surfaces, colloidal suspensions of the particles are relatively stable (as monitored for 120 days).     

Highly polarized luminescence from an AIEE-active luminescent liquid crystalline film

Luminescent liquid crystals (LLCs) have attracted significant interest for organic optoelectronic applications, especially for the generation of linear polarized light. Here, a novel LLC molecule, 2-(4-(nonanealkoxy)phenyl)-3-(4-formamidephenyl)-acrylonitrile (CN-NPFA), is reported, which shows strong fluorescence in the solid state due to the aggregation-induced enhanced emission (AIEE) effect. Moreover, a well-aligned liquid crystalline film using AIEE-active molecules, is obtained using an in-plane electric field with an alignment layer. It exhibits highly polarized luminescence (ρ = 0.74) with a high fluorescence quantum yield. The device is both cheap and easy to fabricate, and has the potential to be used in practical electro-optic applications.     

飞秒激光流动烧蚀制备ZnSe有机复合量子点

采用飞秒激光流动烧蚀法制备了聚乙烯亚胺(PEI)包覆的ZnSe量子点水相分散液。水相分散液外观呈现亮黄色透明液体状。多个ZnSe有机复合量子点在水中聚集形成球形胶束,通过扫描电子显微镜(SEM)检测发现,胶束粒径为40~100 nm。利用高分辨透射电子显微镜(HRTEM)和X射线衍射(XRD)研究ZnSe晶体学特性变化,结果表明制得的ZnSe量子点保持了块体ZnSe的立方闪锌矿晶型。该ZnSe有机复合量子点的水分散液在365 nm紫外光照射下显示出明亮的绿色荧光,荧光中心波长约在500 nm处。采用光致发光光谱和紫外可见吸收光谱研究了该有机复合量子点的pH值响应特性,结果表明随着分散液中pH值由9降低到4,光致发光光谱显示出蓝移特性,波长最大蓝移量为25 nm。讨论了绿色荧光的来源与荧光波长调谐的可能机理。     

wavelength dependent time development of the intensity of dye solution lasers

It has been observed that the intensity of laser emission from two different dye solution lasers (DTTC in DMSO and cryptocyanine in glycerol) reaches a maximum at the shortest wavelength in the emission band before it peaks at the longest. A simple model of dye solution lasers which explains this wavelength-time effect is presented. This effect can be interpreted to yield information on the rate of relaxation of internal energy of the dye molecule. The evidence suggests that, on the time scale of the laser action in these experiments (∼20 ns) the ground state of the dye molecule is inhomogeneously broadened. In addition, it is shown that certain other of the dye laser's properties may be understood by analysis of the solution's absorption and fluorescence spectra.     

Generation of terahertz electromagnetic pulses from quantum-wellstructures

Terahertz generation from semiconductor quantum-well structures pumped by a femtosecond optical pulse is studied. We propose a three-level model for the electrons and holes in the quantum wells. We then solve the coupled optical Bloch equations directly using a Runge-Kutta method and calculate the terahertz radiation field. We study optical rectification and quantum beats caused by charge oscillations in 1) a coupled quantum well in which quantum beats occur between two electron states of the coupled system and 2) a single-quantum-well structure in which quantum beats occur between light-hole and heavy-hole excitons. Our theoretical results agree very well with the experimentally measured terahertz data     

Quantum Yield‐Engineered Biocompatible Probes Illuminate Lung Tumor Based on Viscosity Confinement‐Mediated Antiaggregation

Low quantum yield and aggregation‐mediated quenching are two concerns for fluorescence imaging. However, there are not yet general means available for addressing these issues. Herein, a viscosity confinement‐mediated antiaggregation strategy is established to enable the improved fluorescence properties of entrapped fluorophores in dye‐encapsulation nanotechnology including quantum yield, fluorescence lifetime, and photostability. To instantiate this strategy, solid DL‐menthol (DLM) is introduced to disperse entrapped indocyanine green (ICG) fluorophores when coencapsulating DLM and ICG molecules in organic poly(lactic‐co‐glycolic acid) carriers. Depending on the robust ability of highly viscous DLM to augment the migration barrier and diminish diffusion coefficient, ICG aggregation and aggregation‐mediated quenching are demonstrated to be theoretically and experimentally inhibited, resulting in prolonged fluorescence lifetime, increased quantum yield, and facilitated radiative process. Consequently, the fluorescence imaging ability and photostability are significantly improved, enabling the in vitro, cellular‐level, and in vivo fluorescence imaging. More significantly, this solid DLM‐mediated antiaggregation strategy can act as a general method to extend to the intermolecular fluorescence resonance energy transfer (FRET) process and improve FRET efficiency via inhibiting the aggregation‐mediated quenching.     

碘分子BпOu+态荧光激发谱研究

本文以染料激光器的输出激发碘分子,采用荧光激发谱技术对碘分子BпOu+态进行了实验研究,对所得荧光激发谱进行了标识,在此基础上计算了碘分子该态的分子常数,与理论值符合较好。     

乙酸的光谱学及其特性的研究

采用光栅光谱仪获得了波长为 2 5 4nm(Δλ1 /2 4nm)的紫外光激励乙酸溶液的紫外吸收光谱和不同浓度溶液的荧光光谱 ,并对其产生机理和谱线特性进行了研究。实验结果和理论分析表明 ,波长为 2 5 4nm的紫外光诱导乙酸分子发出的荧光是由乙酸分子上的荧光团 -C =O -产生的 ,其量子转换效率可达 5 0 %以上 ;乙酸溶液的荧光量子产额将随浓度发生明显的变化。研究乙酸的紫外光谱和荧光光谱及其特性可为其作为溶剂和催化剂时对其他有机大分子光谱特性的影响提供参考     

量子拍频数据拟合与分析

利用快速傅里叶变换的方法对有限激光脉宽、有限仪器响应时间条件下的量子拍频光谱数据进行拟合,讨论了非理想实验条件对拟合结果的影响,并对２２４￣２３５ｎｍ范围内ＳＯ２分子的量子拍频数据进行了拟合与分析。发展观察到的最子拍频信号是来自ＳＯ２Ｃ（＾１Ｂ２）态与基态高振动态的耦合。     

Synthesis,Characterization, and Application of Antibody Functionalized Fluorescent Silica Nanoparticles

Fluorescent silica nanoparticles (FSNs) are prepared by incorporating dye into a mesoporous silica nanoparticle (MSN) synthesis procedure. FSNs containing sulforhodamine B, hydrophobically modified sulforhodamine B, and Cascade Blue hydrazide are made. The MSN‐based FSNs do not leach dye under simulated physiological conditions and have strong, stable fluorescence. FSNs prepared with sulforhodamine B are compared to FSNs prepared with hydrophobically modified sulforhodamine B. The data indicate that FSNs prepared with sulforhodamine B are equally as stable but twice as fluorescent as particles made with hydrophobically modified sulforhodamine B. The fluorescence of a FSN prepared with sulforhodamine B is 10 times more intense than the fluorescence of a 4.5 nm core–shell CdSe/ZnS quantum dot. For diagnostic applications, a method to selectively and covalently bind antibodies to the surface of the FSNs is devised. FSNs that are functionalized with antibodies specific for Neisseria gonorrhoeae specifically bind to Neisseria gonorrhoeae in flow cytometry experiments, thus demonstrating the functionality of the attached antibodies and the potential of MSN‐based FSNs to be used in diagnostic applications.     

单分子的双光子激发光漂白速率

研究了多种条件下的光漂白几率与激发光强度间的定量依赖关系。利用MRC1024多光子激发显微系统和单光子计数技术,测量了单个若丹明B（RhB）分子在不同强度光激发时的双光子激发（TPE）和光漂白寿命。实验结果表明：单个RhB分子和TPE光漂白寿命与激发光强度倒数的平方成正比,亦即光漂白速率与荧光基团分子处于激发态的几率成线性依赖关系,该结果与单光子激发（1PE）时的光漂白结果相同,但是却不同于多分子TPE光漂白的实验结果。     

采用激光光热偏转法直接测量稀染料溶液的绝对荧光量子产额

报道了一种采用激光光热偏转法直接测量稀染料溶液的绝对荧光量子产额的新方法，以若丹明６Ｇ甲醇溶液为样品，证实了该方法的可行性，并讨论了其优缺点。     

Conjugated Polymers Combined with a Molecular Beacon for Label‐Free and Self‐Signal‐Amplifying DNA Microarrays

A conjugated polymer (CP) and molecular‐beacon‐based solid‐state DNA sensing system is developed to achieve sensitive, label‐free detection. A novel conjugated poly(oxadiazole) derivative exhibiting amine and thiol functional groups ( POX‐SH ) is developed for unique chemical and photochemical stability and convenient solid‐state on‐chip DNA synthesis. POX‐SH is soluble in most nonpolar organic solvents and exhibits intense blue fluorescence. POX‐SH is covalently immobilized onto a maleimido‐functionalized glass slide by means of its thiol group. Molecular beacons having a fluorescent dye or quencher molecule as the fluorescence resonance energy transfer (FRET) acceptor are synthesized on the immobilized POX‐SH layer through direct on‐chip oligonucleotide synthesis using the amine side chain of POX‐SH . Selective hybridization of the molecular beacon probes with the target DNA sequence opens up the molecular beacon probes and affects the FRET between POX‐SH and the dye or quencher, producing a sensitive and label‐free fluorescence sensory signal. Various molecular design parameters, such as the size of the stem and loop of the molecular beacon, the choice of dye, and the number of quencher molecules are systematically controlled, and their effects on the sensitivity and selectivity are investigated.     

罗丹明6G的非简并双光子吸收特性研究

利用飞秒激光泵浦-探测技术,在实验上研究了常用荧光染料分子罗丹明6G的非简并双光子激发荧光特性,并测试了其非简并双光子吸收截面。与等效波长下文献报道的罗丹明6G的简并双光子吸收截面作对比,发现其非简并双光子吸收截面总是大于简并双光子吸收截面,从实验上证明了双光子吸收过程中的中间态共振增强效应。基于有效态模型,用量子化学的方法从理论上分析罗丹明6G的双光子吸收截面,将理论拟合与实验测试结果进行对比,发现理论与实验具有很好的一致性。     

Panchromatic Chromophore Mixtures in an AlPO4‐5 Molecular Sieve: Spatial Separation Effects and Energy Transfer Cascades

Dye‐loaded AlPO₄‐5 single crystals were prepared by microwave‐assisted hydrothermal synthesis from a batch, containing a mixture of three chromophores (Coumarin 40, Rhodamine BE50, and Oxazine 1) differing in their absorption range, molecular dimensions, and solubilities. Confocal fluorescence images reveal a spatial separation effect of the dye molecules, where the slimmer, more‐soluble dye molecule (Coumarin 40) is uniformly distributed in the body of the single crystal, and the bulky and/or less‐soluble ones (Rhodamine BE50, Oxazine 1) are situated in distinct domains. Visible spectra show good panchromatic absorption of visible light. Fluorescence lifetime measurements indicate the presence of an energy transfer cascade of the entirely fixed dye molecules from Coumarin 40 to Oxazine 1. The transfer mechanism is predominantly radiative.     

All‐in‐One Phototheranostics: Single Laser Triggers NIR‐II Fluorescence/Photoacoustic Imaging Guided Photothermal/Photodynamic/Chemo Combination Therapy

Development of single near‐infrared (NIR) laser triggered phototheranostics for multimodal imaging guided combination therapy is highly desirable but is still a big challenge. Herein, a novel small‐molecule dye DPP‐BT is designed and synthesized, which shows strong absorption in the first NIR window (NIR‐I) and fluorescence emission in the second NIR region (NIR‐II). Such a dye not only acts as a dual‐modal contrast agent for NIR‐II fluorescence and photoacoustic (PA) imaging, but also serves as a combined therapeutic agent for photothermal therapy (PTT) and photodynamic therapy (PDT). The single NIR laser triggered all‐in‐one phototheranostic nanoparticles are constructed by encapsulating the dye DPP‐BT, chemotherapy drug DOX, and natural phase‐change materials with a folic acid functionalized amphiphile. Notably, under NIR laser irradiation, DOX can effectively release from such nanoparticles via NIR‐induced hyperthermia of DPP‐BT. By intravenous injection of such nanoparticles into Hela tumor‐bearing mice, the tumor size and location can be accurately observed via NIR‐II fluorescence/PA dual‐modal imaging. From in vitro and in vivo therapy results, such nanoparticles simultaneously present remarkable antitumor efficacy by PTT/PDT/chemo combination therapy, which is triggered by a single NIR laser. Overall, this work provides an innovative strategy to design and construct all‐in‐one nanoplatforms for clinical phototheranostics.     

Structural systematic features of photoelectric effect in aromatic polymers with polymethine dyes

The structural systematic features of quantum-yield variation in charge-carrier photogeneration are investigated for polymer systems with molecules into which polymethine dyes of various structures had been introduced. The correlations between the quantum yields and the second-harmonic-generation efficiency in the media containing such dyes are revealed, and relations of the quantum yields to such dye-molecule structural parameters as the ionization potential of its donor fragment, the electron affinity of its acceptor fragment, and the electron-transfer distance between donor and acceptor fragments of the dye molecule are established.     

The perylene derivative BASF-241 solution as a new tunable dyelaser in the visible

Basic optical properties of the perylene derivative BASF-241 solution in chloroform relevant to its application as a dye laser were measured. The fluorescence spectrum, excited by frequency-doubled (532-nm) Nd:YAG laser pulses, shows three pronounced peaks centered at 540, 580, and 630 nm, with a Stokes shift and mirror image in relation to the absorption spectrum. The quantum yield was about a unity, with a lifetime of 5.0±0.5 ns. Addition of trichloroacetic acid (CCl₃COOH) causes a red shift of absorption and fluorescence spectra by about 750 cm^-1-L/mol. In a cavity consisting of a ~100% reflecting back mirror and an 8% reflecting output coupler, lasing was obtained at 577 nm, with a threshold of ~10 μJ/pulse. Using a grating, a tuning range of almost 20 nm was obtained, centered at the 0-1 fluorescence emission peaks     

双窗口电磁诱导透明的相干瞬态研究

通过求解准A-型四能级系统的含时密度矩阵方程,研究了系统从单窗口电磁诱导透明(EIT)向双窗口EIT转换的相干瞬态过程.该过程表现为一种量子拍频形式,并利用缀饰态理论很好地解释了量子拍频的规律,指出这种量子拍频效应源于射频驱动场所引起劈裂能级间的量子相干.结果表明:当探测场与相应的裸态跃迁能级共振作用时,拍频频率等于射频驱动场Rabi频率的二分之一;当探测场与强射频驱动场和原子系统相互作用所产生的缀饰态跃迁能级共振时,拍频频率等于射频驱动场的Rabi频率.