Investigation of ultrafast dynamics of CdTe quantum dots by femtosecond fluorescence up-conversion spectroscopy

The ultrafast carrier relaxation processes in CdTe quantum dots are investigated by femtosecond fluorescence upconversion spectroscopy.Photo-excited hole relaxing to the edge of the forbidden gap takes a maximal time of ～ 1.6 ps with exciting at 400 nm,depending on the state of the photo-excited hole.The shallow trapped states and deep trap states in the forbidden gap are confirmed for CdTe quantum dots.In addition,Auger relaxation of trapped carriers is observed to occur with a time constant of ～ 5 ps.A schematic model of photodynamics is established based on the results of the spectroscopy studies.Our work demonstrates that femtosecond fluorescence up-conversion spectroscopy is a suitable and effective tool in studying the transportation and conversion dynamics of photon energy in a nanosystem.

Study on the Binding Interaction of Nanomaterials Tio_2 with Bovine Serum Albumin by Three-Dimensional Fluorescence Spectrometry (TDFS)

Although scientific and policy bodies have stated that nanomaterials are not intrinsically toxic, there is interest in evaluating if and how many engineered nanomaterials may do harm to the health of mankind and the ecological environment. The interaction between nano-TiO2 and bovine serum albumin (BSA) was studied by using TDFS and UV methods in this research.

Up-Conversion Properties of Oxy-Fluoride Glasses Co-Doped with Ho^(3+) and Yb^(3+)

Oxy-fluoride glasses with composition of 25SiO2-65PbF2-9.4AlF3-0.1HoF3-0.5YbF3 were prepared. Their up-conversion fluorescence characteristics were investigated by 980 nm laser. Two emission peaks were observed at 540 and 650 nm. The up-conversion mechanism and processes were analyzed. The relationship between pumping power and relative intensity of emissions was discussed. From the dependence, it is known that the emissions centered at 540 and 650 nm are both attributed to two-photon process.

Green and red up-conversion emissions and thermometric application of Er^(3+) -doped silicate glass

The green and red up-conversion emissions centred at about 534, 549 and 663 nm of wavelength, corresponding respectively to the ^2H11/2 → ^4I15/2, ^4S3/2 → ^4I15/2 and ^4F9/2 → ^4I15/2 transitions of Er^3＋ ions, have been observed for the Er^3＋-doped silicate glass excited by a 978 nm semiconductor laser beam. Excitation power dependent behaviour of the up-conversion emission intensity indicates that a two-photon absorption up-conversion process is responsible for the green and red up-conversion emissions. The temperature dependence of the green up-conversion emissions is also studied in a temperature range of 296-673 K, which shows that Er^3＋-doped silicate glass can be used as a sensor in high-temperature measurement.

Narrow-bandwidth emissive carbon dots:A rising star in the fluorescent material family

Fluorescent carbon dots(CDs)have recently become a research hotspot in multidisciplinary fields owing to their distinctive advantages,including outstanding photoluminescence properties,high biocompatibility,low toxicity,and abundant raw materials.Among the promising CDs,narrow‐bandwidth emissive CDs with high color purity have emerged as a rising star in recent years because of their significant potential applications in bioimaging,information sensing,and photoelectric displays.In this review,the state-of-the-art advances of narrow-bandwidth emissive CDs are systematically summarized,and the factors influencing the emission bandwidth,preparation methods,and applications of narrow-bandwidth emissive CDs are described in detail.Besides,existing challenges and future perspectives for achieving high-performance narrow-bandwidth emissive CDs are also discussed.This overview paper is expected to generate more interest and promote the rapid development of this significant research area.

Preparation,Properties,and Applications of Low-Dimensional Molecular Organic Nanomaterials

In recent years, great progress has been made in research and development of small-molecule organic materials with various low-dimensional nanostructures. This paper presents a comprehensive review of recent research progress in this field, including preparation, electronic and optoelectronic properties and applications. First, an introduction gives to the reprecipitation, soft templates methods, and progress in synthesis and morphological control of low-dimensional small-molecule organic nanomaterials. Their unique optical and electronic properties and research progress in these aspects are reviewed and discussed in detail. Applications based on low-dimensional small-molecule organic nanomaterials are briefly described. Finally, some perspectives to the future development of this field are addressed.

基于磁性纳米材料Fe_(3)O_(4)@PPy和聚集诱导发光材料(TTAPE)检测肝素药品中的多硫酸软骨素残留

合成了一种聚吡咯修饰的磁性纳米颗粒(Fe_(3)O_(4)@PPy),通过结合AIE荧光探针四苯基乙烯衍生物(TTAPE)建立了一种检测肝素药品中多硫酸软骨素的检测方法。肝素和多硫酸软骨素与TTAPE结合导致运动受限,进而释放荧光,而Fe_(3)O_(4)@PPy加入后可以猝灭其荧光。研究了肝素和多硫酸软骨素与TTAPE结合后荧光增强规律和Fe_(3)O_(4)@PPy对它们的荧光猝灭规律,建立了不同的猝灭曲线,进而同时检测肝素和多硫酸软骨素。实验确定了肝素和多硫酸软骨素的最佳荧光检测波长为482 nm,Fe_(3)O_(4)@PPy的使用量为5 mg,检测浓度的线性范围为0~3.5 mg/L,肝素浓度的相对偏差在0.5%以下。肝素实际样品中多硫酸软骨素的回收率为90%和96.67%,相对标准偏差为4.4%和4.1%。

Recent development of organic small-molecule and nanomaterial fluorescent probes for hydrazine

Hydrazine,an essential chemical,has been used within a wide spectrum of industries,including pesticides,pharmaceuticals and even satellite-launching systems.However,the excessive consumption of hydrazine raised the risk of environmental pollution accidents and occurrence of diseases because of its high toxicity and volatility.This led to the discovery of diverse fluorescent probes for the monitoring of the dangerous substance,including those based on organic small molecules and emerging nanomaterials.Herein,we are going to present a comprehensive review of recently reported hydrazine fluorescent probes,and discuss their structure design strategies and detection mechanisms.In particular,both organic small-molecule and nanomaterial fluorescent probes for hydrazine will be discussed together for the first time.

拟除虫菊酯农药类特异性传感体系构建及其在柑橘农残检测中的应用

拟除虫菊酯类农药在我国柑橘等果品中的施用量占全球第一,对其残留的快速筛查和监管对于保障我国果品食用安全具有重要意义。该文研究多功能纳米材料(NaYF_(4)∶Yb,Er-Fe_(3)O_(4)@MIP)的制备条件,采用傅里叶变换红外光谱、透射电子显微镜对该材料进行表征,通过对NaYF_(4)∶Yb,Er-Fe_(3)O_(4)@MIP的吸附和选择性实验,验证了其对4种拟除虫菊酯类农药具有较好的选择性和吸附性能,并构建基于该材料的拟除虫菊酯农药类特异性传感体系对柑橘果品菊酯类农残进行快速检测。结果表明,该传感体系在0.02~2.5 mg/L内对拟除虫菊酯类农药(溴氰菊酯、氯氰菊酯、氟氯氰菊酯、氰戊菊酯)具有良好的线性关系,检出限分别为6.17×10^(-4)、6.65×10^(-4)、7.21×10^(-4)、9.61×10^(-4)、6.43×10^(-4)mg/L。结合柑橘鲜果专属前处理技术进行实际柑橘样品检测,加标回收率为87.9%~105.8%,相对标准偏差为0.53%~6.41%,方法准确、灵敏、稳定,可以用于实际柑橘样品中拟除虫菊酯类农药的检测。

荧光纳米材料在食源性致病菌检测方面的应用进展

食源性致病菌是威胁人类健康的重要因素,严重威胁人类健康和社会经济。食源性致病菌的高效快速检测是其有效防治的基础。荧光纳米材料具有尺寸小、荧光性强、光稳定性好和生物相容性高等特性,可与各种检测方法结合,近年来在食源性致病菌检测方面的应用越来越广泛。该文对量子点、上转换纳米颗粒、金属纳米簇和碳点4种纳米材料在食源性致病菌检测方面的研究和应用进行综述,以期为食源性致病菌的快速检测提供参考。

纳米材料在食品检验鉴定中的应用研究进展

食品安全直接影响到国家安全稳定和人民群众的身心健康。食品检验鉴定技术在食品领域的违法犯罪案件中发挥着重要证据固定作用。近年来,运用纳米材料可以使食品检测更加简便、灵敏、高效。本文主要从纳米材料修饰的电化学传感器、荧光纳米材料和荧光染料修饰的适配体传感器和纳米表面增强拉曼光谱分析技术三方面介绍了纳米材料在食品检测鉴定中的应用研究,并对纳米技术在食品检测方面的发展趋势进行了总结和展望。

荧光免疫层析法结合智能手机在食品危害物质快速检测中的研究进展

免疫层析法因其经济、简便、灵敏、特异等优点,被广泛应用于多个领域的快速检测。相对于胶体金纳米颗粒在定量和抗干扰上的局限,荧光纳米材料因优异光学性能已成为免疫层析法中重要的信号标签。本文简要综述了量子点、上转换纳米粒子、时间分辨荧光微球、持续发光纳米粒子等荧光纳米标签的制备和性能,重点介绍荧光免疫层析法应用于食源性致病菌、真菌毒素、农药兽药、抗生素、激素和内分泌干扰物、重金属等食品危害物中的检测与分析,阐述荧光免疫层析法与智能手机的联合使用,可为食品安全检测和现场实时监测提供参考。

Novel colorimetric,photothermal and up-conversion fluorescence triple-signal sensor for rosmarinic acid detection

Rosmarinic acid(RA)is promising as a natural and nontoxic food additive.However,many analysis methods for RA generally depend on large instruments and single signals for quantitative detection.A new upconversion fluorescence,colorimetric and photothermal multi-modal sensing strategy is developed for the quantification of RA.β-cyclodextrin(CD)modified citric acid(Cit)wrapped NaYF_(4):Yb/Er-Cit-CD(Y:Yb/Er-Cit-CD)up-conversion nanocomposite has been synthesized,which emits green fluorescence at 550nm under 980nm near-infrared(NIR)excitation.In the presence of oxidized 3,3',5,5'-tetramethylbenzidine(oxTMB),the green fluorescence is significantly quenched attributed to the fluorescence inner filter effect(IFE)between oxTMB and Y:Yb/Er-Cit-CD.When RA is intervened,blue oxTMB is reduced to colorless 3,3',5,5'-tetramethylbenzidine(TMB)inducing the recovery of up-conversion fluorescence.At the same time,colorimetric and photothermal signals readout can be easily achieved thanks to the color indication and photothermal effect of the oxTMB.The constructed Y:Yb/Er-Cit-CD/oxTMB sensor displays high sensitivity,visibility and simplicity for RA,and the limits of detection(LOD)for fluorescence,colorimetric and photothermal were 0.004μmol/L,0.036μmol/L and 0.043μmol/L,respectively.This sensing system is successfully performed for the detection of RA in food samples.

Repurposing organic semiconducting nanomaterials to accelerate clinical translation of NIR-II fluorescence imaging

Optical imaging possesses important implications for early disease diagnosis,timely disease treatment,and basic medical as well as biological research.Compared with the traditionary near-infrared(NIR-I)window(650-950 nm)optical imaging,the emerging second near-infrared(NIR-II)window optical imaging technology owns the great superiorities of non-invasiveness,nonionizing radiation,and real-time dynamic imaging with the low biological interference,can significantly improve the tissue penetration depth and detection sensitivity,thus expecting to achieve accurate and precise diagnosis of major diseases.Inspired by the conspicuous superiorities,an increasing number of versatile NIR-II fluorophores have been legitimately designed and engineered for precisely deep-tissue mapping-mediated theranostics of life-threatening diseases.Organic semiconducting nanomaterials(OSNs)are derived from organic conjugated molecules withπ-electron delocalized skeletons,which show greatly preponderant prospects in the biomedicine field due to the excellent photoelectric property,tunable energy bands,and fine biocompatibility.In this review,the superiorities of NIR-II fluorescence imaging using OSNs for brilliant visualization various of diseases,including tongue cancer,ovarian cancer,osteosarcoma,bacteria or pathogens infection,kidney dysfunction,rheumatoid arthritis,liver injury,and cerebrovascular function,are emphatically summarized.Finally,the reasonable prospects and persistent efforts for repurposing OSNs to facilitate the clinical translation of NIR-II fluorescence phototheranostics are outlined.

Fluorescent Silicon-based Nanomaterials Imaging Technology in Diseases

Fluorescence imaging analysis of microscale dynamic process(e.g.,metabolism,mitosis,endocytosis,exocytosis,etc.)is of particular significance to study the related pathogenesis and design the intracellular drug delivery systems.Owing to unique physical,chemical and/or biological properties,silicon(Si)-based nanomaterials have been employed to design and construct different types of nanoprobes for the imaging analysis of diseases.Thus,we herein present an overview of recent advances in fluorescent silicon nanomaterials imaging technology for analyzing and diagnosing diseases.Firstly,we mainly introduce the construction of Si nanomaterials-based bioprobes for long-term fluorescence imaging analysis of cancer-related biological information,such as tumour cells,biomarkers and nanocarriers.Afterwards,we focus on the Si nanomaterials-based imaging technology for monitoring the dynamic process of pathological changes of various ocular diseases(e.g.,ocular angiogenesis,bacterial keratitis,etc.).Then,we outline the construction of Si-based nanoprobes and their applications in simultaneously imaging and treating the bacteria-induced diseases caused by broad-spectrum bacteria-related pathogens.Finally,we further discuss the major challenges and prospects for developing silicon-based fluorescence imaging technology.

荧光纳米探针在农药残留检测中的研究进展

免疫分析技术因具有快速、简便和低成本等特点在农药残留监测中发挥着重要的作用。基于纳米材料增敏的荧光免疫传感器因灵敏度高、特异性强等优点,近年来逐渐成为研究热点。本文总结近年来荧光免疫传感器的相关研究进展,针对不同种类荧光纳米探针建立的免疫传感器在农药残留检测中的研究进行综述,重点阐述酶基荧光免疫探针、荧光纳米材料免疫探针、纳米酶基免疫探针和纳米支架型免疫探针的原理、特点及应用现状,并展望荧光免疫传感器在农药检测中的应用前景,旨在为荧光纳米探针在食品农药残留检测中的发展、应用提供参考。

多功能光-磁复合纳米材料制备及其在柑橘农残检测中的应用

为构建一种稳定、结构可控的光-磁复合材料并将其用于农药残留检测当中,本实验采用高温溶剂热法制备上转换纳米材料(Upconversion Nanoparticles,UCNPs),研究温度、转速对UCNPs的影响,实现UCNPs的可控制备。采用反相微乳液法制备三种不同结构的多功能光-磁复合纳米材料,借助扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)、振动样品磁强计(VSM)等方法研究多功能纳米材料的形貌、结构等性能。此外,利用此复合纳米材料研究柑橘中各类型农药的响应情况。实验结果表明,温度对UCNPs粒径大小起着决定性的作用。在不同结构的UCNPs-Fe_(3)O_(4)复合材料中,A结构(UCNPs材料粒径更大的卫星结构)的荧光特性更强;B结构(两种原材料粒径相近的交织结构)在室温下同时具有20.5 emu·g^(-1)的饱和磁化强度和较高的荧光强度,性能平衡;C结构(Fe_(3)O_(4)材料粒径更大的卫星结构)的磁性最佳。同时,该复合材料对柑橘中菊酯类农药、新烟碱类农药、氨基甲酸酯类农药、有机磷农药均有一定响应,对菊酯类农药的响应最强,可用于开发菊酯类农药生物传感器。本研究采用简单普适的合成方法,为其他复合材料合成研究提供一定的理论思路,该材料有较佳的光-磁特性和生物相容性,在药物递送、成像等领域都有较大的应用潜力。

基于YVO_(4):Eu荧光纳米悬浮液的手印显现研究

在水相体系中,以柠檬酸为修饰剂,稀土氯化物、原钒酸钠为反应原料,利用水热法合成出荧光优异、粒径较小的YVO_(4):Eu荧光纳米材料。将YVO_(4):Eu荧光纳米材料应用于悬浮液显现技术,配制出YVO_(4):Eu荧光纳米悬浮液,对该显现试剂的影响因素进行优化,确定手印显现的最佳模式,并详细考察手印的显现效果。实验结果表明,在254 nm紫外光激发下,显现后的手印发射较强的红色荧光,与客体对比反差强烈,纹线特征清晰连贯、反映明显。综上所述,YVO_(4):Eu荧光纳米悬浮液手印显现技术能够高质量显现光滑非渗透性客体表面上的潜在手印,在公安一线实务操作中具有良好的应用前景。

生物质基碳量子点的绿色合成及其LED应用

各类生态友好型生物质都可以作为绿色碳源制备新型零维碳纳米发光材料碳量子点(CQDs)。本文以农林废弃物、园林绿化垃圾、餐厨垃圾为原料,一步水热法制备生物质基CQDs。采用高分辨透射电镜、拉曼光谱、傅里叶红外光谱、X射线光电子能谱、紫外-可见光吸收光谱、荧光光谱等对各类CQDs进行表征分析,探究生物质种类对CQDs荧光性能的影响规律。实验结果表明:各类生物质基CQDs在紫外光激发下均发出蓝色荧光,农林废弃物制备的CQDs荧光量子产率(QY)普遍较低,鸡蛋壳、梧桐叶和柠檬皮基CQDs荧光QY分别达到9.29%、9.03%和4.51%,这三种生物质及制备的CQDs中均含有N或S元素,说明含有N或S元素的天然生物质有助于提高CQDs的荧光QY。将生物质基CQDs制作荧光粉,制成的发光二极管(LED)的光学性能指标与CQDs的荧光性能呈现出一定的映射关系,相关结论为生物质基CQDs的绿色合成及LED的绿色制备提供了有力指导。

ZnO@Au的制备及在免分离荧光测定microRNA-21中的应用

本论文利用水热法与原位生长策略,在FTO表面制备了多孔ZnO@Au复合纳米材料,并在其表面修饰捕获探针以特异性识别肿瘤标志物microRNA-21。借助于外切酶ExoⅢ对双链的剪切作用,吸附有目标RNA的捕获探针被剪切从而释放出荧光基团,造成荧光信号的显著增强,以此实现microRNA-21的荧光传感。结果表明,所制备的ZnO@Au复合材料及传感策略有效地避免了荧光分析中分离步骤可能出现的假阳性现象,在1 nM-500 nM浓度范围内具有良好的线性关系,检测限低至1 nM。