首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Extending the spectral absorption of organolead halide perovskite solar cells from visible into near‐infrared (NIR) range renders the minimization of non‐absorption loss of solar photons with improved energy alignment. Herein, we report on, for the first time, a viable strategy of capitalizing on judiciously synthesized monodisperse NaYF4:Yb/Er upconversion nanoparticles (UCNPs) as the mesoporous electrode for CH3NH3PbI3 perovskite solar cells and more importantly confer perovskite solar cells to be operative under NIR light. Uniform NaYF4:Yb/Er UCNPs are first crafted by employing rationally designed double hydrophilic star‐like poly(acrylic acid)‐block‐poly(ethylene oxide) (PAA‐b‐PEO) diblock copolymer as nanoreactor, imparting the solubility of UCNPs and the tunability of film porosity during the manufacturing process. The subsequent incorporation of NaYF4:Yb/Er UCNPs as the mesoporous electrode led to a high efficiency of 17.8 %, which was further increased to 18.1 % upon NIR irradiation. The in situ integration of upconversion materials as functional components of perovskite solar cells offers the expanded flexibility for engineering the device architecture and broadening the solar spectral use.  相似文献   

2.
建立了一种利用碱基堆积原理并以上转换纳米粒子荧光作为内参的精准检测DNA的方法。该方法首先利用热分解法制备NaYF_4∶Yb,Er上转换荧光纳米颗粒(upconversion nanoparticles,UCNPs),再通过表面羧基化变性牛血清蛋白修饰后与氨基化探针核酸单链共价偶联,形成上转换荧光标记显示探针。最后再基于碱基堆积原理进行杂交检测。研究结果表明以NaYF_4∶Yb,Er荧光强度为内参,根据FAM/UCNP的强度比来定量检测目标DNA浓度比单一的以报告DNA中FAM荧光强度定量检测目标DNA浓度要更为精准,有效地避免了实验中出现的人为操作和仪器误差。本方法不需要进行扩增,检测底限可达到5 nmol·L~(-1),且在较大的浓度范围内有较好的线性关系,同时该方法也有着良好的特异性,能有效区分单碱基错配序列。  相似文献   

3.
建立了一种利用碱基堆积原理并以上转换纳米粒子荧光作为内参的精准检测DNA的方法。该方法首先利用热分解法制备NaYF4:Yb,Er上转换荧光纳米颗粒(upconversion nanoparticles,UCNPs),再通过表面羧基化变性牛血清蛋白修饰后与氨基化探针核酸单链共价偶联,形成上转换荧光标记显示探针。最后再基于碱基堆积原理进行杂交检测。研究结果表明以NaYF4:Yb,Er荧光强度为内参,根据FAM/UCNP的强度比来定量检测目标DNA浓度比单一的以报告DNA中FAM荧光强度定量检测目标DNA浓度要更为精准,有效地避免了实验中出现的人为操作和仪器误差。本方法不需要进行扩增,检测底限可达到5 nmol·L-1,且在较大的浓度范围内有较好的线性关系,同时该方法也有着良好的特异性,能有效区分单碱基错配序列。  相似文献   

4.
陈钰雪  燕照霞  姜磊 《化学通报》2021,84(9):919-925
以NaYF_4材料为基质的上转换纳米颗粒(UCNPs)是最早报道的、应用范围最广的上转换材料之一。掺杂了稀土离子的颗粒不但可以在不同激发条件下发射出不同波长和强度的荧光,而且可以与多种光敏分子搭配使用,通过荧光共振能量转移产生单线态氧,实现生物医学成像或诊疗方面的应用。但是其形貌和荧光性能均受制备方法和工艺条件的影响较大。本文通过水热法合成了两类掺杂不同稀土离子的十种NaYF_4 UCNPs,在保持掺杂离子的终浓度不变的条件下,探究离子类型与比例对纳米材料的结构和上转换发光性能的影响。在此基础上,探索了多种卟啉类光敏剂分子与NaYF_4 UCNPs发生能量转换及单线态氧的产生能力。本工作可为基于NaYF_4材料的上转换颗粒的规模化制备和工艺升级提供数据支撑和理论参考。  相似文献   

5.
Currently, highly luminescent colloidal upconversion nanoparticles (UCNPs) have expanded an increasing interest of researchers because of their facilitating lability in the biomedical/clinical field. In this study, NaYF4:Yb,Er UCNPs are prepared by eco-friendly metal complexation-based thermal decomposition method at a lower temperature in aqueous media. The phase structure, crystallinity, phase purity, morphology, colloidal dispersibility, surface structure, surface charge, and optical and luminescent properties were evaluated carefully by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive x-ray analysis (EDX), Thermogravimetric analysis (TGA), zeta potential, Fourier transform infrared (FTIR), UV/visible and photoluminescent spectroscopic techniques. XRD pattern shows a pure single-phase cubic structure with an average grain size of 30–35 nm. TEM and SEM micrographs exhibited irregularly shaped spherical morphologies, porous surface structures highly aggregated UCNPs with the narrow-size distribution. Positive zeta potential has shown value signifying high absorption in the visible region which indicates particle's good colloidal stability in aqueous media. Under NIR-laser light excitation, the UCNPs emit strong UC emission transitions in the visible region. A broad infrared absorption peak of hydroxyl groups (–OH) in FTIR spectrum and mass loss at a lower temperature in TGA verified the surface functionality of UCNPs, with high colloidal stability, and excellent biocompatibility in aqueous media. In terms of their surface characteristics and high luminescent properties, the NaYF4:Yb,Er UCNPs could be interestingly applied in tagging of biomolecules, drug delivery, proteins labeling, and therapeutic and thermostats applications.  相似文献   

6.
Rare earth-doped upconversion nanoparticles (UCNPs) have promising potentials in biodetection due to their unique frequency upconverting capability and high detection sensitivity. This paper reports an improved UCNPs-based fluorescence probe for dual-sensing of Aflatoxin B1 (AFB1) and Deoxynivalenol (DON) using a magnetism-induced separation and the specific formation of antibody-targets complex. Herein, the improved UCNPs, which were namely NaYF4:Yb/Ho/Gd and NaYF4:Yb/Tm/Gd, were systematically studied based on the optimization of reaction time, temperature and the concentration of dopant ions with simultaneous phase and size controlled NaYF4 nanoparticles; and the targets were detected using the pattern of competitive combination assay. Under an optimized condition, the advanced fluorescent probes revealed stronger fluorescent properties, broader biological applications and better storage stabilities compared to traditional UCNPs-based ones; and ultrasensitive determinations of AFB1 and DON were achieved under a wide sensing range of 0.001–0.1 ng ml−1 with the limit of detection (LOD) of 0.001 ng ml−1. Additionally, the applicability of the improved nanosensor for the detection of mycotoxins was also confirmed in adulterated oil samples.  相似文献   

7.
A new luminescence energy transfer (LET) system has been designed for the detection of thrombin in the near‐infrared (NIR) region by utilizing NIR‐to‐NIR upconversion lanthanide nanophosphors (UCNPs) as the donor and gold nanorods (Au NRs) as the acceptor. The use of upconverting NaYF4:Yb3+,Tm3+ nanoparticles with sharp NIR emission peaks upon NIR excitation by an inexpensive infrared continuous wave laser diode provided large spectral overlap between the donor and the acceptor. Both the Au NRs and carboxyl‐terminated NaYF4:Yb3+,Tm3+ UCNPs were first modified with different thrombin aptamers. When thrombin was added, a LET system was then formed because of the specific recognition between the thrombin aptamers and thrombin. The LET system was used to monitor thrombin concentrations in aqueous buffer and human blood samples. The limits of detection for thrombin are as low as 0.118 nM in buffer solution and 0.129 nM in human serum. The method was also successfully applied to thrombin detection in blood samples.  相似文献   

8.
We report a new strategy to fabricate a multifunctional composite photoanode containing TiO2 hollow spheres (TiO2-HSs), Au nanoparticles (AuNPs) and novel NaYF4 : Yb,Er@NaLuF4 : Eu@SiO2 upconversion nanoparticles (UCNPs). The AuNPs are grown on the photoanode film including TiO2-HSs and UCNPs by a simple in situ plasmonic treatment. As a result, an impressive power conversion efficiency of 14.13 % is obtained, which is a record for N719 dye-based dye-sensitized solar cells, demonstrating great potential for the solar cells toward commercialization. This obvious enhancement is ascribed to a collaborative mechanism of the TiO2-HSs exhibiting excellent light-scattering ability, of the UCNPs converting near-infrared photons into visible photons and of the AuNPs presenting outstanding surface plasmon resonance effect. Notably, a steady-state experiment further reveals that the champion cell exhibits 95.33 % retainment in efficiency even after 180 h of measurements, showing good device stability.  相似文献   

9.
Assembling nanomaterials from two classes with exceptional control at the nanoscale can lead to new nanohybrids with novel properties. Here, we report the tunable up-conversion luminescence properties of CsPb(Br1-x/Ix)3 perovskite nanocrystals (PeNCs) sensitized by NaYF4:Yb,Tm@NaYF4 up-conversion nanoparticles (UCNPs) at 980 nm excitation. The up-conversion luminescence of NaYF4:Yb3+,Tm3+@NaYF4/CsPb(Br1-x/Ix)3 composite demonstrates that the radiative photon reabsorption process is accountable for the UC energy transfer from excited levels of Tm3+-based UCNPs to PeNCs. The long-lived Tm3+ states feed PeNCs carriers with intrinsic lifetimes extending from nanoseconds to microseconds. By varying the UCNPs/PeNCs concentration ratio, the NaYF4:Yb3+,Tm3+@NaYF4/CsPb(Br0.55I0.45)3 composite generates UC white light emission. The near-infrared excited white light-emitting devices are more compatible with human tissues than blue light-excited ones. Therefore, the prototype of UC white light-emitting diode is developed by coupling the UCNPs/PeNCs composite coated glass plate onto a commercial 940 nm-light-emitting diode chip. To overcome the counterfeiting risk that arises in the case of a single fluorescence mode, we developed a simple dual-model strategy based on manipulation of UC and down-conversion luminescence in anti-counterfeiting under 980 nm and 365 nm excitation, which makes it difficult to encrypt the information. In addition, the UCNPs/PeNCs composite exhibited better photostability under near-infrared illumination, retaining 85% of initial photoluminescence intensity, solving the problem of photo-instability.  相似文献   

10.
A novel assay of chromium(III) ion based on upconversion fluorescence resonance energy transfer was designed and established. Lysine-capped NaYF4:Yb/Er upconversion nanoparticles (UCNPs) and dimercaptosuccinic acid-capped gold nanoparticles (AuNPs) were used as the energy donor and acceptor, respectively. They were bound together via electrostatic interaction, resulting in the quenching of the fluorescence of UCNPs by AuNPs. Chromium(III) ions can specifically and strongly interact with dimercaptosuccinic acid that was modified on the surface of AuNPs, leading to the separation of AuNPs from UCNPs and the recovery of fluorescence of UCNPs. The fluorescence recovery of UCNPs showed a good linear response to Cr3+ concentration in the range of 2–500 nM with a detection limit of 0.8 nM. This method was further applied to determine the levels of Cr3+ in urine. Compared with other fluorescence methods, current method displayed very high sensitivity and signal-to-noise ratio because of the excitation of near-infrared that can eliminate autofluorescence, providing a promising examination of biological samples for the diagnostic purposes.  相似文献   

11.
Upconverting nanoparticles (UCNPs) with fascinating properties hold great potential as nanotransducers for solving the problems that traditional photodynamic therapy (PDT) has been facing. In this report, by using well‐selected bifunctional gadolinium (Gd)‐ion‐doped UCNPs and water‐soluble methylene blue (MB) combined with the water‐in‐oil reverse microemulsion technique, we have succeeded in developing a new kind of UCNP/MB‐based PDT drug, NaYF4:Er/Yb/Gd@SiO2(MB), with a particle diameter less than 50 nm. Great efforts have been made to investigate the drug‐formation mechanism and provide detailed physical and photochemical characterizations and the potential structure optimization of the as‐designed PDT drug. We envision that such a PDT drug will become a potential theranostic nanomedicine for future near‐infrared laser‐triggered photodynamic therapy and simultaneous magnetic/optical bimodal imaging.  相似文献   

12.
Lanthanide‐doped upconversion nanoparticles (UCNPs) have shown great promise in versatile bioapplications. For the first time, organosilica‐shelled β‐NaLuF4:Gd/Yb/Er nanoprobes with a rattle structure have been designed for dual‐modal imaging and photodynamic therapy (PDT). Benefiting from the unique rattle structure and aromatic framework, these nanoprobes are endowed with a high loading capacity and the disaggregation effect of photosensitizers. After loading of β‐carboxyphthalocyanine zinc or rose Bengal into the nanoprobes, we achieved higher energy transfer efficiency from UCNPs to photosensitizers as compared to those with conventional core–shell structure or with pure‐silica shell, which facilitates a large production of singlet oxygen and thus an enhanced PDT efficacy. We demonstrated the use of these nanoprobes in proof‐of‐concept X‐ray computed tomography (CT) and UC imaging, thus revealing the great potential of this multifunctional material as an excellent nanoplatform for cancer theranostics.  相似文献   

13.
Upconversion emissions from rare‐earth nanoparticles have attracted much interest as potential biolabels, for which small particle size and high emission intensity are both desired. Herein we report a facile way to achieve NaYF4:Yb,Er@CaF2 nanoparticles (NPs) with a small size (10–13 nm) and highly enhanced (ca. 300 times) upconversion emission compared with the pristine NPs. The CaF2 shell protects the rare‐earth ions from leaking, when the nanoparticles are exposed to buffer solution, and ensures biological safety for the potential bioprobe applications. With the upconversion emission from NaYF4:Yb,Er@CaF2 NPs, HeLa cells were imaged with low background interference.  相似文献   

14.
NaYF4:Er,Yb upconversion luminescent nanoparticles (UCNPs) were prepared by hydrothermal methods at 180 °C for 24 h. The X-ray diffraction (XRD) and TEM (transmission electron microscopy) images show that the resulting 60 nm UCNPs possess a hexagonal structure. In this work, maleic anhydride (MA) was grafted on the surface of UCNPs to induce hydrophilic properties. The photoluminescence spectra (PL) show upconversion emissions centered around 545 nm and 660 nm under excitation at 980 nm. The luminescent inks, including UCNPs@MA, polyvinyl alcohol (PVA), deionized water (DI), and ethylene glycol (EG), exhibit suitable properties for screen printing, such as high stability, emission intensity, and tunable dynamic viscosity. The printed patterns with a height of 5 mm and a width of 1.5 mm were clearly observed under the irradiation of a 980 nm laser. Our strategy provides a new route for the controlled synthesis of hydrophilic UCNPs, and shows that the UCNPs@MAs have great potential in applications of anti-counterfeiting packing.  相似文献   

15.
A crystal design strategy is described that generates hexagonal‐phased NaYF4:Nd/Yb@NaYF4:Yb/Tm luminescent nanocrystals with the ability to emit light at 803 nm when illuminated at 745 nm. This is accomplished by taking advantage of the large absorption cross‐section of Nd3+ between 720 and 760 nm plus efficient spatial energy transfer and migration through Nd3+→Yb3+→Yb3+→Tm3+. Mechanistic investigations suggest that a cascaded two‐photon energy transfer upconversion process underlies the emission mechanism. This protocol enables deep‐tissue imaging to be achieved while mitigating the attenuation effect associated with the visible emission and the overheating constraint imposed by conventional 980 nm excitation.  相似文献   

16.
Novel β‐NaGdF4/Na(Gd,Yb)F4:Er/NaYF4:Yb/NaNdF4:Yb core/shell 1/shell 2/shell 3 (C/S1/S2/S3) multi‐shell nanocrystals (NCs) have been synthesized and used as probes for in vivo imaging. They can be excited by near‐infrared (800 nm) radiation and emit short‐wavelength infrared (SWIR, 1525 nm) radiation. Excitation at 800 nm falls into the “biological transparency window”, which features low absorption by water and low heat generation and is considered to be the ideal excitation wavelength with the least impact on biological tissues. After coating with phospholipids, the water‐soluble NCs showed good biocompatibility and low toxicity. With efficient SWIR emission at 1525 nm, the probe is detectable in tissues at depths of up to 18 mm with a low detection threshold concentration (5 nM for the stomach of nude mice and 100 nM for the stomach of SD rats). These results highlight the potential of the probe for the in vivo monitoring of areas that are otherwise difficult to analyze.  相似文献   

17.
《印度化学会志》2023,100(5):100990
The emerging upconversion nanoparticles (UCNP) have gained substantial consideration in the field of bioanalytical as well as diagnostic applications. Therefore, great progress has been made in the synthesis and surface modification of luminescent UCNPs over the last two decades. In this paper, we have reported monodispersed and high luminescent upconversion nanoparticles NaYF4: 20%Yb3+, 2%Tm3+ have been synthesized using a solvothermal method, followed by a coating of the NaYF4 shell with a thin layer of SiO2 on the surface to afford the core-shell NaYF4:Yb3+, Tm3+@SiO2 nanoparticles (NP@SiO2). The prepared nanoparticles were of strong upconversion fluorescent emission intensity, hexagonal phase, and with an average size of about 8 ± 1 nm, which have been characterized by luminescence spectroscopy, powder X-ray diffraction (P-XRD), Dynamic light scattering (DLS), and Transmission electron microscopy (TEM). The results indicate that the NP@SiO2 can be used for the conjugation of fluorescent probes for various biomolecules and can find applications in cancer cell imaging and disease diagnosis.  相似文献   

18.
An ultrasensitive fluorescence resonance energy transfer (FRET) bioassay was developed to detect staphylococcal enterotoxin B (SEB), a low molecular exotoxin, using an aptamer-affinity method coupled with upconversion nanoparticles (UCNPs)-sensing, and the fluorescence intensity was prominently enhanced using an exonuclease-catalyzed target recycling strategy. To construct this aptasensor, both fluorescence donor probes (complementary DNA1–UCNPs) and fluorescence quencher probes (complementary DNA2–Black Hole Quencher3 (BHQ3)) were hybridized to an SEB aptamer, and double-strand oligonucleotides were fabricated, which quenched the fluorescence of the UCNPs via FRET. The formation of an aptamer–SEB complex in the presence of the SEB analyte resulted in not only the dissociation of aptamer from the double-strand DNA but also both the disruption of the FRET system and the restoration of the UCNPs fluorescence. In addition, the SEB was liberated from the aptamer–SEB complex using exonuclease I, an exonuclease specific to single-stranded DNA, for analyte recycling by selectively digesting a particular DNA (SEB aptamer). Based on this exonuclease-catalyzed target recycling strategy, an amplified fluorescence intensity could be produced using different SEB concentrations. Using optimized experimental conditions produced an ultrasensitive aptasensor for the detection of SEB, with a wide linear range of 0.001–1 ng mL−1 and a lower detection limit (LOD) of 0.3 pg mL−1 SEB (at 3σ). The fabricated aptasensor was used to measure SEB in a real milk samples and validated using the ELISA method. Furthermore, a novel aptasensor FRET assay was established for the first time using 30 mol% Mn2+ ions doped NaYF4:Yb/Er (20/2 mol%) UCNPs as the donor probes, which suggests that UCNPs are superior fluorescence labeling materials for food safety analysis.  相似文献   

19.
A new method is presented for preparing gram amounts of very small core/shell upconversion nanocrystals without additional codoping of the particles. First, ca. 5 nm β‐NaYF4:Yb,Er core particles are formed by the reaction of sodium oleate, rare‐earth oleate, and ammonium fluoride, thereby making use of the fact that a high ratio of sodium to rare‐earth ions promotes the nucleation of a large number of β‐phase seeds. Thereafter, a 2 nm thick NaYF4 shell is formed by using 3–4 nm particles of α‐NaYF4 as a single‐source precursor for the β‐phase shell material. In contrast to the core particles, however, these α‐phase particles are prepared with a low ratio of sodium to rare‐earth ions, which efficiently suppresses an undesired nucleation of β‐NaYF4 particles during shell growth.  相似文献   

20.
由于近红外光在太阳光谱中占44%,因此,近红外光驱动的光催化剂的研制具有十分重要的意义.上转换发光材料可将低能量的近红外光子转换为高能光子,这种高能光子可以通过构建荧光共振转移系统将能量转移并活化量子效率较高的半导体材料,对于太阳能的转化利用具有潜在的应用前景.在本文中,通过胶体化学的过程在电纺丝制备的内嵌CdS纳米颗粒以及上转换荧光纳米颗粒(UCNPs)的二氧化硅复合纳米纤维表面外延生长一层二氧化钛层,通过高温煅烧得到二氧化钛复合纳米管.我们通过二氧化硅结构将CdS纳米颗粒与上转换荧光纳米颗粒紧紧束缚在一起,实现较高的荧光共振能量转移.而且,选择β-NaYF4:Yb(30%),Tm(0.5%)@NaYF4:Yb(20%),Er(2%)作为纳米能量转换器,替代以前研究工作中使用的β-NaYF4:Yb(30%),Tm(0.5%)或者β-NaYF4:Yb(30%),Tm(0.5%)@NaYF4纳米颗粒,来进一步提高近红外光的转换效率.通过透射电子显微镜照片很清楚的观察到制备的TiO2复合纳米管内部内嵌有大量的CdS与上转换纳米颗粒.通过X-射线衍射以及X-射线光电子能谱能仪器对产物的物相以及表面的化学组成进行了细致的表征.结果显示,通过本实验方法已经成功获得了TiO2复合纳米管.用稳态与瞬态荧光仪研究了最终样品的荧光性质.研究结果揭示,与上转换纳米颗粒以及二氧化硅复合纳米纤维相比,复合二氧化钛纳米管可以将上转换荧光纳米颗粒的(UV-Vis)部分荧光完全淬灭了.特别是,铒离子的荧光(650 nm)也被有效淬灭转移,说明本研究采用β-NaYF4:Yb(30%),Tm(0.5%)@NaYF4:Yb(20%),Er(2%)纳米能量转换器,可以提高近红外光的转换效率,紫外-可见吸收光谱证实,这种二氧化钛纳米管在紫外-可见光区中的吸收光谱与β-NaYF4:Yb(30%),Tm(0.5%)@NaYF4:Yb(20%),Er(2%)纳米颗粒的荧光光谱具有较大的重叠,使得上转换荧光纳米颗粒与CdS以及二氧化钛组分之间的荧光共振转移的效率大大提高,进而会显著提高光催化的效果.以罗丹明染料作为污染物为模型,我们研究了罗丹明染料在氙灯下或者近红外光光照下的光催化分解实验.研究结果表明,90%的罗丹明染料分子在20 min内就被降解掉,效率高于其它的近红外光催化剂.上转换荧光纳米颗粒的能量转换效率可以得到大幅度提高,本研究工作中制备的光催化剂利用太阳能的效率将会得到极大提高,在未来为能源危机以及环境保护提供一种可供选择的方法与技术.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号