Advances in second near-infrared fluorescent nanoprobes-based in vivo imaging for biomedical applications / 上海交通大学学报（医学版）

Besides the advantages of high sensitivity, non-invasive, and real-time imaging that the general optical imaging technologies have, the second near-infrared (1 000-1 700 nm) in vivo imaging is regarded as one of the most promising optical imaging technologies in clinical applica-tion at present due to its advantages such as low autofluorescence background, deep tissue penetration and clear imaging. In the second near-infrared imaging system, the fluorescence probe is the most critical technical difficulty and the current research hotspot. Thereinto, due to the unique physical and chemical properties of nanomaterials, the second near-infrared fluorescent nanoprobe is an ideal contrast agent for the current second near-infrared optical imaging technology. The reported inorganic materials that can be used as the second near-infrared fluores-cent nanoprobes include quantum dots, rare earth nanoparticles, and single-walled carbon nanotubes, and the reported organic materials are mainly conjugated polymers. In this paper, the research progresses of the second near-infrared fluorescence nanoprobes mentioned above are re-viewed in order to better understand their application to the field of biomedicine, and promote the further research and clinical application of the second near-infrared in vivo imaging to the biomedical field.

Design of SERS nanoprobes for Raman imaging: materials, critical factors and architectures

Raman imaging yields high specificity and sensitivity when compared to other imaging modalities, mainly due to its fingerprint signature. However, intrinsic Raman signals are weak, thus limiting medical applications of Raman imaging. By adsorbing Raman molecules onto specific nanostructures such as noble metals, Raman signals can be significantly enhanced, termed surface-enhanced Raman scattering (SERS). Recent years have witnessed great interest in the development of SERS nanoprobes for Raman imaging. Rationally designed SERS nanoprobes have greatly enhanced Raman signals by several orders of magnitude, thus showing great potential for biomedical applications. In this review we elaborate on recent progress in design strategies with emphasis on material properties, modifying factors, and structural parameters.

Determination of Tryptophan Based on Inner Filter Effect of FluorescentYttrium Vanadate: Europium Nanoprobes / 分析化学

Yttrium vanadate:europium nanoprobes (YVO4∶Eu NPs) with good fluorescence properties and water solubility were synthesized by solvent thermal method.Due to the overlapping of the excitation spectrum of YVO4∶Eu NPs and the absorption spectrum of tryptophan, fluorescent internal filter effect (IFE) occurred, in which YVO4∶Eu NPs were the fluorophore and tryptophan was the absorber, leading the fluorescence of YVO4∶Eu NPs was quenched.Therefore, a new method for the determination of tryptophan was established by using fluorescent YVO4∶Eu as nanoprobes based on IFE.Some experimental parameters, such as the adding amount of YVO4∶Eu NPs, pH value of the reacting solution, and reacting time, were investigated.Under the optimum reaction conditions, the linear range of the method was 4.0×10-6-4.0×104 mol/L and the detection limit was 1.0×10-6 mol/L (3σ).The content of tryptophan in the soy sauce was determined with the recovery of 95.2% and 97.3%.This method is simple, rapid, sensitive and accurate.

Click-Functionalized Fluorescent Nanoprobes with Folate Receptor-Targeting Ability for Cancer Cell Imaging / 分析化学

Folate receptor ( FR )-targeted fluorescent nanoprobes ( RSiNPs-Folate ) were constructed by modifying Rubpy-doped silica nanoparticles ( RSiNPs) with folic acid ( FA) based on click chemistry coupling method, which was successfully used for cancer cell imaging. Firstly, RSiNPs were prepared by St?ber method and modified with azide groups through the hydrolysis of silane coupling agents ( Az-PTES ) , then propargyl folate were conjugated onto the nanoparticle surfaces via click reaction. It was demonstrated that the FA-functionalized nanoprobes were successfully prepared by monitoring the characteristic peak of the azide group at 2105 cm-1 before and after coupling. In the condition of physiological pH, the nanoprobes exhibited strong red emission at 601 nm when excited at the 458 nm excitation wavelength. The cell imaging results showed that RSiNPs-Folate could effectively target FR-positive HeLa cells, while no obvious fluorescence was observed for FR-negative A549 cells. The receptor-mediated imaging mechanism was confirmed by free FA competition experiments. More importantly, HeLa cells could be selectively recognized and imaged in the mixing cell system. Compared with the carbodiimide conjugation protocols, the click-functionalized nanoprobes had many advantages such as simple synthesis procedures, mild reaction conditions and high yields, which could be potentially used for fluorescent labeling and imaging of different cancer cells.

An Ultrasensitive Simultaneous Immunoassay Based on Arsenic and Mercury Ions Labeled SiO2@Au Nanoparticle Probes / 分析化学

An ultrasensitive immunoassay was developed based on As3+ and Hg2+ labeled SiO2 @ Au nanoparticles signal tags and hydride generation-atomic fluorescence spectrometry (HG-AFS) for the detection of carcinoembryonic antigen(CEA) and carbohydrate antigen 19-9 (CA 19-9) respectively. Firstly, amino SiO2@ Au NPs were synthesized for selective absorption of As3+ and Hg2+ ions respectively. Subsequently,the secondary antibody (Ab2) of CEA and CA 19-9 was respectively labeled on As3+ or Hg2+-SiO2 @ Au NPs to prepare the corresponding signal tags for CEA and CA 19-9. Based on the sandwich immunoassay scheme, the tags, two antigen and corresponding first antibodies were bio-conjugated on the bottom of 96-well plate at room temperature to form the immunocomplex. After it was dissolved in alkali solution, As3+ and Hg2+ ions were released in solution and detected by HG-AFS, which concentration was proportional with logarithms of CEA and CA 19-9. The reaction conditions were optimized and the tags were characterized. This assay was based on determination of the concentration of As3+ and Hg2+ for quantization of the corresponding CEA and CA 19-9 antigen. The assay showed a wide linear range from 0. 001 to 100. 0 μg / L for CEA and 0. 01-80 U/ mL for CA 19-9, and a lower detection limit of 0. 5 ng / L and 0. 005 U/ mL respectively. This proposed method was used in real serums samples, the results were consistence with that by ELISA. The immunoassay showed three orders of magnitude of sensitivity lower than that of ELISA, which provides a promising simultaneous immunoassay for the early diagnosis of cancer .