Chen Xueyuan's team of Fujian Institute of physical composition has developed a near infrared two region rare earth doped CAS nano fluorescent labeling material excited by blue LED

Rare earth doped near infrared two region (nir-ii: 1000-1700 nm) nano fluorescent labeling materials have the advantages of good photochemical stability, narrow linewidth, long fluorescence life, deep biological tissue penetration, no background fluorescence interference and low toxicity, and have important application prospects in the biomedical field However, due to the f → f parity forbidden transition of rare earth ions, there are some bottlenecks in the NIR-II nano fluorescent materials, such as weak absorption strength and low fluorescence quantum efficiency How to improve the absorption efficiency of materials and develop rare earth nano fluorescent labeling materials with high efficient nir-ii luminescence is the focus of attention and a major technical challenge in this field Chen Xueyuan, the Key Laboratory of functional nanostructure and assembly of the Chinese Academy of Sciences, Fujian Institute of physical architecture, supported by projects such as the special project of strategic leading science and technology of the Chinese Academy of Sciences, the international team of innovation of the Chinese Academy of Sciences, the channel joint fund of the national Natural Science Foundation and the general fund of the National Natural Science Foundation, the youth Promotion Association of the Chinese Academy of Sciences and the spring seedling program of the Haixi Academy of Sciences chaired by Zheng Wei, A unique high-temperature coprecipitation method has been developed for the first time to synthesize rare earth doped CAS nanocrystals with single dispersion, controllable morphology / particle size and high efficient nir-ii luminescence (Figure 1) The team systematically studied the luminescent properties of CE 3 + single doped, CE 3 + / Er 3 + and CE 3 + / Nd 3 + Co doped CAS nanocrystals by means of steady-state / transient fluorescence spectrum and fluorescence quantum yield, and revealed the influence of nanocrystal size and doping concentration on luminescent efficiency and energy transfer efficiency The absorption efficiency of the material is improved by the f → D absorption allowed transition of CE 3 + in the 450 nm blue light region, and the efficient nir-ii luminescence of Er 3 + and Nd 3 + can be realized by the energy transfer of CE 3 + → Er 3 + and CE 3 + → Nd 3 +, among which the highest energy transfer efficiency from CE 3 + to Er 3 + and Nd 3 + is 85.1% and 82.6%, respectively The absolute quantum yields of nir-ii fluorescence are 9.3% and 7.7%, respectively (Fig 2) Because the strong absorption of Ce3 + at 450 nm is in good agreement with the emission of GaN Blue LED chip, the nanocrystalline can be used as a new and efficient nir-ii fluorescent nano probe excited by blue LED after being coated by amphiphilic phospholipid molecules, which can be used for the high sensitive and specific in vitro detection of xanthine, a disease marker, with a detection limit of 32 nm This work breaks through the technical bottleneck of weak absorption and low efficiency of F → f forbidden transition of rare earth fluorescent nanoprobes It provides a universal method for the development of efficient rare earth based nir-ii fluorescent nanoprobes using transition antenna sensitization, and also opens a new way for the application of nir-ii nanoprobes in the field of instant detection (POCT) The results were recently published online in the Journal of German Applied Chemistry (angel Chem Int ed 2019, DOI: 10.1002/anie.201905040) The first author of this paper is Zhang Meiran, associate student of the Institute of physical architecture / Fujian Normal University Fig 1 Rare earth doped CAS nir-i I nano fluorescent labeling material: a) synthesis diagram, B-I) preparation of different size CAS: Ce3 + nanocrystals by changing the proportion of oleic acid (OA) / oleamine (OM) (source: angelw Chem Int ed.) Fig 2 CAS: Ce3 + / Er3 + and CAS: Ce3+ /Nd 3 + nir-ii nano fluorescent labeling materials: Er 3 + concentration related a) emission spectrum, b) er 3 + fluorescence attenuation curve and C) C E 3 + fluorescence attenuation curve; Nd 3 + concentration related d) emission spectrum, e) nd 3 + fluorescence attenuation curve and F) ce 3 + fluorescence attenuation curve; G, H) energy transfer diagram (source: angel Chem Int ed.) Prior to that, Chen Xueyuan's team has made a series of important progress in the research of electronic structure, optical properties and biological application of near-infrared rare earth nano fluorescent labeling materials For example, taking EU 3 + as the structural probe, the local electronic energy level structure of Nd 3 + in liluf 4 nanocrystals is revealed and the high sensitive temperature detection is realized (adv SCI 2019, 6, 1802282); a CAS: EU 2 + / Sm 3 + photoexcited nanofluorescence probe with near-infrared wide spectral response is developed to realize the targeted fluorescence imaging of tumor cells overexpressing biotin receptor (chem SCI 2019, 10, 5452, outside back cover); design and synthesis of nacef 4: Er 3 + near-infrared two zone fluorescence nanoprobe, to achieve high-sensitivity detection of uric acid in human serum and high-resolution imaging of deep tissues in mice (chem SCI 2018, 9, 4682)