The scientists obtained highly doped up-conversion nanoparticles

Led by Australia’s Macquarie university professor da-yong jin advanced cell instrument laboratory and engineering college of Beijing university department of biomedical engineering XiPeng research joint research, found the new nano photonics light-emitting mechanism, and implements the high concentration of doping on the conversion of nanoparticles (Upconversionnanocrystals) technology, which shows the most sensitive nano fluorescent material yet. The paper was published in Nature Nanotechnology.

Upconversion nanoparticles, a novel fluorescent material, are promising a wide range of applications with their unique optical properties, especially in biomedical imaging, immunoassay, solar cells, 3d display and other fields. It is usually composed of an inorganic matrix and rare earth doped ions embedded therein. Because the excitation is in the near infrared, the penetration depth is deeper than that of visible light. However, it is well known in the industry that the material has low conversion efficiency and low fluorescence intensity, which hinders further application of upconversion particles. Although increasing the doping concentration can increase the luminous efficiency intuitively, the traditional up-conversion nanoparticles are mostly limited to the lower doping concentration because of the serious fluorescence quenching caused by the high doping concentration.

In view of this bottleneck problem, it is found for the first time in this paper that the limitation of fluorescence quenching can be solved by high excitation light energy density, so that the up-conversion nanoparticles with high concentration doping can be realized. The combination of high doping and high excitation power finally makes the fluorescence signal intensity significantly enhanced compared with conventional low-doping nanoparticles, making the remote detection of single nanoparticle assisted by optical fiber a reality for the first time. The new nanoparticles are three orders of magnitude more sensitive than the traditional quantum dot. The nanoparticle has been named SuperDotTM because highly doped up-conversion nanotechnology provides ultra-sensitive optical inspection. This achievement has greatly promoted the application of up-conversion nanotechnology in infrared detection, biometric identification, medical imaging, high-throughput single-cell detection, anti-counterfeiting technology and other fields.

For many years, professor Kim dayong’s research group in Australia has been committed to the combination of optical detection and up-conversion nanoparticles to realize new technologies such as flow cytometry without background, high speed and high quantum yield, slide cell detection, and high-speed detection of rare event mass samples. The research areas of the xi peng group at Peking University include ultra diffraction limit resolution microimaging, laser confocal scanning microimaging, multiphoton microimaging, and optical coherence tomography. The cooperation between the two research groups dates back to 2010, and seven articles have been published in well-known international journals. (source: Responsible editor: li hao)

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