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Multi-shelled upconversion nanostructures with enhanced photoluminescence intensity <i>via</i> successive epitaxial layer-by-layer formation (SELF) strategy for high-level anticounterfeiting
摘要： Owing to the ability to convert near-infrared (NIR) incident light into high-energy ultraviolet or visible light photons, lanthanide-doped upconversion nanoparticles (UCNPs) have attracted great attention in anticounterfeiting applications as appealing and unparalleled agents. To facilitate the efficient energy transfer and overcome the bottleneck of low upconverted photoluminescence, we report a one-pot successive epitaxial layer-by-layer formation (SELF) strategy based on ion layer adsorption and Oswald ripening to synthesize a series of high-quality monodispersed multi-shelled UCNPs with narrow size distribution (coefficient of variation less than 5 %). Up to 30 layers of uniform shell are successfully deposited by successive introduction of the shell precursor solutions, which results in fold change of 300 and 200 in upconverted emission intensities for Er3+ and Tm3+-doped multi-shelled UCNPs, respectively. Using as-prepared multi-shelled UCNPs via SELF approach in conjunction with fabricated downconversion nanoparticles (DCNPs), we develop a facile and cost-effective strategy based on dual-modal manipulation of luminescence in anticounterfeiting to provide extra high-level security protection. The genuine pattern with true information is easier to visualize with the naked eye under excitation of 980 nm near-infrared (NIR) laser, while the false information could be readily read out when exposed to ultraviolet (UV) light. Meanwhile, latent fingerprint recognition with low background interference and distinguishable details in ridge patterns is achieved taking advantage of the significantly improved brightness in multi-shelled UCNPs.
关键词： anticounterfeiting,Upconversion,enhanced photoluminescence,multi-shell,latent fingerprint
更新于2025-11-19 16:46:39
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Red-emissive conjugated oligomer/silica hybrid nanoparticles with high affinity and application for latent fingerprint detection
摘要： Latent fingerprint detection plays a great role in forensic science, and considerable efforts have been made on developing efficient and simple strategy to realize clear visualization of latent fingerprints. Among them, fluorescent nanoparticles have attracted increasing interests due to their easy fabrication, good photostability, and low toxicity, but insufficient affinity toward fingerprints has limited their further application. Herein, we report a red-emissive conjugated oligomer/silica hybrid nanoparticle with enhanced affinity toward fingerprints, showing a promising performance on fluorescent detection on latent fingerprints. The conjugated oligomer is covalently doped into the silica nanoparticles, which effectively guarantee its fluorescent quantum yield and photostability. Moreover, the red emission of these nanoparticles also enables the latent fingerprint detection on substrates with fluorescent background, such as plastic and various papers. Most importantly, the introduction of epoxy groups on the silica surface largely enhances its affinity toward fingerprints, compared to that with hydroxy or amino groups, which possibly can be ascribed to its electrostatic attraction and hydrophobic interaction with amino acids and sebaceous substances of fingerprints, respectively.
关键词： Latent fingerprint detection,High affinity,Red emission,Fluorescence,Conjugated oligomer
更新于2025-09-23 15:23:52