NIR-I Activated Orthogonal NIR-IIb/c Emissions in a Lanthanide-Doped Nanoparticle for Fluorescence Imaging and Information Encryption

Advances in Lanthanide-Based NIR-IIb Probes for In Vivo Biomedical Imaging

The past decades have witnessed the significant development and practical interest of in vivo biomedical imaging technologies and optical materials in the second-near infrared (NIR-II, 1000-1700 nm) window. Imaging with the extended emission wavelength toward the long-wavelength end (NIR-IIb, 1500-1700 nm) further offers micrometer imaging resolution and centimeter tissue penetration depth by taking advantage of the much-reduced photon scattering and near-zero tissue autofluorescence background, which have become a very hot research area. This review focuses on the recent advances in the development of lanthanide-based NIR-IIb probes for in vivo biomedical applications. The progress including ratiometric imaging, multiplexed imaging for wide-field and microscopy, lifetime multiplexing and sensing, persistent luminescence, and multimodal imaging is summarized. Challenges and future directions concerning the investigation of the photophysical and photochemical properties of NIR-IIb probes, the selection of near-infrared cameras as well as the potential extension of the NIR-IIb imaging sub-window are pointed out. This review will inspire readers who have a strong interest in developing optical imaging technology and long-wavelength fluorescence probes for high-contrast in vivo biomedical applications.

Challenges and Opportunities of Upconversion Nanoparticles for Emerging NIR Optoelectronic Devices

Upconversion nanoparticles (UCNPs), incorporating lanthanide (Ln) dopants, can convert low-energy near-infrared photons into higher-energy visible or ultraviolet light through nonlinear energy transfer processes. This distinctive feature has attracted considerable attention in both fundamental research and advanced optoelectronics. Challenges such as low energy-conversion efficiency and nonradiative losses limit the performance of UCNP-based optoelectronic devices. Recent advancements including optimized core-shell structures, tailed Ln-doping concentration, and surface modifications show significant promise for improving the efficiency and stability. In addition, combining UCNPs with functional materials can broaden their applications and improve device performance, paving the way for the innovation of next-generation optoelectronics. This paper first categorizes and elaborates on various upconversion mechanisms in UCNPs, focusing on strategies to boost energy transfer efficiency and prolong luminescence. Subsequently, an in-depth discussion of the various materials that can enhance the efficiency of UCNPs and expand their functionality is provided. Furthermore, a wide range of UCNP-based optoelectronic devices is explored, and multiple emerging applications in UCNP-based neuromorphic computing are highlighted. Finally, the existing challenges and potential solutions involved in developing practical UCNPs optoelectronic devices are considered, as well as an outlook on the future of UCNPs in advanced technologies is provided.

Bio-Inspired Multiple Responsive NIR II Nanophosphors for Reversible and Environment-Interactive Information Encryption

Inspired by the natural responsive phenomena, herein the multiple responsive persistent luminescent Zn1.2Ga1.6Ge0.2O4:Ni2+ (ZGGO:Ni) nanoparticles with near-infrared  (NIR) II emission peak ≈1330 nm derived from the Ni2+ doping through controlled synthesis based on hydrothermal method are obtained. The obtained NIR II persistent luminescent ZGGO:Ni can not only respond to temperature but also the specific solvent stimulus. The results demonstrate that the NIR II persistent luminescence intensity decreases in hydroxyl containing solvent such as water (H2O) and ethyl alcohol (C2H6O), while the PL intensity remains in solvent without hydroxyl groups such as n-hexane (C6H14) and deuterated water (D2O). This NIR II luminescence quenching is attributed to the adsorption of interaction hydroxyl groups in specific solvents with the amino group on the surface of ZGGO:Ni and the subsequent fluorescence resonance energy transfer mechanism. Benefiting from the multiple responsive properties, the obtained NIR II persistent luminescent ZGGO:Ni is utilized for high-order dynamic optical information encryption, providing increased security level. The multi-responsive NIR II persistent luminescence strategy outlined in this study is anticipated to offer a straightforward methodology for optimizing the optical characteristics of NIR II persistent luminescent materials. Moreover, it is set to expand the scope of their applications in the realm of dynamic and environment-interactive information encryption, thereby opening frontiers for their utilization in advanced security measures.