Kai Huang

Dye-sensitized upconversion nanoparticles (UCNPs) are promising for biological and photonic applications, but their performance is limited by Yb3+–Er3+ back-energy transfer and excitation migration to surface quenchers. In conventional hexagonal NaY(Gd)F4 hosts, these coupled losses restrict the optimal Yb3+ content to approximately 20–30%, preventing the use of densely doped Yb3+–Er3+ cores for dye sensitization. Here, we overcome this limitation through host–topology codesign in LiYbF4:Er@LiLu1–xYbxF4@LiLu1–yNdyF4 nanoparticles. The tetragonal LiLuF4-type lattice enables a core containing 98% Yb3+ and 2% Er3+ with reduced concentration quenching and a more favorable net energy-transfer balance than hexagonal NaYF4. An Nd3+-rich outer shell captures dye-derived excitation, while a Yb3+-rich intermediate shell directs energy inward and suppresses surface dissipation. These elements are mutually enabling: the host supports the high-Yb3+ core, and the shell topology converts it into an efficient dye-sensitized emitter. The resulting architecture produces a >150-fold enhancement in 808-nm-excited green upconversion luminescence relative to dye-sensitized low-Yb3+ core nanoparticles. As a proof of concept, reaction-product-dependent turn-on signals enable discrimination of ortho-, meta-, and para-mercaptobenzoic acid at 1 μg mL–1. This work establishes host–topology codesign as a general strategy for controlling directional energy transfer in lanthanide nanostructures.

Yb³⁺-doped lead halide perovskites are promising near-infrared (NIR) emitters, but their practical implementation is often limited by poor environmental stability, defect-induced nonradiative loss, and difficulties in achieving reproducible doping and device integration. Herein, we report a mesoporous silica nanoreactor (MSN) strategy for the controlled synthesis of CsPbCl₃:Yb-MSN nanocomposites with efficient 980 nm emission. The confined growth environment provided by the mesoporous silica matrix enables regulated crystallization of Yb³⁺-doped perovskite nanocrystals while reducing surface exposure and improving resistance to environmental degradation. As a result, the obtained CsPbCl₃:Yb-MSN nanocomposites exhibit enhanced structural robustness, superior optical stability, and an absolute photoluminescence quantum yield of 146%, indicating efficient Yb³⁺-activated near-infrared emission. To demonstrate practical applicability, the as-prepared nanocomposite was integrated into a single-chip NIR LED using a UV excitation chip. The resulting device shows stable down-converted NIR output, and after optical filtering, the emission is centered at 980 nm with a relatively narrow full width at half-maximum (fwhm) of 35 nm. Imaging experiments further confirmed the practical utility of the device. The packaged NIR LED enables clear object visualization, while leaf transillumination demonstrates its capability for active NIR transmission imaging with improved visualization of internal tissue structures. This work establishes a practical route from stable Yb-doped perovskite nanomaterials to compact NIR devices and highlights their potential in portable sensing and related optical applications.

Persistent luminescence nanoparticles (PLNPs) are unique optical nanomaterials that emit a long-lasting afterglow in the absence of real-time excitation, enabling biosensing with near-zero background interference. This review summarizes recent advances in PLNP-based biosensing, highlighting how persistent luminescence improves analytical sensitivity, specificity, and operational simplicity in biological environments. We first outline foundational principles for constructing PLNP biosensors, including signal transduction via (1) analyte-regulated luminescence resonance energy transfer, (2) capture and enrichment of PLNPs for time-gated readout, and (3) ratiometric persistent luminescence. We then comprehensively discuss sensing strategies across major analyte classes, including biomolecules, small molecules, ions, and physiological parameters, such as local temperature. Finally, we examine current challenges in PLNP synthesis, surface engineering, multiplexing, and biosafety, and outline future directions toward next-generation persistent luminescence biosensors with enhanced brightness, programmability, and translational potential. Together, these developments position PLNPs as powerful and increasingly versatile platforms for high-performance biosensing and bioanalysis.

Self-driving laboratories (SDLs) integrating automation and data-driven control are increasingly used in materials synthesis. Existing SDLs still face challenges in hardware integration and stable flow operation. Here, we report a modular fluidic-microwave SDL for the automated synthesis of perovskite nanocrystals (PNCs) with programmable thermal profiles and inline photoluminescence monitoring. Its constant-pressure fluidics and batch microwave design decouple reaction temperature from residence time, suppress flow pulsation, and yield reproducible low-noise data sets. Using CsPbX₃ (X = Cl, Br, I), the platform achieves relative standard deviations of 1.53% in fwhm, 0.06% in peak wavelength, and 1.85% in PL intensity across runs. Automated parameter screening identifies an optimal synthesis window (120-140 °C, 28 °C min^-1, 120-180 s, Pb/Cs = 2-3) that produces phase-pure nanocrystals with narrow emission line widths (∼18-19 nm). This SDL provides a reproducible, programmable basis for closed-loop optimization and AI-guided nanomaterials synthesis.

Persistent luminescence nanoparticle scintillators (PLNS) have been attempted for X-ray-induced photodynamic therapy (X-PDT) because persistent luminescence after ceasing radiation can make PLNS use less cumulative irradiation time and dose to generate the same amount of reactive oxygen species (ROS) compared with conventional scintillators to combat cancer cells. However, excessive surface defects in PLNS reduce the luminescence efficiency and quench the persistent luminescence, which is fatal to the efficacy of X-PDT. Herein, the PLNS of SiO₂@Zn₂SiO₄:Mn²⁺, Yb³⁺, Li⁺ was designed by the energy trap engineering and synthesized by a simple template method, which has excellent X-ray and UV-excited persistent luminescence and continuously tunable emission spectra from 520 to 550 nm. Its luminescence intensity and afterglow time are more than 7 times that of the reported Zn₂SiO₄:Mn²⁺ used for X-PDT. By loading a Rose Bengal (RB) photosensitizer, an effective persistent energy transfer from the PLNS to photosensitizer is observed even after the removal of X-ray irradiation. The X-ray dose of nanoplatform SiO₂@Zn₂SiO₄:Mn²⁺, Yb³⁺, Li⁺@RB in X-PDT of HeLa cancer cells was reduced to 0.18 Gy compared to the X-ray dose of 1.0 Gy for Zn₂SiO₄:Mn for X-PDT. This indicates that the Zn₂SiO₄:Mn²⁺, Yb³⁺, Li⁺ PLNS have great potential for X-PDT applications.

Metal‐free long‐wavelength light‐driven prodrug photoactivation is highly desirable for applications such as neuromodulation, drug delivery, and cancer therapy. Herein, via triplet fusion, we report on the far‐red light‐driven photo‐release of an anti‐cancer drug by coupling the boron‐dipyrromethene (BODIPY)‐based photosensitizer with a photocleavable perylene‐based anti‐cancer drug. Notably, this metal‐free triplet fusion photolysis (TFP) strategy can be further advanced by incorporating an additional functional dopant, i.e. an immunotherapy medicine inhibiting the indoleamine 2,3‐dioxygenase (IDO), with the far‐red responsive triplet fusion pair in an air‐stable nanoparticle. With this IDO inhibitor‐assisted TFP system we observed efficient inhibition of primary and distant tumors in a mouse model at record‐low excitation power, compared to other photo‐assisted immunotherapy approaches. This metal‐free TFP strategy will spur advancement in photonics and biophotonics fields.

A novel near-infrared persistent luminescent phosphor Na₂CaSn₂Ge₃O₁₂(NCSGO) doped with Ho³⁺, Er³⁺, Tm³⁺and Yb³⁺was synthesized by a high-temperature solid-state reaction.