Facile Multistep Synthesis of ZnO-Coated β-NaYF4:Yb/Tm Upconversion Nanoparticles as an Antimicrobial Photodynamic Therapy for Persistent Staphylococcus aureus Small Colony Variants

Near-Infrared Luminescent Materials Incorporating Rare Earth/Transition Metal Ions: From Materials to Applications

The spotlight has shifted to near-infrared (NIR) luminescent materials emitting beyond 1000 nm, with growing interest due to their unique characteristics. The ability of NIR-II emission (1000-1700 nm) to penetrate deeply and transmit independently positions these NIR luminescent materials for applications in optical-communication devices, bioimaging, and photodetectors. The combination of rare earth metals/transition metals with a variety of matrix materials provides a new platform for creating new chemical and physical properties for materials science and device applications. In this review, the recent advancements in NIR emission activated by rare earth and transition metal ions are summarized and their role in applications spanning bioimaging, sensing, and optoelectronics is illustrated. It started with various synthesis techniques and explored how rare earths/transition metals can be skillfully incorporated into various matrixes, thereby endowing them with unique characteristics. The discussion to strategies of enhancing excitation absorption and emission efficiency, spotlighting innovations like dye sensitization and surface plasmon resonance effects is then extended. Subsequently, a significant focus is placed on functionalization strategies and their applications. Finally, a comprehensive analysis of the challenges and proposed strategies for rare earth/transition metal ion-doped near-infrared luminescent materials, summarizing the insights of each section is provided.

Electrodeposited NaYF4:Yb3+, Er3+ up-conversion films for flexible neural device construction and near-infrared optogenetics

Near-infrared optogenetics based on up-conversion materials provides a promising tool for the dissection of neural circuit functions in deep brain regions. However, it remains a challenge to combine near-infrared up-conversion optogenetic stimulation with high-density electrophysiological recording in a minimally invasive manner. Here, we develop a flexible device for simultaneous electrophysiological recording and near-infrared optogenetics. The flexible device is constructed by integrating polymer-based flexible recording microelectrodes with electrodeposited NaYF₄:Yb³⁺, Er³⁺ up-conversion films that can convert deep-tissue-penetrating near-infrared light into visible light for optogenetic activation of C1V1-expressing neurons. The emission properties of the up-conversion films are optimized for green light emission to stimulate C1V1 opsins. Owing to their minimized surgical footprint and high mechanical compliance, chronically implanted devices enable simultaneous electrophysiological recording and near-infrared optogenetic modulation of neuronal activities in the brain.

Rare earth-doped nanocrystals for bioimaging in the near-infrared region

Rare earth-doped nanocrystals are widely used in medical diagnostics and bioimaging due to their narrow luminescence emission spectra (10-20 nm), long lifetime, and no photobleaching properties. Especially in the near-infrared (NIR) region, deeper tissue imaging can be achieved with low background luminescence and high spatial resolution. Further precise image-guided diagnosis and treatment can be achieved by using multimodal imaging such as MRI/CT/NIR/PA. Here, we focus on the construction of rare earth-doped nanocrystals, optical properties, and progress of such nanocomposites for bioimaging in the NIR region. In addition, the limitations at this stage in the field of bioimaging and the prospects for future technological development of rare earth-doped nanocrystals are present.

A metal–organic framework nanocomposite with oxidation and near-infrared light cascade response for bacterial photothermal inactivation

Photothermal treatment is an effective and precise bacterial disinfection method that can reduce the occurrence of bacterial drug resistance. However, most conventional photothermal treatment strategies have the problem that the photothermal response range does not match the infection area. Herein, a metal–organic framework (MOF) nanocomposite responding to the oxidation state of the bacterial infection microenvironment was constructed for near-infrared (NIR) photothermal bacterial inactivation. In this strategy, the MOF was used as a nanocarrier to load tetramethylbenzidine (TMB) and horseradish peroxidase (HPR). The high oxidation state of the bacterial infection microenvironment can trigger the enzyme-catalyzed reaction of the nanocomposite, thereby generating oxidation products with the NIR photothermal effect for bacterial disinfection. The synthesis and characterization of the nanocomposite, oxidation state (H₂O₂) response effect, photothermal properties, and antibacterial activities were systematically studied. This study provides a new idea for building a precision treatment system for bacterial infection.