Synthesis of stable core-shell perovskite based nano-heterostructures

NIR-Triggered Release of Nitric Oxide by Upconversion-Based Nanoplatforms to Enhance Osteogenic Differentiation of Mesenchymal Stem Cells for Osteoporosis Therapy

Stem cell therapy is an attractive approach to bone tissue regeneration in osteoporosis (OP); however, poor cell engraftment and survival within injured tissues limits its success in clinical settings. Nitric oxide (NO) is an important signaling molecule involved in various physiological processes, with emerging evidence supporting its diverse roles in modulating stem cell behavior, including survival, migration, and osteogenic differentiation. To control and enhance osteogenic differentiation of mesenchymal stem cells (MSCs) for OP therapy, we designed a near-infrared (NIR) light-triggered NO-releasing nanoplatform based on upconversion nanoparticles (UCNPs) that converts 808-nm NIR light into visible light, stimulating NO release by light control. We demonstrate that the UCNP nanoplatforms can encapsulate a light-sensitive NO precursor, Roussin's black salt (RBS), through the implementation of a surface mesoporous silica coating. Upon exposure to 808-nm irradiation, NO is triggered by the controlled upconversion of UCNP visible light at the desired time and location. This controlled release mechanism facilitates photoregulated differentiation of MSCs toward osteogenic lineage and avoids thermal effects and phototoxicity on cells, thus offering potential therapeutic applications for treating OP in vivo. Following the induction of osteogenic differentiation, the UCNP nanoplatforms exhibit the capability to serve as nanoprobes for the real-time detection of differentiation through enzymatic digestion and fluorescence recovery of UCNPs, enabling assessment of the therapeutic efficacy of OP treatment. Consequently, these UCNP-based nanoplatforms present a novel approach to control and enhance osteogenic differentiation of MSCs for OP therapy, simultaneously detecting osteogenic differentiation for evaluating treatment effectiveness.

Near-infrared light triggered upconversion nanocomposites with multifunction of enhanced antimicrobial photodynamic therapy and gas therapy for inflammation regulation

Antibacterial photodynamic therapy (aPDT) is highly effective in killing bacteria, while the problem of hypoxia and limited light penetration in deep tissue has not been properly solved. In addition, few aPDT works take into account the regulation of inflammation, which is an important regulatory process after antimicrobial therapy and the final purpose of treatment. In this work, to address the above isssues, we have designed a multi-functional composite UCNPs-Ce6-Mn(CO)5Br@Silane (referred to as UCM@Si), which consists of several key components: Up-conversion nanoparticles (UCNPs: NaErF4:Tm3+@NaYF4:Yb3+), Chlorin e6 (Ce6) and Manganese pentacarbonyl bromide (Mn(CO)5Br). When exposed to near-infrared (NIR) light (980 nm), the UCNPs can emit strong red light at 655 nm which further trigger the aPDT of Ce6. The generated reactive oxygen (ROS) subsequently break the metal carbonyl bond of Mn(CO)5Br, leading to the production of carbon monoxide (CO) molecules as well as manganese ions (Mn2+), which further decomposes hydrogen peroxide (H2O2) in the microenvironment to oxygen (O2). Therefore, this simple nanocomposite not only provides substantial self-oxygen replenishment for enhanced aPDT, but also facilitates effective inflammation regulation via CO across a wide range of deep infections. This approach leverages the unique properties of these materials to combat bacterial infections by simultaneously killing bacteria, regulating inflammation, and enhancing the oxygen levels in the affected microenvironment. This O2 and CO gas based aPDT treatment system offers a promising approach to comprehensively address microbial-induced infectious diseases, particularly deep infections, holding the potential clinical applications.

Heteroepitaxial Growth to Construct Hexagonal/Hexagonal β-NaYF4:Yb,Tm/Cs4PbBr6 Multi-Code Emitting Core/Shell Nanocrystals

Synthesis of upconversion nanoparticles (UCNPs)-metal halide perovskites (MHPs) heterostructure is garnered immense attentions due to their unparalleled photophysical properties. However, the obvious difference in their structural forms makes it a huge challenge. Herein, hexagonal β-NaYF4 and hexagonal Cs4PbBr6 are filtrated to construct the UCNP/MHP heterostructural luminescent material. The similarity in their crystal structures facilitate the heteroepitaxial growth of Cs4PbBr6 on the surface of β-NaYF4 NPs, leading to the formation of high-quality β-NaYF4:Yb,Tm/Cs4PbBr6 core/shell nanocrystals (NCs). Interestingly, this heterostructure endows the core/shell NCs with typically narrow-band green emission centered at 524 nm under 980 nm excitation, which should be attributed to the Förster resonance energy transfer (FRET) from Tm3+ to Cs4PbBr6. It is noteworthy that the FRET efficiency of β-NaYF4:Yb,Tm/Cs4PbBr6 core/shell NCs (58.33%) is much higher than that of the physically mixed sample (1.84%). In addition, the reduced defect density, lattice anchoring effect, as well as diluted ionic bonding proportion induced by the core/shell structure further increase the excellent water-resistance and thermal cycling stability of Cs4PbBr6. These findings open up a new way to construct UCNP/MHP heterostructure with better multi-code luminescence performance and stability and promote its wide optoelectronic applications.

Axially lattice-matched wurtzite/rock-salt GaAs/Pb1-xSnxTe nanowires

We investigate the full and half-shells of Pb1-xSnxTe topological crystalline insulator deposited by molecular beam epitaxy on the sidewalls of wurtzite GaAs nanowires (NWs). Due to the distinct orientation of the IV-VI shell with respect to the III-V core the lattice mismatch between both materials along the nanowire axis is less than 4%. The Pb1-xSnxTe solid solution is chosen due to the topological crystalline insulator properties above some critical concentrations of Sn (x ≥ 0.36). The IV-VI shells are grown with different compositions spanning from binary SnTe, through Pb1-xSnxTe with decreasing x value down to binary PbTe (x = 0). The samples are analysed by scanning transmission electron microscopy, which reveals the presence of (110) or (100) oriented binary PbTe and (100) Pb1-xSnxTe on the sidewalls of wurtzite GaAs NWs.

Efficient sky-blue cesium lead bromide light-emitting diodes with enhanced stability via synergistic interfacial induction and polymer scaffold inhibition

All inorganic CsPbX3 perovskite has aroused broad interests in building efficient light-emitting devices with wide color gamut and flexible fabrication process. So far, the realization of high-performance blue perovskite light-emitting devices (PeLEDs) is still a critical challenge. Herein, we propose an interfacial induction strategy to generate low-dimensional CsPbBr3 with sky blue emission by employing γ-aminobutyric acid (GABA) modified poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The interaction between GABA and Pb2+ inhibited the formation of bulk CsPbBr3 phase. Further assisted by the polymer networks, the sky-blue CsPbBr3 film exhibited much improved stability under both photoluminescence and electrical excitation. This can be ascribed to the scaffold effect and the passivation function of the polymer. Consequently, the obtained sky-blue PeLEDs exhibited an average external quantum efficiency (EQE) of 5.67% (maximum of 7.21%) with a maximum brightness of 3308 cd/m2 and a working lifespan reaching 0.41 h. The strategy in this work provides a new opportunity for exploitation the full potential of blue PeLEDs towards application in lighting and display devices.

Recent Advances and Perspectives of Metal Halide Perovskite Heteronanocrystals

Heteronanocrystals that combine multiple semiconductors into a nanoscale heterostructure possess excellent optical performance and flexibility in property engineering compared with their single-component counterparts. The successes in fabricating lead halide perovskite-based heteronanocrystals (PHNCs) have drastically improved the stability and tunability of the optical and electrical properties. However, the epitaxial growth of semiconductor materials on perovskite nanocrystals remains a fundamental challenge because of the mismatch in their surface structure and crystal growth kinetics. Here, we review recent progress in the development of PHNCs with emphasis on their synthesis methods and surface chemistry that led to new insights and reaction protocols for the design and fabrication of PHNCs. In addition, the optical features of different types of PHNCs and nanocomposites and their application perspectives are summarized. Finally, we conclude with a discussion of the remaining issues, challenges, and opportunities in epitaxial growth of Janus and core-shell structure PHNCs.

Efficient full solar spectrum-driven photocatalytic hydrogen production on low bandgap TiO2/conjugated polymer nanostructures

The development of photocatalysts that can utilize the entire solar spectrum is crucial to achieving efficient solar energy conversion. The utility of the benchmark photocatalyst, TiO2, is limited only to the UV region due to its large bandgap. Extending the light harvesting properties across the entire spectrum is paramount to enhancing solar photocatalytic performance. In this work, we developed low bandgap TiO2/conjugated polymer nanostructures which exhibit full spectrum activity for efficient H2 production. The highly mesoporous structure of the nanostructures together with the photosensitizing properties of the conjugated polymer enabled efficient solar light activity. The mesoporous TiO2 nanostructures calcined at 550 °C exhibited a defect-free anatase crystalline phase with traces of brookite and high surface area, resulting in the best performance in hydrogen production (5.34 mmol g-1 h-1) under sunlight simulation. This value is higher not only in comparison to other TiO2-based catalysts but also to other semiconductor materials reported in the literature. Thus, this work provides an effective strategy for the construction of full spectrum active nanostructured catalysts for enhanced solar photocatalytic hydrogen production.

Background-free and signal-amplified upconversion fluorescent biosensing platform for sensitive detection of CYFRA21-1

Accurate and ultrasensitive detection of cytokeratin 19 fragment (CYFRA21-1) is of vital importance for screening and diagnosis of potential lung cancer patient. In this paper, surface-modified upconversion nanomaterials (UCNPs) capable of aggregation by atom transfer radical polymerization (ATRP) were used as luminescent materials for the first time to achieve signal-stable, low-biological background, and sensitive detection of CYFRA21-1. Upconversion nanomaterials (UCNPs) feature extremely low biological background signals and narrow emission peaks, making them ideal sensor luminescent materials. The combination of UCNPs and ATRP not only improves sensitivity, but also reduces biological background interference for detecting CYFRA21-1. The target CYFRA21-1 was captured by specific binding of the antigen and the antibody. Subsequently, the end of the sandwich structure with the initiator reacts with monomers modified on UCNPs. Then, massive UCNPs are aggregated by ATRP that amplify the detection signal exponentially. Under optimal conditions, a linear calibration plot of the logarithm of CYFRA21-1 concentration versus the upconversion fluorescence intensity was obtained in the range of 1 pg/mL to 100 μg/mL with a detection limit of 38.7 fg/mL. The proposed upconversion fluorescent platform can distinguish the analogues of the target with excellent selectivity. Besides, the precision and accuracy of the developed upconversion fluorescent platform were verified by clinical methods. As an enhanced upconversion fluorescent platform of CYFRA21-1, it is expected to be useful in screening potential patients with NSCLC and provides a promising solution for the high-performance detection of other tumor markers.