Comprehensive Neurotoxicity of Lead Halide Perovskite Nanocrystals in Nematode Caenorhabditis elegans.

To date, all-inorganic lead halide perovskite quantum dots have emerged as promising materials for photonic, optoelectronic devices, and biological applications, especially in solar cells, raising numerous concerns about their biosafety. Most of the studies related to the toxicity of perovskite quantum dots (PeQDs) have focused on the potential risks of hybrid perovskites by using zebrafish or human cells. So far, the neurotoxic effects and fundamental mechanisms of PeQDs remain unknown. Herein, a comprehensive methodology is designed to investigate the neurotoxicity of PeQDs by using Caenorhabditis elegans as a model organism. The results show that the accumulation of PeQDs mainly focuses on the alimentary system and head region. Acute exposure to PeQDs results in a decrease in locomotor behaviors and pharyngeal pumping, whereas chronic exposure to PeQDs causes brood decline and shortens lifespan. In addition, some abnormal issues occur in the uterus during reproduction assays, such as vulva protrusion, impaired eggs left in the vulva, and egg hatching inside the mother. Excessive reactive oxygen species formation is also observed. The neurotoxicity of PeQDs is explained by gene expression. This study provides a complete insight into the neurotoxicity of PeQD and encourages the development of novel nontoxic PeQDs.

Evolutionary Generation of Phosphor Materials and Their Progress in Future Applications for Light-Emitting Diodes.

Light-emitting diodes (LEDs) are attracting considerable attention around the world. Phosphor materials, as crucial color-converted components, play central roles in LED development. The demands for phosphor materials have become increasingly stringent over the past decades, from high brightness to narrowband emission or function-dependent spectrum engineering. Although substantial progress has been made for currently developed phosphor materials, simultaneously satisfying all requirements for high-level applications remains challenging. In this review, we aim to provide a comprehensive understanding of the development of phosphor materials in different generations and to elucidate the key designed mechanisms concerning the activators and the host structures to fulfill the aforementioned aspects. We highlight the developments in phosphor materials through the classification of demands for high luminescence, high thermal stability, narrowband emission for high color gamut, and broadband emission for near-infrared. We also focus on elucidating the key designed mechanisms of phosphor materials in different generations. Furthermore, future perspectives about micro-LED applications and nanoluminescent materials are provided. This study opens up an avenue for designing the luminescent materials of the future.

Effect of Temperature and Pressure on Structural and Optical Properties of Organic-Inorganic Hybrid Manganese Halides.

Organic-inorganic hybrid metal halides have recently attracted attention in the global research field for their bright light emission, tunable photoluminescence wavelength, and convenient synthesis method. This study reports the detailed properties of (C10H16N)2MnBr4, which emits bright green light with a high photoluminescence quantum yield. Results of powder X-ray diffraction, photoluminescence, thermogravimetric analysis, and Raman spectra show the phase transition of (C10H16N)2MnBr4 at 430 K. This phase transition was identified as the solid to liquid state of (C10H16N)2MnBr4. Moreover, the pressure- and temperature-induced relationship between structural and optical properties in (C10H16N)2MnBr4 can be identified. This investigation provides deep insights into the luminescent properties of metal halide crystals and promotes further research.

Chromium Ion Pair Luminescence: A Strategy in Broadband Near-Infrared Light-Emitting Diode Design.

Portable near-infrared (NIR) light sources are in high demand for applications in spectroscopy, night vision, bioimaging, and many others. Typical phosphor designs feature isolated Cr3+ ion centers, and it is challenging to design broadband NIR phosphors based on Cr3+-Cr3+ pairs. Here, we explore the solid-solution series SrAl11.88-xGaxO19:0.12Cr3+ (x = 0, 2, 4, 6, 8, 10, and 12) as phosphors featuring Cr3+-Cr3+ pairs and evaluate structure-property relations within the series. We establish the incorporation of Ga within the magentoplumbite-type structure at five distinct crystallographic sites and evaluate the effect of this incorporation on the Cr3+-Cr3+ ion pair proximity. Electron paramagnetic measurements reveal the presence of both isolated Cr3+ and Cr3+-Cr3+ pairs, resulting in NIR luminescence at approximately 650-1050 nm. Unexpectedly, the origin of broadband NIR luminescence with a peak within the range 740-820 nm is related to the Cr3+-Cr3+ ion pair. We demonstrate the application of the SrAl5.88Ga6O19:0.12Cr3+ phosphor, which possesses an internal quantum efficiency of ∼85%, a radiant flux of ∼95 mW, and zero thermal quenching up to 500 K. This work provides a further understanding of spectral shifts in phosphor solid solutions and in particular the application of the magentoplumbites as promising next-generation NIR phosphor host systems.

Near-Infrared Nanophosphor Embedded in Mesoporous Silica Nanoparticle with High Light-Harvesting Efficiency for Dual Photosystem Enhancement.

Light-harvesting and conversion ability is important to promote plant growth, and especially when resources are limited. A near-infrared (NIR) nanophosphor embedded with mesoporous silica nanoparticles (MSN), ZnGa2 O4 :Cr3+ ,Sn4+ (ZGOCS), was developed and its optical properties were harnessed to enhance the photosynthetic ability of Brassica rapa spp. chinensis. The broad excitation of ZGOCS from the ultraviolet to the visible region allowed the conversion of extra light into near-infrared light (650-800 nm) and thus promoted the dual photosystem via the Emerson effect. ZGOCS@MSN was spherical with a size of 65±10 nm and good dispersion. A light conversion ability of up to 75 % under different wavelengths was achieved. Moreover, the electron transfer rate of photosynthesis increased by 100 % with a suitable ZGOCS@MSN concentration. Plant and animal models were used to explore the effects of the nanophosphor. ZGOCS@MSN distribution was tracked by monitoring its NIR emission in plant and animal tissues, demonstrating that this nanophosphor can be potentially utilized in plant growth.

Broadband Cr3+ , Sn4+ -Doped Oxide Nanophosphors for Infrared Mini Light-Emitting Diodes.

Light-emitting diodes break barriers of size and performance for displays. With devices becoming smaller, the materials also need to get smaller. Chromium(III)-doped oxide phosphors, which emit near-infrared (NIR) light, have recently been used in small electronic devices. In this work, mesoporous silica nanoparticles were used as nanocarriers. The nanophosphor ZnGa2 O4 :Cr3+ ,Sn4+ formed in the mesopore after sintering. Good dispersity and morphology were performed with average diameters of 71±7 nm. It emitted light at 600-850 nm; the intensity was optimized by tuning the doping ratio of Cr3+ and Sn4+ . Meanwhile, the light conversion efficiency increased from 7.8 % to 37 % and the molar concentration increased from 0.125 m to 0.5 m. The higher radiant flux of 3.3 mW was obtained by operating an input current of 45 mA. However, the NIR nanophosphor showed good performance on mini light-emitting diode chips.

Supersensitive visual pressure sensor based on the exciton luminescence of a perovskite material.

Accurate, rapid, and remote detection of pressure, one of the fundamental physical parameters, is vital for scientific, industrial, and daily life purposes. However, due to the limited sensitivity of luminescent manometers, the optical pressure monitoring has been applied mainly in scientific studies. Here, we developed the first supersensitive optical pressure sensor based on the exciton-type luminescence of the Bi3+-doped, double perovskite material Cs2Ag0.6Na0.4InCl6. The designed luminescent manometer exhibits an extremely high sensitivity, i.e. dλ/dp = 112 nm GPa-1. It also allows multi-parameter sensing, using both blue-shift and rarely observed band narrowing with pressure. Importantly, this material has small temperature dependence for the manometric parameter used, i.e. spectral shift, allowing detection under extreme pressure and temperature conditions. The developed sensor operates in the visible range, and its emission shifts from orange to blue with pressure. This approach allowed us to demonstrate the real-world application of this sensor in detecting small changes in pressure with a designed uniaxial pressure device, with unprecedented resolution of the order of a few bars, demonstrating the technological potential of this sensor for remote, online monitoring of cracks and strains in heavy construction facilities.

Nanostructure Control of GaN by Electrochemical Etching for Enhanced Perovskite Quantum Dot LED Backlighting.

Upgraded technology has realized miniaturization and promoted transformation in each field. Miniaturized light-emitting diode (LED) chips enable higher resolution and create a full sense of immersion in displays. Porous GaN is a structure that can reduce excitation light leakage and enhance the light conversion efficiency. Perovskite quantum dots with the highest optical density as candidate materials for loading in pores can significantly decrease the aggregation phenomenon and increase the path of light absorption. Here, the porous tunability is explored by electrochemical etching under a range of voltages, concentrations, and etching times with acid and base electrolytes, such as oxalic acid and potassium hydroxide. Based on scanning electron microscopy images, the distribution of the pores and the morphology of pore channels can be distinguished under acid and base etching. Larger pore sizes and distorted channels (∼680 nm) are presented on the oxalic acid-etched GaN chip. In contrast, smaller pore sizes and straight-deeper channels (∼5650 nm) are demonstrated on the GaN by potassium hydroxide etching. Therefore, the hybrid nanostructure is etched by oxalic acid and potassium hydroxide, separately. The green and red light conversion efficiencies of perovskite quantum dots pumped by a blue LED can be improved by 3 and 10 times, respectively, resulting in a color gamut of approximately 124%.

Plant Growth Modeling and Response from Broadband Phosphor-Converted Lighting for Indoor Agriculture.

The rapid change in population, environment, and climate is accompanied by the food crisis. As a new type of farming, indoor agriculture opens the possibility of addressing this crisis in the future. In this study, a phosphor-converted light-emitting diode (pc-LED), as energy-saving lighting for indoor agriculture, was used to evaluate the response and effect on the growth of Lactuca sativa. Red phosphors, SrLiAl3N4:Eu2+ (SLA) and CaAlSiN3:Eu2+ (CASN), were characterized and analyzed with crystal structure, morphology, and optical properties. Eu2+-doped phosphors provided the red emission of around 650 nm which is highly matched with the absorption of chlorophyll. Under the same luminescence intensity, broader emission of CASN pc-LED demonstrated a 100% increase of photosynthetically active photon flux density and 130% promotion of plant weight than the SLA pc-LED, which reflected the positive result of the carbon fixation. The chlorophyll and nitrate responses have also revealed the effect of broader red light on indoor agriculture.

Amplification of oxidative stress by lipid surface-coated single-atom Au nanozymes for oral cancer photodynamic therapy.

Single-atom nanozymes (SANs) are the latest trend in biomaterials research and promote the application of single atoms in biological fields and the realization of protein catalysis in vivo with inorganic nanoparticles. Carbon quantum dots (CDs) have excellent biocompatibility and fluorescence properties as a substrate carrying a single atom. It is difficult to break through pure-phase single-atom materials with quantum dots as carriers. In addition, there is currently no related research in the single-atom field in the context of oral cancer, especially head and neck squamous cell carcinoma. This research developed a lipid surface-coated nanozyme combined with CDs, single-atomic gold, and modified lipid ligands (DSPE-PEG) with transferrin (Tf) to treat oral squamous cell carcinoma. The study results have demonstrated that surface-modified single-atom carbon quantum dots (m-SACDs) exhibit excellent therapeutic effects and enable in situ image tracking for diagnosing and treating head and neck squamous carcinoma (HNSCC).

Photoluminescence enhancement study in a Bi-doped Cs2AgInCl6 double perovskite by pressure and temperature-dependent self-trapped exciton emission.

Here, we report a halide precursor acid precipitation method to synthesize Cs2AgIn1-xBixCl6 (x = 0, 0.02, 0.04, 0.08, 0.16, 0.32, 0.64, and 1) microcrystals. Cs2AgInCl6 and Bi derivative double perovskites show broadband white light emission via self-trapped excitons (STEs) and have achieved the highest internal quantum efficiency of up to 52.4% at x = 0.08. Synchrotron X-ray diffraction confirmed the linear increase of lattice parameters and cell volume with Bi3+ substitution at In3+ sites. Absorbance, photocurrent excitation, and photoluminescence excitation spectra are used to observe possible transitions from the valence to the conduction band or free exciton (FE) states as well as transitions within local Bi3+ states. The broadband photoluminescence is quenched via a single nonradiative process with an activation energy ΔE = 1490 cm-1 for Cs2AgIn0.92Bi0.08Cl6. Under normal conditions, we observed STE emission, but applying external pressure alters the electronic structure such that at elevated pressure, the only emission via the FE state is observed. We anticipate that structure, temperature and pressure-dependent photoluminescence studies will help the future use of a single-source lead-free double perovskite for white light-emitting diode applications.

Progress and Viewpoints of Multifunctional Composite Nanomaterials for Glioblastoma Theranostics.

The most common malignant tumor of the brain is glioblastoma multiforme (GBM) in adults. Many patients die shortly after diagnosis, and only 6% of patients survive more than 5 years. Moreover, the current average survival of malignant brain tumors is only about 15 months, and the recurrence rate within 2 years is almost 100%. Brain diseases are complicated to treat. The reason for this is that drugs are challenging to deliver to the brain because there is a blood-brain barrier (BBB) protection mechanism in the brain, which only allows water, oxygen, and blood sugar to enter the brain through blood vessels. Other chemicals cannot enter the brain due to their large size or are considered harmful substances. As a result, the efficacy of drugs for treating brain diseases is only about 30%, which cannot satisfy treatment expectations. Therefore, researchers have designed many types of nanoparticles and nanocomposites to fight against the most common malignant tumors in the brain, and they have been successful in animal experiments. This review will discuss the application of various nanocomposites in diagnosing and treating GBM. The topics include (1) the efficient and long-term tracking of brain images (magnetic resonance imaging, MRI, and near-infrared light (NIR)); (2) breaking through BBB for drug delivery; and (3) natural and chemical drugs equipped with nanomaterials. These multifunctional nanoparticles can overcome current difficulties and achieve progressive GBM treatment and diagnosis results.

The optical research progress of nanophosphors composed of transition elements in the fourth period of near-infrared windows I and II for deep-tissue theranostics.

Research in the field of nano-optics is advancing by leaps and bounds, among which near-infrared (NIR) light optics have attracted much attention. NIR light has a longer wavelength than visible light, such that it can avoid shielding caused by biological tissues. This advantage has driven its importance and practicality in human treatment applications and has attracted significant attention from researchers in academia and industry. In the broad spectrum of infrared light wavelengths, the most noticeable ones are the NIR biological window I of 700-900 nm and window II of 1000-1700 nm. Luminescent materials can effectively cover the NIR biological window with different doping strategies. These doped elements are mostly transition elements with multielectron orbitals. Several nanomaterials based on narrow-spectrum lanthanides have been developed to correspond to biological applications of different wavelengths. However, this review explicitly introduces the absorption and reflection/luminescence interactions between NIR light and biological tissues independently. Unlike the adjustment of the wavelength of the lanthanide series, this review analyzes the NIR optical properties of the fourth-period element ions in transition elements (such as Cr3+ and Ni2+). These elements have a broadband wavelength of NIR light emission and higher quantum efficiency, corresponding to the absorption and emission spectrum and photobiological absorption of different NIR windows for therapeutic diagnosis. Finally, this review lists and explores other broadband NIR phosphors and has tried to discover the possibility of non-invasive precision medicine in the future.

Enhancement of self-trapped excitons and near-infrared emission in Bi3+/Er3+ co-doped Cs2Ag0.4Na0.6InCl6 double perovskite.

Erbium (Er) complexes are used as optical gain materials for signal generation in the telecom C-band at 1540 nm, but they need a sensitizer to enhance absorption. Na+ substitution for Ag+ and Bi3+ doping at the In3+ site is a possible strategy to enhance the broadband emission of Cs2AgInCl6, which could be used as a sensitizer for energy transfer to rare-earth elements. Herein, self-trapped exciton (STE) energy transfer to Er3+ at 1540 nm in double perovskite is reported. An acid precipitation method was used to synthesize Cs2AgInCl6 and its derivatives with Er3+, Bi3+, and Na+. Bare Cs2AgInCl6:Er emission signals were found to be weak at 1540 nm, but Bi3+ doping increased them by 12 times, and Bi3+ and Na+ doping increased signal intensity by up to 25 times. Electron paramagnetic resonance spectroscopy characterized a decrease in axial symmetry over the Er3+ ions after the substitutions of Na+ and Bi3+ in Cs2AgInCl6 at low temperatures (<7 K) for the first time. Moreover, an increase in pressure compressed the structure, which tuned the STE transition for free exciton emission, and a further increase in pressure distorted the cubic phase above 70 kbar.

Natural Carbon Nanodots: Toxicity Assessment and Theranostic Biological Application.

This review outlines the methods for preparing carbon dots (CDs) from various natural resources to select the process to produce CDs with the best biological application efficacy. The oxidative activity of CDs mainly involves photo-induced cell damage and the destruction of biofilm matrices through the production of reactive oxygen species (ROS), thereby causing cell auto-apoptosis. Recent research has found that CDs derived from organic carbon sources can treat cancer cells as effectively as conventional drugs without causing damage to normal cells. CDs obtained by heating a natural carbon source inherit properties similar to the carbon source from which they are derived. Importantly, these characteristics can be exploited to perform non-invasive targeted therapy on human cancers, avoiding the harm caused to the human body by conventional treatments. CDs are attractive for large-scale clinical applications. Water, herbs, plants, and probiotics are ideal carbon-containing sources that can be used to synthesize therapeutic and diagnostic CDs that have become the focus of attention due to their excellent light stability, fluorescence, good biocompatibility, and low toxicity. They can be applied as biosensors, bioimaging, diagnosis, and treatment applications. These advantages make CDs attractive for large-scale clinical application, providing new technologies and methods for disease occurrence, diagnosis, and treatment research.

Plasmon-Triggered Upconversion Emissions and Hot Carrier Injection for Combinatorial Photothermal and Photodynamic Cancer Therapy.

Despite the unique ability of lanthanide-doped upconversion nanoparticles (UCNPs) to convert near-infrared (NIR) light to high-energy UV-vis radiation, low quantum efficiency has rendered their application unpractical in biomedical fields. Here, we report anatase titania-coated plasmonic gold nanorods decorated with UCNPs (Au NR@aTiO2@UCNPs) for combinational photothermal and photodynamic therapy to treat cancer. Our novel architecture employs the incorporation of an anatase titanium dioxide (aTiO2) photosensitizer as a spacer and exploits the localized surface plasmon resonance (LSPR) properties of the Au core. The LSPR-derived near-field enhancement induces a threefold boost of upconversion emissions, which are re-absorbed by neighboring aTiO2 and Au nanocomponents. Photocatalytic experiments strongly infer that LSPR-induced hot electrons are injected into the conduction band of aTiO2, generating reactive oxygen species. As phototherapeutic agents, our hybrid nanostructures show remarkable in vitro anticancer effect under NIR light [28.0% cancer cell viability against Au NR@aTiO2 (77.3%) and UCNP@aTiO2 (98.8%)] ascribed to the efficient radical formation and LSPR-induced heat generation, with cancer cell death primarily following an apoptotic pathway. In vivo animal studies further confirm the tumor suppression ability of Au NR@aTiO2@UCNPs through combinatorial photothermal and photodynamic effect. Our hybrid nanomaterials emerge as excellent multifunctional phototherapy agents, providing a valuable addition to light-triggered cancer treatments in deep tissue.

Next-Generation Cancer-Specific Hybrid Theranostic Nanomaterials: MAGE-A3 NIR Persistent Luminescence Nanoparticles Conjugated to Afatinib for In Situ Suppression of Lung Adenocarcinoma Growth and Metastasis.

The rate of lung cancer has gradually increased in recent years, with an average annual increase of 15%. Afatinib (AFT) plays a key role in preventing non-small cell lung carcinoma (NSCLC) growth and spread. To increase the efficiency of drug loading and NSCLC cell tracking, near infrared-persistent luminescence nanomaterials (NIR PLNs), a silica shell-assisted synthetic route for mono-dispersal, are developed and used in the nanovehicle. After optimizing their physical and chemical properties, the NIR PLNs are able to absorb light energy and emit NIR luminescence for several hours. In this research, NIR PLNs are functionalized for drug-carrying capabilities. Effective accumulation of target drugs, such as AFT, using PLN nanomaterials can lead to unique anticancer therapeutic benefits (AFT-PLN). To minimize side effects and increase drug accumulation, nanomaterials with targeting abilities are used instead of simple drugs to inhibit the growth of tumor cells. Thus, the specific targeting aptamer, MAGE-A3 (MAp) is identified, and the PLN to increase its targeting ability (AFT-PLN@MAp) accordingly modified. The advancement of nanoscale techniques in the field of lung cancer is urgently needed; this research presents a plausible diagnostic strategy and a novel method for therapeutic administration.

Theranostic nanobubble encapsulating a plasmon-enhanced upconversion hybrid nanosystem for cancer therapy.

Nanobubble (NB), which simultaneously enhances ultrasound (US) images and access therapeutic platforms, is required for future cancer treatment. Methods: We designed a theranostic agent for novel cancer treatment by using an NB-encapsulated hybrid nanosystem that can be monitored by US and fluorescent imaging and activated by near-infrared (NIR) light. The nanosystem was transported to the tumor through the enhanced permeability and retention effect. The hybrid nanosystem comprised upconversion nanoparticle (UCNP) and mesoporous silica-coated gold nanorod (AuNR@mS) with the photosensitizer merocyanine 540 to realize dual phototherapy. Results: With the NIR light-triggered, the luminous intensity of the UCNP was enhanced by doping holmium ion and emitted visible green and red lights at 540 and 660 nm. The high optical density state between the UCNP and AuNR@mS can induce plasmonic enhancement to improve the photothermal and photodynamic effects, resulting in cell death by apoptosis. The nanosystem showed excellent stability to avoid the aggregation of nanoparticles during the treatment. JC-1 dye was used as an indicator of mitochondrial membrane potential to identify the mechanism of cell death. The results of in vitro and in vivo analyses confirmed the curative effect of improved dual phototherapy. Conclusion: We developed and showed the therapeutic functions of a novel nanosystem with the combination of multiple theranostic nanoplatforms that can be triggered and activated by 808 nm NIR laser and US.

Ultra-broadband near-infrared emission CuInS2/ZnS quantum dots with high power efficiency and stability for the theranostic applications of mini light-emitting diodes.

Broadband near-infrared CuInS2/ZnS quantum dots with up to 94.8% quantum yield were synthesized with fast precursor decomposition leading to monomer conversion improvement. In the mini-LED package, the device showed high power efficiency and stability was also demonstrated with a penetration test and vein imaging showing its potential biomedical application in the theranostics field.

Thermally Stable and Deep Red Luminescence of Sr1-xBax[Mg2Al2N4]:Eu2+ (x = 0-1) Phosphors for Solid State and Agricultural Lighting Applications.

The systematic substitution of Ba in the Sr site of Sr[Mg2Al2N4]:Eu2+ generates a deep-red-emitting phosphor with enhanced thermal luminescence properties. Gas pressure sintering (GPS) of all-nitride starting materials in Molybdenum (Mo) crucibles yields pure-phase red-orange-colored phosphors. Peaks in the synchrotron X-ray diffraction (SXRD) data show a systematic shift toward smaller angles due to the introduction of the larger Ba cation in the same crystal structure. The photoluminescence property reveals that Ba substitution shifts the original emission wavelength of Sr[Mg2Al2N4]:Eu2+ (625 nm) toward ∼690 nm for Ba[Mg2Al2N4]:Eu2+. Thermal stability measurement of Sr1-xBax[Mg2Al2N4] indicates a systematic increase in stability from x = 0 to x = 1. X-ray absorption near-edge spectroscopy (XANES) results demonstrate the coexistence of Eu2+ and Eu3+. The red-shift and the enhanced thermal stability reveals that the distance of the emitting 5d level to the conduction band of Ba[Mg2Al2N4]:Eu2+ is large. The ionic size mismatch of Eu occupying a Ba site reduces the symmetry, thereby further splitting the degenerate emitting 5d level and lowering the energy of the emitting center. The development of deep-red phosphors emitting at 670-690 nm (x = 0.8-1.0) offers possible candidates for plant lighting applications.