The performance of the near‐infrared phosphor‐converted light‐emitting diodes (NIR pc‐LEDs) mainly depends on the NIR emitting phosphors used. Cr3+ doped materials can be excited by blue light chips, but their emission is located in the NIR‐I region (650–1000 nm). Ni2+ doped materials are mainly located in the NIR‐II region (1000–1700 nm), but they cannot be effectively excited by blue light chips. Herein, Cr3+, Ni2+ mono‐doped, and co‐doped Sr2GaTaO6 NIR emitting phosphors are prepared and investigated. Cr3+ and Ni2+ ions occupy two octahedral sites of Ga3+ and Ta5+. The co‐doping of Cr3+ ions has achieved two breakthroughs. One is to shift the optimal excitation wavelength from violet light to blue light due to the energy transfer (efficiency up to 70%) from Cr3+ to Ni2+. The other is to achieve the broadband and continuous emission across NIR‐I and NIR‐II regions (650–1700 nm, with a full width at half maximum (FWHM) of 410 nm (173 nm + 237 nm)). The prepared Sr2GaTaO6: 0.02Cr3+, 0.01Ni2+ phosphor is combined with a commercial 460 nm blue chip to realize its application in organic compounds identification, night vision, and biological imaging. This work points out a direction for the future development of efficient super broadband NIR‐emitting phosphors.

Super Broadband Emission Across NIR‐I and NIR‐II Under Blue Light Excitation of Cr3+, Ni2+ Co‐Doped Sr2GaTaO6 Phosphor Achieved by Two‐Site Occupation and Effective Energy Transfer

A review of the antiviral activity of cationic antimicrobial peptides

Near-infrared phosphor converted light-emitting diode (NIR pc-LED) has many advantages over traditional NIR light sources, and has broad application prospects in night vision surveillance, non-destructive testing, bioimaging, and other fields. Phosphors are typically synthesized by the high-temperature solid-phase method as chunks or large granules, which need to be ground to small particles for practical application. This process introduces surface defects and reduces the luminous efficiency of phosphors. In this work, near-infrared phosphors composed of spinel MgAl2O4:Ni2+ with particle size less than 100 nm was synthesized in high-purity by sol-gel combustion method using nitrate salts with citric acid were used as raw materials. Under 365 nm excitation, MgAl2O4:Ni2+ phosphors emit broadband near-infrared luminescence of 1000–1600 nm with a width at half maximum of 237 nm. The optimal Ni2+ doping concentration was determined to be 1.5 mol% and the optimal sintering temperature was 1200 °C. The thermal activation energy of this phosphor was found to be 0.409 eV and the phosphor had good luminescence thermal stability. An NIR pc-LED device was assembled from the phosphor and commercially available near-ultraviolet LED, which showed a current-dependent increased of NIR luminescence up to 160 mA and an efficiency drop appeared with further increase of the current, suggesting a thermal dependent quenching may have occurred. On the other hand, the output of NIR luminescence increased nearly linearly with the increased of current when a 360 nm laser diode was used as the excitation light source, indicating the NIR phosphor has a very high fluorescence saturation threshold. Our study provides the utility for the sol-gel method in the preparation and the potential application of the nanoscale NIR-II phosphor materials. 

Sol-gel combustion synthesis and near-infrared luminescence of Ni2+-doped MgAl2O4 spinel phosphor

Zika virus (ZIKV) is an arbovirus whose infection in humans can lead to severe outcomes. This article reviews studies reporting the anti-ZIKV activity of natural products (NPs) and derivatives published from 1997 to 2022, which were carried out with NPs obtained from plants (82.4%) or semisynthetic/synthetic derivatives, fungi (3.1%), bacteria (7.6%), animals (1.2%) and marine organisms (1.9%) along with miscellaneous compounds (3.8%). Classes of NPs reported to present anti-ZIKV activity include polyphenols, triterpenes, alkaloids, and steroids, among others. The highest values of the selectivity index, the ratio between cytotoxicity and antiviral activity (SI = CC50/EC50), were reported for epigallocatechin gallate (SI ≥ 25,000) and anisomycin (SI ≥ 11,900) obtained from Streptomyces bacteria, dolastane (SI = 1246) isolated from the marine seaweed Canistrocarpus cervicorni, and the flavonol myricetin (SI ≥ 862). NPs mostly act at the stages of viral adsorption and internalization in addition to presenting virucidal effect. The data demonstrate the potential of NPs for developing new anti-ZIKV agents and highlight the lack of studies addressing their molecular mechanisms of action and pre-clinical studies of efficacy and safety in animal models. To the best of our knowledge, none of the active compounds has been submitted to clinical studies.

https://www.mdpi.com/1999-4915/15/5/1211/pdf?version=1684811532

Natural Products and Derivatives as Potential Zika virus Inhibitors: A Comprehensive Review

Near-infrared (NIR) phosphor conversion light-emitting diodes (pc-LEDs) have great application potential as NIR light sources in many fields such as food analysis, night vision illumination, and bioimaging for noninvasive medical diagnosis. In general, phosphors synthesized by a high-temperature solid-phase method have large particle sizes and have to be processed to fine powders by a grinding process, which may introduce surface defects and lower the luminous efficiency. Here, we report a sol-gel sintering method with ammonium nitrate and citric acid as the sacrificing agents to synthesize high purity, nanosized (less than 50 nm) Zr4+/Ni2+ codoped MgAl2O4 spinel NIR phosphors, in which MgAl2O4 spinel is the matrix, Ni2+ is the luminous center, and Zr4+ acts as the charge compensator. We systematically characterized the crystal structures and NIR luminescence properties of the Ni2+-doped MgAl2O4 and the Zr4+/Ni2+ codoped MgAl2O4. Under 390 nm light excitation, the emission spectrum of the Ni2+-doped MgAl2O4 phosphor covers 900-1600 nm, the half-peak width is 251 nm, and the peak position is located at 1230 nm. We demonstrated that by incorporating small amounts of Zr4+ as the charge compensator, the NIR emission intensity of the Zr4+/Ni2+ codoped MgAl2O4 nanosized phosphor was doubled over that of the Ni2+-doped MgAl2O4 phosphor. The optimal content of the charge compensator was 2 mol %. More importantly, the inclusion of Zr4+ led to a NIR phosphor with improved thermal stability in luminous properties, and the luminous intensity measured at 100 °C was 33.83% of that measured at room temperature (20 °C). This study demonstrates that NIR phosphor nanomaterials with high-purity and enhanced optical properties can be designed and synthesized through the charge compensation strategy by a sol-gel sintering method. 

Strategy of Charge Compensation for High-Performance Ni2+-Activated MgAl2O4 Spinel Near-Infrared Phosphor Synthesis via the Sol–Gel Combustion Method

As far as we are concerned, the phenomenon of Ni2+ luminescence in tetrahedral coordination has not been reported. For the first time, a new NIR phosphor Ca2GeO4:Ni2+ is developed in this work. It is found that the NIR emission from this phosphor is a sharp peak attributed to the unusual Ni2+-occupied GeO4 site in the lattice, instead of the conventional broadband luminescence of Ni2+ in the octahedrally coordinated site. Crystal-field analysis has been applied, and the parameters Dq, B, and Δ are calculated to reveal the relationship between the emission profile and the crystal field strength. The optimal Ni2+ doping concentration is found to be 1%. Ca2GeO4:Ni2+ provides an efficient sharp-line (fwhm = 16 nm) emission centered at 1164 nm which originates from the 1T2 → 3T1 transition with an internal quantum efficiency of 23.1% and a decay lifetime of about 300 μs. This work could provide some new insights to explore novel NIR luminescent materials based on transition-metal elements. 

Sharp-Line Near-Infrared Emission from Tetrahedron-Occupied Ni2+ in Ca2GeO4.

Several years have passed since the Zika virus (ZIKV) pandemic reoccurred in 2015–2016. However, there is still a lack of proved protective vaccines or effective drugs against ZIKV. The peptide brevinin-2GHk (BR2GK), pertaining to the brevinin-2 family of antimicrobial peptides, has been reported to exhibit only weak antibacterial activity, and its antiviral effects have not been investigated. Thus, we analyzed the effect of BR2GK on ZIKV infection. BR2GK showed significant inhibitory activity in the early and middle stages of ZIKV infection, with negligible cytotoxicity. Furthermore, BR2GK was suggested to bind with ZIKV E protein and disrupt the integrity of the envelope, thus directly inactivating ZIKV. In addition, BR2GK can also penetrate the cell membrane, which may contribute to inhibition of the middle stage of ZIKV infection. BR2GK blocked ZIKV E protein expression with an IC50 of 3.408 ± 0.738 μΜ. In summary, BR2GK was found to be a multi-functional candidate and a potential lead compound for further development of anti-ZIKV drugs.

Brevinin-2GHk, a Peptide Derived from the Skin of Fejervarya limnocharis, Inhibits Zika Virus Infection by Disrupting Viral Integrity

Sepsis is an exacerbated inflammatory reaction induced by severe infection. As important defensive molecules in innate immunity, several AMPs are reported to prevent septic shock. In this study, we characterized a novel cathelicidin, FM-CATH, from the frog skin of F. multistriata. FM-CATH was found to adopt an amphipathic α-helix structural in membrane-mimetic environments and possess favorable antimicrobial effects against bacteria and fungus. In addition, it triggered the agglutination of bacteria. It could also strongly bind to LPS and LTA. Additionally, FM-CATH affected the enzymatic activities of thrombin, plasmin, β-tryptase, and tPA, leading to coagulation inhibition in vitro and in vivo. Finally, we observed that FM-CATH improved survival rate and inhibited pathological alteration, bacterial count, serum biochemistry, and pro-inflammatory cytokine expression in the cecal ligation and puncture-induced sepsis mice. Taken together, these findings suggest that FM-CATH might be served as a promising agent for the treatment of sepsis.

/pdf/fm-cath-a-novel-cathelicidin-from-fejervarya-multistriata-506fem9pvt.pdf

FM-CATH, A Novel Cathelicidin From Fejervarya Multistriata, Shows Therapeutic Potential for Treatment of CLP-Induced Sepsis

Synthesis and luminescent property of Ce3+-doped NaSrY(BO3)2 efficient blue-emitting phosphor as luminescent thermometer

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Sharp-Line Near-Infrared Emission from Tetrahedron-Occupied Ni2+ in Ca2GeO4.

Brevinin-2GHk, a Peptide Derived from the Skin of Fejervarya limnocharis, Inhibits Zika Virus Infection by Disrupting Viral Integrity

FM-CATH, A Novel Cathelicidin From Fejervarya Multistriata, Shows Therapeutic Potential for Treatment of CLP-Induced Sepsis

Synthesis and luminescent property of Ce3+-doped NaSrY(BO3)2 efficient blue-emitting phosphor as luminescent thermometer