Aggregation-Induced Generation of Reactive Oxygen Species: Mechanism and Photosensitizer Construction

Luminogens with aggregation-induced emission (AIEgens) have been widely applied in the field of photodynamic therapy. Among them, aggregation-induced emission photosensitizers (AIE–PSs) are demonstrated with high capability in fluorescence and photoacoustic bimodal imaging, as well as in fluorescence imaging-guided photodynamic therapy. They not only improve diagnosis accuracy but also provide an efficient theranostic platform to accelerate preclinical translation as well. In this short review, we divide AIE–PSs into three categories. Through the analysis of such classification and construction methods, it will be helpful for scientists to further develop various types of AIE–PSs with superior performance.     

Reactive Oxygen Species (ROS) Activated Liposomal Cell Delivery using a Boronate-Caged Guanidine Lipid

We report boronate-caged guanidine-lipid 1 that activates liposomes for cellular delivery only upon uncaging of this compound by reactive oxygen species (ROS) to produce cationic lipid products. These liposomes are designed to mimic the exceptional cell delivery properties of cell-penetrating peptides (CPPs), while the inclusion of the boronate cage is designed to enhance selectivity such that cell entry will only be activated in the presence of ROS. Boronate uncaging by hydrogen peroxide was verified by mass spectrometry and zeta potential (ZP) measurements. A microplate-based fluorescence assay was developed to study the ROS-mediated vesicle interactions between 1 -liposomes and anionic membranes, which were further elucidated via dynamic light scattering (DLS) analysis. Cellular delivery studies utilizing fluorescence microscopy demonstrated significant enhancements in cellular delivery only when 1 -liposomes were incubated with hydrogen peroxide. Our results showcase that lipid 1 exhibits strong potential as an ROS-responsive liposomal platform for targeted drug delivery applications.     

Dithiocarbamates as hazardous remediation agent: A critical review on progress in environmental chemistry for inorganic species studies of 20th century

This article provides a critical review and a wide range of applications of dithiocarbamates (DTCs) in environmental samples. The characteristics of DTCs are reviewed with particular emphasis on inorganic speciation studies using state-of-the-art analytical instrumentation coupled with computational methods of analysis.     

Structure activity relationship of bergenin,p-hydroxybenzoyl bergenin, 11-O-galloylbergenin as potent antioxidant and urease inhibitor isolated from Bergenia ligulata

Ethanol extract of the aerial parts of Bergenia ligulata was subjected to solvent–solvent separation followed by various chromatographic techniques that lead to isolation of bergenine (1), p-hydroxybenzoyl bergenin (2), 11-O-galloylbergenin (3) and methyl gallate (4) as major constituents. Ethyl acetate fraction showed a dose-dependent urease inhibitory pattern with IC₅₀ value of 54μg/mL. Structures of compounds 1 and 3 were established by XRD and 2, 4 by NMR. All these compounds were subjected to DPPH scavenging activity, reducing power assay and urease inhibitory activity. The EC₅₀ 7.45 ± 0.2 μg/mL and 5.39 ± 0.28 μg/mL values in terms of antioxidant and reducing power, respectively, were less for 3. Compounds 1–3 showed moderate to significant urease inhibitory potential with IC₅₀ 57.1 ± 0.7, IC₅₀ 48.4 ± 0.3 and 38.6 ± 1.5. Antioxidant activities and urease inhibitory potential were investigated and compound 3 was found to be the most active.     

Thiomaleimide Functionalization for Selective Biological Fluorescence Detection of Peroxynitrite as Tested in HeLa and RAW 264.7 Cells

The role of fluorescent molecules in diagnosis, treatment as well as in biomedical research has great current medicinal significance and is the focus of concentrated effort across the scientific research spectrum. Related research continues to reveal new practical sensing systems that bear enhanced features for interfacing of substituted molecules with biological systems. As part of an effort to better understand chalcogenide systems, a new dithiomaleimide BODIPY ( BDP‐NGM ) probe has been designed, synthesized and characterized. The fluorescence of BDP‐NGM was quenched by the incorporation of [3,4‐bis (phenylthio)] on the maleimide‐4‐phenyl moiety which is, in turn, placed at the meso ‐position of the BODIPY system. The probe shows a turn‐on fluorescence response upon reaction with ONOO⁻; mass spectral evidence reveals peaks in agreement with products involving oxidation of the sulfur groups to sulfone groups. An about 18.0‐fold emission intensity enhancement was found. By comparison, the emission signal from another ROS/RNS, superoxide, gave a modest turn on signal (≈5.0‐fold). The reaction is complete within 10 min, judging from the monitoring of the turn‐on fluorescence process; the detection limit was found to be 0.4 μm . BDP‐NGM can be used for the detection of ONOO⁻ under both acidic and basic conditions. Live cell imaging showed that the current probe can be used for the selective detection of ONOO⁻ in living systems.     

Driving the photoluminescent and structural properties of X2-Y2SiO5 by varying the dopant Dy3+ concentration towards cool WLED applications

Dy³⁺ doped Y₂SiO₅ nanophosphors were synthesized by solution combustion technique using Calotropis gigantean milk latex and NaCl as fuel and flux respectively. Powder X-ray diffraction (PXRD) confirmed the formation of monoclinic X₂-phase Y₂SiO₅ belonging to the phase group C₂/c. Fourier transform infrared spectroscopy (FTIR) shows characteristic metal–oxygen (Y–O) vibration band at 721 cm⁻¹. Transmission electron microscopic (TEM) and Scanning electron microscopic (SEM) morphological feature exhibits non-uniform almost spherical shaped nanosized particles. The photoluminescence (PL) emission peaks, recorded at 388 nm, showed radiative emissions at 483, 575 and 636 nm respectively. Judd–Ofelt (JO) analysis was carried out to estimate the radiative (A_R) properties, radiative life time (τ_R), branching ratio (β_R) and stimulated emission crossection (σλ_p). The CIE and CCT was estimated using McCamy empirical formula. In the beginning, the CIE co-ordinate values were lying in the light blue region. However, with increase in Dy³⁺ concentration the values shifted towards white region. CCT value was found to be ∼6984 K. Therefore, Y₂SiO₅:Dy³⁺ (9 mol%) can be used for cool day light and WLED applications.     

Ferric Single-Site Catalyst Confined in a Zeolite Framework for Propane Dehydrogenation

Non-oxidative dehydrogenation of propane is a highly efficient approach for industrial preparation of propene that is commonly catalyzed by noble Pt or toxic Cr catalysts and suffers from coking. In this work, ferric catalyst confined in a zeolite framework was synthesized by a hydrothermal procedure. The isolated Fe in the framework formed distorted tetrahedra, which were beneficial for the selective dehydrogenation of propane and reached over 95 % propene selectivity and over 99 % total olefins selectivity. This catalyst had a silanol-free structure and was oxygen tolerant, hydrothermally stable, and coke free, with a deactivation constant of 0.01 h⁻¹. This study provided guidance for the synthesis of structural heteroatomic zeolite and efficient propane non-oxidative dehydrogenation over early transition metals.     

Combustion synthesis of mesoporous CoAl2O4 for peroxymonosulfate activation to degrade organic pollutants

A mesoporous cobalt aluminate (CoAl₂O₄) spinel is synthesized through a combustion method and adopted for the activation of peroxymonosulfate (PMS) to degrade organic pollutants. Multiple characterization procedures are conducted to investigate the morphology and physicochemical properties of the CoAl₂O₄ spinel. Due to its mesoporous structure, large surface area, and high electrical conductivity, the obtained CoAl₂O₄ exhibits remarkable catalytic activity for Rhodamine B (RhB) degradation. Its RhB degradation rate is 89.0 and 10.5 times greater than those of Co₃O₄ and CoAl₂O₄ spinel prepared by a precipitation method, respectively. Moreover, the mesoporous CoAl₂O₄ spinel demonstrates a broad operating pH range and excellent recyclability. The influence of several parameters (catalyst amount, PMS concentration, initial pH, and coexisting inorganic anions) on the oxidation of RhB is evaluated. Through quenching tests and electron paramagnetic resonance experiments, sulfate radicals are identified as the predominant reactive species in RhB degradation. This paper provides new insights for the development of efficient, stable, and reusable cobalt-based heterogeneous catalysts and promotes the application of persulfate activation technology for the treatment of refractory organic wastewater.     

Synthesis of strontium substituted hydroxyapatite by solution combustion route

Hydroxyapatite is a versatile compound resembling natural bone mineral. HAP insinuates feasibility with substitution ensuing in its application in various fields. The properties of calcium and strontium are cognate and pose as a bone-seeking trace-element that accumulates in new trabecular bone. Strontium substituted hydroxyapatite, Ca₉.₅Sr_0.5(OH)₂(PO₄)₆, was synthesized using citric acid as fuel and calcined 900 ​°C. The as-prepared product notably was characterized by powder X-ray diffraction, Fourier - Transform Infrared spectroscopy and Scanning Electron Microscope along with Energy Dispersive Spectroscopy. FT-IR analysis exhibited stretching and bending vibrations of (PO₄)^3- and OH⁻ groups along without any signal of carbonate group. Studies showed that product formed is strontium substituted hydroxyapatite, and calcination temperature plays an essential role in the formation of hydroxyapatite phase. The precursors when calcined resulted in 46–50 ​nm of Sr substituted hydroxyapatite.     

低功率超声增强碘帕醇氯氧化的效果和路径

研究了低功率超声(US, <38 W)对NaClO氧化非离子型碘代X射线造影剂—碘帕醇(IPM)的增强作用及机理, 考察了NaClO添加浓度和超声功率的影响, 分析并计算了体系中的主要活性物种及其贡献. 采用高效液相色谱/串联质谱(HPLC/MS/MS)对降解产物进行分析, 推测IPM的降解路径. 结果表明, 低功率US显著增强了NaClO对IPM的氧化效果, 在25 ℃, pH=5.8, NaClO浓度为0.12 mmol/L条件下, 10 mg/L IPM在60 min的降解率达到85.8%. 其中NaClO氧化、 HO·和活性氯自由基(RCSs)是US/NaClO增强IPM降解的主要原因, 自由基分析计算它们的贡献率分别为15.82%, 4.65%和79.53%. NaClO浓度在0~0.24 mmol/L范围内, IPM的降解率随NaClO浓度升高而增加, 60 min后降解率由4.75%增加到91.12%; 超声功率为28.5 W, 降解率达到最高. 在 15~45 ℃温度范围内, IPM的降解过程符合表观一级反应动力学, 反应活化能(E_a)为59.03 kJ/mol. HPLC/MS/MS共检测出5种中间产物, 结合密度泛函理论(DFT)计算结果, 初步推测了IPM在US/NaClO体系中的降解途径和机理.