Recent advancements in deciphering the therapeutic properties of plant secondary metabolites: phenolics, terpenes, and alkaloids.

Plants produce a diverse range of secondary metabolites that serve as defense compounds against a wide range of biotic and abiotic stresses. In addition, their potential curative attributes in addressing various human diseases render them valuable in the development of pharmaceutical drugs. Different secondary metabolites including phenolics, terpenes, and alkaloids have been investigated for their antioxidant and therapeutic potential. A vast number of studies evaluated the specific compounds that possess crucial medicinal properties (such as antioxidative, anti-inflammatory, anticancerous, and antibacterial), their mechanisms of action, and potential applications in pharmacology and medicine. Therefore, an attempt has been made to characterize the secondary metabolites studied in medicinal plants, a brief overview of their biosynthetic pathways and mechanisms of action along with their signaling pathways by which they regulate various oxidative stress-related diseases in humans. Additionally, the biotechnological approaches employed to enhance their production have also been discussed. The outcome of the present review will lead to the development of novel and effective phytomedicines in the treatment of various ailments.

Impact of Co-Doping on the Visible Light-Driven Photocatalytic and Photoelectrochemical Activities of Eu(OH)3.

The microwave-assisted synthesis approach was used to synthesize Eu(OH)3 and Co-Eu(OH)3 nanorods. Various techniques were used to investigate the structural, optical, and morphological features of the Eu(OH)3 and Co-Eu(OH)3 NRs. Both Eu(OH)3 and Co-Eu(OH)3 NRs were found to be hexagonal with crystallite sizes ranging from 21 to 35 nm. FT-IR and Raman spectra confirmed the formation of Eu(OH)3 and Co-Eu(OH)3. Rod-shaped Eu(OH)3 and Co-Eu(OH)3 with average lengths and diameters ranging from 27 to 50 nm and 8 to 12 nm, respectively, were confirmed by TEM. The addition of Co was found to increase the particle size. Furthermore, with increased Co doping, the band gap energies of Co-Eu(OH)3 NRs were lowered (3.80-2.49 eV) in comparison to Eu(OH)3, and the PL intensities with Co doping were quenched, suggesting the lessening of electron/hole recombination. The effect of these altered properties of Eu(OH)3 and Co-Eu(OH)3 was observed through the photocatalytic degradation of brilliant green dye (BG) and photoelectrochemical activity. In the photocatalytic degradation of BG, 5% Co-Eu(OH)3 had the highest response. However, photoelectrochemical experiments suggested that 10% Co-Eu(OH)3 NRs showed improved activity when exposed to visible light. As a result, Co-Eu(OH)3 NRs have the potential to be a promising visible-light active material for photocatalysis.

Photocatalytic degradation of brilliant green and 4-nitrophenol using Ni-doped Gd(OH)3 nanorods.

Gadolinium hydroxide (Gd(OH)3) was synthesized via a microwave-assisted synthesis method. Nickel ion (Ni2+) was doped into Gd(OH)3, in which 4-12% Ni-Gd(OH)3 was synthesized, to study the effect of doping. The structural, optical, and morphological properties of the synthesized materials were analyzed. The crystallite sizes of the hexagonal structure of Gd(OH)3 and Ni-Gd(OH)3, which were 17-30 nm, were obtained from x-ray diffraction analysis. The vibrational modes of Gd(OH)3 and Ni-Gd(OH)3 were confirmed using Raman and Fourier-transform infrared spectroscopies. The band gap energy was greatly influenced by Ni-doping, in which a reduction of the band gap energy from 5.00 to 3.03 eV was observed. Transmission electron microscopy images showed nanorods of Gd(OH)3 and Ni-Gd(OH)3 and the particle size increased upon doping with Ni2+. Photocatalytic degradations of brilliant green (BG) and 4-nitrophenol (4-NP) under UV light irradiation were carried out. In both experiments, 12% Ni-Gd(OH)3 showed the highest photocatalytic response in degrading BG and 4-NP, which is about 92% and 69%, respectively. Therefore, this study shows that Ni-Gd(OH)3 has the potential to degrade organic pollutants.

Ultraviolet Light-Assisted Decontamination of Chemical Warfare Agent Simulant 2-Chloroethyl Phenyl Sulfide on Metal-Loaded TiO2 /Ti Surfaces.

The application of ultraviolet (UV) light for the decontamination of chemical warfare agents (CWAs) has gained recognition as an effective method, especially for treating hard-to-reach areas where wet chemical methods are impractical. In this study, TiO2 /Ti was employed as a model catalyst, which was contaminated with 2-chloroethyl phenyl sulfide (CEPS), and subjected to photocatalytic decontamination using both UVB and UVC light. Additionally, photocatalytic decontamination efficiency by introducing Au, Pt, and Cu onto the TiO2 /Ti surface was explored. During the photodecomposition process under UVC light, at least eight distinct secondary byproducts were identified. It was observed that the introduction of overlayer metals did not significantly enhance the photodecomposition under UVC light instead overlaid Au exhibited substantially improved activity under UVB light. Whereas, photodecomposition process under UVB light, only five secondary products were detected, including novel compounds with sulfoxide and sulfone functional groups. This novel study offers valuable insights into the generation of secondary products and sheds light on the roles of overlayer metals and photon wavelength in the photodecontamination process of CWA.

α-Glucosidase Inhibitory Activity and Cytotoxicity of CeO2 Nanoparticles Fabricated Using a Mixture of Different Cerium Precursors.

A mixture of three distinct cerium precursors (Ce(NO3)3·6H2O, CeCl3·7H2O, and Ce(CH3COO)3·H2O) was used to prepare cerium oxide nanoparticles (CeO2 NPs) in a polyol-mediated synthesis. Different ratios of diethylene glycol (DEG) and H2O were utilized in the synthesis. The properties of the synthesized CeO2 NPs, such as structural and morphological properties, were investigated to observe the effect of the mixed cerium precursors. Crystallite sizes of 7-8 nm were obtained for all samples, and all synthesized samples were confirmed to be in the cubic phase. The average particle sizes of the spherical CeO2 were between 9 and 13 nm. The successful synthesis of CeO2 can also be confirmed via the vibrational band of Ce-O from the FTIR. Antidiabetic properties of the synthesized CeO2 NPs were investigated using α-glucosidase enzyme inhibition assay, and the concentration of the synthesized CeO2 NPs was varied in the study. The biocompatibility properties of the synthesized CeO2 NPs were investigated via cytotoxicity tests, and it was found that all synthesized materials showed no cytotoxic properties at lower concentrations (62.5-125 µg/mL).

Application of nanopesticides and its toxicity evaluation through Drosophila model.

Insects feed on plants and cause the growth of plants to be restricted. Moreover, the application of traditional pesticides causes harmful effects on non-target organisms and poses serious threats to the environment. The use of conventional pesticides has negative impacts on creatures that are not the intended targets. It also presents significant risks to the surrounding ecosystem. Insects that are exposed to these chemicals eventually develop resistance to them. This review could benefit researcher for future development of nanopesticides research. This is because a holistic approach has been taken to describe the multidimensional properties of nanopesticides, health and environmental concerns and its possible harmful effects on non-target organisms and physiochemical entities. The assessment of effects of the nanopesticides is also being discussed through the drosophotoxicology. The future outlooks have been suggested to take a critical analysis before commercialization or formulation of the nanopesticides.

Sn-doped BiOCl for photoelectrochemical activities and photocatalytic dye degradation under visible light.

In this work, bismuth oxychloride (BiOCl) and Sn-doped BiOCl (SBCl) with improved visible light photocatalytic activity were synthesized via the co-precipitation method. The XRD analysis determined the tetragonal phase of BiOCl, 1 %, 5 %, and 10 % SBCl. The crystallite sizes were in the range of 20-34 nm. These results confirmed that the Sn ion was successfully incorporated into the BiOCl lattice. This was further confirmed by FT-IR and Raman analysis. The optical properties, such as the band gap energy, were studied using UV-vis DRS. It was found that doping BiOCl with Sn has a minor effect on the band gap tuning. BET shows that the SBCl samples have acquired a larger specific surface area (14.66-42.20 m2/g) than BiOCl (13.49 m2/g). The photocatalytic performance showed that SBCl samples have higher photocatalytic activity than BiOCl in degrading Rhodamine B (RhB) dye under visible light irradiation. Among the SBCl samples, 5 % SBCl exhibited the highest photocatalytic efficiency which degraded 91.2 % of the RhB dye in 60 min. Moreover, the photoelectrochemical activities of the as-synthesized BiOCl and SBCl were investigated using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) in the dark and under visible light irradiation. Both studies showed that SBCl exhibits enhanced photoelectrochemical activities than BiOCl. Hence, it can be suggested that SBCl possesses visible light active properties and can be potentially used as a photocatalyst and photoelectrode material.

Doped Ceria Nanomaterials: Preparation, Properties, and Uses.

Doping is a powerful strategy for enhancing the performance of ceria (CeO2) nanomaterials in a range of catalytic, photocatalytic, biomedical, and energy applications. The present review summarizes recent developments in the doping of ceria nanomaterials with metal and non-metal dopants for selected applications. The most important metal dopants are grouped into s, p, d, and f block elements, and the relevant synthetic methods, novel properties, and key applications of metal doped ceria are collated and critically discussed. Non-metal dopants are similarly examined and compared with metal dopants using the same performance criteria. The review reveals that non-metal (N, S, P, F, and Cl) doped ceria has mainly been synthesized by calcination and hydrothermal methods, and it has found applications mostly in photocatalysis or as a cathode material for LiS batteries. In contrast, metal doped ceria nanomaterials have been prepared by a wider range of synthetic routes and evaluated for a larger number of applications, including as catalysts or photocatalysts, as antibacterial agents, and in devices such as fuel cells, gas sensors, and colorimetric detectors. Dual/co-doped ceria containing both metals and non-metals are also reviewed, and it is found that co-doping often leads to improved properties compared with single-element doping. The review concludes with a future outlook that identifies unaddressed issues in the synthesis and applications of doped ceria nanomaterials.

Recent developments in tuning the efficacy of different types of sunscreens.

Due to recent global warming threats, the changes in the atmosphere have caused significant ultraviolet (UV) radiation exposure, primarily emitted by the sun, which creates more awareness of photoprotection. Sunscreen development has been a convenient and crucial approach to photoprotection against ultraviolet radiation. Due to high demand, upgrading the quality of sunscreen products and certifying methods are necessary to guarantee the safety of commercial sunscreen products for use. Sunscreen products should have a satisfactory amount of sun protection factor (SPF), ultraviolet A protection factor, as well as the photostability of the sunscreens for them to be considered effective and safe for use. A rigorous study on the effectiveness of the sunscreen components and their safety standards is essential for the productive use and further improvement of the available sunscreen materials. This article summarizes the effects and issues, protective measures of sunscreen usage, and its components, mainly ultraviolet filters.

Recent development of metal oxides and chalcogenides as antimicrobial agents.

Pathogenic microbes are a major concern in hospitals and other healthcare facilities because they affect the proper performance of medical devices, surgical devices, etc. Due to the antimicrobial resistance or multidrug resistance, combatting these microbial infections has grown to be a significant research area in science and medicine as well as a critical health concern. Antibiotic resistance is where microbes acquire and innately exhibit resistance to antimicrobial agents. Therefore, the development of materials with promising antimicrobial strategy is a necessity. Amongst other available antimicrobial agents, metal oxide and chalcogenide-based materials have shown to be promising antimicrobial agents due to their inherent antimicrobial activity as well as their ability to kill and inhibit the growth of microbes effectively. Moreover, other features including the superior efficacy, low toxicity, tunable structure, and band gap energy has makes metal oxides (i.e. TiO2, ZnO, SnO2 and CeO2 in particular) and chalcogenides (Ag2S, MoS2, and CuS) promising candidates for antimicrobial applications as illustrated by examples discussed in this review.

Effects of NO3-, Cl-, and CH3COO- anions and diethylene glycol on the morphological, structural, antidiabetic, and cell viability properties of CeO2 nanoparticles.

Cerium oxide (CeO2) nanoparticles (NPs) were synthesized using a modified conventional polyol method. The ratio of diethylene glycol (DEG) and water in the synthesis was varied, and three different cerium precursor salts (Ce(NO3)3, CeCl3, and Ce(CH3COO)3) were used. The structure, size, and morphology of the synthesized CeO2 NPs were studied. An average crystallite size of 13 to 33 nm was obtained from the XRD analysis. Spherical and elongated morphologies of the synthesized CeO2 NPs were acquired. Average particle sizes in the range of 16-36 nm were obtained by varying different ratios of DEG and water. The presence of DEG molecules on the surface of CeO2 NPs was confirmed using FTIR. Synthesized CeO2 NPs were used to study the antidiabetic and cell viability (cell cytotoxicity) properties. Antidiabetic studies were carried out using α-glucosidase enzymes inhibition activity. CeO2 synthesized using Ce(NO3)3 and CeCl3 precursors showed approximately 40.0% α-glucosidase enzyme inhibition activity, while CeO2 synthesized using Ce(CH3COO)3 showed the lowest α-glucosidase enzyme inhibition activity. Cell viability properties of CeO2 NPs were investigated using an in vitro cytotoxicity test. CeO2 NPs prepared using Ce(NO3)3 and CeCl3 were non-toxic at lower concentrations, while CeO2 NPs prepared using Ce(CH3COO)3 were non-toxic at all concentrations. Therefore, polyol-mediated synthesized CeO2 NPs showed quite good α-glucosidase inhibition activity and biocompatibility.

Visible-Light-Induced Photocatalytic and Photoantibacterial Activities of Co-Doped CeO2.

As one of the most significant rare earth oxides, the redox ability of cerium oxide (CeO2) has become the primary factor that has attracted considerable interest over the past decades. In the present study, irregular pentagonal CeO2 (S-CeO2) and different amounts of (1, 4, 8, and 12% Co) cobalt-doped CeO2 nanoparticles (Co-CeO2 NPs) with particle sizes between 4 and 13 nm were synthesized via the microwave-assisted synthesis method. The structural, optical, and morphological studies of S-CeO2 and Co-CeO2 were carried out using various techniques. The shifts in the conduction band and valence band were found to cause the reduction of the band gap energies of S-CeO2 and Co-CeO2 NPs. Moreover, the quenching of photoluminescence intensity with more Co doping showed the enhanced separation of charge carriers. The photocatalytic activities of S-CeO2 and Co-CeO2 NPs for methylene blue dye degradation, 4-nitrophenol reduction, and their photoantibacterial properties under visible-light irradiation were investigated. Findings showed that, due to the lower band gap energy (2.28 eV), more than 40% of both photocatalytic activities were observed for 12% Co-CeO2 NPs. On the other hand, higher antibacterial impact in the presence of light shows that the Co doping has a considerable influence on the photoantibacterial response of Co-CeO2. Therefore, microwave-assisted synthesized CeO2 and Co-CeO2 NPs have shown potential in photocatalytic dye degradation, chemical reduction, and photoantibacterial activities.

Sunlight harvesting for heat generation inside water using biosynthesized magnetite nanoparticles.

A low-cost, simple, inexpensive, and environmentally friendly method has been employed for synthesizing magnetite nanoparticles (Fe3O4 NPs). In this study, weeping willow (Salix babylonica L.) aqueous leaf extract has been utilized as a reducing, capping, and stabilizing agent. The synthesized Fe3O4 NPs were characterized by ultraviolet-visible (UV-Vis) spectroscopy, FT-IR spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), dynamic light scattering (DLS), zeta potential analysis, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The localized surface plasmon resonance (LSPR) performance of the Fe3O4 NPs was examined. It has been shown that the biosynthesized Fe3O4 NPs once dispersed in water can raise the temperature of water significantly when they absorb solar radiation through surface plasmon resonance (SPR). The impact of the pH value on the Fe3O4 NPs was also investigated. It has been shown that the optimum pH value among the examined pH values was pH 6. At this pH, the biosynthesized Fe3O4 NPs were able to increase the temperature of water from 25 °C to ∼36 °C. This dramatic increase in temperature was owing to the Fe3O4 NPs synthesized at pH 6 which acquired high crystallinity, monodispersity, high purity, minimum agglomeration, a small particle size, and high stability. In addition, the mechanism of converting solar energy to thermal energy has been discussed intensively. To the best of our knowledge, this study is unique and the novelty of this investigation is that Fe3O4 NPs acquire plasmonic-like properties under solar radiation. Also, they are anticipated to be an innovative photothermal adaptation material for solar-based water heating and heat absorption.

Determination of urinary spermine using controlled dissolution of polysulfide modified gold electrode.

Spermine (SPM) is considered a biomarker for prostate cancer and detecting it becomes highly challenging due to its electro- and optical-inactive nature. SPM has a tendency to interact with groups such as phosphates and sulfides to form macrocyclic arrangements known as nuclear aggregates of polyamines. Using this tendency, an electrochemical sensor has been developed using a polysulfide (PS) modified Au electrode (PS@Au electrode). PS has been synthesized from elemental sulfur by hydrothermal method and characterized using UV-Vis, fluorescence, FTIR, SEM, and XPS analyses. The PS@Au electrode was employed for electrochemical sensing of SPM. In the presence of SPM, a decrease in gold oxide reduction current was noted which is proportional to the concentration of SPM. The decrease in gold oxide reduction (0.5 V) current was attributed to the complexing nature of SPM-PS at the electrode interface. The reason for the decrease in current has been substantiated using XRF, XPS, and spectroelectrochemical studies. Under the optimized conditions, the PS@Au electrode exhibited a linear range of 1.55-250 µM with LOD of 0.511 ± 0.02 µM (3σ). The electrochemical strategy for SPM sensing exhibited better selectivity even in the presence of possible interferents. The selectivity stems from the selective interaction of SPM with PS on the Au electrode surface; the tested amino acids, and other molecules do not complex with PS and hence they could not interfere. The PS@Au electrode has been subjected to the determination of SPM in artificial urine samples and exhibited outstanding performance in the synthetic sample.

Zr, La-dual doped silver niobate for photocatalytic degradation of dyes under visible light irradiation.

Sol-gel-assisted synthesis of silver niobate, 1%, 5%, and 10% Zr, La-dual doped silver niobates were carried out. Analysis done using XRD showed that increasing Zr and La dual doping caused the synthesized materials to adopt an AgNbO3-like structure. This is also supported by FT-IR results. FESEM revealed that the silver niobate has a prism-like morphology while Zr, La-dual doped samples are irregular in shape. EDX mapping of the 10% Zr, La dual silver niobate confirmed the presence of Nb, Ag, Zr, and La metals. When compared with the silver niobate, the band gap energy of Zr, La-dual doped silver niobates are narrower, as shown by UV-Vis DRS measurements. It was revealed that dual doping of silver niobates with Zr and La has significantly improved the photocatalytic degradation of methylene blue (MB) and Rhodamine B (RhB) dyes. The 1% Zr, La-dual doped silver niobate showed the best photocatalytic results in terms of degrading MB while 10% Zr, La-dual doped silver niobate achieved the best performance when degrading RhB.

Understanding and combating COVID-19 using the biology and chemistry of SARS-CoV-2.

The coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Symptoms of COVID-19 can range from asymptomatic to severe, which could lead to fatality. Like other pathogenic viruses, the infection of SARS-CoV-2 relies on binding its spike glycoprotein to the host receptor angiotensin-converting enzyme 2 (ACE 2). Molecular studies suggested that there is a high affinity between the spike glycoprotein and ACE 2 that might arise due to their hydrophobic interaction. This property is mainly responsible for making this virus highly infectious. Apart from this, the transmissibility of the virus, prolonged viability in certain circumstances, and rapid mutations also contributed to the current pandemic situation. Nanotechnology provides potential alternative solutions to combat COVID-19 with the development of i. nanomaterial-based COVID-19 detection technology, ii. nanomaterial-based disinfectants, iii. nanoparticle-based vaccines, and iv. nanoparticle-based drug delivery. Hence, this review provides diverse insight into understanding COVID-19.

Recent Progress of Metal-Organic Frameworks and Metal-Organic Frameworks-Based Heterostructures as Photocatalysts.

In the field of photocatalysis, metal-organic frameworks (MOFs) have drawn a lot of attention. MOFs have a number of advantages over conventional semiconductors, including high specific surface area, large number of active sites, and an easily tunable porous structure. In this perspective review, different synthesis methods used to prepare MOFs and MOFs-based heterostructures have been discussed. Apart from this, the application of MOFs and MOFs-based heterostructures as photocatalysts for photocatalytic degradation of different types of pollutants have been compiled. This paper also highlights the different strategies that have been developed to modify and regulate pristine MOFs for improved photocatalytic performance. The MOFs modifications may result in better visible light absorption, effective photo-generated charge carriers (e-/h+), separation and transfer as well as improved recyclability. Despite that, there are still many obstacles and challenges that need to be addressed. In order to meet the requirements of using MOFs and MOFs-based heterostructures in photocatalysis for low-cost practical applications, future development and prospects have also been discussed.

Molybdenum Disulfide-Based Nanomaterials for Visible-Light-Induced Photocatalysis.

Visible-light-responsive photocatalytic materials have a multitude of important applications, ranging from energy conversion and storage to industrial waste treatment. Molybdenum disulfide (MoS2) and its variants exhibit high photocatalytic activity under irradiation by visible light as well as good stability and recyclability, which are desirable for all photocatalytic applications. MoS2-based materials have been widely applied in various fields such as wastewater treatment, environmental remediation, and organic transformation reactions because of their excellent physicochemical properties. The present review focuses on the fundamental properties of MoS2, recent developments and remaining challenges, and key strategies for tackling issues related to the utilization of MoS2 in photocatalysis. The application of MoS2-based materials in visible-light-induced catalytic reactions for the treatment of diverse kinds of pollutants including industrial, environmental, pharmaceutical, and agricultural waste are also critically discussed. The review concludes by highlighting the prospects of MoS2 for use in various established and emerging areas of photocatalysis.

Role of Anions in the Synthesis and Crystal Growth of Selected Semiconductors.

The ideal methods for the preparation of semiconductors should be reproducible and possess the ability to control the morphology of the particles with monodispersity yields. Apart from that, it is also crucial to synthesize a large quantity of desired materials with good control of size, shape, morphology, crystallinity, composition, and surface chemistry at a reasonably low production cost. Metal oxides and chalcogenides with various morphologies and crystal structures have been obtained using different anion metal precursors (and/or different sulfur sources for chalcogenides in particular) through typical synthesis methods. Generally, spherical particles are obtained as it is thermodynamically favorable. However, by changing the anion precursor salts, the morphology of a semiconductor is influenced. Therefore, precursors having different anions show some effects on the final forms of a semiconductor. This review compiled and discussed the effects of anions (NO3 -, Cl-, SO4 2-, CH3COO-, CH(CH3)O-, etc.) and different sources of S2- on the morphology and crystal structure of selected metal oxides and chalcogenides respectively.

ZnO-based antimicrobial coatings for biomedical applications.

Rapid transmission of infectious microorganisms such as viruses and bacteria through person-to-person contact has contributed significantly to global health issues. The high survivability of these microorganisms on the material surface enumerates their transmissibility to the susceptible patient. The antimicrobial coating has emerged as one of the most interesting technologies to prevent growth and subsequently kill disease-causing microorganisms. It offers an effective solution a non-invasive, low-cost, easy-in-use, side-effect-free, and environmentally friendly method to prevent nosocomial infection. Among antimicrobial coating, zinc oxide (ZnO) stands as one of the excellent materials owing to zero toxicity, high biocompatibility to human organs, good stability, high abundancy, affordability, and high photocatalytic performance to kill various infectious pathogens. Therefore, this review provides the latest research progress on advanced applications of ZnO nanostructure-based antibacterial coatings for medical devices, biomedical applications, and health care facilities. Finally, future challenges and clinical practices of ZnO-based antibacterial coating are addressed.