A sustainable future demands innovative breakthroughs in science and technology today, especially in the energy sector. Earth‐abundant resources can be explored and used to develop renewable and ...sustainable resources of energy to meet the ever‐increasing global energy demand. Efficient solar‐powered conversion systems exploiting inexpensive and robust catalytic materials for the photo‐ and photo‐electro‐catalytic water splitting, photovoltaic cells, fuel cells, and usage of waste products (such as CO2) as chemical fuels are appealing solutions. Many electrocatalysts and nanomaterials have been extensively studied in this regard. Low overpotentials, catalytic stability, and accessibility remain major challenges. Metal nanoclusters (NCs, ≤3 nm) with dimensions between molecule and nanoparticles (NPs) are innovative materials in catalysis. They behave like a “superatom” with exciting size‐ and facet‐dependent properties and dynamic intrinsic characteristics. Being an emerging field in recent scientific endeavors, metal NCs are believed to replace the natural photosystem II for the generation of green electrons in a viable way to facilitate the challenging catalytic processes in energy‐conversion schemes. This Review aims to discuss metal NCs in terms of their unique physicochemical properties, possible synthetic approaches by wet chemistry, and various applications (mostly recent advances in the electrochemical and photo‐electrochemical water splitting cycle and the oxygen reduction reaction in fuel cells). Moreover, the significant role that MNCs play in dye‐sensitized solar cells and nanoarrays as a light‐harvesting antenna, the electrochemical reduction of CO2 into fuels, and concluding remarks about the present and future perspectives of MNCs in the frontiers of surface science are also critically reviewed.
Gathering atoms for energy: Water splitting and oxygen evolution and reduction reactions are challenging processes, which may provide a viable solution to future energy supply and fuel demands. In this regard, metal nanoclusters are new emerging electrocatalytic materials with the potential to replace the existing nanoscale materials. This Review will provide a comprehensive assessment of energy‐based catalysis using metal nanoclusters and offer scientific insights to better understand their role and future potential.
Post-operative surgical site infections (SSI) present a serious threat and may lead to complications. Currently available dressings for SSI lack mucoadhesion, safety, efficacy and most importantly ...patient compliance. We aimed to address these concerns by developing a bioactive thiolated chitosan-alginate bandage embedded with zinc oxide nanoparticles (ZnO-NPs) for localized topical treatment of SSI. The FTIR, XRD, DSC and TGA of bandage confirmed the compatibility of ingredients and modifications made. The porosity, swelling index and lysozyme degradation showed good properties for wound healing and biodegradation. Moreover, in-vitro antibacterial activity showed higher bactericidal effect as compared to ZnO-NPs free bandage. In-vivo wound healing in murine model showed significant improved tissue generation and speedy wound healing as compared to positive and negative controls. Over all, thiolated bandage showed potential as an advanced therapeutic agent for treating surgical site infections, meeting the required features of an ideal surgical dressing.
The chromate resistant Gram-positive Bacillus cereus strain b-525k was isolated from tannery effluents, demonstrating optimal propagation at 37 °C and pH 8. The minimum inhibitory concentration (MIC) ...test showed that B. cereus b-525k can tolerate up to 32 mM Cr6+, and also exhibit the ability to resist other toxic metal ions including Pb2+ (23 mM), As3+ (21 mM), Zn2+ (17 mM), Cd2+ (5 mM), Cu2+ (2 mM), and Ni2+ (3 mM) with the resistance order as Cr 6+ > Pb2+ > As3+ >Zn2+ >Cd2+ >Ni2+ >Cu2+. B. cereus b-525k showed maximum biosorption efficiency (q) of 51 mM Cr6+/g after 6 days. Chromate stress elicited pronounced production of antioxidant enzymes such as catalase (CAT) 191%, glutathione transferase (GST) 192%, superoxide dismutase (SOD) 161%, peroxidase (POX) 199%, and ascorbate peroxidase (APOX) (154%). Within B. cereus b-525k, the influence of Cr6+ stress (2 mM) did stimulate rise in levels of GSH (907%) and non-protein thiols (541%) was measured as compared to the control (without any Cr6+ stress) which markedly nullifies Cr6+ generated oxidative stress. The pilot scale experiments utilizing original tannery effluent showed that B. cereus b-525k could remove 99% Cr6+ in 6 days, thus, it could be a potential candidate to reclaim the chromate contaminated sites.
The multiple metal resistant Staphylococcus sp. strain AS6, isolated from wastewater of Pakistan, was able to resist 25 mM arsenite and 150 mM arsenate. SEM analysis showed that no significant change ...in bacterial morphology under arsenite exposure was observed while EDX and FTIR analyses confirmed the surface adsorption and uptake of arsenite into the bacterial cells exposed to 15 mM arsenite. The GSH/GSSG ratio and NPSHs were increased 45.0 and 76.50% in 15 mM arsenite stress while antioxidant enzymes (SOD, CAT, POX, and APX) showed varied response in arsenic presence. The genome of strain AS6 was sequenced through Illumina NextSeq 550 sequencer and the genes confer resistance to arsenic such as arsR, arsB, and arsC were identified. The bacterial stain AS6 was able to oxidize arsenite 91%/8h and removed 93%/10 h arsenite through its inactivated biomass from the medium. The strain AS6 has great potential, due to its hyper-metal resistance and high arsenite oxidation ability, to be used as a bioresource for green chemistry to eliminate toxic arsenite from the environment.
Plastic is a fundamental polymer used in routine life and disposed of in sewage. It leads to microplastic pollution in aquatic organisms, introducing it into the food chain and affecting human ...health. In the present study, samples were collected from sewage wastewater to isolate the bacteria that could potentially reduce plastic. The six samples were incubated with plastic pieces in minimal salt media for 120 days. After 120 days, the weight loss experiment showed that samples SH5B and SH6B degraded 25% plastic. After chemical and molecular characterization, these strains were identified as Pseudomonas sp. SH5B and Pseudomonas aeruginosa SH6B. The Fourier-transform infrared spectroscopy (FTIR) analysis showed peaks shifting, indicating bond stretching, bond bending, and new bond formation. The Gas Chromatography-Mass Spectrometry (GC–MS) analysis revealed various new compounds produced during plastic degradation by these bacterial strains. The plastic biodegradation potential makes these bacteria an impending foundation for green chemistry to eradicate tough pollutants from the environment.
We demonstrate the synthesis of hydrophobic silica nanoparticles from sodium silicate and their application in separation of the oil–water mixture. For this, hydrophobic silica nanoparticles of size ...35 ± 8 nm were initially synthesized by sol–gel method using sodium silicate and trimethylchlorosilane, and further deposited on commercially available filter paper and polyurethane foam by dip coating technique. The coating cycles were optimized for filter paper to ensure that fibers of the filter paper have been completely covered with hydrophobic silica nanoparticles to provide an ideal porous superhydrophobic/superoleophilic framework for gravity based separation of oil–water mixtures. It was confirmed by water contact angle of ~155° and sliding angle <5°. Whereas the superhydrophobic polyurethane foam was utilized for collection of oil from oil–water mixtures via absorption. The capability of these materials to separate oil from water was tested against the mixtures of water with n-hexane, gasoline, diesel, kerosene oil and engine oil. Moreover, the produced particles can also be used for fabrication of semi-transparent superhydrophobic surfaces.
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Due to rising populations and human activities, heavy metals (HM) toxicity has become a serious problem for all life forms. The present study deals with isolating and identifying lead-resistant ...bacteria from contaminated wastewater of tanneries effluents. Two isolated strains were identified as Bacillus cereus (ID1), and Bacillus sp. (ID3), and both strains resisted a 25 mM concentration of Lead nitrate (Pb (NO3)2). After four days of treatment, Bacillus cereus (ID1) showed 80% lead uptake, and Bacillus sp. (ID3) showed 88%. Lead uptake was confirmed by Energy dispersive X-Ray (EDX) analysis. Fourier transform infrared spectroscopy (FTIR) showed that structural alterations had occurred in functional groups of the treated samples compared to the controls. Our research indicates that these Bacillus strains may be useful in bioremediating heavy metals from polluted environments. Further investigation into the processes involved in the uptake and homeostasis of heavy metals by these strains is required, as is the identification of the genes and enzymes responsible for Pb-bioremediation.
Cancer is one of the major deadly diseases globally. The alarming rise in the mortality rate due to this disease attracks attention towards discovering potent anticancer agents to overcome its ...mortality rate. The discovery of novel and effective anticancer agents from natural sources has been the main point of interest in pharmaceutical research because of attractive natural therapeutic agents with an immense chemical diversity in species of animals, plants, and microorganisms. More than 60% of contemporary anticancer drugs, in one form or another, have originated from natural sources. Plants and microbial species are chosen based on their composition, ecology, phytochemical, and ethnopharmacological properties. Plants and their derivatives have played a significant role in producing effective anticancer agents. Some plant derivatives include vincristine, vinblastine, irinotecan, topotecan, etoposide, podophyllotoxin, and paclitaxel. Based on their particular activity, a number of other plant-derived bioactive compounds are in the clinical development phase against cancer, such as gimatecan, elomotecan, etc. Additionally, the conjugation of natural compounds with anti-cancerous drugs, or some polymeric carriers particularly targeted to epitopes on the site of interest to tumors, can generate effective targeted treatment therapies. Cognizance from such pharmaceutical research studies would yield alternative drug development strategies through natural sources which could be economical, more reliable, and safe to use.
The past few decades have witnessed significant advances in the development of functionalized metal/metal oxide nanoparticles including those of inorganic noble metals and magnetic materials ...stabilized by various polymeric ligands. Recent applications of such functionalized nanoparticles, including those in bio-imaging, sensing, catalysis, drug delivery, and other biomedical applications have triggered the need for their facile and reproducible preparation with a better control over their size, shape, and surface chemistry. In this perspective, the multidentate polymer ligands containing functional groups like thiol, thioether, and ester are important surface ligands for designing and synthesizing stable nanoparticles (NPs) of metals or their oxides with reproducibility and high yield. These ligands have offered an unprecedented control over the particle size of both nanoparticles and nanoclusters with enhanced colloidal stability, having tunable solubility in aqueous and organic media, and tunable optical, magnetic, and fluorescent properties. This review summarizes the synthetic methodologies and stability of nanoparticles and fluorescent nanoclusters of metals (Au, Ag, Cu, Pt, and other transition metal oxides) prepared by using thioether based ligands and highlights their applications in bio-imaging, sensing, drug delivery, magnetic resonance imaging (MRI), and catalysis. The future applications of fluorescent metal NPs like thermal gradient optical imaging, single molecule optoelectronics, sensors, and optical components of the detector are also envisaged.
In the present study genotypic resistance of bacterial strain to first- and second-line anti-tuberculosis drugs was determined by Line probe assay. Toxic effect of tellurite on the growth of ...Mycobacterium tuberculosis (MTB) was determined by growing cells in different concentrations of tellurite (1 to 5 mM). Morphological effects of tellurite and uptake of metal in bacterial cells were confirmed by Scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis. Change in fold expression of the efflux pump gene was measured by RT-PCR. Mycobacterial strain was characterized as XDR-TB based on the genotypic resistance to rifampicin and isoniazid, along with resistance to fluoroquinolones and second line injectable. XDR-TB showed black colonies in tellurite presence and growth was delayed (2–3 weeks) when compared with the control. The reduced cell size, metal accumulation and the characteristic tellurite peaks appeared in metal-treated cells. MTB showed MIC value of 1 mM and had high susceptibility for higher concentrations (2–5 mM). However, no significant metal inhibitory effect on the mmpL7 efflux system was determined. Tellurite shows significant growth reduction potential against XDR-TB strain. However, the exact mechanism of action needs to be elucidated with further research.
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