: Water pollution due to waste effluents of the textile industry is seriously causing various health problems in humans. Water pollution with pathogenic bacteria, especially Escherichia coli (E. coli) and other microbes is due to the mixing of fecal material with drinking water, industrial and domestic sewage, pasture and agricultural runoff. Among the chemical pollutants, organic dyes due to toxic nature, are one of the major contaminants of industrial wastewater. Adequate sanitation services and drinking quality water would eliminate 200 million cases of diarrhea, which results in 2.1 million less deaths caused by diarrheal disease due to E. coli each year. Nanotechnology is an excellent platform as compared to conventional treatment methods of water treatment and remediation from microorganisms and organic dyes. In the current study, toxicity and carcinogenicity of the organic dyes have been studied as well as the remediation/inactivation of dyes and microorganism has been discussed. Remediation by biological, physical and chemical methods has been reviewed critically. A physical process like adsorption is cost-effective, but can’t degrade dyes. Biological methods were considered to be ecofriendly and cost-effective. Microbiological degradation of dyes is cost-effective, eco-friendly and alternative to the chemical reduction. Besides, certain enzymes especially horseradish peroxidase are used as versatile catalysts in a number of industrial processes. Moreover, this document has been prepared by gathering recent research works related to the dyes and microbial pollution elimination from water sources by using heterogeneous photocatalysts, metal nanoparticles catalysts, metal oxides and enzymes.

Hydrogels are three-dimensional, cross-linked, and supramolecular networks that can absorb significant volumes of water. Hydrogels are one of the most promising biomaterials in the biological and biomedical fields, thanks to their hydrophilic properties, biocompatibility, and wide therapeutic potential. Owing to their nontoxic nature and safe use, they are widely accepted for various biomedical applications such as wound dressing, controlled drug delivery, bone regeneration, tissue engineering, biosensors, and artificial contact lenses. Herein, this review comprises different synthetic strategies for hydrogels and their chemical/physical characteristics, and various analytical, optical, and spectroscopic tools for their characterization are discussed. A range of synthetic approaches is also covered for the synthesis and design of hydrogels. It will also cover biomedical applications such as bone regeneration, tissue engineering, and drug delivery. This review addressed the fundamental, general, and applied features of hydrogels in order to facilitate undergraduates, graduates, biomedical students, and researchers in a variety of domains.

Substances at nanoscale commonly known as “nanomaterials” have always grabbed the attention of the researchers for hundreds of years. Among these different types of nanomaterials, magnetic nanomaterials have been the focus of overwhelming attention during the last two decades as evidenced by an extraordinary increase in number of research papers. Iron oxide magnetic nanoparticles have occupied a vital position in imaging phenomena; as drug vehicles, controlled/sustained release phenomena and hyperthermia; atherosclerosis diagnosis; prostate cancer. In fact, these are wonderful “theranostic” agents with some are under clinical trials for human use. In this review, we have attempted to highlight the advances taking place in the field of magnetic nanoparticles as theranostic agents. Extensive progress has been made in the two most important parameters viz. control over size and shape which decide the importance of iron oxide magnetic nanoparticles by developing suitable procedures like precipitation, co-precipitation, thermal decomposition, hydrothermal synthesis, microemulsion synthesis and plant mediated synthesis. After suitable synthetic route, workers encounter the most daunting task linked with the materials at nanoscale i.e. the protection against corrosion. Only properly protected iron oxide magnetic nanoparticles can be further connected to different functional systems to make building blocks for application in catalysis, biology and medicines. Finally, iron oxide magnetic nanoparticles play a key role in imaging applications for diagnostic purposes, drug delivery vehicles and above all the combined effect of previous two phenomena “theranostics”. With all the potential uses, toxicity of the of iron oxide magnetic nanoparticles has also been discussed. In the end, attention has been drawn to address the future of research trends of iron oxide magnetic nanoparticles in theranostics.

Mesoporous Co₃O₄ has been prepared using porous silica as a hard template via a nanocasting route and its electrocatalytic properties were investigated as an oxygen evolution catalyst for the electrolysis of water. The ordered mesostructured Co₃O₄ shows dramatically increased catalytic activity compared to that of bulk Co₃O₄. Enhanced catalytic activity was achieved with high porosity and surface area, and the water oxidation overpotential (η) of the ordered mesoporous Co₃O₄ decreases significantly as the surface area increases. The mesoporous Co₃O₄ also shows excellent structural stability in alkaline media. After 100 min under 0.8 V (versus Ag/AgCl) applied bias, the sample maintains the ordered mesoporous structure with little deactivation of the catalytic properties.