The discharge of untreated tannery wastewater containing biotoxic substances of heavy metals in the ecosystem is one of the most important environmental and health challenges in our society. Hence, there is a growing need for the development of novel, efficient, eco-friendly, and cost-effective approach for the remediation of inorganic metals (Cr, Hg, Cd, and Pb) released into the environment and to safeguard the ecosystem. In this regard, recent advances in microbes-base heavy metal have propelled bioremediation as a prospective alternative to conventional techniques. Heavy metals are nonbiodegradable and could be toxic to microbes. Several microorganisms have evolved to develop detoxification mechanisms to counter the toxic effects of these inorganic metals. This present review offers a critical evaluation of bioremediation capacity of microorganisms, especially in the context of environmental protection. Furthermore, this article discussed the biosorption capacity with respect to the use of bacteria, fungi, biofilm, algae, genetically engineered microbes, and immobilized microbial cell for the removal of heavy metals. The use of biofilm has showed synergetic effects with many fold increase in the removal of heavy metals as sustainable environmental technology in the near future.

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Toxicity and Bioremediation of Heavy Metals Contaminated Ecosystem from Tannery Wastewater: A Review

Gelatin is a promising material as scaffold with therapeutic and regenerative characteristics due to its chemical similarities to the extracellular matrix (ECM) in the native tissues, biocompatibility, biodegradability, low antigenicity, cost-effectiveness, abundance, and accessible functional groups that allow facile chemical modifications with other biomaterials or biomolecules. Despite the advantages of gelatin, poor mechanical properties, sensitivity to enzymatic degradation, high viscosity, and reduced solubility in concentrated aqueous media have limited its applications and encouraged the development of gelatin-based composite hydrogels. The drawbacks of gelatin may be surmounted by synergistically combining it with a wide range of polysaccharides. The addition of polysaccharides to gelatin is advantageous in mimicking the ECM, which largely contains proteoglycans or glycoproteins. Moreover, gelatin-polysaccharide biomaterials benefit from mechanical resilience, high stability, low thermal expansion, improved hydrophilicity, biocompatibility, antimicrobial and anti-inflammatory properties, and wound healing potential. Here, we discuss how combining gelatin and polysaccharides provides a promising approach for developing superior therapeutic biomaterials. We review gelatin-polysaccharides scaffolds and their applications in cell culture and tissue engineering, providing an outlook for the future of this family of biomaterials as advanced natural therapeutics.

Gelatin-polysaccharide composite scaffolds for 3D cell culture and tissue engineering: Towards natural therapeutics.

Metallic species mobilized and released into the environment by the technological activities of human tend to persist indefinitely, circulating and eventually accumulating throughout the food chain, thus posing a serious threat to the environment, animals and humans. It is essential to realize that the metal is only removed from solution when it is appropriately immobilized. Apart from slow natural process of metal mineralization, ultimate removal is attained only when the metal becomes concentrated to the point that it can be either returned to the process or resold. The metallic pollutants can be sorbed by biosorbant material. The mechanism of biosorption is complex, mainly ion exchange, chelation, adsorption by physical forces, entrapment in inter and intrafibrilliar capillaries and spaces of the structural polysaccharide network as a result of the concentration gradient and diffusion through cell walls and membranes. Due to the extensive research and significant economic benefits of biosorption, some new biosorbant resources are poised for commercial exploitation.

Biosorption of Heavy Metals: A Review

Water is polluted by various harmful toxic chemical substances, precisely heavy metals, dyes, and pathogens, which have a disastrous effect on the ecological balance of human as well as animal life. Therefore, there is an urgent need for new technologies to remove these noxious pollutants from water/wastewater. Adsorption is one of the predominant method among all the reported techniques for the removal of heavy metals. Nano technological applications in this direction, i.e. development of nano-sized materials, tubes and composites as adsorbents have engrossed rapidly. In this review, current trends of nanomaterials for the removal of heavy metals from water/wastewater are concisely discussed. Applications of different engineered nanomaterials based on iron oxide, titanium oxide, silica, carbon, graphene oxide, and bio-nanomaterials are largely focused. Different strategies and surface modifiers have been used for the surface modifications/functionalization of these nanomaterials, which in turn enhanced the adsorption capacities by many folds. Toxic effects of various nanoparticles are also discussed, and various strategies like embedding, encapsulation to prevent their releases into the environment are deliberated. In addition, the selection of NPs for the removal of various metals has also been discussed in the respective sections. This review will provide an insight into the latest researches, which is expected to offer worthy implications to academicians and industry professionals working in environmental engineering domain for the removal of heavy metals from water/wastewater.

Engineered nanomaterials and their surface functionalization for the removal of heavy metals: A review

Nano-biocomposite scaffolds of chitosan, carboxymethyl cellulose and silver nanoparticle modified cellulose nanowhiskers for bone tissue engineering applications

Remediation of heavy metal-contaminated soils has been drawing our attention toward it for quite some time now and a need for developing new methods toward reclamation has come up as the need of the hour. Conventional methods of heavy metal-contaminated soil remediation have been in use for decades and have shown great results, but they have their own setbacks. The chemical and physical techniques when used singularly generally generate by-products (toxic sludge or pollutants) and are not cost-effective, while the biological process is very slow and time-consuming. Hence to overcome them, an amalgamation of two or more techniques is being used. In view of the facts, new methods of biosorption, nanoremediation as well as microbial fuel cell techniques have been developed, which utilize the metabolic activities of microorganisms for bioremediation purpose. These are cost-effective and efficient methods of remediation, which are now becoming an integral part of all environmental and bioresource technology. In this contribution, we have highlighted various augmentations in physical, chemical, and biological methods for the remediation of heavy metal-contaminated soils, weighing up their pros and cons. Further, we have discussed the amalgamation of the above techniques such as physiochemical and physiobiological methods with recent literature for the removal of heavy metals from the contaminated soils. These combinations have showed synergetic effects with a many fold increase in removal efficiency of heavy metals along with economic feasibility.

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Recent advances in conventional and contemporary methods for remediation of heavy metal-contaminated soils

This study describes the preparation of composite film using chitosan (CS) and polyvinylpyrrolidone (PVP) with incorporated cellulose nanowhiskers (CNWs) for drug delivery application. CNWs were prepared by acid hydrolysis of cellulose with sulfuric acid. Field emission scanning electron microscopy studies revealed nanofibrous morphology of CNWs with 20-30 nm diameter and 200-250 nm in length. X-ray powder diffraction analysis confirmed highly crystalline nature of CNWs with 92.81% crystallinity. Incorporation of CNWs enhanced the thermal and mechanical properties of films. Fourier transform infrared spectroscopy data showed physical interactions between polymer-polymer and polymer-drug. Films prepared with CNWs showed improved swelling behavior which resulted in sustained drug release from polymeric matrix. In vitro curcumin release data were fitted with two-step release model; Step 1 as desorption from the outer surface of the film, and Step 2 as diffusion from within the film and subsequent desorption. The release kinetics confirmed biphasic release profile with different release rates along with diffusion controlled curcumin release. Prepared films showed high biocompatibility with excellent antibacterial activities. Overall, the performed studies confirmed CS-PVP-CNWs based release system can as a potential candidate for wound dressing applications with sustained drug release. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2391-2404, 2017.

Fabrication and characterization of chitosan, polyvinylpyrrolidone, and cellulose nanowhiskers nanocomposite films for wound healing drug delivery application.

A novel adsorbent, iron oxide nanoparticles and A. fabrum strains encapsulated in calcium alginate, was prepared for the removal of lead. The crude oil degrading strain was isolated from core samples from Assam Oilfield, India and was able to resist lead up to 2900 mg L−1 thus proving to be a highly lead tolerant. Chemically synthesized Fe3O4 magnetic nanoparticles (10–20 nm) by co-precipitation method were characterized using various techniques. Vibrating Sample Magnetometer (VSM) showed saturation magnetization of 46.6 emu g−1, indicating superparamagnetic nature of synthesized MNPs, which will aid in separation of biosorbent after adsorption. Lead removal was studied using the bio-sorbent synthesized by immobilizing biomass and MNPs in calcium alginate beads at 200 rpm and 37 °C, and the adsorption capacity was found to be maximum at pH 5.5. Adsorption kinetics was examined using pseudo first order, pseudo second order and intra-particle diffusion (IPD) models. The kinetic data agreed to pseudo second order model and the adsorption rate constant (k2) decreased with an increase in initial concentrations. Initial adsorption rate (h, mg g−1 min−1) was found to be kinetically controlled and the function of initial Pb(II) concentration. The IPD was found rate limiting step after 60 min of adsorption. Adsorption data were fitted well to Langmuir isotherm. The maximum adsorption capacity of the synthesized bio-sorbent was found to be 197.02 mg g−1. Thermodynamic studies suggested that the adsorption process was spontaneous and endothermic in nature. Biosorbent showed good adsorption capacity even after repeatedly using them for five consecutive cycles without compromising much with adsorption efficiency.

A novel bio-sorbent comprising encapsulated Agrobacterium fabrum (SLAJ731) and iron oxide nanoparticles for removal of crude oil co-contaminant, lead Pb(II)

Background & objective Over the last two decades, Alzheimer disease (AD) associated research has accomplished an overwhelming momentum, as it is one of the major current healthcare issues in the developed world. AD is characterized by the presence of Aβ mediated extracellular amyloid fibrils and tau-mediated intracellular neurofibrillar tangles and reports have highlighted their subsequent effects on neuronal synaptic activity, antioxidant response and recently explored mitochondrial dysfunction. Additionally, recent reports have demonstrated the mitochondrial dysfunction and associated physiological as well as cellular alterations triggered by fibrillar structures inside the brain tissue. Accumulated evidence indicated that mitochondrial dysfunction also plays a detrimental role in AD pathogenesis and reduction in mitochondrial dysfunction may provide an additional beneficial effect in AD patients. Currently available drugs are ineffective in disease progression and more symptomatic while mechanism oriented drug explorations have been intensively investigated. Therefore, search for effective therapeutic approaches in Alzheimer disease has directed the ongoing research more towards specific biomarker selection, physicochemical properties of drugs and its subsequent interaction with target molecules. Conclusion In present review, we have comprised an overview of the therapeutic advancement in Alzheimer disease with a prevalent hypothesis and current ongoing putative therapeutic approaches to provide recent insights in AD pathogenesis.

Therapeutic Advancement in Alzheimer Disease: New Hopes on the Horizon?

Plants produce biologically active metabolites that have been utilised to cure a variety of severe and persistent illnesses. There is a possibility that understanding how these bioactive molecules work would allow researchers to come up with better treatments for diseases including malignancy, cardiac disease, and neurological disorders. A triterpene called Ursolic acid (UA) is a pentacyclic prevalent triterpenoids found in fruits, leaves, herbs and blooms. The biological and chemical aspects of ursolic acid, their presence, plant sources & biosynthesis, traditional and newer technology of extraction are discussed in this review. Due to its biological function in the creation of new therapeutic techniques, UA is a feasible option for the evolution and medical management of a wide range of medical conditions, which include cancer and other life threatening diseases. Despite this, the substance's poor solubility in aquatic environments makes it unsuitable for medicinal purposes. This hurdle was resolved via a lot of different ways. The inclusion of UA into various pharmaceutical delivery approaches was found to be quite effective in this investigation. This review also describes the properties of UA and its pharmacokinetics, therapeutic applications of UA for cancer, inflammatory diseases, antidiabetic, immunomodulatory, hepatoprotective, cardiovascular diseases, and antimicrobials. Some of the recent findings related to novel nano sized carrier as delivery system for UA and the patents related to the applications of Ursolic acid and its various derivatives are covered in this review article. The analytical study of UA, OA and other phytoconstituents by UV, HPLC, HPTLC, GC are discussed in this article. In future; UA could be explored for in-vivo study using various animal models and regulatory status about UA needs to be explored. This article is protected by copyright. All rights reserved.

Sakshi Tiwari

Papers

Recent advances in conventional and contemporary methods for remediation of heavy metal-contaminated soils

Fabrication and characterization of chitosan, polyvinylpyrrolidone, and cellulose nanowhiskers nanocomposite films for wound healing drug delivery application.

A novel bio-sorbent comprising encapsulated Agrobacterium fabrum (SLAJ731) and iron oxide nanoparticles for removal of crude oil co-contaminant, lead Pb(II)

Therapeutic Advancement in Alzheimer Disease: New Hopes on the Horizon?

Therapeutic potential and novel formulations of Ursolic Acid and its Derivatives: An updated review.