Rajender S Varma

Rajender S Varma
United States Environmental Protection Agency | US EPA · Center for Environmental Solutions and Emergency Response

PhD

About

1,006
Publications
254,722
Reads
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46,424
Citations
Introduction
(H-Index 122, Highly Cited Researchers 2016,18, 19, 20, 21) Strong supporter of green and sustainable strategies as applied to chemical discipline; ~840 Papers, 57,400 citations.
Additional affiliations
August 2014 - present
Palacký University Olomouc
Position
  • Visiting scientist
Description
  • Visiting scientist at the Regional Center of Advanced Technologies and Materials
June 1999 - September 2020
United States Environmental Protection Agency
Position
  • Senior Researcher
Description
  • 48 years of multi-disciplinary research experience in development of Environmentally Benign Synthetic Methods, Greener Synthesis of Nanomaterials and Nanocomposites and their Applications in Catalysis and Sustainable Remediation of Hazardous Pollutants.
June 1999 - October 2019
United States Environmental Protection Agency
Position
  • Senior Researcher
Education
May 1973 - June 1976
University of Delhi
Field of study
  • Organic (Natural Products) Chemistry

Publications

Publications (1,006)
Article
Full-text available
Metal-organic frameworks (MOFs) endowed with unique structural features, namely permanent porosity, high surface area, tunable pore size, and potential applications in diverse domains, have garnered immense attention in recent decades. The availability of large numbers of organic linkers, metal nodes, and multiple synthetic tactics has broadened th...
Article
The present work demonstrates a systematic study of pore size and specific surface area (SSA) of biomass-derived carbon and the choice of electrolyte concentrations affecting charge-storage mechanism (surface controlled and diffusion controlled) and electrochemical behaviour. Porous nanocarbons derived from Caesalpinia Sappan pods were synthesized...
Article
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1H-Indole-3-carbaldehyde and related members of the indole family are ideal precursors for the synthesis of active molecules. 1H-Indole-3-carbaldehyde and its derivatives are essential and efficient chemical precursors for generating biologically active structures. Multicomponent reactions (MCRs) offer access to complex molecules. This review highl...
Article
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Synthesis of bi-functional covalent organic polymers in two distinctive morphologies has been accomplished by simply switching the solvent from DMF to DMSO when 1,3,5-tribenzenecarboxyldehyde and 2,5-diaminobenzene sulfonic acid were reacted via Schiff base condensation reaction to afford covalent organic polymers (COPs) encompassing flower (F-COP...
Article
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Beta (β)-thalassemia is a group of human inherited abnormalities caused by various molecular defects, which involves a decrease or cessation in the balanced synthesis of the β-globin chains in hemoglobin structure. Traditional treatment for β-thalassemia major is allogeneic bone marrow transplantation (BMT) from a completely matched donor. The limi...
Article
The requirement of green and sustainable materials to prepare heterogeneous catalysts has intensified for practical reasons over the past few decades. Carbohydrates are possibly the most plentiful and renewable organic materials in nature with inimitable physiochemical properties, plausible low-cost and large-scale production, and sustainability fe...
Article
Heavy metal removal using genetically engineered organisms (GEOs) offer more cost and energy-efficient, safer, greener, and environmentally-friendly opportunities as opposed to conventional strategies requiring hazardous or toxic chemicals, complex processes, and high pressure/temperature. Additionally, GEOs exhibited superior potentials for biosyn...
Article
In the biomedical field, stimuli-responsive systems comprising smart nanoplatforms based on metal–organic frameworks (MOFs) have garnered immense attention in view of their high surface area, biocompatibility, facile synthesis, tunable structural features, adjustable pore size, and highly versatile composition. Interestingly, stimuli-responsive MOF...
Article
MXenes and their related nanocomposites with superior physicochemical properties such as high surface area, ease of synthesis and functionalization, high drug loading capacity, collective therapy potentials, pH-triggered drug release behavior,...
Article
Liposomes mainly comprise an aqueous core surrounded by a lipid bilayer, akin to cellular membranes. The encapsulation, loading, and release properties of therapeutic agents in both, the core and lipid bilayer can be prominently affected by the preparative processes for liposome which include hydration of lipid thin films, detergent removal, solven...
Article
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Supercapacitors (SCs) are highly promising electrochemical energy conversion and storage devices. SCs display an outstanding power performance, excellent reversibility, long-term stability, simple operation, and high feasibility for integration into electronic devices, including consumer electronics, memory backup systems, and industrial power and...
Article
Scientists have always been inspired by nature to design complex nanostructures and architectures with special features and functions. Latest among these is the construction of bioinspired MXenes and MXene-based structures...
Article
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Carbon nanotubes (CNTs) with attractive physicochemical characteristics such as high surface area, mechanical strength, functionality, and electrical/thermal conductivity have been widely studied in different fields of science. However, the preparation...
Article
Significant upsurge in animal by-products such as skin, bones, wool, hides, feathers, and fats has become a global challenge and, if not properly disposed of, can spread contamination and viral diseases. Animal by-products are rich in proteins, which can be used as nutritional, pharmacologically functional ingredients, and biomedical materials. The...
Article
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Exosomes, ranging in size from 30 to 150 nm as identified initially via electron microscopy in 1946, are one of the extracellular vesicles (EVs) produced by many cells and have been the subject of many studies; initially, they were considered as cell wastes with the belief that cells produced exosomes to maintain homeostasis. Nowadays, it has been...
Article
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Bioengineered nanoparticles display unique characteristics at the cellular, atomic, and molecular levels with their geometric shapes dictating suitable actions and use. In the present study, bioengineered and bio-compatible silver nanoparticles (AgNPs) were obtained from Thalictrum foliolosum leaf extract which served as a capping and reducing agen...
Article
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The use of a cheap and effective adsorption approach based on biomass-activated carbon (AC) to remediate heavy metal contamination is clearly desirable for developing countries that are economically disadvantaged yet have abundant biomass. Therefore, this review provides an update of recent works utilizing biomass waste-AC to adsorb commonly-encoun...
Article
Design and development of new materials and their hybrids are key to addressing current energy issues. Thanks to their tunable textural and physiochemical properties, metal–organic frameworks (MOFs) show great potential toward gas sorption, catalysis, sensing, and electrochemical energy applications. Nevertheless, practical applications of MOFs hav...
Article
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Nanosponges have shown promising capabilities for efficient removal of organic/inorganic pollutants from water based on absorption/adsorption and disinfection processes. The application of nanosponges (especially cyclodextrin-based nanosponges) can be considered a cost-effective strategy with minimal energy and time requirements in comparison to ot...
Article
The release of pharmaceuticals into the environment induces adverse effects on the metabolism of humans and other living species, calling for advanced remediation methods. Conventional removal methods are often non-selective and cause secondary contamination. These issues may be partly solved by the use of recently-developped adsorbents such as mol...
Article
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MXene quantum dots (QDs), with their unique structural, optical, magnetic, and electronic characteristics, are promising contenders for various pharmaceutical and biomedical appliances including biological sensing/imaging, cancer diagnosis/therapy, regenerative medicine, tissue engineering, delivery of drugs/genes, and analytical biochemistry. Alth...
Article
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Plants encompass numerous phytochemicals like flavonoids, alkaloids, tannins, saponins, and other metabolites that have a major impact on the generation of nanomaterials with chief implications in current therapeutic methods for a variety of diseases including cancers; herbal extracts serve as potential means for the generation of nanomaterial via...
Article
Background 2-Hydroxy-1,4-Naphthoquinone (HNQ; Lawsone) is one of the most useful and the simplest naturally occurring naphthoquinones and have stimulated resurgence of interest in the past decades due to their wide range of pharmacological activities. Introduction and method This activity has led to unusually large emphasis being placed on the des...
Article
The efficiency of pollutant rejection (PR, %) and water purification of the zeolite membranes is highly dependent on their topology, i.e., porosity and chemical composition. Nevertheless, mechanisms controlling such a physicochemical phenomenon have been limitedly discussed. Herein, we provide insights into the physics and dynamics of water purific...
Article
With the world developing exponentially every day, the collateral damage to air is incessant. There are many methods to purify the air but using carbon nanotubes (CNTs) as adsorbents remains one of the most efficient and reliable methods, due to their high maximum adsorption capacity which renders them extremely useful for removing pollutants from...
Article
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Liver performs number of critical physiological functions in human system. Intoxication of liver leads to accumulation of free radicals that eventually cause damage, fibrosis, cirrhosis and cancer. Carbon tetrachloride (CCl 4 ) belongs to hepatotoxin is converted to a highly reactive free radical by cytochrome P450 enzymes that causes liver damage....
Article
The release of pharmaceuticals and their metabolites into the environment has garnered much attention amidst societies and the scientific community because they induce detrimental effects on metabolic bioprocesses in humans and other living beings. Effective and efficient removal of these noxious chemical species before they enter the food chain is...
Article
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A novel polysaccharide structure (PS-T80) was collected from Ophiocordyceps sobolifera biomass and characterized via a combination of chemical and spectral analyses. Employing high-performance gel permeation chromatography (HPGPC), the average molecular weight is proven to be 7.4 × 104 Da. Furthermore, a sugar composition analysis of the obtained p...
Article
Advanced nanotechnology is an enormously growing area due to its massive scope of applications for diverse domains of applied science and engineering. Numerous types of synthetic procedures are utilized for the creation of nanoparticles (NPs) due to their myriad application scenarios. However, known conventional physical and chemical strategies hav...
Article
Electrochemical conversion of CO2 to fuels and chemicals as a sustainable solution for waste transformation has garnered tremendous interest to combat the fervent issue of the prevailing high atmospheric CO2 concentration while contributing to the generation of sustainable energy. Monometallic palladium (Pd) has been shown promising in electrochemi...
Article
Biosensors are gaining interest in biomedical and environmental sciences. In particular, graphene-based biosensors are promising due to the unique properties of graphene. Here we review the synthesis, characterization, and applications of graphene in enzymatic sensors, immunosensors, DNA sensors, and wearable sensors. Graphene displays advantages s...
Article
Metal-organic frameworks (MOFs) biocompatible systems can host enzymes/bacteria/viruses. Herein we synthesized a series of fatty acid amide hydrolase (FAAH)-decorated UiO-66-NH2 based on Citrus tangerine leaf extract for drug delivery and biosensor applications. Five chemically manipulated FAAH-like benzamides were localized on the UiO-66-NH2 surfa...
Article
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Polymeric nanocomposites have been outstanding functional materials and have garnered immense attention as sustainable materials to address multi-disciplinary problems. MXenes have emerged as a newer class of 2D materials that produce metallic conductivity upon interaction with hydrophilic species, and their delamination affords monolayer nanoplate...
Article
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Cancer is one of the most critical human challenges which endangers many people's lives every year with enormous direct and indirect costs worldwide. Unfortunately, despite many advanced treatments used in cancer clinics today, the treatments are deficiently encumbered with many side effects often encountered by clinicians while deploying general m...
Article
Magnetic resonance imaging (MRI) is an effectual imaging technique for medical diagnosis, its non-invasive nature being a noteworthy attribute, in which magnetic contrast agents are employed to improve sensitivity and accuracy. Graphene exhibits excellent mechanical and physicochemical properties, and notable biocompatibility. In the quest for supe...
Article
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Graphene-based materials have shown immense pertinence for sensing/ imaging, gene/drug delivery, cancer therapy/diagnosis, and tissue engineering/ regenerative medicine. Indeed, the large surface area, ease of functionalization, high drug loading capacity, and reactive oxygen species induction potentials have rendered graphene-(G-) and graphene oxi...
Article
Ionic liquids (ILs), are the organic salts and have been referred to as greener solvent, oftentimes also termed as designer solvents. They are separated into classes namely room temperature ILs (RTILs), task-specific ILs (TSILs), polyionic liquids (PLILs), and supported ILs, among others. ILs are used as solvents because of their low vapour pressur...
Chapter
The progression of conducting polymers has been prolific in recent years due to the extraordinary progress achieved by these materials. The types of preparative methods for conducting polymers and their nanocomposites as well as factors such as temperature, pH, the concentration of monomers, and oxidants can affect the polymers’ shape and physical-...
Chapter
Conducting polymers have been the focus of increased research in numerous fields due to their physicochemical, mechanical, and biological properties. This is especially true for their electrical conductivity because of the ease with which electrons pass along and between the polymer backbones. Dopants play a significant role in improving physicoche...
Article
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The utilization of renewable and abundant agricultural waste such as Pomegranate (Punica granatum L.) peel extract has been developed wherein a simple extraction of dried peel in water offered a natural sensor; ensuing yellowish solution comprising phenolic compounds reacted explicitly to detect Fe⁺³ and I⁻ solutions by naked-eye. The UV–Vis absorp...
Preprint
Today, according to the progression and prevalence of cancer, efforts to discover new compounds to suppress the tumor and associated with less toxicity. Metal oxide nanoparticles have wide applications in biology and biomedicine due to their unique physical and chemical properties. They have great potential in the treatment of cancer, tumor targeti...
Article
The present study describes the enhanced photodegradation of organic pollutant dyes, congo red (CR) and rhodamine B (RhB) dyes under visible light irradiation. AgIO4 nanorods decorated on Bi2S3 nanoflakes in various proportions were synthesized via sono-chemical route wherein the deposition of varying amounts of AgIO4 on Bi2S3 plays a pivotal role...
Article
The application of quantum dots (QDs) for detecting and treating various types of coronaviruses is very promising, as their low toxicity and high surface performance make them superior among other nanomaterials; in conjugation with fluorescent probes they are promising semiconductor nanomaterials for the detection of various cellular procedures and...
Article
The present study highlighted the evaluation of visible light-driven catalytic efficiency of ZnFe2O4 decorated CeO2 nanocomposite (CeO2/ZnFe2O4 NCs) fabricated by chemical co-precipitation method for degradation of methylene blue (MB) dye. HRTEM, SEM, and SAED confirmed it to be spherical shaped with polycrystalline nature and chemical states being...
Preprint
Bioengineered nanoparticles display unique characteristics at the cellular, atomic, and molecular levels with their geometric shapes dictating suitable actions and use. In the present study, bioengineered and bio-compatible silver nanoparticles (AgNPs) were obtained from Thalictrum foliolosum DC leaf extract (TFLE) which served as a capping and red...
Article
Hybrid nanostructures and nanoarchitectures possess unique physicochemical properties such as high activity/functionality, enhanced physicochemical stability, and improved biocompatibility, which renders them suitable for various biomedical, pharmaceutical, environmental, and catalytic applications. In this context, core–shell nanophotocatalysts ha...
Article
Nanoencapsulation is a promising approach to enhance the therapeutic potential of a drug. Herein, three selected naphthoquinone (NTQ) derivatives, based on the IC50 value against Trypanosoma evansi, were encapsulated using gum damar as biocompatible and biodegradable natural gum via nanoprecipitation method. Nanoformulation of NTQs (NNTQs) was less...
Article
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Direct consideration for both, the catalytically active species and the host materials provides highly efficient strategies for the architecture design of nanostructured catalysts. The conventional wet chemical methods have limitations in achieving such unique layer-by-layer design possessing one body framework with many catalyst parts. Herein, an...
Article
The development of more efficient and greener catalytic strategies for the upgrading of biomass to value-added chemicals is crucial to achieve a more sustainable future. In recent years, cutting-edge single-atom...
Article
Nanoclays, 2D layered mineral silicates, have been used for centuries and have retained a prominent role in advancing materials science and technology. This class of materials has gained importance over other layered nanomaterials, owing to their abundance, low cost, diverse morphologies, and multiple chemical compositions, imparting them with exce...
Article
Non-lithium ion ( e.g. , Al ³⁺ , Ca ²⁺ , K ⁺ , Mg ²⁺ , Na ⁺ , and Zn ²⁺ ) batteries have emerged as a promising platform for next-generation energy storage systems.
Article
A wide variety of wastes are generated all around the world, from fruits, marines, plants, among several other sources. The remains of animal skeletal encompass many precious compounds, which undergo...
Article
A straightforward and mild protocol for photochemical in-situ selective hydrogenation is described via Al-H2O system as hydrogen donor and deploying Pd-g-C3N4 photocatalyst under visible light at ambient conditions. Water, a...
Article
Covalent organic frameworks (COFs) are porous and crystalline materials which are assembled by dynamic covalent bonds with two- or three-dimensional (2D or 3D) features. Unlike other polymers, COFs have significant...
Article
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The developmental rapidity of nanotechnology poses the higher risks of exposure to humans and the environment through manufactured nanomaterials. The multitude of biological interfaces, like DNA, proteins, membranes, and cell organelles, which come into contact with nanoparticles, are influenced by colloidal and dynamic force. Consequently, the ens...
Article
Covalent organic frameworks (COFs) are crystalline porous organic structures with two- or three-dimensional (2D or 3D) features and composed of building blocks being connected via covalent bonds. The manifold applications of COFs in optoelectronic devices, energy conversion and storage, adsorption, separation, sensing, organocatalysis, photocatalys...
Article
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Transition metal‐free sulfenylation of C−H bonds for C−S bond formation has recently emerged as sustainable protocols for the functionalisation of various molecules. Researchers have extensively developed such protocols for the construction of biologically relevant sulfur scaffolds. There has been a gradual shift from metal‐catalyzed to metal‐free...
Article
Ti3C2Tx MXene nanostructures have garnered attention for various catalytic applications due to their built-in electronic properties. Herein, we rationally design highly exfoliated two-dimensional Ti3C2Tx nanosheets (Tx= O, OH, and F)...
Article
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In this study, the acidity of urazole (pKa 5–6) was exploited to fabricate a hydrogel in two simple and scalable steps. Commercially available poly(hexamethylene)diisocyanate was used as a precursor to synthesize an urazole containing gel. The formation of urazole was confirmed by FT-IR and 1H-NMR spectroscopy. The hydrogel was characterized by mic...
Article
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Astaxanthin (AXT) is one of the most important fat soluble carotenoids that have abundant and diverse therapeutic applications namely in liver disease, cardiovascular disease, cancer treatment, protection of the nervous system, protection of the skin and eyes against UV radiation, and boosting the immune system. However, due to its intrinsic reacti...
Article
Non‐precious transition metal oxide nanomaterials offer numerous opportunities for cost‐effective various electrochemical applications. This review article features the design and advancement of such nanomaterials with unique features applied for the fabrication of electrochemical devices. Also, it discusses various new syntheses of TMOs NPs via mu...
Article
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Pollen grains and plant spores have emerged as innovative biomaterials for various applications such as drug/vaccine delivery, catalyst support, and the removal of heavy metals. The natural microcapsules comprising spore shells and pollen grain are designed for protecting the genetic materials of plants from exterior impairments. Two layers make up...
Article
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Efficient strategies to promote microvascularization in vascular tissue engineering, a central priority in regenerative medicine, are still scarce; nano- and micro-sized aggregates and spheres or beads harboring primitive microvascular beds are promising methods in vascular tissue engineering. Capillaries are the smallest type and in numerous blood...
Article
An efficient, solvent-free, and environmentally benign route via mechanochemical means is described for the synthesis of azo-linked 2-amino-4H-chromene derivatives. The four-component reaction of azo-linked salicylaldehydes, malononitrile, ethyl acetoacetate, and hydrazine hydrochloride has exploited recyclable magnetic nano-catalyst, Fe3O4@SiO2@KI...
Article
Infectious diseases caused by new or unknown bacteria and viruses, such as anthrax, cholera, tuberculosis and even COVID-19, are a major threat to humanity. Thus, the development of new synthetic compounds with efficient antimicrobial activity is a necessity. Herein, rationally designed novel multifunctional cationic alternating copolymers were dir...