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Rohit Kumar Sharma

Other affiliations: University of Puerto Rico
Bio: Rohit Kumar Sharma is an academic researcher from University of Puerto Rico, Río Piedras. The author has contributed to research in topics: Apoptosis & Transferrin. The author has an hindex of 5, co-authored 8 publications receiving 80 citations. Previous affiliations of Rohit Kumar Sharma include University of Puerto Rico.

Papers
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Journal ArticleDOI
TL;DR: By closely examining the biological use of TiO2 and the influence of biomolecules on its stability and solubility, the reactivity of the material is reassessed in the presence and absence of UV energy.
Abstract: Titanium is one of the most abundant elements in the earth’s crust and while there are many examples of its bioactive properties and use by living organisms, there are few studies that have probed its biochemical reactivity in physiological environments. In the cosmetic industry, TiO2 nanoparticles are widely used. They are often incorporated in sunscreens as inorganic physical sun blockers, taking advantage of their semiconducting property, which facilitates absorbing ultraviolet (UV) radiation. Sunscreens are formulated to protect human skin from the redox activity of the TiO2 nanoparticles (NPs) and are mass-marketed as safe for people and the environment. By closely examining the biological use of TiO2 and the influence of biomolecules on its stability and solubility, we reassess the reactivity of the material in the presence and absence of UV energy. We also consider the alarming impact that TiO2 NP seepage into bodies of water can cause to the environment and aquatic life, and the effect that it can have on human skin and health, in general, especially if it penetrates into the human body and the bloodstream.

38 citations

Journal ArticleDOI
12 Apr 2018-PLOS ONE
TL;DR: The neo-conjugate developed has promise for future development to target cancers with enhanced transferrin receptor expression and maintained an IC50 value similar to the well known drug cisplatin in A549 cancer cells but also was nontoxic to the normal lung (MRC5) cells.
Abstract: One of the major drawbacks of many of the currently used cancer drugs are off-target effects. Targeted delivery is one method to minimize such unwanted and detrimental events. To actively target lung cancer cells, we have developed a conjugate of the apoptosis inducing protein cytochrome c with transferrin because the transferrin receptor is overexpressed by many rapidly dividing cancer cells. Cytochrome c and transferrin were cross-linked with a redox sensitive disulfide bond for the intra-cellular release of the protein upon endocytosis by the transferrin receptor. Confocal results demonstrated the cellular uptake of the cytochrome c-transferrin conjugate by transferrin receptor overexpressing A549 lung cancer cells. Localization studies further validated that this conjugate escaped the endosome. Additionally, an in vitro assay showed that the conjugate could induce apoptosis by activating caspase-3. The neo-conjugate not only maintained an IC50 value similar to the well known drug cisplatin (50 μM) in A549 cancer cells but also was nontoxic to the normal lung (MRC5) cells. Our neo-conjugate holds promise for future development to target cancers with enhanced transferrin receptor expression.

31 citations

Journal ArticleDOI
01 Sep 2019
TL;DR: In this paper, three formulations were employed in three different organic solvents (n-heptane, 1,4-dioxane, and t-butanol) to produce biodiesel using cooking oil (UCO) and brown grease (BG) in the transesterification reaction with ethanol and methanol.
Abstract: Inexpensive but resourceful sources of lipids, for example, used cooking oil (UCO) and brown grease (BG), which often contain large amounts of free fatty acids (FFA), are difficult to convert into biodiesel economically and in good yield. Candida rugosa lipase nanoparticles (cNP) were formed first and subsequently cross-linked nanoparticles (CLNP) were obtained by crosslinking of them. Alternatively, cNP were conjugated to magnetic nanoparticles (mNP) to achieve a cNP-mNP conjugate. All three formulations were employed in three different organic solvents (n-heptane, 1,4-dioxane, and t-butanol) to produce biodiesel using BG and UCO in the transesterification reaction with ethanol and methanol. The radii of nanoparticles (NP) were 5.5, 75, 100, 85 nm for mNP, cNP, CLNP, and cNP-mNP, respectively, as measured by scanning/transmission electron microscopy and dynamic light scattering. The catalytic efficiency (Kcat/KM) of cNP, CLNP, and cNP-mNP was increased ca. -25, -68, -176 folds in n-heptane and -35, -131, -262 folds in 1,4-dioxane compared to the lyophilized lipase in the model transesterification reaction of p-nitrophenyl palmitate (PNPP) with ethanol. In biodiesel formation, the best performance with 100% conversion of BG was achieved under optimum conditions with cNP-mNP, ethanol at a 1:3 molar ratio of lipid-to-alcohol, NP at a 1:0.1 weight ratio of lipid-to-enzyme, and water at a 1:0.04 weight ratio of enzyme-to-water at 30 oC for 35 h. The operational stability of the CLNP and cNP-mNP was sustained even after five consequent biodiesel batch conversions while 50% and 82% residual activity (storage stability) were retained after 40 d.

22 citations

Journal ArticleDOI
24 Dec 2018
TL;DR: A nanoparticulate Rhizopus arrhizus lipase formulation was developed to enhance its activity and to increase the conversion yield of lipids into fatty acid methyl esters (FAME), a.k.a., biodiesel.
Abstract: We developed a nanoparticulate Rhizopus arrhizus lipase formulation to enhance its activity and to increase the conversion yield of lipids into fatty acid methyl esters (FAME, a.k.a., biodiesel). More than 95% purity of the lipase was achieved in a two-step purification. Nanoparticle formulation was afforded by co-lyophilization of the lipase with methyl-β-cyclodextrin (MβCD), an established lyoprotectant. Scanning electron microscopy and dynamic light scattering measurements showed a size of 75–200 nm for the nanoparticles depending on the ratio of lipase-to-MβCD employed during co-lyophilization. Fourier transform infrared spectroscopic analysis by Gaussian curve fitting of the resolution-enhanced amide I region of lyophilized and nanoparticulate lipase indicated a more native-like secondary structure in the latter. A 98% substrate-to-FAME conversion was achieved in 10 h in n-hexane by lipase nanoparticles, whereas the crude and lyophilized enzyme showed 65 and 70% conversion in 18 h, respectively. In t...

10 citations

Journal ArticleDOI
TL;DR: E engineered graphene oxide in the nanocomposite form of iron oxide nanoparticles (IO)-graphene oxide (GO) with tunable core magnetism and magnetic resonance transverse relaxivity (r2) demonstrates the clear potential of magnetic graphene oxide for magnetic resonance imaging (MRI) applications.
Abstract: The engineering of materials with controlled magnetic properties by means other than a magnetic field is of great interest in nanotechnology. In this study, we report engineered magnetic graphene oxide (MGO) in the nanocomposite form of iron oxide nanoparticles (IO)-graphene oxide (GO) with tunable core magnetism and magnetic resonance transverse relaxivity (r2). These tunable properties are obtained by varying the IO content on GO. The MGO series exhibits r2 values analogous to those observed in conventional single core and cluster forms of IO in different size regimes—motional averaging regime (MAR), static dephasing regime (SDR), and echo-limiting regime (ELR) or slow motion regime (SMR). The maximum r2 of 162 ± 5.703 mM−1s−1 is attained for MGO with 28 weight percent (wt%) content of IO on GO and hydrodynamic diameter of 414 nm, which is associated with the SDR. These findings demonstrate the clear potential of magnetic graphene oxide for magnetic resonance imaging (MRI) applications.

9 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, a review of various methods of high FFAs-lipidic feedstocks pretreatment including acid esterification, steam stripping, nanocatalytic technology, biological conversion, glycerolysis and simultaneous in situ conversion is presented.

191 citations

Journal ArticleDOI
TL;DR: Progress in engineering the architecture and biological functions of peptide-based biomaterials —naturally derived, chemically synthesized and recombinant— with a focus on the molecular features that modulate their structure-function relationships for drug delivery are discussed.

132 citations

Journal ArticleDOI
TL;DR: An overview of the key role played by the cytochrome c-cardiolipin interaction in apoptosis is provided, which provides interesting perspectives for applications in clinical diagnostics that use the protein as a biomarker.

107 citations

Journal ArticleDOI
TL;DR: Current findings on the safety of titanium dioxide nanoparticles (TiO2 NPs) used as a food additive or a sunscreen compound are reviewed and systematized and perspectives and directions for further studies on the toxicity of TiO1 NPs are proposed.
Abstract: Titanium dioxide (TiO2) is a material of diverse applications commonly used as a food additive or cosmetic ingredient. Its prevalence in products of everyday use, especially in nanosize, raises concerns about safety. Current findings on the safety of titanium dioxide nanoparticles (TiO2 NPs) used as a food additive or a sunscreen compound are reviewed and systematized in this publication. Although some studies state that TiO2 NPs are not harmful to humans through ingestion or via dermal exposure, there is a considerable number of data that demonstrated their toxic effects in animal models. The final agreement on the safety of this nanomaterial has not yet been reached among researchers. There is also a lack of official, standardized guidelines for thorough characterization of TiO2 NPs in food and cosmetic products, provided by international authorities. Recent advances in the application of ‘green-synthesized’ TiO2 NPs, as well as comparative studies of the properties of ‘biogenic’ and ‘traditional’ nanoparticles, are presented. To conclude, perspectives and directions for further studies on the toxicity of TiO2 NPs are proposed.

106 citations