Papers by Tridib Kumar Sarma
ACS omega, Aug 2, 2019
Development of nanozymes, which are nanomaterials with intrinsic enzymatic properties, has emerge... more Development of nanozymes, which are nanomaterials with intrinsic enzymatic properties, has emerged as an appealing alternative to the natural enzymes with tremendous application potential from the chemical industry to biomedicine. The selfassembled growth of micrometer-sized oxide materials with controlled nonspherical shapes can be an important tool for enhancing activity as artificial enzymes, as the formation of these superstructures often results in high surface area with favorable impact on catalytic activity. Herein, the growth of rod-shaped Fe 3 O 4 microstructures via a one-pot microwavebased method and using a water-poly(ethylene glycol) mixture as a solvent is reported, without the involvement of external shape-directing agents. The precursor metal salt played a key role in the size, shape, and phase selective evolution of iron oxide micro/ nanomaterials. Whereas self-assembled microrod superstructures were obtained using Fe(NO 3 ) 3 as the metal salt precursor, use of FeCl 3 or Fe-acetate as precursors afforded hollow Fe 2 O 3 microparticles and Fe 3 O 4 nanoparticles, respectively. A graphitic layer was deposited on the Fe 3 O 4 surface, imparting a negative surface charge as a result of a high-temperature treatment of poly(ethylene glycol). The rod-shaped Fe 3 O 4 microcrystals show efficient peroxidase-mimicking activity toward 3,3,5,5′-tetramethylbenzidine and pyrogallol as peroxidase substrates with a Michaelis-Menten rate constant (K m ) value of 0.05 and 0.52 mM, respectively. The proficient enzyme mimicking behavior of these magnetic superstructures was further explored for the degradation of organic dyes that includes rhodamine B, methylene blue, and methyl orange with a rate constant (k) of 0.038, 0.011, and 0.007 min -1 respectively, using H 2 O 2 . This fast and simple method could help to develop a new pathway for differently shaped oxide nanoparticles in a sustainable and economical manner that can be harnessed as nanozymes for industrial as well as biological applications.
Graphene Oxide - Applications and Opportunities, 2018
Nanochemistry has evolved as an important part in catalysis for both academic as well as industri... more Nanochemistry has evolved as an important part in catalysis for both academic as well as industrial research. Traditional homogeneous catalytic systems have gained significant importance due to the molecular level analysis of their catalytic activity and the excellent homogeneity of the catalysts and the reactants. However, removal of the catalysts from the reaction mixture without product contamination requires tedious purification steps. With increasing ecological and economical demands towards sustainable chemical synthesis, the recovery and reuse of catalysts has been an important factor. In this drive, various heterogeneous catalytic systems including mesoporous materials, solid catalysts, organometallics, noble-metal nanoparticles, etc. have been developed for photochemical and electrochemical conversion, environmental remediation as well as catalyst for important chemical transformations. Carbon nanomaterial specially graphene oxide and carbon dots have received significant research importance due to their large scale availability, easy surface modification, non-toxicity and other surface properties. Here, we review the continuous progress in the development of graphene based materials and their catalytic activity in organic synthesis.
The Journal of organic chemistry, Jan 17, 2017
Herein, we report the fluorescent carbon dots as an effective and recyclable carbocatalyst for th... more Herein, we report the fluorescent carbon dots as an effective and recyclable carbocatalyst for the generation of carbon-heteroatom bond leading to quinazolinone derivatives and aza-Michael adducts under mild reaction conditions. The results establish this nanoscale form of carbon as an alternative carbocatalyst for important acid catalyzed organic transformations. The mild surface acidity of carbon dots imparted by -COOH functionality could effectively catalyze the formation of synthetically challenging spiro/glycoquinazolinones under the present reaction conditions.
New Journal of Chemistry, 2018
The interaction of Zn2+ ions with pure nucleobases guanine and cytosine under alkaline conditions... more The interaction of Zn2+ ions with pure nucleobases guanine and cytosine under alkaline conditions leads to the formation of nanoscale metal–organic nanofibers and nanoflowers with excellent photocatalytic activity for the degradation of organic pollutant dyes.
Metal-Organic Framework Composites - Volume I, 2019
Enzymes are a class of highly selective and efficient natural catalysts. The use of enzymes for c... more Enzymes are a class of highly selective and efficient natural catalysts. The use of enzymes for catalysis often requires them to be immobilized onto solid supports so that they can be efficiently recycled, the contamination due to presence of enzymes in the product can be minimized and their application in biomedicine can be explored. Various strategies for the use of metal-organic frameworks (MOFs) as host material for the encapsulation of enzymes have been discussed. Recent developments on the preparative strategies and applications of MOF encapsulated enzyme with special focus on catalysis are summarized in this chapter. The enhancement/retention of enzymatic activity of the composite material compared to free enzymes in denaturation conditions and advantages of encapsulation of the enzymes has been reviewed.
Carbon Dots as Nanodispersants for Multiwalled Carbon Nanotubes: Reduced Cytotoxicity and Metal Nanoparticle Functionalization
Langmuir, 2017
The colloidal stabilization of multiwalled carbon nanotubes (MWCNTs) in an aqueous medium through... more The colloidal stabilization of multiwalled carbon nanotubes (MWCNTs) in an aqueous medium through noncovalent interactions has potential benefits toward the practical use of this one-dimensional carbonaceous material for biomedical applications. Here, we report that fluorescent carbon nanodots can efficiently function as dispersing agents in the preparation of stable aqueous suspensions of CNTs at significant concentrations (0.5 mg/mL). The amphiphilic nature of carbon dots with a hydrophobic graphitic core could effectively interact with the CNT surface, whereas hydrophilic oxygenated functionalization on the C-dot surface provided excellent water dispersibility. The resultant CNT-C-dot composite showed significantly reduced cytotoxicity compared to that of unmodified or protein-coated CNTs, as demonstrated by cell viability and proliferation assays. Furthermore, the reducing capability of C-dots could be envisaged toward the formation of a catalytically active metal nanoparticle-CNT-C-dot composite without the addition of any external reducing or stabilizing agents that showed excellent catalytic activity toward the reduction of p-nitrophenol in the presence of NaBH4. Overall, the present work establishes C-dots as an efficient stabilizer for aqueous dispersions of CNTs, leading to an all-carbon nanocomposite that can be useful for different practical applications.
Journal of Materials Chemistry B, 2014
Biogenic synthesis of Au nanoparticles and Au nanoparticle–polyaniline composite could be accompl... more Biogenic synthesis of Au nanoparticles and Au nanoparticle–polyaniline composite could be accomplished taking advantage of the reducing and catalytic activity of glucose oxidase.
Nanoscale, 2015
Au@C-dot nanocomposite functions as a fluorescent turn-on sensor for the selective assay of bioth... more Au@C-dot nanocomposite functions as a fluorescent turn-on sensor for the selective assay of biothiols based on ligand exchange occurring on the Au nanoparticle surface and replacement of C-dots.
Nanoscale, 2015
Au@C-dot nanocomposite functions as a fluorescent turn-on sensor for the selective assay of bioth... more Au@C-dot nanocomposite functions as a fluorescent turn-on sensor for the selective assay of biothiols based on ligand exchange occurring on the Au nanoparticle surface and replacement of C-dots.
Dalton Transactions, 2013
Macromolecular Rapid Communications, 2010
High-density poly(ethylene glycol) (PEG)-coated iron-oxide-gold core-shell nanoparticles (AuIONs)... more High-density poly(ethylene glycol) (PEG)-coated iron-oxide-gold core-shell nanoparticles (AuIONs) were developed as T 2 -weighted magnetic resonance imaging (MRI) contrast agents for cancer imaging. The PEG-coated iron-oxide-gold core-shell nanoparticles (PEG-AuIONs) were approximately 25 nm in diameter with a narrow distribution. Biodistribution experiments in mice bearing a subcutaneous colon cancer model prepared with C26 murine colon adenocarcinoma cells showed high accumulation of the PEG-AuIONs within the tumor mass and low nonspecific accumulation in the liver and spleen, resulting in high specificity to solid tumors. T 2 -weighted MR images following intravenous injection of PEG-AuIONs showed selective negative enhancement of tumor tissue in an orthotopic pancreatic cancer model prepared with Mia-PaCa-2 human pancreatic adenocarcinoma cells. These results indicate that PEG-AuIONs are a promising MRI contrast agent for diagnosis of malignant tumors, including pancreatic cancer.
Uploads
Papers by Tridib Kumar Sarma