@article { ISI:000293756800010, title = {Facile synthesis of unusual glycosyl carbamates and amino acid glycosides from propargyl 1,2-orthoesters as glycosyl donors}, journal = {Organic \& Biomolecular Chemistry}, volume = {9}, number = {17}, year = {2011}, month = {MAR}, pages = {5951-5959}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Propargyl 1,2-O-orthoesters are exploited for the synthesis of 1,2-trans O-glycosides of protected amino acids. N-Fmoc- and N-Cbz protected serine/threonine - benzyl/methyl esters reacted well with glucosyl-, galactosyl-, mannosyl- and lactosyl- derived propargyl 1,2-orthoesters affording respective 1,2-trans glycosides in good yields under AuBr(3)/4 angstrom MS Powder/CH(2)Cl(2)/rt. t-Boc serine derivative gave serine 1,2-orthoester and glycosyl carbamate. Optimized conditions enabled preparation of new glycosyl carbamates from N-Boc protected amines in a single step using gold catalysts and propargyl 1,2-orthoesters in excellent yields.

}, issn = {1477-0520}, doi = {10.1039/c1ob05056g}, author = {Shaikh, Ashif Y. and Sureshkumar, Gopalsamy and Pati, Debasish and Sen Gupta, Sayam and Hotha, Srinivas} } @article { ISI:000293464100028, title = {Fe(III) complex of biuret-amide based macrocyclic ligand as peroxidase enzyme mimic}, journal = {Chemical Communications}, volume = {47}, number = {28}, year = {2011}, month = {JUN}, pages = {8016-8018}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

An Fe(III) complex of a biuret-amide based macrocyclic ligand that exhibits both excellent reactivity for the activation of H(2)O(2) and high stability, especially at low pH and high ionic strength, is reported.

}, issn = {1359-7345}, doi = {10.1039/c1cc12686e}, author = {Panda, Chakadola and Ghosh, Munmun and Panda, Tamas and Banerjee, Rahul and Sen Gupta, Sayam} } @article { ISI:000294701600022, title = {Functionalization of SBA-15 mesoporous materials using {\textquoteleft}{\textquoteleft}thiol-ene click{\textquoteright}{\textquoteright} michael addition reaction}, journal = {Journal of Physical Chemistry C }, volume = {115}, number = {36}, year = {2011}, month = {SEP}, pages = {17774-17781}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Methacrylate-labeled SBA-15 has been successfully synthesized from calcined SBA-15 and commercially available 3-trichlorosilyl propylmethacrylate. This material undergoes efficient thiol-ene {\textquoteleft}{\textquoteleft}click reaction{\textquoteright}{\textquoteright} with a variety of both thiol and disulfide-containing substrates in aqueous and organic media. The products were thoroughly characterized by a variety of analytical techniques including multinuclear (C-13, Si-29) solid-state NMR, TG-DTA, and nitrogen adsorption desorption studies. Disulfide-containing substrates in which the TCEP-mediated reduction of the disulfide bond and its subsequent addition to the methacrylate group anchored in SBA-15 in one-pot were used to synthesize a silica-protein hybrid material composed of biotin-labeled SBA-15 and streptavidin. Electrochemically active material was synthesized from the reaction of ferrocene-containing thiol and the methacrylate-labeled SBA-15. The ease of synthesis for the methacrylate-labeled SBA-15 material together with its ability to undergo efficient chemoselective thiol-ene reaction would make it a very attractive platform for the development of covalently anchored enzymes and sensors.

}, issn = {1932-7447}, doi = {10.1021/jp2056442}, author = {Kumari, Sushma and Malvi, Bharmana and Ganai, Anal Kumar and Pillai, Vijayamohanan K. and Sen Gupta, Sayam} } @article { ISI:000341122000068, title = {Fe-TAML encapsulated inside mesoporous silica nanoparticles as peroxidase mimic: femtomolar protein detection}, journal = {ACS Applied Materials \& Interfaces}, volume = {6}, number = {16}, year = {2014}, month = {AUG}, pages = {13866-13873}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Peroxidase, such as horseradish peroxidase (HRP), conjugated to antibodies are routinely used for the detection of proteins via an ELISA type assay in which a critical step is the catalytic signal amplification by the enzyme to generate a detectable signal. Synthesis of functional mimics of peroxidase enzyme that display catalytic activity which far exceeds the native enzyme is extremely important for the precise and accurate determination of very low quantities of proteins (fM and lower) that is necessary for early clinical diagnosis. Despite great advancements, analyzing proteins of very low abundance colorimetrically, a method that is most sought after since it requires no equipment for the analysis, still faces great challenges. Most reported HRP mimics that show catalytic activity greater than native enzyme (similar to 40-fold) are based on metal/metal-oxide nanoparticles such as Fe3O4. In this paper, we describe a second generation hybrid material developed by us in which approximately 25 000 alkyne tagged biuret modified Fetetraamido macrocyclic ligand (Fe-TAML), a very powerful small molecule synthetic HRP mimic, was covalently attached inside a 40 nm mesoporous silica nanopartide (MSN). Biuret-modified Fe-TAMLs represent one of the best small molecule functional mimics of the enzyme HRP with reaction rates in water close to the native enzyme and operational stability (pH, ionic strength) far exceeding the natural enzyme. The catalytic activity of this hybrid material is around 1000-fold higher than that of natural HRP and 100-fold higher than that of most metal/metal oxide nanoparticle based HRP mimics reported to date. We also show that using antibody conjugates of this hybrid material it is possible to detect and, most importantly, quantify femtomolar quantities of proteins colorimetrically in an ELISA type assay. This represents at least 10-fold higher sensitivity than other colorimetric protein assays that have been reported using metal/metal oxide nanoparticles as HRP mimic. Using a human IgG expressing cell line, we were able to demonstrate that the protein of interest human IgG could be detected from a mixture of interfering proteins in our assay.

}, keywords = {colorimetrically, immuno assay, MSN, peroxidase mimic, signal amplification}, issn = {1944-8244}, doi = {10.1021/am503275g}, author = {Kumari, Sushma and Dhar, Basab B. and Panda, Chakadola and Meena, Abhishek and Sen Gupta, Sayam} } @article { ISI:000338980500002, title = {Formation of a room temperature stable Fe-V(O) complex: reactivity toward unactivated C-H bonds}, journal = {Journal of American Chemical Society}, volume = {136}, number = {27}, year = {2014}, month = {JUL}, pages = {9524-9527}, publisher = {AMER CHEMICAL SOC}, type = {Article}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

An Fe-V(O) complex has been synthesized from equimolar solutions of (Et4N)(2)[Fe-III(Cl)(biuretamide)] and mCPBA in CH3CN at room temperature. The Fe-V(O) complex has been characterized by UV-vis, EPR, Mossbauer, and HRMS and shown to be capable of oxidizing a series of alkanes having C-H bond dissociation energies ranging from 99.3 kcal mol(-1) (cyclohexane) to 84.5 kcal mori (cumene). Linearity in the Bell-Evans-Polayni graph and the finding of a large kinetic isotope effect suggest that hydrogen abstraction is engaged the rate-determining step.

}, issn = {0002-7863}, doi = {10.1021/ja412537m}, author = {Ghosh, Munmun and Singh, Kundan K. and Panda, Chakadola and Weitz, Andrew and Hendrich, Michael P. and Collins, Terrence J. and Dhar, Basab B. and Sen Gupta, Sayam} }