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Engineering, Turkey

Polymer Research Center

Engineering, Turkey
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News Article | September 21, 2016
Site: www.nanotech-now.com

Abstract: It seems like almost every week another food product is being recalled because of contamination. One of the more common culprits is a pathogenic strain of E. coli. To help prevent illnesses caused by this bacteria in food or water, researchers have developed a new nanosensor to rapidly detect its presence. The study appears in the journal ACS Infectious Diseases. Millions of illnesses and more than 1,000 deaths every year in the U.S. are attributable to foodborne illness caused by known pathogens, according to the Centers for Disease Control and Prevention. Conventional methods to screen food to find sickness-causing microbes can take as long as 24 hours, which is often too slow to efficiently catch tainted products before they hit store shelves. Faster methods exist, but have limitations. Magnetic resonance, for example, can detect extremely low levels of bacteria, but loses its effectiveness at higher bacteria concentrations. Fluorescence is the opposite. Tuhina Banerjee, Santimukul Santra and colleagues wanted to see if they could combine the two techniques to make a better detector. The researchers developed a hybrid nanosensor incorporating magnetic resonance and fluorescence. Lab testing of milk showed the detector could sense varying concentrations of a pathogenic strain of E. coli known as O157:H7 in less than an hour. They also used their sensor to analyze E. coli levels in untreated lake water, which serves as a source of household water in some developing areas. Additionally, the device could be customized to detect a wide range of pathogens beyond E. coli, the researchers say. The authors acknowledge funding from the Kansas Soybean Commission and Pittsburgh State University. For more information, please click Contacts: Tuhina Banerjee, Ph.D. Department of Chemistry Kansas Polymer Research Center Pittsburg State University Pittsburg, KS 66762 Phone: 620-235-4749 or or Santimukul Santra, Ph.D. Department of Chemistry Kansas Polymer Research Center Pittsburg State University Pittsburg, KS 66762 Phone: 620-235-4861 or Michael Bernstein 202-872-6042 Katie Cottingham, Ph.D. 301-775-8455 If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Gofman Y.,Helmholtz Center Geesthacht | Gofman Y.,Tel Aviv University | Haliloglu T.,Polymer Research Center | Haliloglu T.,Bogazici University | Ben-Tal N.,Tel Aviv University
Nucleic Acids Research | Year: 2012

The MCPep server (http://bental.tau.ac.il/MCPep/) is designed for non-experts wishing to perform Monte Carlo (MC) simulations of helical peptides in association with lipid membranes. MCPep is a web implementation of a previously developed MC simulation model. The model has been tested on a variety of peptides and protein fragments. The simulations successfully reproduced available empirical data and provided new molecular insights, such as the preferred locations of peptides in the membrane and the contribution of individual amino acids to membrane association. MCPep simulates the peptide in the aqueous phase and membrane environments, both described implicitly. In the former, the peptide is subjected solely to internal conformational changes, and in the latter, each MC cycle includes additional external rigid body rotational and translational motions to allow the peptide to change its location in the membrane. The server can explore the interaction of helical peptides of any amino-acid composition with membranes of various lipid compositions. Given the peptide's sequence or structure and the natural width and surface charge of the membrane, MCPep reports the main determinants of peptide-membrane interactions, e.g. average location and orientation in the membrane, free energy of membrane association and the peptide's helical content. Snapshots of example simulations are also provided. © 2012 The Author(s).

Ozer N.,Polymer Research Center | Ozer N.,Bogazici University | Ozer N.,Marmara University | Schiffer C.A.,University of Massachusetts Medical School | And 2 more authors.
Biophysical Journal | Year: 2010

The structural fluctuations of HIV-1 protease in interaction with its substrates versus inhibitors were analyzed using the anisotropic network model. The directions of fluctuations in the most cooperative functional modes differ mainly around the dynamically key regions, i.e., the hinge axes, which appear to be more flexible in substrate complexes. The flexibility of HIV-1 protease is likely optimized for the substrates' turnover, resulting in substrate complexes being dynamic. In contrast, in an inhibitor complex, the inhibitor should bind and lock down to inactivate the active site. Protease and ligands are not independent. Substrates are also more flexible than inhibitors and have the potential to meet the dynamic distributions that are inherent in the protease. This may suggest a rationale and guidelines for designing inhibitors that can better fit the ensemble of binding sites that are dynamically accessible to the protease. © 2010 by the Biophysical Society.

Mane S.R.,Polymer Research Center | Dinda H.,Polymer Research Center | Sathyan A.,Polymer Research Center | Das Sarma J.,Indian Institute of Science | Shunmugam R.,Polymer Research Center
ACS Applied Materials and Interfaces | Year: 2014

Stimuli responsive polymeric nanocarrier (RCOP-2) functionalized with frontline antituberculosis drug (Rifampicin) is demonstrated for sustained release. Bioavailability of Rifampicin is taken care of by conjugating this drug through a acylhydrazine linker to the polymeric backbone. The poly(ethylene glycol) structural motif is introduced in the copolymer architecture for water solubility. Releasing retinal along with Rifampicin is hypothesized to reduce the risk of side effects due to Rifampicin. The self-assembly of RCOP-2, due to the amphiphilicity present in the copolymer, is explored in detail. The pH responsiveness of RCOP-2 is demonstrated in mild acidic environment as well as in cell lines. The 4T cell line, due to its acidic nature, shows time-dependent cellular internalization. On the basis of the results, our unique design is expected to provide an increased bioavalaibility of Rifampicin with reduced side effects. From the flow cytometry results on A549 cell lines, it is clear that the newly designed copolymer RCOP-2 can internalize efficiently and serve as an effective Rifampicin delivery system. © 2014 American Chemical Society.

Narayanan A.,Polymer Research Center | Chandel S.,Indian Institute of Science | Ghosh N.,Indian Institute of Science | De P.,Polymer Research Center
Analytical Chemistry | Year: 2015

Probing volume phase transition behavior of superdiluted polymer solutions both micro- and macroscopically still persists as an outstanding challenge. In this regard, we have explored 4 × 4 spectral Mueller matrix measurement and its inverse analysis for excavating the microarchitectural facts about stimuli responsiveness of "smart" polymers. Phase separation behavior of thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) and pH responsive poly(N,N-(dimethylamino)ethyl methacrylate) (PDMAEMA) and their copolymers were analyzed in terms of Mueller matrix derived polarization parameters, namely, depolarization (Δ), diattenuation (d), and linear retardance (δ). The Δ, d, and δ parameters provided useful information on both macro- and microstructural alterations during the phase separation. Additionally, the two step action ((i) breakage of polymer-water hydrogen bonding and (ii) polymer-polymer aggregation) at the molecular microenvironment during the cloud point generation was successfully probed via these parameters. It is demonstrated that, in comparison to the present techniques available for assessing the hydrophobic-hydrophilic switch over of simple stimuli-responsive polymers, Mueller matrix polarimetry offers an important advantage requiring a few hundred times dilute polymer solution (0.01 mg/mL, 1.1-1.4 M) at a low-volume format. © 2015 American Chemical Society.

Patil N.,Polymer Research Center | Soni J.,Indian Institute of Science | Ghosh N.,Indian Institute of Science | De P.,Polymer Research Center
Journal of Physical Chemistry B | Year: 2012

Thermodynamically favored polymer-water interactions below the lower critical solution temperature (LCST) caused swelling-induced optical anisotropy (linear retardance) of thermoresponsive hydrogels based on poly(2-(2- methoxyethoxy)ethyl methacrylate). This was exploited to study the macroscopic deswelling kinetics quantitatively by a generalized polarimetry analysis method, based on measurement of the Mueller matrix and its subsequent inverse analysis via the polar decomposition approach. The derived medium polarization parameters, namely, linear retardance (δ), diattenuation (d), and depolarization coefficient (Δ), of the hydrogels showed interesting differences between the gels prepared by conventional free radical polymerization (FRP) and reversible addition-fragmentation chain transfer polymerization (RAFT) and also between dry and swollen state. The effect of temperature, cross-linking density, and polymerization technique employed to synthesize hydrogel on deswelling kinetics was systematically studied via conventional gravimetry and corroborated further with the corresponding Mueller matrix derived quantitative polarimetry characteristics (δ, d, and Δ). The RAFT gels exhibited higher swelling ratio and swelling-induced optical anisotropy compared to FRP gels and also deswelled faster at 30 °C. On the contrary, at 45 °C, deswelling was significantly retarded for the RAFT gels due to formation of a skin layer, which was confirmed and quantified via the enhanced diattenuation and depolarization parameters. © 2012 American Chemical Society.

Mane S.R.,Polymer Research Center | Rao N V.,Polymer Research Center | Chaterjee K.,Polymer Research Center | Dinda H.,Polymer Research Center | And 4 more authors.
Macromolecules | Year: 2012

A unique polymersome from amphiphilic, norbornene-derived thiobarbiturate homopolymers (NDTH) and its application as nanocarrier for cancer therapy are elaborately discussed. Various experiments like structural characterizations, control studies, cell viability studies, encapsulation studies, and MTT assay against 4T cancer cells are performed on these NDTH polymersomes to substantiate our claims. All of these results demonstrate that these self-assembled NDTH vesicles have great scope in the world of medicine, and they also symbolize promising carriers for the stimuli-triggered intracellular delivery of hydrophobic drugs. © 2012 American Chemical Society.

Rao N V.,Polymer Research Center | Dinda H.,Polymer Research Center | Venu P.,Polymer Research Center | Sarma J.D.,Indian Institute of Science | Shunmugam R.,Polymer Research Center
RSC Advances | Year: 2014

A stimuli responsive, multi-anticancer drug derived nanocarrier has been synthesized by conjugating doxorubicin, chlorambucil, folate to the backbone of a norbornene polymer. Monomers namely NOR-DOX (mono 1), NOR-CHO (mono 2), and norbornene grafted poly(ethyleneglycol)-folate NOR-PEG-FOL (mono 3), are connected to the norbornene backbone by ester linkers to demonstrate the pH responsive capabilities. The complete chemical and biological properties of the nanocarriers, intended for combination cancer chemotherapy, are discussed. This nanocarrier, DOX-CHO-FOL is designed in such a way that doxorubicin, and chlorambucil, are both conjugated to the same polymer. The presence of the PEG-FOL functionality makes the system water-soluble as well as site-specific. The nanocarrier capabilities are tested by dynamic light scattering, scanning electron and transmission electron microscopies. The drug release profile shows the importance of having the ester linker which helps the drug at the mild acidic conditions resembling the pH of the cancerous cells. Confocal microscope studies confirm the cell internalization of the nanocarrier. MTT assay against 4T cells suggests the importance of the nanocarrier in the anticancer efficacy. © 2014 the Partner Organisations.

Vijayakameswara Rao V.,Polymer Research Center | Mane S.R.,Polymer Research Center | Kishore A.,Indian Institute of Science | Das Sarma J.,Indian Institute of Science | Shunmugam R.,Polymer Research Center
Biomacromolecules | Year: 2012

The synthesis and complete characterization of both norbornene-derived doxorubicin (mono 1) and polyethylene glycol (mono 2) monomers are clearly described, and their copolymerization by ring-opening metathesis polymerization (ROMP) to get the block copolymer (COPY-DOX) is vividly elaborated. The careful design of these conjugates exhibits properties like well-shielded drug moieties and well-defined nanostructures; additionally, they show solubility in both water and biological medium and also have the important tendency of rendering acid-triggered drug release. The drug release profile suggests the importance of having the hydrazone linker that helps to release the drug exactly at the mild acidic conditions resembling the pH of the cancerous cells. It is also observed that the drug release from micelles of COPY-DOX is significantly accelerated at a mildly acidic pH of 5.5-6, compared to the physiological pH of 7.4, suggesting the pH-responsive feature of the drug delivery system with hydrazone linkages. Confocal laser scanning microscopy (CLSM) measurements indicate that these COPY-DOX micelles are easily internalized by living cells. MTT assays against HeLa and 4T cancer cells showing COPY-DOX micelles have a high anticancer efficacy. All of these results demonstrate that these polymeric micelles that self-assembled from COPY-DOX block copolymers have great scope in the world of medicine, and they also symbolize promising carriers for the pH-triggered intracellular delivery of hydrophobic anticancer drugs. © 2011 American Chemical Society.

Rao N V.,Polymer Research Center | Ganivada M.N.,Polymer Research Center | Sarkar S.,Polymer Research Center | Dinda H.,Polymer Research Center | And 4 more authors.
Bioconjugate Chemistry | Year: 2014

A site-specific, stimuli-responsive nanocarrier has been synthesized by conjugating folate, magnetic particles and doxorubicin to the backbone of norbornene polymer. Monomers, namely, cis-5-norbornene-6-(diethoxyphosphoryl) hexanote (mono 1), norbornene grafted poly(ethyleneglycol)-folate (mono 2), and norbornene derived doxorubicin (mono 3) are carefully designed to demonstrate the smart nanorcarrier capabilities. The synthesis and complete characterization of all three monomers are elaborately discussed. Their copolymerization is done by controlled/living ring-opening metathesis polymerization (ROMP) to get the triblock copolymer PHOS-FOL-DOX. NMR spectroscopy and gel permeation chromatography confirm the formation of the triblock copolymer, while FT-IR spectroscopy, thermogravimetric analysis, along with transmission electron microscope confirm the anchoring of iron particle (Fe3O4) to the PHOS-FOL-DOX. Drug release profile shows the importance of having the hydrazone linker that helps to release the drug exactly at the mild acidic conditions resembling the pH of the cancerous cells. The newly designed nanocarrier shows greater internalization (about 8 times) due to magnetic field. Also, increased intracellular DOX release is observed due to the folate receptor. From these results, it is clear that PHOS-FOL-DOX has the potential to act as a smart nanoreservoir with the magnetic field guidance, folate receptor targeting, and finally pH stimulation. © 2013 American Chemical Society.

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