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Li X.,Clemson University | Murthy N.S.,New Jersey Center for Biomaterials | Latour R.A.,Clemson University
Macromolecules | Year: 2012

The effect of hydration on the molecular structure of amorphous poly(d,l-lactic acid) (PDLLA) with 50:50 L-to-D ratio has been studied by combining experiments with molecular simulations. X-ray diffraction measurements revealed significant changes upon hydration in the structure functions of the copolymer. Large changes in the structure functions at ∼10 days of incubation coincided with the large increase in the water uptake from ∼1 to ∼40% and the formation of voids in the film. Computer modeling based on the recently developed TIGER2/TIGER3 mixed sampling scheme was used to interpret these changes by efficiently equilibrating both dry and hydrated models of PDLLA. Realistic models of bulk amorphous PDLLA structure were generated as demonstrated by close agreement between the calculated and the experimental structure functions. These molecular simulations were used to identify the interactions between water and the polymer at the atomic level including the change of positional order between atoms in the polymer due to hydration. Changes in the partial O-O structure functions, about 95% of which were due to water-polymer interactions, were apparent in the radial distribution functions. These changes, and somewhat smaller changes in the C-C and C-O partial structure functions, clearly demonstrated the ability of the model to capture the hydrogen-bonding interactions between water and the polymer, with the probability of water forming hydrogen bonds with the carbonyl oxygen of the ester group being about 4 times higher than with its ether oxygen. © 2012 American Chemical Society. Source

Lewis D.R.,Rutgers University | Kamisoglu K.,Rutgers University | York A.W.,New Jersey Center for Biomaterials | Moghe P.V.,Rutgers University
Wiley Interdisciplinary Reviews: Nanomedicine and Nanobiotechnology | Year: 2011

Coronary arterial disease, one of the leading causes of adult mortality, is triggered by atherosclerosis. A disease with complex etiology, atherosclerosis results from the progressive long-term combination of atherogenesis, the accumulation of modified lipoproteins within blood vessel walls, along with vascular and systemic inflammatory processes. The management of atherosclerosis is challenged by the localized flare-up of several multipronged signaling interactions between activated monocytes, atherogenic macrophages and inflamed or dysfunctional endothelial cells. A new generation of approaches is now emerging founded on multifocal, targeted therapies that seek to reverse or ameliorate the atheroinflammatory cascade within the vascular intima. This article reviews the various classes and primary examples of bioactive configurations of nanoscale assemblies. Of specific interest are polymer-based or polymer-lipid micellar assemblies designed as multimodal receptor-targeted blockers or drug carriers whose activity can be tuned by variations in polymer hydrophobicity, charge, and architecture. Also reviewed are emerging reports on multifunctional nanoassemblies and nanoparticles for improved circulation and enhanced targeting to atheroinflammatory lesions and atherosclerotic plaques. © 2011 John Wiley and Sons, Inc. Source

Treiser M.D.,Rutgers University | Yang E.H.,Rutgers University | Gordonov S.,Rutgers University | Cohen D.M.,University of Pennsylvania | And 4 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2010

Stem cells that adopt distinct lineages cannot be distinguished based on traditional cell shape. This study reports that higher-order variations in cell shape and cytoskeletal organization that occur within hours of stimulation forecast the lineage commitment fates of human mesenchymal stem cells (hMSCs). The unique approach captures numerous early (24 h), quantitative features of actin fluororeporter shapes, intensities, textures, and spatial distributions (collectively termed morphometric descriptors). The large number of descriptors are reduced into "combinations" through which distinct subpopulations of cells featuring unique combinations are identified. We demonstrate that hMSCs cultured on fibronectin-treated glass substrates under environments permissive to bone lineage induction could be readily discerned within the first 24 h from those cultured in basal- or fat-inductive conditions by such cytoskeletal feature groupings. We extend the utility of this approach to forecast osteogenic stem cell lineage fates across a series of synthetic polymeric materials of diverse physico-chemical properties. Within the first 24 h following stem cell seeding, we could successfully "profile" the substrate responsiveness prospectively in terms of the degree of bone versus nonbone predisposition. The morphometric methodology also provided insights into how substrates may modulate the pace of osteogenic lineage specification. Cells on glass substrates deficient in fibronectin showed a similar divergence of lineage fates, but delayed beyond 48 h. In summary, this high-content imaging and single cell modeling approach offers a framework to elucidate and manipulate determinants of stem cell behaviors, as well as to screen stem cell lineage modulating materials and environments. Source

Kohn J.,New Jersey Center for Biomaterials
Journal of Materials Science: Materials in Medicine | Year: 2013

The Fellows Session brought together six prominent scientists, expressing their personal views on a significant scientific question. As highlighted above, the perhaps most valuable and most exciting aspect of this session was the diversity of opinions expressed and the different approaches taken by the individual authors in answering the question. It is rare that we have an opportunity to present such a comprehensive collection of divergent opinions. It seems that by studying all six papers in this collection, the reader will be exposed to virtually any argument that can reasonably be made in regard to our future ability to regenerate complex human body parts. Source

Lewitus D.Y.,New Jersey Center for Biomaterials | Landers J.,Rutgers University | Branch J.R.,New Jersey Center for Biomaterials | Smith K.L.,New York State Department of Health | And 3 more authors.
Advanced Functional Materials | Year: 2011

A novel approach for producing carbon nanotube fibers (CNF) composed with the polysaccharide agarose is reported. Current attempts to make CNFs require the use of a polymer or precipitating agent in the coagulating bath that may have negative effects in biomedical applications. It is shown that, by taking advantage of the gelation properties of agarose, one can substitute the bath with distilled water or ethanol and, hence, reduce the complexity associated with alternating the bath components or the use of organic solvents. It is also demonstrated that these CNF can be chemically functionalized to express biological moieties through available free hydroxyl groups in agarose. Agarose CNF are not only conductive and nontoxic; in addition, their functionalization is shown to facilitate cell attachment and response both in vitro and in vivo. Our findings suggest that agarose/CNT hybrid materials are excellent candidates for applications involving neural tissue engineering and biointerfacing with the nervous system. A novel approach for producing carbon nanotube fibers (CNF) composed with the polysaccharide agarose is reported. The TOC image shows representative immunohistochemical images of rat brain slices after insertion of CNT/agarose fiber-electrodes. Cell types shown are microglia (blue), astrocytes (orange), and neurons (green). A is a control electrode and B is an electrode functionalized with laminin, a neural extracellular matrix protein. Close inspection and quantification of the cell response reveals favorable tissue reaction to the laminin tethered electrode. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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