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Dinerman A.A.,University of Maryland, Baltimore | Dinerman A.A.,Centocor | Cappello J.,Protein Polymer Technologies Inc. | El-Sayed M.,University of Maryland, Baltimore | And 4 more authors.
Macromolecular Bioscience

The influence of solute hydrophobicity and charge on partitioning and diffusion in physically crosslinked networks of a genetically engineered SELP polymer was investigated. A series of fluorescent dyes were used to assess the impact of solute charge and hydrophobicity on release behavior. The mechanism of solute release from the SELP hydrogel appeared to vary as a function of dye hydrophobicity. The extent of FITC attachment to amine-terminated G4 dendrimers influenced SELP hydrogel partitioning more than dendrimer diffusion properties. Results suggest the possibility of controlling solute release from SELP hydrogels by modifying the hydrophobicity and surface charge of drugs and drug/polymer conjugates as well as the possibility of "designing-in" solute-specific interactions.Diffusion of small molecular weight compounds and macromolecular probes in silk-elastin-like hydrogels depends on size, charge, and hydrophobicity of the solutes (probes are not depicted in scale). Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Teng W.,University of Arizona | Huang Y.,University of Arizona | Cappello J.,Protein Polymer Technologies Inc. | Wu X.,University of Arizona
Journal of Physical Chemistry B

Recombinant protein polymers, evaluated exten-sively as biomaterials for applications in drug delivery and tissue engineering, are rarely reported as being optically transparent. Here we report the notable optical transparency of films composed of a genetically engineered silk-elastinlike protein polymer SELP-47K. SELP-47K films of 100 μm in thickness display a transmittance of 93% in the wavelength range of 350-800 nm. While covalent cross-linking of SELP-47K via glutaraldehyde decreases its transmittance to 77% at the wavelength of 800 nm, noncovalent cross-linking using methanol slightly increases it to 95%. Non- and covalent cross-linking of SELP-47K films also influences their secondary structures and water contents. Cell viability and proliferation analyses further reveal the excellent cytocompatibility of both non- and covalently cross-linked SELP-47K films. The combination of high optical transparency and cytocompatibility of SELP-47K films, together with their previously reported outstanding mechanical properties, suggests that this protein polymer may be useful in unique, new biomedical applications. © 2011 American Chemical Society. Source

Chang J.,University of Maryland University College | Peng X.-F.,Case Western Reserve University | Hijji K.,University of Maryland University College | Cappello J.,Protein Polymer Technologies Inc. | And 3 more authors.
Journal of the American Chemical Society

One-dimensional nanostructures are ideal building blocks for functional nanoscale assembly. Peptide-based nanofibers have great potential in building smart hierarchical structures due to their tunable structures at the single residue level and their ability to reconfigure themselves in response to environmental stimuli. We observed that pre-adsorbed silk-elastin-based protein polymers self-assemble into nanofibers through conformational changes on a mica substrate. Furthermore, we demonstrate that the rate of self-assembly was significantly enhanced by applying a nanomechanical stimulus using atomic force microscopy. The orientation of the newly grown nanofibers was mostly perpendicular to the scanning direction, implying that the new fiber assembly was locally activated with directional control. Our method provides a novel way to prepare nanofiber patterned substrates using a bottom-up approach. © 2011 American Chemical Society. Source

Gustafson J.A.,University of Utah | Price R.A.,University of Utah | Greish K.,University of Utah | Cappello J.,Protein Polymer Technologies Inc. | Ghandehari H.,University of Utah
Molecular Pharmaceutics

Recombinant silk-elastin-like protein polymers (SELPs) are well-known for their highly tunable properties on both the molecular and macroscopic hydrogel levels. One specific structure of these polymers, SELP-815K, has been investigated as an injectable controlled delivery system for the treatment of head and neck cancer via a gene-directed enzyme prodrug therapy (GDEPT) approach. Due to its pore size and gelation properties in vivo, SELP restricts the distribution and controls the release of therapeutic viruses for up to one month. It has been shown that SELP-mediated delivery significantly improves therapeutic outcome of the herpes simplex virus thymidine kinase (HSVtk)/ganciclovir (GCV) system in xenograft models of human head and neck cancer. However little is known about potential benefits of this approach with regard to toxicity in the presence of a fully intact immune system. The studies presented here were designed to assess the change in toxicity of the SELP-mediated viral delivery compared to free viral injection in a non-tumor-bearing immune competent mouse model. Toxicity was assessed at 1, 2, 4, and 12 weeks via body weight monitoring, complete blood count (CBC), and blood chemistry. It was found that in the acute and subacute phases (weeks 1-'4) there is significant toxicity in groups combining the virus and the prodrug, and matrix-mediated gene delivery with SELP demonstrates a reduction in toxicity from the 2 week time point through the 4 week time point. At the end of the subchronic phase (12 weeks), signs of toxicity had subsided in both groups. Based on these results, recombinant SELPs offer a significant reduction in toxicity of virus-mediated GDEPT treatment compared to free virus injection in the acute and subacute phases. © 2010 American Chemical Society. Source

Qiu W.,University of Arizona | Huang Y.,University of Arizona | Teng W.,University of Arizona | Cohn C.M.,University of Arizona | And 2 more authors.

Due to their improved biocompatibility and specificity over synthetic materials, protein-based biomaterials, either derived from natural sources or genetically engineered, have been widely fabricated into nanofibrous scaffolds for tissue engineering applications. However, their inferior mechanical properties often require the reinforcement of protein-based tissue scaffolds using synthetic polymers. In this study, we report the electrospinning of a completely recombinant silk-elastinlike protein-based tissue scaffold with excellent mechanical properties and biocompatibility. In particular, SELP-47K containing tandemly repeated polypeptide sequences derived from native silk and elastin was electrospun into nanofibrous scaffolds, and stabilized via chemical vapor treatment and mechanical preconditioning. When fully hydrated in 1× - PBS at 37°C, mechanically preconditioned SELP-47K scaffolds displayed elastic moduli of 3.4-13.2 MPa, ultimate tensile strengths of 5.7-13.5 MPa, deformabilities of 100-130% strain, and resilience of 80.6-86.9%, closely matching or exceeding those of protein-synthetic blend polymeric scaffolds. Additionally, SELP-47K nanofibrous scaffolds promoted cell attachment and growth, demonstrating their in vitro biocompatibility. © 2010 American Chemical Society. Source

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