Autoclaving as a chemical-free process to stabilize recombinant silk-elastinlike protein polymer nanofibers.
Ontology highlight
ABSTRACT:
SUBMITTER: Qiu W
PROVIDER: S-EPMC3144965 | biostudies-other | 2011 Jun
REPOSITORIES: biostudies-other
Similar Datasets
Project description:Recombinant protein polymers, evaluated extensively 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 ?m 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.
| S-EPMC3041846 | biostudies-literature
Project description:Self-assembled peptide/polypeptide nanofibers are appealing building blocks for creating complex three-dimensional structures. However, ordering assembled peptide/polypeptide nanofibers into three-dimensional structures on the microscale remains challenging and often requires the employment of top-down approaches. We report that silk-elastin-like protein polymers self-assemble into nanofibers in physiologically relevant conditions, the assembled nanofibers further form fiber clusters on the microscale, and the nanofiber clusters eventually coalesce into three-dimensional structures with distinct nanoscale and microscale features. It is believed that the interplay between fiber growth and molecular diffusion leads to the ordering of the assembled silk-elastin-like nanofibers at the microscale.
| S-EPMC3977850 | biostudies-other
Project description:We evaluated the drug release capability of optically transparent recombinant silk-elastinlike protein polymer, SELP-47K, films to sustainably deliver the common ocular antibiotic, ciprofloxacin. The ciprofloxacin release kinetics from drug-loaded SELP-47K films treated with ethanol or methanol vapor to induce different densities of physical crosslinking was investigated. Additionally, the drug-loaded protein films were embedded in a protein polymer coating to further prolong the release of the drug. Drug-loaded SELP-47K films released ciprofloxacin for up to 132 h with near first-order release kinetics. Polymer coating of drug-loaded films prolonged drug release for up to 220 h. The antimicrobial activity of ciprofloxacin released from the drug delivery matrices was not impaired by the film casting process or the ethanol or methanol treatments. The mechanism of drug release was elucidated by analyzing the physical properties of the film specimens, including equilibrium swelling, soluble fraction, surface roughness and hydrophobicity. Additionally, the conformation of the SELP-47K and its physical crosslinks in the films was analyzed by FTIR and Raman spectroscopy. A three-parameter physics based model accurately described the release rates observed for the various film and coating treatments and attributed the effects to the degree of physical crosslinking of the films and to an increasing affinity of the drug with the polymer network. Together, these results indicate that optically transparent silk-elastinlike protein films may be attractive material candidates for novel ophthalmic drug delivery devices.
| S-EPMC3220799 | biostudies-literature
Project description:Cell-biomaterial interactions can be controlled by modifying the surface chemistry or nanotopography of the material, to induce cell proliferation and differentiation if desired. Here we combine both approaches in forming silk nanofibers (SNFs) containing gold nanoparticles (AuNPs) and subsequently chemically modifying the fibers. Silk fibroin mixed with gold seed nanoparticles was electrospun to form SNFs doped with gold seed nanoparticles (SNF(seed)). Following gold reduction, there was a 2-fold increase in particle diameter confirmed by the appearance of a strong absorption peak at 525 nm. AuNPs were dispersed throughout the AuNP-doped silk nanofibers (SNFs(Au)). The Young's modulus of the SNFs(Au) was almost 70% higher than that of SNFs. SNFs(Au) were modified with the arginine-glycine-aspartic acid (RGD) peptide. Human mesenchymal stem cells that were cultured on RGD-modified SNF(Au) had a more than 2-fold larger cell area compared to the cells cultured on bare SNFs; SNF(Au) also increased cell size. This approach may be used to alter the cell-material interface in tissue engineering and other applications.
| S-EPMC3468663 | biostudies-literature
Project description:Energy harvested from human body movement can produce continuous, stable energy to portable electronics and implanted medical devices. The energy harvesters need to be light, small, inexpensive, and highly portable. Here we report a novel biocompatible device made of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers on flexible substrates. The nanofibers are prepared with electrospinning followed by a stretching process. This results in aligned nanofibers with diameter control. The assembled device demonstrates high mechanical-to-electrical conversion performance, with stretched PVDF-HFP nanofibers outperforming regular electrospun samples by more than 10 times. Fourier transform infrared spectroscopy (FTIR) reveals that the stretched nanofibers have a higher β phase content, which is the critical polymorph that enables piezoelectricity in polyvinylidene fluoride (PVDF). Polydimethylsiloxane (PDMS) is initially selected as the substrate material for its low cost, high flexibility, and rapid prototyping capability. Bombyx Mori silkworm silk fibroin (SF) and its composites are investigated as promising alternatives due to their high strength, toughness, and biocompatibility. A composite of silk with 20% glycerol demonstrates higher strength and larger ultimate strain than PDMS. With the integration of stretched electrospun PVDF-HFP nanofibers and flexible substrates, this pilot study shows a new pathway for the fabrication of biocompatible, skin-mountable energy devices.
| S-EPMC6418575 | biostudies-literature
Project description: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.
| S-EPMC3006068 | biostudies-literature
Project description:Hepatocellular carcinoma annually affects over 700,000 people worldwide and trends indicate increasing prevalence. Patients ineligible for surgery undergo loco-regional treatments such as transarterial chemoembolization (TACE) to selectively target tumoral blood supply. Using a microcatheter, chemotherapeutics are infused followed by an embolic agent, or the drug is encapsulated by the embolic moiety; simultaneously inducing stasis while delivering localized chemotherapy. Presently, several products are used, but no universally accepted system is promoted because very disparate limitations exist. The goal of this investigation was to design and develop in situ gelling recombinant silk-elastinlike protein polymers (SELPs) for TACE. Two SELP compositions, SELP-47K and SELP-815K, with varying lengths of silk and elastin blocks, were investigated to formulate a new embolic that was injectable through commercially available microcatheters. The goal was to develop a composition providing maximal permeation of tumor vasculature while exhibiting effective embolic activity. The SELPs evaluated remain soluble until reaching 37 °C, when irreversible transition ensues forming a solid hydrogel network. SELP-815K formulated at 12% w/w with shear processing demonstrated acceptable rheological properties and clear embolic capability under flow conditions in vitro. A rabbit model showed feasibility of embolization in vivo allowing selective occlusion of lobar hepatic arterial branches.
| S-EPMC4429515 | biostudies-literature
Project description:New types of air filter technologies are being called because air pollution by particulate matters (PMs) and volatile organic compounds has raised serious concerns for public health. Conventional air filters have limited application and poor degradability and they become non-disposable wastes after use. Here, we report a highly efficient, eco-friendly, translucent, and multifunctional air purification filter that is highly effective for reducing air pollution, protecting the environment, and detecting hazardous chemical vapors encountered in everyday life. Uniform silk protein nanofibers were directly generated on a window screen by an electrospinning process. Optical properties (translucence and scattering) of the silk nanofibrous air filters (SNAFs) are advantageous for achieving viewability and controlling the room temperature. Air filtration efficiencies of the fabricated SNAFs could reach up to 90% and 97% for PMs with sizes under 2.5 and 10 μm, respectively, exceeding the performances of commercial semi-high-efficiency particulate air (semi-HEPA) filters. After use, the SNAFs could be naturally degraded. Furthermore, we demonstrate the ability of SNAFs impregnated with organic dyes to sense hazardous and volatile vapors encountered in everyday life.
| S-EPMC6018553 | biostudies-literature
Project description:Structural arrangement and dimension play vital roles in wave transport and amplification as they can restrict the volume explored by the waves. However, it is challenging to systematically investigate the interplay among structural, optical, and mechanical properties, in part because of limited experimental platforms that modulate the structural arrangement in a continuous manner. We present light amplification action in Rhodamine B doped silk fibroin (SF) nanofibrous scaffolds and its modulation via the control of the alignment or directionality of SF nanofibers through an electrospinning procedure. Random lasing features of such scaffolds are examined as a function of structural arrangement of the SF nanofibers, and optical-structural-mechanical relationships of the SF-based structures are examined. As SF nanofibers are aligned parallel undergoing a transition from three to quasi-two dimension, light amplification features (e.g., lasing threshold and output power) enhanced, which also strongly correlated with mechanical characteristics (i.e., Young's moduli) of the scaffolds. We confirm such optical characteristics using quasi-mode analyses based on the finite element method. We further demonstrate non-contact, in situ measurement of alternations in lasing features of the scaffolds while the specimens are under tensile loads. These results may highlight potential utility of the scaffolds as a flexible and biocompatible sensor.
| S-EPMC5495807 | biostudies-other
Project description:Fluorescent silk fibroin nanofibers were fabricated via electrospinning method with three kinds of fluorescent dyes. Electrospun fluorescent nanofibers showed smooth surfaces and average diameters of 873 ± 135 nm, 835 ± 195 nm, and 925 ± 205 nm, respectively, for silk fibroin-fluorescein sodium, silk fibroin-rhodamine B, and silk fibroin-acridine orange nanofibers containing 2.0 wt% fluorescent dyes. At the same time, the secondary structure of silk fibroin in fluorescent nanofibers was predominantly amorphous conformation without influence by adding different concentrations of fluorescent dyes, as characterized by Fourier transform infrared spectroscopy and X-ray diffraction. Thermal degradation behavior of fluorescent silk fibroin nanofibers with a dramatic decrease in weight residue was observed at around 250 °C. The fluorescence effect of fluorescent silk fibroin nanofibers was changed by changing the concentration of different fluorescent dyes. These fluorescent nanofibers may make promising textile materials for large scale application.
| S-EPMC6631164 | biostudies-other