Fabrication and Characterization of Recombinant Silk‐Elastin‐Like‐Protein (SELP) Fiber

Abstract

Silk‐elastin‐like‐protein polymers (SELPs) are genetically engineered recombinant protein sequences consisting of repeating units of silk‐like and elastin‐like blocks. By combining these entities, it is shown that both the characteristic strength of silk and the temperature‐dependent responsiveness of elastin can be leveraged to create an enhanced stimuli‐responsive material. It is hypothesized that SELP behavior can be influenced by varying the silk‐to‐elastin ratio. If the responsiveness of the material at different ratios is significantly different, this would allow for the design of materials with specific temperature‐based swelling and mechanical properties. This study demonstrates that SELP fiber properties can be controlled via a temperature transition dependent on the ratio of silk‐to‐elastin in the material. SELP fibers are experimentally wet spun from polymers with different ratios of silk‐to‐elastin and conditioned in either a below or above transition temperature (T t) water bath prior to characterization. The fibers with higher elastin content showed more stimuli‐responsive behavior compared to the fibers with lower elastin content in the hot (57–60 °C) versus cold (4–7 °C) environment, both computationally and experimentally. This work builds a foundation for developing SELP materials with well‐characterized mechanical properties and responsive features.

Elastin‐Like Recombinamers: Deconstructing and Recapitulating the Functionality of Extracellular Matrix Proteins Using Recombinant Protein Polymers

“…Interesting biomaterials with customized properties can be achieved by combining ELRs with order-promoting protein domains ( Table 1) such as leucine zippers, [194] coiled-coils, [195,196] or SADs from other structural proteins, such as silk or resilin. [197][198][199][200][201] Additionally, self-assembling properties of different SADs can converge synergistically leading the formation of physical hydrogels with improved features. For instance, an innovative bioink has been fabricated by the rational combination of silk-like blocks, leucine zippers, and ELRs: [202] In this arrangement, silk domains promote the formation of highly stable and insoluble β-sheets, thus imparting thermal and mechanical resistance, leucine zipper-containing motif selfassembles into α-helical structures that dimerizes specifically, and the amphiphilic elastin-like block co-recombinamer undergoes thermal coacervation.…”

“…Silk-like motifs (GAGAGS) n Hard crystalline domain Irreversible β-sheet formation Strength and structure [197][198][199][200] Resilin-like motifs (QYPSDGRG) n Rubber-like protein UCST phase behavior Elasticity [201] Leucine zippers KENQIAIRASFLEKENSALRQEVADLRKE(L/C) GKCKNILAKYEA Stable dimeric coiled-coil interactions [194,203] Cartilage oligomeric matrix protein (COMPcc)…”

Optical Waveguides and Integrated Optical Devices for Medical Diagnosis, Health Monitoring and Light Therapies

“…What distinguishes SELPs is the convenience to design intended forms and to function by varying the silk-to-elastin ratios. By adjusting the ratios, materials with specific temperature-based swelling and mechanical properties can be achieved [ 28 ].…”

Trends in the design and use of elastin-like recombinamers as biomaterials

“…Furthermore, it is also noteworthy the increasing number of works describing the combination of ELRs with other polymers or structural proteins, giving blends or biohybrids that recapitulate the properties of all the components. The first, and probably the most exploited blend, came from the recombinant fusion of ELRs with silk-like domains to give silk-elastin-like recombinamers (SELRs) that are able to form fibers and hydrogels, among other structures, whose stability relies on the β-sheet cross-linking between silk-like motifs [8,71,[121][122][123]. Collagen-like peptides have also been explored as partners of ELRs in a recombinant way [124], even achieving nanoplatelets [125].…”