Search for: All records

The unique biophysical and biochemical properties of intrinsically disordered proteins (IDPs) and their recombinant derivatives, intrinsically disordered protein polymers (IDPPs) offer opportunities for producing multistimuli‐responsive materials; their sequence‐encoded disorder and tendency for phase separation facilitate the development of multifunctional materials. This review highlights the strategies for enhancing the structural diversity of elastin‐like polypeptides (ELPs) and resilin‐like polypeptides (RLPs), and their self‐assembled structures via genetic fusion to ordered motifs such as helical or beta sheet domains. In particular, this review describes approaches that harness the synergistic interplay between order‐promoting and thermoresponsive building blocks to design hybrid biomaterials, resulting in well‐structured, stimuli‐responsive supramolecular materials ordered on the nanoscale.

 

Chronic wounds are an unmet clinical need affecting millions of patients globally, and current standards of care fail to consistently promote complete wound closure and prevent recurrence. Disruptions in growth factor signaling, a hallmark of chronic wounds, have led researchers to pursue growth factor therapies as potential supplements to standards of care. Initial studies delivering growth factors in protein form showed promise, with a few formulations reaching clinical trials and one obtaining clinical approval. However, protein‐form growth factors are limited by instability and off‐target effects. Gene therapy offers an alternative approach to deliver growth factors to the chronic wound environment, but safety concerns surrounding gene therapy as well as efficacy challenges in the gene delivery process have prevented clinical translation. Current growth factor delivery and gene therapy approaches have primarily used single growth factor formulations, but recent efforts have aimed to develop multi‐growth factor approaches that are better suited to address growth factor insufficiencies in the chronic wound environment, and these strategies have demonstrated improved efficacy in preclinical studies. This review provides an overview of chronic wound healing, emphasizing the need and potential for growth factor therapies. It includes a summary of current standards of care, recent advances in growth factor, cell‐based, and gene therapy approaches, and future perspectives for multi‐growth factor therapeutics.

 

Collagen-targeting strategies have proven to be an effective method for targeting drugs to pathological tissues for treatment of disease. The use of collagen-like peptides for controlling the assembly of drug delivery vehicles, as well as their integration into collagen-containing matrices, offers significant advantages for tuning the morphologies of assembled structures, their thermoresponsiveness, and the loading and release of both small-molecule and macro-molecular cargo. In this contribution, we summarize the design and development of collagen-peptide-based drug delivery systems introduced by the Kiick group and detail the expansion of our understanding and the application of these unique molecules through collaborations with experts in computational simulations (Jayaraman), osteoarthritis (Price), and gene delivery (Sullivan). Kiick was inducted as a Fellow of the National Academy of Inventors in 2019 and was to deliver an address describing the innovations of her research. Given the cancellation of the NAI Annual Meeting as a result of coronavirus travel restrictions, her work based on collagen-peptide-mediated assembly is instead summarized in this contribution. 

The self-assembly of nanostructures from conjugates of elastin-like peptides and collagen-like peptides (ELP-CLP) has been studied as means to produce thermoresponsive, collagen-binding drug delivery vehicles. Motivated by our previous work in which ELP-CLP conjugates successfully self-assembled into vesicles and platelet-like nanostructures, here, we extend our library of ELP-CLP bioconjugates to a series of tryptophan/phenylalanine-containing ELPs and GPO-based CLPs [W 2 F x - b -(GPO) y ] with various domain lengths to determine the impact of these modifications on the thermoresponsiveness and morphology. The lower transition temperature of the conjugates with longer ELP or CLP domains enables the formation of well-defined nanoparticles near physiological temperature. Moreover, the morphological transition from vesicles to platelet-like nanostructures occurred when the ratio of the lengths of ELP/CLP decreased. Given the previously demonstrated ability of many ELP-CLP bioconjugates to bind to both hydrophobic drugs and collagen-containing materials, our results suggest new opportunities for designing specific thermoresponsive nanostructures for targeted biological applications. 

Thermoresponsive resilin‐like polypeptides (RLPs) of various lengths were genetically fused to two different computationally designed coiled coil‐forming peptides with distinct thermal stability, to develop new strategies to assemble coiled coil peptides via temperature‐triggered phase separation of the RLP units. Their successful production in bacterial expression hosts was verified via gel electrophoresis, mass spectrometry, and amino acid analysis. Circular dichroism (CD) spectroscopy, ultraviolet‐visible (UV/Vis) turbidimetry, and dynamic light scattering (DLS) measurements confirmed the stability of the coiled coils and showed that the thermosensitive phase behavior of the RLPs was preserved in the genetically fused hybrid polypeptides. Cryogenic‐transmission electron microscopy and coarse‐grained modeling revealed that functionalizing the coiled coils with thermoresponsive RLPs leads to their thermally triggered noncovalent assembly into nanofibrillar assemblies.

 

Thermoresponsive resilin‐like polypeptides (RLPs) of various lengths were genetically fused to two different computationally designed coiled coil‐forming peptides with distinct thermal stability, to develop new strategies to assemble coiled coil peptides via temperature‐triggered phase separation of the RLP units. Their successful production in bacterial expression hosts was verified via gel electrophoresis, mass spectrometry, and amino acid analysis. Circular dichroism (CD) spectroscopy, ultraviolet‐visible (UV/Vis) turbidimetry, and dynamic light scattering (DLS) measurements confirmed the stability of the coiled coils and showed that the thermosensitive phase behavior of the RLPs was preserved in the genetically fused hybrid polypeptides. Cryogenic‐transmission electron microscopy and coarse‐grained modeling revealed that functionalizing the coiled coils with thermoresponsive RLPs leads to their thermally triggered noncovalent assembly into nanofibrillar assemblies.