Cross-linking of a biopolymer-peptide co-assembling system

Abstract

The ability to guide molecular self-assembly at the nanoscale into complex macroscopic structures could enable the development of functional synthetic materials that exhibit properties of natural tissues such as hierarchy, adaptability, and self-healing. However, the stability and structural integrity of these kinds of materials remains a challenge for many practical applications. We have recently developed a dynamic biopolymer-peptide co-assembly system with the capacity to grow and undergo morphogenesis into complex shapes. Here we explored the potential of different synthetic (succinimidyl carboxymethyl ester [SCM-PEG-SCM], poly (ethylene glycol) ether tetrasuccinimidyl glutarate [4S-StarPEG] and glutaraldehyde) and natural (genipin) cross-linking agents to stabilize membranes made from these biopolymer-peptide co-assemblies. We investigated the cross-linking efficiency, resistance to enzymatic degradation, and mechanical properties of the different cross-linked membranes. We also compared their biocompatibility by assessing the metabolic activity and morphology of adipose-derived stem cells (ADSC) cultured on the different membranes. While all cross-linkers successfully stabilized the system under physiological conditions, membranes cross-linked with genipin exhibited better resistance in physiological environments, improved stability under enzymatic degradation, and a higher degree of in vitro cytocompatibility compared to the other cross-linking agents. The results demonstrated that genipin is an attractive candidate to provide functional structural stability to complex self-assembling structures for potential tissue engineering or in vitro model applications. Statement of SignificanceMolecular self-assembly is widely used for the fabrication of complex functional biomaterials to replace and/or repair any tissue or organ in the body. However, maintaining the stability and corresponding functionality of these kinds of materials in physiological conditions remains a challenge. Chemical cross-linking strategies (natural or synthetic) have been used in an effort to improve their structural integrity. Here we investigate key performance parameters of different cross-linking strategies for stabilising self-assembled materials with potential biomedical applications using a novel protein-peptide co-assembling membrane as proof-of-concept. From the different cross-linkers tested, the natural cross-linker genipin exhibited the best performance. This cross-linker successfully enhanced the mechanical properties of the system enabling the maintenance of the structure in physiological conditions without compromising its bioactivity and biocompatibility. Altogether, we provide a systematic characterization of cross-linking alternatives for self-assembling materials focused on biocompatibility and stability and demonstrate that genipin is a promising alternative for the cross-linking of such materials with a wide variety of potential applications such as in tissue engineering and drug delivery.

A fluidic device for the controlled formation and real-time monitoring of soft membranes self-assembled at liquid interfaces

“…The interaction between different molecules at the interface can lead to spontaneous formation of hydrogels or membranes, whose microstructure, permeability and functional properties can be finely tuned by choosing the appropriate molecular building blocks 4 . While in our group we are mostly interested in self-assembling membranes for tissue engineering 5 – 7 , self-assembling membranes are of interest for a variety of other applications, including energy storage 8 , optoelectrical devices 9 , 10 , sensors 11 , polymeric actuators 11 , catalysis 12 , and drug delivery 13 , 14 .…”

Biofabrication strategies for 3D in vitro models and regenerative medicine

“…Biological studies need to be accompanied by technological development to ultimately achieve a high degree of similarity between native tissues and organs and biofabricated constructs. Biomaterials need to be developed that mimic the dynamics of the ECM, for example, by exploiting hydrophilic and hydrophobic interactions 216 , electrical properties 217 or molecular self-assembly 218 . Experimental observations need to be coupled with multiparametric models of bioink viscosity to understand biomaterial behaviour during tissue fabrication.…”

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

“…Furthermore, other non-polypeptide polymers have been combined with ELRs, including the widely used polyethylene glycol (PEG) [126,127], inorganic bioglass [128], hyaluronic acid (HA) [129], self-assembling peptides [130], and lipids [131]. All these examples highlight the interest of using ELRs in combination with other biomaterials to obtain superior structures, such as hydrogels, that recapitulate the properties of their components, hence getting closer to the complexity of biological tissues and matrices.…”