Stimuli‐Responsive Thin Coatings Using Elastin‐Like Polymers for Biomedical Applications

Abstract

Smart thin coatings using a recombinant elastin‐like polymer (ELP) containing the cell attachment sequence arginine–glycine–(aspartic acid) (RGD) are fabricated for the first time through simple deposition of the ELP dissolved in aqueous‐based solutions. The biopolymer is produced and characterized using electrophoresis and mass spectroscopy. The temperature and pH responsiveness are assessed by aggregate size measurements and differential scanning calorimetry. The deposition of the studied ELP onto chitosan is followed in situ with a quartz‐crystal microbalance with dissipation monitoring (QCM‐D). Contact angle measurements are performed at room temperature and at 50 °C, showing reversible changes from a moderate hydrophobic behavior to an extremely wettable surface. AFM analysis performed at room temperature reveals a smooth surface and no organized structure. At 50 °C, the surface presents spherical nanometer‐sized structures of collapsed biopolymer chains. Such results suggest that the ELP chains, when collapsed, aggregate into micelle‐like structures at the surface of the substrate, increasing its water affinity. Cell adhesion tests on the developed coatings are conducted using a SaOS‐2 cell line. Enhanced cell adhesion could be observed in the H‐RGD6‐coated surfaces, as compared with the original chitosan monolayer. An intermediate behavior is found in chitosan coated with the corresponding ELP without the RGD sequence. Therefore, the developed films have great potential as biomimetic coatings of biomaterials for different biomedical applications, including tissue engineering and controlled delivery of bioactive agents. Their thermo‐responsive behavior can also be exploited for tunable cell adhesion and controlled protein adsorption.

Natural polymers for the microencapsulation of cells

“…The transition temperature is influenced by the molecular weight, the concentration in solution and the amino acid composition but can be easily controlled to be between room and body temperature. Furthermore, biodegradation sequences [199,200] or specific cell adhesion motifs can be added to the polymer chain [201,202]. For example, a negatively charged ELR containing the RGD motif was produced by Costa et al [203] to fabricate microcapsules with a layer-by-layer technique using chitosan as a polycation.…”

Fabrication of Thermo-Responsive Molecular Layers from Self-Assembling Elastin-Like Oligopeptides Containing Cell-Binding Domain for Tissue Engineering

“…Furthermore, the ELPs potentially offer several advantages over PNIPAM such as biocompatibility and biodegradablility characters. Based on such interesting properties, ELPs have already been employed as useful molecular tools for biological applications such as protein purification, drug delivery and artificial ECM [17][18][19][20][21][22][23][24][25][26]. In most of these studies, genetically engineered ELPs with high molecular weights were used on the subjects.…”

Recent Contributions of Elastin-Like Recombinamers to Biomedicine and Nanotechnology

“…An intermediate behavior was found in the chitosan coated with an ELR lacking the RGD sequence. [80] These films have great potential as biomimetic biomaterial coatings.…”