Surface Tailoring Of Materials For Tissue Engineering Via Biofunctional Comb-shaped PEG

Poly(ethyleneglycol) or PEG has been widely investigated in biomedical, biological and pharmaceutical fields due to its water solubility, lack of toxicity, weak immunogenicity and ready clearance . The branched PEGs have been reported to have much better performance in preventing non-specific adsorption and the ability to maintain protein naturation than that of the traditional linear PEG in terms of its chemical stability, inertness and noninteracting nature and higher entropic repulsion. The comb-shaped PEG and biofunctional comb-shaped PEG were explored to surface tailoring of materials for tissue engineering.Surface modification of PET with lysine/RGD tethered Comb-like PEG for Promoting Cytocompatibility — A novel comb-like hydroxyl-capped PEG (CPEG) was synthesized through Atom Transfer Radical Polymerization(ATRP). The hydroxyl end groups was transferred into reactive aldehyde, which was further covalent bond to aminolyzied PET surface. Lysine and RGD were then immobilized at the end of PEG chain of Comb-like PEG via reaction between aldehyde groups and amino groups. As a control, Linear PEGs with different molecule weight (Mw=4000 and 10000) were also investigated. The results of attenuated total reflectance-Fourier transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and contact angle measurement showed that the PEGs were successfully immobilized onto PET substrate. The two kind of PEGs were compared regarding their ability to prevent non-specific interaction and promote cyto-compatibility. Due to its highly branched-arm structure, the comb-like PEG modified surface achieved stronger entropic repulsion than the linear PEG . Meanwhile, more ligands were tethered onto the comb-like PEG modified surface with the great amount of reactive end groups, which increased cell proliferation. Evaluated by adherence, proliferation, cell protein content, the glycocalyx mimicking surface designed by comb-shaped PEG end-tethered by RGD peptide was proved to present non-specific resistance and excellent cyto-compatibility simultaneously. The surface modification of reactive CPEG will provide a good selection to tether ligands and cell induce factors on biomaterial surfaces.Stable coating surface fabricated by Comb-like PEG — The Comb-shaped Poly(ethylene glycol) was explored to form a stable polymer coating on PET substrate via a simple coating technology. ATR-FTIR, XPS, contact angle measurement and weight decrement testing proved the stable coating surface of CPEG on PET could be developed via a simple dip-coating. Platelet, bacteria, endothelial cell adherence onto linear PEG grafted surface and CPEG coated surface was compared. CPEG Coated surface reacted extremely weakly with biocomponents such as proteins and platelet and showed much more excellent thrombus resistance than that of on the linear PEG grafted surface. Ligands or amino acid were also tethered on the comb-like PEG tailoring surface, which enhanced the cell adherence, proliferation and MTT activation compared with linear PEG modified surface immobilizing bioactive groups.Meanwhile, the comb-shaped PEG coated surface was also demonstrated to have the capacity in loading drugs and showed a controlled drug release property. The RD6G was used as model drug to prepare drug-containing coating due to the network of the CPEG. Drug-releasing curve also demonstrated the stability of the CPEG coating. The unique property of the coating provided the potential application in the immobilization and release of aqueous drug, including protein and peptide, which had a potential application in medical apparatuses such as hemodialysis appliance and drug-eluting stent.In-situ Construction of Cytocompatible Surface on PLA surface via Amphiphile-amino acid (RGD) Hybrid Self-segregation — Solvent cast films of amphiphilic comb-like poly(ethylene glycol) and poly(lactic acid) (PLA) have also been investigated over a wide range of compositions. The results of ATR-FTIR, XPS and dynamic contact angle were utilized to demonstrate the self-migrating of amino acid tethered CPEG side chains.The osteoblast cytocompatibility test on amphiphilic CPEG-aminoacid hybrid modified PDL-LA membranes showed that the cell attachment, growth and activity were promoted on PLA membranes modified by 2 % CPEG, while the result was opposite on content of 8% and 15% CPEG due to the dynamic self-migrating of the molecular chains.