Inspired Chemistry for a Simple but Highly Effective Immobilization of Vascular Endothelial Growth Factor on Gallic Acid‐functionalized Plasma Polymerized Film

Abstract

Biomolecules with thiol or amine groups can be easily covalently immobilized onto a material substrate equipped with quinone groups in a simple mild alkali buffer solution based on Schiff base and Michael addition reaction. In this study we report a novel two‐step approach to creating a functional coating with abundant quinone groups for a facile immobilization of vascular endothelial growth factor (VEGF) in chemical mild phosphate buffered saline (PBS, pH = 7.4). This approach firstly involves the deposition of plasma polymerized allylamine (PPAam) thin coating onto a substrate to introduce the amine groups. Then gallic acid (3,4,5‐trihydroxybenzoic acid, GA) is chosen to functionalize PPAam for introducing phenol groups through a water‐soluble carbodiimide (WSC) coupling procedure. The results of infrared spectroscopy (IR), X‐ray photoelectron spectroscopy (XPS), and water contact angles reveal the effective conjugation of GA to PPAam and further immobilization of VEGF to GA functionalized PPAam. The results of quartz crystal microbalance equipped with dissipation monitoring (QCM‐D) show that 120 ng · cm−2 of VEGF is successfully immobilized onto GA functionalized surface. The VEGF functionalized surface shows a significant enhancement of human umbilical vein endothelial cell (HUVEC) proliferation, revealing a good bioactivity of VEGF. This functional coating not only provides a novel facile strategy for the covalent immobilization of biomolecules in a chemical mild reaction condition, but also can be adapted for a wide range of materials without surface pretreatment.

Grafting of Gallic Acid onto a Bioactive Ti6Al4V Alloy: A Physico-Chemical Characterization

“…The complex compound formation can involve both the carboxylate ion of GA and Ti-O − as donor groups. The formation of the coordination compound influences the chemical reactivity of polyphenols, for instance they are able to polymerize and to form coatings [56,57]: Particularly, in the present case it is shown that they were much more prone to be grafted on a surface. The possible formation of the complex and its binding to the surface is reported in Figure 2.…”

Gallic acid grafting to a ferrimagnetic bioactive glass-ceramic

“…The employment of citric acid-sodium citrate buffer and the addition of citric acid were considered in order to avoid an excessive pH increase of GA solutions during functionalization and avoid its degradation [37,38]. In fact, the glass ceramic can induce a significant increase in the solution pH, due to ionic exchange, during the functionalization period [13].…”

Surface functionalization of bioactive glasses with natural molecules of biological significance, part II: Grafting of polyphenols extracted from grape skin

“…A basic environment can favor both a further hydroxylation of the glass [26] and the oxidation of catechol groups of phenols to quinone groups [31], giving the typical brownish color that was noticed both on the glass surfaces and in the uptake solutions.…”