Immobilisation of proteins on synthetic material surfaces enables a range of applications from biosensing to industrial biocatalysis. However, common chemical immobilization methods are effective only on specific materials, a number of traditional methods can lead to denatured proteins, and specific linkers can be costly. We recently reported that plant polyphenols are useful precursors for forming “universal” coatings on many surfaces under mild aqueous conditions. For example, tannic acid (TA) and pyrogallol (PG) (polyphenols) can self-crosslink into stable transparent coatings under a range of pH. We now demonstrate the application of such polyphenol coatings as versatile and chemically reactive interfacial layers for biomolecules immobilization. We present results on exploiting TA, PG, and pyrogallol-2-aminoethane coatings on different materials such as alumina, cellulose, stainless steel and polyester. These coated materials were used for the immobilisation of immunoglobulin G, avidin, and a range of enzymes. Different conditions for both coating and immobilization such as pH and precursor and enzyme concentrations were tested. The effectiveness of the polyphenol was evaluated by measuring the immobilized enzyme activities. The results were compared with physisorbed and immobilized enzymes via polydopamine (pDA) coatings. The presence and thickness of the coating and enzyme layers were further quantified by X-ray photoelectron spectroscopy (XPS). Solid NMR was used to characterize finger print regions of the coatings and immobilized enzymes. It was found that polyphenol coatings were able to immobilize a wide range of proteins from antibodies to enzymes, and were up to 12 times more effective than both pDA coatings and physisorption for certain proteins and materials. The pH during coating and immobilisation were found to be key parameters influencing both enzyme activity and stability. The immobilization depended also on the underlying surface charge of the material support and the chemical nature of the coatings formed at different pH. In summary, we demonstrated that polyphenol coatings are effective interfacial layers for the immobilization of complex biomolecules. Polyphenol coatings can provide unique advantages ranging from their plant-based availability to their extended range of preparation pH and enhanced effectiveness on specific materials.

Plant-based polyphenol coatings for surface functionalization with proteins and enzymes

254th National Meeting (2017)

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