Piezoelectric ink jet printing of horseradish peroxidase on fibrous substrates

Abstract

Solid phase bioanalysis relies on the creation of a highly selective and sensitive layer of bioagent on a solid support capable of recognizing specific target analytes. Using ink jet printing technology picoliter volumes of bioagents can be precisely patterned over large surfaces with controlled uniformity. Despite the advantages of bioanalytical methods and the flexibility of ink jet printers, producing this type of functional materials is challenging. Solid supports can affect the biological activity, the spatial distribution and the binding capacity of the bioagent causing problems during post print detection. In this study a bioink containing the enzyme horseradish peroxidase (HRP) was jetted with a piezoelectric-based ink-jet deposition system on various fibrous substrates with differences in composition, surface chemistry and pore structure. Enzyme activity in solution and after printing was tested colorimetrically using 2, 2′-azino-di-(3- ethylbenzthiazoline) 6-sulphonate (ABTS) as chromogen. It was found that the papers tested have significantly different bioanalytical response in the detection of hydrogen peroxide. The uncoated papers showed the most sensitive green color response; whereas, the uncoated wood free paper gave the broader range of measurement and the highest color intensity. In contrast, the coated papers developed lower color intensity and the cast coated paper produced a pink color response possibly due to enzyme intermediate compounds produced under conditions of substrate inhibition.