Pnolezoelectric ink-jet printing of horseradish peroxidase: Effect of ink viscosity modifiers on activity

In this study a bioink containing the horseradish peroxidase (HRP) enzyme was formulated and jetted with a piezoelectric-based ink-jet deposition system. A number of polymers with different molecular weights, functional groups and electric charge were tested as viscosity modifiers. The impact of viscosity modifiers on HRP activity was systematically studied. It was found that viscosity modifiers typically used in commercial ink formulations significantly impaired HRP activity possibly due limitations diffusion. contrast, carboxymethyl cellulose increased viscosity to the desired range for piezoelectric jetting without negatively affecting the HRP activity. Good jettability was obtained for the HRP bioink by adding a suitable surfactant, a viscosity modifier and a humectant.