Inkjet Printing of Biological Macromolecules for Use in Biology and Medicine

  • Christopher Cook

    Student thesis: Doctor of Engineering

    Abstract

    This thesis presents an investigation into the viability of utilising piezoelectric drop ondemand printing as a tool for the deposition of proteins for the rapid prototyping of biologicalsensors. The work has focussed on several main aspects; the effect of printing parameterson drop characteristics, the effect of printing parameters on protein survivability, theinfluence of surface characteristics on the drop formation at the surface of the sensor, andthe electrochemical properties of the sensors after printing. The main objective of this studywas to derive a method for the rapid prototyping of sensors using the piezoelectric drop ondemand printer.The first section details the influence of waveform amplitude on the characteristics of theprinted drop including droplet weight and volume. It was established that proteins weresuitable for printing in both a Phosphate buffered saline solution and a sugar based carriersolution as supplied by AET. Protein survivability experiments suggested that there wassome loss of activity during the printing process which required further investigation.Research into the effect of printing parameters on the viability of proteins, specificallyGlucose Oxidase (GOX) has been categorised according to protein structure and proteinconformation. No damage was found to occur to either protein conformation or structure afteranalysis of the samples using light scattering, analytical centrifugation and circular dichroismafter printing at 40, 60 and 80V. Further analysis revealed that there was a loss of mass ofprotein after the printing process compared to a non printed sample.Surface analysis was employed to quantify the effect of the surface of the electrodes on thedrop behaviour after printing through a piezoelectric drop on demand printhead. Proteinswere printed onto different carbon surfaces for comparison in different holding solutions andthe surfaces analysed for both the drop behaviour when wet and the form and size of thedried enzyme on the carbon surface. Printed samples were observed to spread best withsurfactant present in the solution and some evidence of a 'coffee staining effect' wasencountered. Further optimisation of the surfactant percentage and the drying conditionsameliorated these effects to produce optimal drying of the solution both on the surface andafter drying.An electrochemical technique was also employed to optimise the number of units of enzymedeposited using the printing technique and to ensure that the current response required wasachievable and repeatable. After optimisation, it was possible to demonstrate that the 3 unitsample provided a current response with an R2 value greater than 0.99, thereforedemonstrating reproducible linearity in the current response. This therefore demonstratedthat piezoelectric drop on demand printing techniques could be used for the rapid prototypingof biosensors, especially for use in the glucose sensing market.
    Date of Award31 Dec 2011
    Original languageEnglish
    Awarding Institution
    • The University of Manchester
    SupervisorBrian Derby (Supervisor)

    Keywords

    • Printing
    • Proteins

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