The Hanks group is working in two broad areas of soft materials synthesis and characterization, taking inspiration and materials from nature to craft functional structures.1 The first involves the preparation of ionomeric composites composed of polycationic conducting polymers such as polypyrrole or poly(3,4-ethylenedioxythiophene) with biopolymers such as dextran sulfate or alginates. Our long-term goals are to create scaffolds for neural tissue engineering and coatings for nervous system implantable electrodes.
We are using 3D extrusion printers to build cell-infused constructs capable of external electrical stimulation.2 In related work, we have developed a method for modifying the surfaces of electronically conducting polymer films that allows for the control of protein adhesion and the prevention of biofouling. While initially of interest for implant materials, this technology also has wider applications as eco-friendly coatings in marine environments.3, 4, 5
A second area of interest is the assembly of liposomes for use in drug delivery and biosensing. Long chain diacetylene amphiphiles assemble into polymerizable vesicles that are intensely blue in color. Physical stress causes a dramatic color change to a red color and also “turns-on” fluorophores embedded in the bilayer that are quenched in the blue form. Surface derivatization of the structures results in an affinity for bacteria and other species and this interaction can be converted into the stress needed to trigger the sensing system.6, 7, 8 We have recently shown that multiple liposomes, each with a different surface modification and fluorophore, can give a fluorescent “fingerprint” characteristic of a particular pathogen. Polymerization of the vesicles also almost completely stops leakage of species entrapped in the aqueous liposome core. We are developing novel methods to “pop” the liposomes in response to external conditions in order to controllably release drugs or other encapsulants.
1 Introduction to Biomimicry and Bioinspiration in Chemistry Hanks, T. W.; Swiegers, G. F. in "Biomimicry and Bioinspiration in Chemistry" Swiegers, G. F. Ed. Wiley Inc., 2012.
2 Characterization of alginate-polypyrrole composites for tissue engineering scaffolds Wright, C.J.; Zhang, B.; Kuester, M.; Molino, P.J.; Hanks, T.W. Front. Bioeng. Biotechnol. Conference: 10th World Biomaterials Congress. 2016. doi: 10.3389/conf.FBIOE.2016.01.00314.
3 Functionalised Inherently Conducting Polymers as Low Biofouling Materials Zhang, B.; Nagle, A.; Wallace, G.G.; Hanks, T.W.; Molino, P.J. Biofouling 2015, 31, 493-502.
4 Polymers with antifouling properties Australian Provisional Patent, Application Number 2013901089, 2013.
5 Modification of Polypyrrole/Biopolymer Composites for Controlled Cellular Adhesion Molino, P. J.; Zhang, B.; Wallace, G. G.; Hanks, T. W. Biofouling 2013, 29, 1155-1167.
6 Polydiacetylene sensor interaction with food sanitizers and surfactants Zhang, Y.; Northcutt, J.; Hanks, T. W.; Miller, I.; Pennington, W. T.; Jelinek, R.; Han, I. Food Chem. 2017, 221, 515-520.
7 Efficient Production of Fluorescent Polydiacetylene-containing Liposomes for Pathogen Detection and Identification Wright-Walker, C. J.; Hansen, C. E.; Evans, M. A.; Nyers, E. S. Hanks, T. W. MRS Proceed., 2013, 1569, mrss13-1569-qq01-03 doi:10.1557/opl.2013.1099.
8 Polydiacetylene-based Smart Packaging Hill, S. C.; Htet, Y.; Kauffman, J.; Han, I. Y. Dawson, P. L. Pennington, W. T. Hanks, T. W. in Physical Methods in Food Analysis ACS Symp. Ser., Vol. 1138, pp 137-154, Tunick, M. H.; Onwulata, C. I., Eds., American Chemical Society, Washington, DC. 2013.