Exploring the mineralisation and functionalisation of recombinant Pyrococcus furiosus ferritin

Abstract

Set against a background of global antimicrobial resistance and an increased mortality rates from sepsis, there is a clear requirement for novel rapid point-of-care diagnostic technologies, especially those that are affordable for use in a poor resource setting. The magnetic labelling of bacteria using functionalised ferritin nanoparticles presents one clear opportunity to capture and identify bacteria from patient samples using magnetic based cell separation techniques. Here, the mineralisation and functionalisation of a recombinant ferritin from Pyrococcus furiosus has been investigated. This involved reconstitution of an iron oxide core within the particle and cationisation of the outer surface to facilitate adhesion to bacterial cell surface using electrostatic interactions. Analysis of the mineralised particles using transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS) provided evidence to suggest the tuneable mineralisation of the iron oxide core without impacting particle polydispersity. Monte Carlo based dummy atom modelling and form factor fitting of SAXS data provides evidence of how the iron core reconstitutes within the particle as core and multi shell models. Super conducting interference magnetometry of the mineralised particles indicated that the experimental conditions promoted the formation of a hydrated iron (III) oxide (Fe2O3·nH2O) core, rather than the desired magnetite (Fe3O4). Successful chemical cationisation of the non- mineralised recombinant ferritin highlights the potential application of these particles, for example in magnetic based microfluidic devices to capture and concentrate bacteria, once magnetic core mineralisation has been achieved. Moreover, the controllable mineralisation demonstrated in this project suggests that individual bacterial selection could be achieved by harnessing the differences in magnetic susceptibility of particles reconstituted under different iron concentrations. Ultimately, such magnetic nanoparticles could facilitate rapid identification and infection diagnosis.

Date of Award	29 Sept 2020
Original language	English
Awarding Institution	University of Bristol
Supervisor	Jim Spencer (Supervisor) & Annela M Seddon (Supervisor)