Electroactive fluorescent polymer films for visualisation of latent fingermarks

PhD funded by a Graduate Teaching Assistantship (GTA)

Highlights

New materials for enhanced latent fingermark visualisation

Correlation of functionalised polymer (electro)chemical and optical characteristics

Electrochemically controlled fingermark image contrast

Project

Background. Fingerprints remain the cornerstone of identification of individuals in criminal investigations. Nonetheless, enhancements in sensitivity, spatial selectivity and image contrast are required: this project delivers these through fluorescence and electrochemical control. Latent fingermarks on forensically relevant metals will be revealed by inclusion of fluorophores, providing greater sensitivity (for degraded marks) and wavelength selection (enhanced background discrimination).

Concept & strategy. A deposited fingermark creates a template on a surface. When the surface is metallic, one can electrochemically drive processes on regions of the surface not covered by fingermark residue, generating a negative image of the fingerprint. This strategy has three advantages: exceptional sensitivity, non-competitive use of reagents interacting with the residue, and DNA extraction from the residue. Three chemical strategies will be employed: monomer functionalisation with a labile group (permitting post-deposition fluorophore reaction), bilayer formation (separating fluorescent polymer from the metal), and redox-controlled ion-exchange of charged fluorophores into electroactive polymer films. These provide wide choice of fluorescent dyes and risk mitigation.

Experimental program. Electrochemical deposition of polymer films (nucleation and growth) will be monitored using coulometric and nanogravimetric (EQCM) data. Fluorophore capture and retention will be determined by nanogravimetric and spectroscopic (visible, FTIR) measurements. Film solvation will be evaluated nanogravimetrically (spatially integrated, temporally resolved) and by neutron reflectivity (spatially resolved, temporally integrated). Fluorophore binding and local mapping will be determined using imaging FTIR (previously funded by UoL). Macroscopic imaging will be carried out in absorption and emission modes (imaging system previously funded by UoL), with control of excitation and observational wavelength; image enhancement software available. Supporting imaging techniques (3DM, AFM, SEM, EDAX) will be applied as required.

Collaborations. Materials novelty is assured through provision of custom synthesised monomers (by Prof Adriana Ribeiro, Federal University of Alagoas, Brazil). These will permit optimisation of polymer solvation and viscoelasticity (mobile species transfer rates), spatial accommodation for large fluorophores and optical properties. Opportunities for DNA acquisition will be explored with Prof Turi King. Existing collaborations with practitioners (DSTL, EMSOU and other UK regional police forces, and Dr Alexandro Assis (Alagoas Federal Police)) provide inputs for methodological optimisation and routes for impact development.

 Entry requirements

Applicants are required to hold/or expect to obtain a UK Bachelor Degree 2:1/1st, or overseas equivalent, in a Chemistry-related subject.  

The University of Leicester English language requirements apply (where applicable).

Informal enquiries

Please email enquiries to [Email Address Removed]

To apply please refer to https://le.ac.uk/study/research-degrees/funded-opportunities/chemistry-gta