Professor Steve Evans

Introduction

The research in the Evans group ranges over 4 major topics.  The longest-standing is on the functionalisation of surfaces and nanomaterials, in particular on the development of materials with new properties from artificial enzymes that can replace biological ones to nanoparticles with bactericidal or anti-tumour properties. Recently, we have developed platforms for the analysis of single cells, using Raman spectroscopy and deformation cytometry, to allow the determination of disease state and its relationship with structural properties of cells as well as following drug uptake and localisation. Our work on targeted micro- and nanobubbles aims at using their echogenicity to provide enhanced in vivo imaging. When coupled with destruction ultrasound destruction pulses our therapeutic bubbles lead to enhanced localised drug delivery with reduced off-site toxicity, offering a combined physicochemical approach for the treatment of cancers and infections.  Finally, we have a long-standing interest in the application of lipid bilayers at solid-liquid and liquid-liquid crystal interfaces for diagnostics and the bottom-up assembly of complex biological architectures.

Current major projects

  • Gold Nanomaterials: from Nanoenzymes to Phototherapy
  • Single Cell Analysis: Cell Deformation & Raman Spectroscopy
  • Micro- and Nano- bubbles for the treatment of Cancers and Biofilms
  • Lipid Bilayers at Gas, Liquid and Solid Interfaces

Detailed research programme

Function Gold Nanomaterials

We have developed a range of gold nanomaterials from hollow-tubes and nanorods to spiky flowers and our most recent gold nano-seaweed “the worlds thinnest gold”. Whilst these have been primarily aimed at photothermal treatment, photo-induced drug release and photoacoustic imaging these materials offer exciting potential as catalysts and nanoenzymes.  As such we have shown improved activity and stability leading to their potential to replace biological enzymes for some applications, e.g. in diagnostic lateral flow test strip devices, for the detection of antigens, antibodies (including SARS-CoV2 IgG, IgM) and small-molecule biomarkers.

Single Cell Analysis

We are developing new platforms that will permit new biomedical research approaches, based on the sequential isolation, manipulation, observation and eventual destructive analysis (or culture and expansion) of single cells. Our approach combines biophysical tools with AI to develop biological insights and capabilities that are relevant to clinical areas of expertise and excellence in Leeds, in this way these discoveries will translate quickly into patient benefit. Examples include:

  • Detection of tumorigenic molecular changes at low levels in cancers, minimal residual disease identification and discovery of secondary changes within premalignant lesions
  • Earlier and more precise classification of disease to inform therapeutic decisions
  • A better understanding of the key events underlying host infection, latency and activation by major infectious pathogens, and the corresponding host immune responses.

Micro- and Nano- bubbles

Micro-bubbles are widely used as contrast enhancement agents for ultrasound imaging and have the potential to enhance therapeutic delivery (small molecules, DNA, RNA, gases,…) to diseases such as cancer and infection.  We have multiple interests from physics, engineering and clinical sciences on developing these theragnostic agents, including:

  • Freeze-drying MBs with an attached therapeutic payload. To overcome issues related to in-clinic production, stability and well-defined drug delivery. This represents an important step for their translation to the clinic.
  • Stability and application of nanobubbles for therapeutic delivery.
  • Structure and function of lipid/polymer shells on the lifetime, mechanical and echogenic properties of bubbles.
  • Molecular targeting to tumours, biofilms, plaques, etc.

Lipid Bilayers at Gas, Liquid and Solid Interfaces

We use model membranes, of increasing complexity, to study membrane proteins and processes using a variety of analytical techniques.  Examples include:

  • Bottom-up construction of bacterial cell walls, for studying antibiotic interactions with cell wall precursors and penicillin binding proteins.
  • Forming supported bilayers with native membranes.
  • In-membrane electrophoresis for protein manipulation and concentration.
  • Antimicrobial Peptide interactions with membranes.