Biomedical Applications of Scanning Probe Microscopy Dr James R Smith School of Pharmacy and Biomedical Science University of Portsmouth

Content What is Scanning Probe Microscopy (SPM) ? Principles of SPM How does it differ from SEM/TEM ? SPM Facilities at Portsmouth Selected Case Studies Summary Questions

What is SPM ? SPM is a revolutionary technique which allows: 3-D imaging nanometre or micrometre scale imaging in a variety of environments with minimal sample preparation

SPM Techniques SPM is a generic name for a number of related ‘probe’ techniques: Scanning Tunnelling Microscopy (STM) Atomic Force Microscopy (AFM) others, such as Scanning Thermal Microscopy (SThM), Scanning Electrochemical Microscopy (SECM), Magnetic Force Microscopy (MFM)

Historical Background Scanning Tunnelling Microscopy (STM) was first reported in 1982 by Binnig et al. Atomic Force Microscope (AFM) first appeared in 1986 Commercial SPM instruments capable of STM and AFM operation available in 1992

Principles of AFM

Advantages of SPM over TEM and SEM Nanometre/atomic resolution Accurate height measurements to within 1 angstrom Three-dimensional representation of images Does not require UHV Ability to perform studies in aqueous environments Manipulation of surfaces on sub-nanometre scale

Other Information from SPM Surface roughness Surface area Hardness/softness Elasticity Adhesion Friction

Nanoindentation of Bacterial Cells

SPM Facilities at Portsmouth TopoMetrix Discoverer TMX2000 Modular SPM

Biomedical Applications of SPM at Portsmouth Surface metrication of hip prostheses Contact lens manufacture and fouling Hair structure and disease Biocide action Polymer binding to human cells Surface roughness of skin RNA/DNA secondary structure anti-cancer drug design

Biodeterioration and Control Biofilm contamination on an intraocular lens Action of a biocide on E. coli

Surface Metrication of Hip Prostheses

Soft Contact Lens Manufacture Polypropylene injection mould Pigment distribution on a tinted soft contact lens (above) and surface roughness (left)

Human Hair Surface roughness/line profile A=‘A’-layer, B=exocuticle, C=endocuticle (above) Same hair sample imaged under water showing swelling (right)

Summary Nanometre/atomic resolution Accurate height measurements to within 1 angstrom Three-dimensional representation of images Does not require UHV Ability to perform studies in aqueous environments Minimal sample preparation Minimal damage to sample Manipulation of surfaces on sub-nanometre scale

Acknowledgements Staff and students at Portsmouth Dr S A Campbell - Portsmouth Prof F C Walsh - Portsmouth Dr B F Shahgaldi - St Thomas’ Hospital, London Dr J A Swift - Unilever/De Montfort University Dr A Gough - Alberto-Culver Company (UK) Ltd Dr D H Morton - Clinic For Special Children, Philadelphia Staff and students at Portsmouth