Protecting Teeth With Silver

  Since arriving in New Zealand three years ago I have had the pleasure of participating in two AMN conferences. This year I was once again impressed by the high caliber of the conference, and thoroughly inspired by dynamic presentations from prominent scientists in the fields of materials science and nanotechnology. The collaborative spirit of the participants was unquestionable. I thoroughly enjoyed catching up with collaborators and colleagues and was grateful for the opportunity to establish new contacts with exceptional researchers from around the world. The work I presented at AMN6 this year was related to an ongoing, interdisciplinary project I am working on in collaboration with Dr. Don Schwass (Department of Oral Rehabilitation, UO), concerning the application of antibacterial silver nanoparticles in clinical dentistry. Our strategy involves the use of iontophoresis for enhanced delivery of highly antimicrobial silver nanocomposite materials deep within dentine for the treatment and prevention of dental caries. Together, we have developed colourless aqueous suspensions of ionic surfactant-stabilised silver nanocomposite assemblies which demonstrate high antimicrobial activity against a range of Gram-positive and Gram-negative microorganisms associated with the oral environment. The antimicrobial properties of the suspensions have also been tested under the influence of an electric current using an in-vitro model developed in-house. Our results indicate that if iontophoresis is used to drive charged silver nanocomposite materials into the tooth structure, the additional benefit of antimicrobial enhancement can be anticipated. Furthermore, based on recent scanning electron microscopy and energy-dispersive X-ray spectroscopy results, we expect that our materials will bind efficiently to tooth tissue. We are currently working towards the commercialisation of our research, so I was particularly interested in the parallel session related to ‘the business of nanotech’ included in the AMN6 programme this year. This silver nanocomposite work is a significant component of my overall research programme, which focuses on the design, development and characterisation of functional nanoparticles and nanocomposite materials. For example, current projects also include the synthesis of shape-controlled magnetic nanoparticles and the investigation of their magnetic resonance properties in suspension for MRI contrast agent applications. We also have a particular interest in microemulsion-based syntheses of solid nanoparticles, due to the fact that adaptations of this method can be used for the preparation of nanoparticles with independent control over particle size, composition and surface coating. We have performed recent studies probing the mode of action of secondary surfactants in microemulsion-based syntheses; new insight gained from these studies has led to the functionalisation of size-controlled metal nanoparticles with novel ligands. We are now working in collaboration with Professor Sally Brooker (PI, Department of Chemistry, OU) towards the further functionalisation of these nanoparticles with magnetically interesting molecules. Carla Meledandri is an Associate Investigator and a Lecturer in the Department of Chemistry at the University of Otago. Her research is focused on the design, synthesis and characterisation of functional nanoscale and nanocomposite materials, and the investigation of their efficacy for applications in the area of biomedicine; specifically, for improved medical diagnosis and targeted therapy, particularly dental therapy.