In situ synthesis of gold nanorods on SiO₂-substrates

Examensarbete för masterexamen
Master's Thesis
Nanotechnology (MPNAT), MSc
Wilson, Sean
The implantation of a medical device introduces a high risk of infection and bacterial biofilm formation on the device surface. These biomaterials-associated infections (BAI) are difficult to treat using conventional methods, such as high dosages of antibiotic treatments, as the bacteria are protected by the biofilm. A promising treatment is to modify the implant surfaces with gold nanorods, which can photothermally eradicate bacteria beneath the biofilm with heat generated from localized surface plasmon resonance (LSPR). As such there is a need to develop methods that reliably produce gold nanorods of a size that produces LSPR at wavelengths within the biological window and that stably bind the particles to the material surface homogeneously. In this thesis, a method has been developed to grow gold nanorods in situ on SiO2-glass and silicon wafers by binding gold nanoparticle seeds to surfaces using (3-Mercaptopropyl)- trimethoxysilane (MPTMS) as a linking molecule. The seeds were then grown into rods using a modified growth solution. The method has also been adapted to surface sensitive analysis to demonstrate the increased possibility to study anisotropic nanoparticles this method brings. In situ quartz crystal microbalance (QCM-D) analysis was used to study the formation of the self-assembled monolayer of MPTMS, the chemisorption of gold nanoparticle seeds, and how the growth rates of the particles vary over time, possibly due to both their increasing size as well as variations in solution concentrations. The developed method produced nanorods with a demonstrated rod yield of ~69% directly on SiO2-glass surfaces. The rods had an aspect ratio (AR) that could be customised to tune the wavelength of LSPR. The ability to tune the optical properties of the rods could allow this method to be used to grow gold nanorods for other applications, such as sensing, as well. Here the tuning was used to demonstrate the effect of silver ions within the growth solution and to produce nanorods with LSPR at the near infrared (NIR) wavelength of ~800nm in the biological window.
gold nanorods , localised surface plasmon resonance , NIR , biofilm , implants , photo-thermal eradication , infection , MPTMS , in-situ growth , QCM-D , insitu analysis
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