Controlled deposition of gold nanoparticles on polystyrene
Examensarbete för masterexamen
Nanotechnology (MPNAT), MSc
Gold nanoparticle (AuNP) number density gradients functionalised with (bio)molecules have applications in the study of e.g. stem cell differentiation. Currently, AuNP number density gradients are available on glass substrates, but many cell cultivation studies are performed on plastic substrates, e.g. polystyrene. Therefore, it is of interest to investigate if AuNP number density gradients can be achieved also on polystyrene. This thesis investigates several methods of depositing AuNPs on polystyrene substrates. The experimental work is limited to uniform AuNP deposition, thus covering a first step towards AuNP gradients on polystyrene substrates. Two different functionalisation paths were tested: silanisation with aminosilane (APDMES, 3-aminopropyldimethylethoxysilane) and coating with poly-l-lysine (PLL). For the silanisation, O2 plasma, UV/O3 treatment and (base) piranha wash were tested as oxidising pre-treatments. For coating with PLL, O2 plasma was tested as pre-treatment for increased surface wettability. AuNP deposition for the different functionalisation methods is determined by scanning electron microscopy (SEM) and the functionalisation methods are evaluated in terms of AuNP number density and range of interparticle dispersion, as determined by spatial descriptive statistics (Ripley’s K function). Furthermore, a rudimental extended random sequential adsorption (RSA) computational model is developed for the system. Of the tested functionalisation methods, silanisation with pre-treatment by UV/O3 exhibited the most promising results with AuNP number density of same order of magnitude as on glass reference samples (5.73 ∙ 1014 m-2, compared to 2.48 ∙ 1015 m-2 for the glass reference) and similar range of dispersion (75 nm, compared to 40-60 nm for the glass reference). It should, however, be noted that the conclusions are based on few experiments and need to be verified by additional experiments. The computational model seems to capture the basic phenomena of AuNP adsorption but underestimates the AuNP number density and the interparticle potential, or at least the range of the interparticle potential.
AuNP, , gradient , polystyrene , APDMES , PLL