Gold nanoparticles deposited on glass: physicochemical characterization and cytocompatibility
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NANO EXPRESS
Open Access
Gold nanoparticles deposited on glass: physicochemical characterization and cytocompatibility Alena Reznickova*, Zdenka Novotna, Nikola Slepickova Kasalkova and Vaclav Svorcik
Abstract Properties of gold films sputtered under different conditions onto borosilicate glass substrate were studied. Mean thickness of sputtered gold film was measured by gravimetry, and film contact angle was determined by goniometry. Surface morphology was examined by atomic force microscopy, and electrical sheet resistance was determined by two-point technique. The samples were seeded with rat vascular smooth muscle cells, and their adhesion and proliferation were studied. Gold depositions lead to dramatical changes in the surface morphology and roughness in comparison to pristine substrate. For sputtered gold structures, the rapid decline of the sheet resistance appears on structures deposited for the times above 100 s. The thickness of deposited gold nanoparticles/layer is an increasing function of sputtering time and current. AFM images prove the creation of separated gold islands in the initial deposition phase and a continuous gold coverage for longer deposition times. Gold deposition has a positive effect on the proliferation of vascular smooth muscle cells. Largest number of cells was observed on sample sputtered with gold for 20 s and at the discharge current of 40 mA. This sample exhibits lowest contact angle, low relative roughness, and only mild increase of electrical conductivity. Keywords: Glass, Gold sputtering, Gold nanoparticles, Surface properties, Cell adhesion and proliferation
Background Gold nanoparticles (GNPs) are currently used as catalysts [1], and chemical [2] and plasmonic sensors [3]. They are also used in surface-enhanced Raman scattering [4] and nonlinear optics [5]. Furthermore, the usage of GNP for diagnosis and even destruction of microorganisms [6] or AuNP for biological applications [7-9] should be mentioned. Although GNPs are believed to be biologically inert, they can be engineered to possess chemical and biological functionality. GNP exhibits a plasmon resonance (PR) at wavelengths from 510 to 580 nm [10] leading to enhanced absorption and scattering in this part of the optical spectrum. The PR is affected by the size and shape of the GNP, the type of the supporting substrate (mainly its refractive index) and/or the surrounding material of the gold nanoparticles. The distance between the nanoparticles is also relevant, especially if it is small enough to enable electromagnetic
coupling [11]. GNPs are usually prepared by precipitation from aqueous solutions [12,13] on various materials, e.g., on etched glass surfaces [13,14]. Thermal annealing of thin gold films produced by evaporation or sputtering [15] can also lead to a gold aggregation into GNP [16]. The formation of GNP from continuous gold layers is driven by the minimization of the surface energy and is denoted as solid state dewetting [17]. However, all the described methods suffer from the poor adhesion of GNP to
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