Plasmon-resonant gold nanoparticles with variable morphology as optical labels and drug carriers for cytological research

In this work, two types of nanocomposites, silica-coated nano-sea-urchins and silica-coated gold nanostars, were fabricated. CTAB-coated nano-sea-urchins with an average size of about 100 nm demonstrate an absorption peak near 600-700 nm and stability in aqueous suspension. CTAB was exchanged with m-PEG-SH by an intermediate PEG layer. A layer of silica was synthesized on the nano-sea-urchins surface with thickness of about 20 nm. Nanostars with an average size of about 60 nm with a number of thin sharp branches were fabricated and functionalized by PVP to improve their stability. PVP-coated nanostars were used in optical coherence tomography experiments to show their contrasting properties. After silica-coating, stable and monodispersed nanoparticles with silica shell thickness about 60 nm were obtained. Nontoxicity of the silica-coated nanostars at least until the concentration of nanoparticles about 400 μg/mL was showed by fluorescent cell viability assay using propidium iodide. Extinction coefficient of the gold nanostars and nanocomposites was estimated by a spectrophotometer system in collimated transmission regime.