Gold Nanoparticles for Biomedical Applications: Synthesis and In Vitro Evaluation

Gold nanoparticles can be synthesized in a wide range of sizes and shapes. They can be coated with molecules, polymers, or phospholipids that yield solubility and stability in biological fluids. Gold is inert and is generally regarded as biocompatible. Depending on their shape and structure, gold nanoparticles can have a number of remarkable properties, such as strong and tunable attenuation of light, fluorescence, conversion of light to heat, and attenuation of X-rays. Due to these properties, gold nanoparticles have a wide range of biomedical applications. They have been used as contrast agents for fluorescence, optical, photoacoustic, and X-ray imaging. They can function as drug or gene delivery vectors. They can also play roles in photothermal or radiosensitization treatment regimens. We herein present methods to synthesize, coat, and purify spherical gold nanoparticles that are 15–100 nm in diameter. We describe protocols to characterize these gold nanoparticles with dynamic light scattering, transmission electron microscopy, inductively coupled plasma-optical emission spectroscopy (ICP-OES) and for computed tomography contrast generation. Last, we detail methods to assess nanoparticle uptake by cells, effect on cell viability, and effect on cell function.