Synthesis and characterization of extremely small gold nanoshells, and comparison of their photothermal conversion capacity with gold nanorods

Encapsidation of Different Plasmonic Gold Nanoparticles by the CCMV CP

Different types of gold nanoparticles have been synthesized that show great potential in medical applications such as medical imaging, bio-analytical sensing and photothermal cancer therapy. However, their stability, polydispersity and biocompatibility are major issues of concern. For example, the synthesis of gold nanorods, obtained through the elongated micelle process, produce them with a high positive surface charge that is cytotoxic, while gold nanoshells are unstable and break down in a few weeks due to the Ostwald ripening process. In this work, we report the self-assembly of the capsid protein (CP) of cowpea chlorotic mottle virus (CCMV) around spherical gold nanoparticles, gold nanorods and gold nanoshells to form virus-like particles (VLPs). All gold nanoparticles were synthesized or treated to give them a negative surface charge, so they can interact with the positive N-terminus of the CP leading to the formation of the VLPs. To induce the protein self-assembly around the negative gold nanoparticles, we use different pH and ionic strength conditions determined from a CP phase diagram. The encapsidation with the viral CP will provide the nanoparticles better biocompatibility, stability, monodispersity and a new biological substrate on which can be introduced ligands toward specific cells, broadening the possibilities for medical applications.

Stimuli-responsive nanoparticle-assisted immunotherapy: a new weapon against solid tumours

The interplay between photo-thermal therapy and immunotherapy allows the realization of new nanotechnology-based cancer treatments for solid tumors.

Cationic Surfactant-Induced Formation of Uniform Gold Nanoparticle Clusters with High Efficiency of Photothermal Conversion under Near-Infrared Irradiation

A novel and simple method for the fabrication of gold nanoparticle (AuNP) clusters was introduced for use as an efficient near-infrared (NIR) photothermal agent. Cationic surfactants were employed to assemble AuNPs into clusters, during which polyvinylpyrrolidone (PVP) was used to stabilize the AuNP clusters. Through this manner, AuNP clusters with a uniform shape and a narrow size distribution (55.4 ± 5.0 nm by electron microscope) were successfully obtained. A mechanism for the formation of AuNP clusters was studied and proposed. Electrostatic interactions between AuNPs and cationic surfactants, hydrophobic interactions between hydrocarbon chains of cationic surfactants, and repulsive steric interactions of PVP were found to play an important role with regard to the formation mechanism. Photothermal effect in the NIR range of the AuNP clusters was demonstrated; results presented a highly efficient photothermal conversion (with a maximum η of 65%) of the AuNP clusters. The clusters could be easily coated by a silica layer, enabling their biocompatibility and colloidal stability in physiological fluids. The easy-to-fabricate AuNP clusters showed high potential of use as an NIR photothermal agent for cancer therapy.