Multilayer coating of gold nanorods for combined stability and biocompatibility

Abstract

Engineering plasmonic nanostructures that simultaneously achieve high colloidal stability, high photothermal stability, low non-specific binding to biological specimens, and low toxicity is of significant interest to research in bionanotechnology. Using gold nanorods, we solved this problem by encapsulating them with a multilayer structure, silica, hydrophobic ligands, and amphiphilic-polymers. In comparison with nanorods covered with the conventional surface chemistries, such as surfactants, polyelectrolytes, thiolated polymers, and silica shells alone, the new nanorods remain single in various solutions and show remarkable stability against laser irradiation. We further demonstrated specific targeting and effective treatment of prostate tumor cells using nanorod–aptamer bioconjugates. This exquisitely formulated nanoencapsulation technology could potentially help stabilize other plasmonic nanostructures that are not in the most thermodynamically or chemically stable states, and should open exciting opportunities in nanotechnology-based imaging and therapeutics.

Complete three-dimensional optical characterization of single gold nanorods

“…concerning the efficiency of solar cells [14]. Especially the fields of bio-sensing and biomedicine (photothermal therapy) are growing rapidly and strong efforts have been made to bring gold nanorods into cells [15] and to stabilize gold nanoparticles in a biological environment [16]. Nevertheless, for all these techniques it is advantageous to image and characterize the gold nanoparticles in a non-invasive way.…”

Acidic pH-Targeted Chitosan-Capped Mesoporous Silica Coated Gold Nanorods Facilitate Detection of Pancreatic Tumors via Multispectral Optoacoustic Tomography

“…16, 21, 24–26 Because gold nanorods change shape and become more spherical upon absorption of OA laser fluence during in vivo imaging, encapsulation of the particle with mesoporous silica (MS) protects the GNRs from thermal deformation, enhances GNR thermal stability, and increases OA signal. 27–29 MS coated gold nanorods (MS-GNRs) have the potential to be used as theranostic particles for tumor imaging and drug delivery. 30 However, the porous nature of MS is also problematic if MS-GNRs are to be used for drug delivery due to the leakage of toxic chemotherapeutics prior to delivery at the target site.…”

BSA modification to reduce CTAB induced nonspecificity and cytotoxicity of aptamer-conjugated gold nanorods

“…17 As another surface coating strategy, silica-coating can also reduce the toxicity while using CTAB as a template to form a silica layer on the surface of AuNRs. 18 Besides coating the bilayer structure of CTAB or making the monomers of CTAB more stable, thiol-terminated ligands can displace CTAB from the AuNR surface and thereby reduce cytotoxicity. 13, 15 Even though there should be batch-to-batch variations for the CTAB quantity on the surface of AuNRs, surface coating strategies have comparable efficiencies in reducing the toxicity of CTAB, but not all of the CTAB can be replaced by the ligand-exchange strategies.…”