Gold nanorods (GNRs) are versatile asymmetric nanoparticles with unique optical properties. These properties make GNRs ideal agents for applications such as photothermal cancer therapy, biosensing,... Show moreGold nanorods (GNRs) are versatile asymmetric nanoparticles with unique optical properties. These properties make GNRs ideal agents for applications such as photothermal cancer therapy, biosensing, and in vivo imaging. However, as-synthesised GNRs need to be modified with a biocompatible stabilising coating in order to be employed in these fields as the ligands used to stabilise GNRs during synthesis are toxic. An issue is that GNR performance in the aforementioned techniques can be affected by these modified coatings. For example if coatings are too thick then GNR entry into cells, or their sensitivity in sensing applications, can be compromised. Here we show that thiolated peptide amphiphiles (PAs) can act as GNR stabilisers and provide a thin and highly-stable coating under physiologically relevant conditions. Additionally, all tested PAs formed highly ordered (51.8-58.8% β-content), and dense (2.62-3.87 peptides per nm2) monolayers on the GNR surface. Moreover, the PA-coated GNRs demonstrated no cytotoxicity in vitro and, via injection in zebrafish embryos, the behavior and cellular interactions of such PA-coated GNRs were visualised in vivo, in real time, with two-photon (2P) microscopy. Show less
Despite the fact that gold nanoparticles (GNPs) are one of the most studied nanoparticles, there is still a necessity for new approaches allowing for effective protective coating to enable wider... Show moreDespite the fact that gold nanoparticles (GNPs) are one of the most studied nanoparticles, there is still a necessity for new approaches allowing for effective protective coating to enable wider use of GNPs in biomedical applications. This dissertation is focusing on the use of self-assembling peptide amphiphiles as stabilizers for spherical GNPs and gold nanorods (GNRs). Peptide amphiphiles stabilize GNPs and GNRs through formation of a self-assembled monolayer on their surface. These gold-peptide amphiphile conjugates are stable under (and beyond) physiologically relevant conditions, do not induce cytotoxicity, and can be readily modified with ligands of interest. To demonstrate the potential of these conjugates, they were used to study T-cell mediated immune responses as function of GNP size and shape. It was shown that GNRs deliver more antigen to the lysosomes and induce better T-helper responses, while larger particles were more effective at mediating antigen delivery to the cytosol, thus inducing better cytotoxic responses. Show less
The functionalization of gold nanoparticles (GNPs) with peptidic moieties can prevent their aggregation and facilitate their use for applications both in vitro and in vivo. To date, no peptide... Show moreThe functionalization of gold nanoparticles (GNPs) with peptidic moieties can prevent their aggregation and facilitate their use for applications both in vitro and in vivo. To date, no peptide-based coating has been shown to stabilize GNPs larger than 30 nm in diameter; such particles are of interest for applications including vaccine development, drug delivery, and sensing. Here, GNPs with diameters of 20, 40, and 100 nm are functionalized with peptide amphiphiles. Using a combination of transmission electron microscopy, UV–vis spectroscopy, and dynamic light scattering, we show that GNPs up to 100 nm in size can be stabilized by these molecules. Moreover, we demonstrate that these peptide amphiphiles form curvature-dependent, ordered structures on the surface of the GNPs and that the GNPs remain disperse at high-salt concentrations and in the presence of competing thiol-containing molecules. These results represent the development of a peptide amphiphile-based coating system for GNPs which has the potential to be beneficial for a wide range of biological applications, in addition to image enhancement and catalysis. Show less
The functionalization of gold nanoparticles (GNPs) with peptidic moieties can prevent their aggregation and facilitate their use for applications both in vitro and in vivo. To date, no peptide... Show moreThe functionalization of gold nanoparticles (GNPs) with peptidic moieties can prevent their aggregation and facilitate their use for applications both in vitro and in vivo. To date, no peptide-based coating has been shown to stabilize GNPs larger than 30 nm in diameter; such particles are of interest for applications including vaccine development, drug delivery, and sensing. Here, GNPs with diameters of 20, 40, and 100 nm are functionalized with peptide amphiphiles. Using a combination of transmission electron microscopy, UV-vis spectroscopy, and dynamic light scattering, we show that GNPs up to 100 nm in size can be stabilized by these molecules. Moreover, we demonstrate that these peptide amphiphiles form curvature-dependent, ordered structures on the surface of the GNPs and that the GNPs remain disperse at high-salt concentrations and in the presence of competing thiol-containing molecules. These results represent the development of a peptide amphiphile-based coating system for GNPs which has the potential to be beneficial for a wide range of biological applications, in addition to image enhancement and catalysis. Show less
