This control particle accounted for any spectral changes due to the entire conjugation process. The AuNP peak absorbance click here red shifted from 523 to 527 nm when carboxyl-PEG-SH bound to the particle surface. When the gp100 peptides were conjugated to the AuNPs, the peak shifted further to 529 nm, indicating successful peptide conjugation onto the nanoparticle surface. The hydroxylamine control particles’ extinction peak did not red shift, indicating

that the red shift of the AuNV absorbance spectra is not a result of the conjugation process alone, but is caused by the peptide linkage (Figure  2A). Figure 2 Characterization of AuNV conjugation process. (A) The absorbance spectra of the initial peptide AuNP conjugates. The full view shows the 400- to 800-nm range, and the zoom insert shows the peaks between 510 and 545 nm. Preconjugate refers to the carboxyl-PEG-AuNPs. The NH2OH control refers to capping the active carboxyl groups on the particles with hydroxylamine. The preconjugates and NH2OH control particles had the same peak, verifying

that the conjugation protocol does not alter the absorbance peak. The particles conjugated with peptides show a 2-nm red shift. (B) TEM images of a 30-nm AuNP coated with PEG and a 30-nm gp100 AuNV. The surface of the peptide-coated AuNV appears rougher and thicker (red arrow) than the PEG-coated selleck chemicals llc AuNP, indicating successful conjugation (scale bar = 10 nm). In Figure  2B, the particles were dried prior to transmission electron microscopy (TEM) imaging, so the normally hydrated PEG molecules collapsed onto the AuNP surface, showing a uniform light rim around the border of the gold particle (Figure  2B). Post-peptide conjugation, the AuNV TEM images showed thickening and rough edges on the AuNP surface, which can be caused by

peptide linkage to the PEG molecule and self-polymerization. AuNV characterization Particle size is important for lymphatic drainage from the injection site, biodistribution, and cellular endocytosis. Dynamic light scattering measurements (DLS) showed that the OVA AuNVs were less than 80 nm in diameter, which is much smaller than other liposomal or polymeric formulations and, therefore, can potentially improve lymphatic drainage when injected subcutaneously. Levetiracetam The zeta potentials correlate well with the free-peptide properties because the gold colloids and COOH-PEG-AuNPs were capped with either citrate or carboxyls; however, the OVA AuNVs show near-neutral potentials because the OVA peptides have no charge at physiologic pH (Table  1). Table 1 DLS results, polydispersity index, and zeta potentials of citrate-capped gold colloids, COOH-PEG-coated AuNPs, and OVA AuNVs   Size (nm) PDI Zeta (mV) Colloids 33.5 ± 6.3 0.124 −37.6 ± 6.5 COOH-PEG-AuNPs 61.5 ± 6.2 0.201 −27.6 ± 12.2 OVA AuNVs 77.9 ± 9.5 0.305 −0.7 ± 6.