We probe how amphiphilic ligands (ALs) of four different types affect the formation of protein coronas on gold nanorods (NRs) and their impact on cellular response. NRs coated with cetyltrimethylammonium bromide were ligand exchanged with polyoxyethylene[10]cetyl ether, oligofectamine, and phosphatidylserine (PS). Protein coronas from equine serum (ES) were formed on these NR-ALs, and their colloidal stability, as well as cell uptake, proliferation, oxidative stress, and gene expression, were examined. We find that the protein corona that forms and its colloidal stability are affected by AL type and that the cellular response to these NR-AL-coronas (NR-AL-ES) is both ligand and corona dependent. We also find that the presence of common cell culture supplement penicillin/streptomycin can impact the colloidal stability and cellular response of NR-AL and NR-AL-ES, showing that the cell response is not necessarily inert to pen/strep when in the presence of nanoparticles. Although the protein corona is what the cells see, the underlying surface ligands evidently play an important role in shaping and defining the physical characteristics of the corona, which ultimately impacts the cellular response. Further, the results of this study suggest that the cellular behavior toward NR-AL is mediated by not only the type of AL and the protein corona it forms but also its resulting colloidal stability and interaction with cell culture supplements.

Peptoids are synthetic molecules that share structure with peptides, but bear side groups on the backbone nitrogen. They are protease resistant and relatively cheap to synthesize. Since many amines can form peptoid side groups, peptoids are more diverse than peptides and can take on various shapes, making them good B cell epitopes or haptens. We aim to develop peptoid-based vaccines by screening on-bead peptoid libraries we have made with broadly neutralizing monoclonal antibodies against pathogens. Resulting peptoids can be attached to carrier proteins (which provide T cell epitopes) to elicit antibodies that should mimic the screening antibody. To test the immunogenicity of peptoid haptens, we generated the first affinity-purified anti-peptoid antibody by immunizing rabbits with a peptoid linked to a carrier and adsorbed to an adjuvant, alum. Antibodies were produced against the hapten, carrier and linker. After affinity purification, an enzyme-linked immunosorbent assay demonstrated a robust, specific response against the peptoid. This vaccine platform will now be applied using broadly neutralizing monoclonal antibodies against West Nile and hepatitis C viruses, mouse norovirus-1 and HIV. Candidate peptoids will be tested for the ability to induce neutralizing antibodies against the pathogen. If successful, this platform could be applied to any pathogen for which a broadly neutralizing monoclonal antibody is available, without structural knowledge of the native epitope.

We form coronas of serum proteins on gold nanorods (NRs) coated with cetyltrimethylammonium bromide (CTAB). These coronas can be exploited for their ability to hold small molecular therapeutics at a capacity much higher (~5-10×) than what covalent conjugation strategies can achieve. Coronas are loaded with DNA oligonucleotides and Doxorubicin, showing that they can hold species of either negative or positive charge. Payload capacity varies with assembly strategy, ionic strength, and loading concentration. Payload release can be achieved by increasing the temperature or by ultrafast laser excitation of the NRs at their longitudinal surface plasmon resonance. DNA leakage from the corona is minimal within the first 3 days of preparation, although Dox leakage was more significant. The coronas also stabilize the NRs in buffer and biological media. This study demonstrates the biological utility of the protein corona around nanomaterials, contrasting the common view of the corona as an undesirable biological response.