Synthesis, characterization and applications of peptide-coated nanoparticles

Ovarian Cancer (OC) is the most lethal female malignancy worldwide, mainly due to its high recurrence rate and poor diagnosis. Most patients present with late stage of the disease, and less than 25% of patients survive the five years mark. Nanotherapy provides significant and unique benefits for drug efficacy, as nanoparticles (NPs) can increase the solubility, bioavailability, and permeability of many potent drugs. Poly(lactic-co-glycolic acid) (PLGA) is one of the most successful biodegradable polymers used in NPs formulations, mainly due to its biocompatibility and biodegradability. Polyethylene glycol (PEG) is one of the most commonly used moieties to prolong the NPs stability in serum. However, studies have shown that the presence of PEG may hinder the NP-cell interactions resulting in minimal NPs uptake by the cells. Herein, we demonstrate a novel strategy to stabilize NPs, by using short peptides instead of PEG. Peptides provide NP stabilization via self-assembly of (phenylalanine- phenylalanine- phenylalanine) FFF motif on the NPs surface, and active tumor/vasculature targeting through v targeting motifs. This thesis describes NPs with three different peptide coatings: 1) RGDFFF to target vasculature via RGD, 2) NGRFFF to target vasculature NGR, and 3) EKHFFF to target low pH of the tumor via isoelectric point of the peptide. Chapter 1 presents the synthesis and characterization of peptide-coated NPs. The NPs were synthesized via a nanoprecipitation method, which is simple, cost-effective, and easily scalable. Also, fluorescent peptide-coated NPs were synthesized, where the PLGA polymer was chemically modified with Cy5.5 fluorophores, to facilitate biological imaging. The NPs are spherical in shape, with diameters: 99.6 ± 9.3 nm, 72.8 ± 2.2 nm, and 111 nm ± 8.0 corresponding to EKHFFF, RGDFFF, and NGRFFF NPs, respectively, and are stable in serum. The peptide coating of the NPs was confirmed using electron microscopy and spectroscopy techniques. Chapter 2 presents the biological characterization of peptide-coated NPs. Selective vasculature/tumor targeting of the NPs has been confirmed in Human Umbilical Vein Endothelial Cells (HUVEC), immortalized human ovarian surface epithelial cells (IOSE), and OC cell lines using flow cytometry and confocal imaging. Notably, in order to better reflect the original tumor characteristics, the uptake of NPs has also been assessed in eight different patient-derived cell lines (PDCLs). Results show that the uptake of NGRFFF and RGDFFF NPs are cell-dependent, while cellular uptake of EKHFFF NPs showed more than 94% percent positivity for all eight PDCLs. In addition, the biosafety of peptide-coated NP platform was evaluated using viability, reactive oxygen species (ROS), and nitric oxide (NO) assays. vi Chapter 3 presents encapsulating of two different therapeutics, namely lonidamine (LND) and Genistein, into peptide-coated NPs. The following formulations were prepared: EKHFFF-LND and NGRFFF-Genistein NPs. TEM imaging confirmed the spherical shape and presence of peptide shells on the drug loaded NPs. The preliminary studies of biological activity of the NPs revealed the increased efficacy of EKHFFF-LND NPs when compared to LND alone, and suitability of the LND and Genistein for incorporating into Pt (II) therapy regimen, which is a golden standard in OC treatment