Engineering of blended nanoparticle platform for cellular uptake improvement

Abstract

Over the past decades, a targeted delivery system based on the polymeric nanoparticles (NPs) gain much interest in cancer therapy. The development of new NPs that can deliver drugs at a controllable rate directly to cancer cells could potentially improve the efficacy and reduce the toxicity. However, one of the major barriers of these NPs is their relatively low cellular uptake and poor penetration into the tumor site. To address this problem, we have designed a novel nanoparticulate system by blending two types of polymers; poly(lactic-co-glycolic acid) (PLGA) and poly(glycerol) adipate conjugated with triphenylphosphonium cation (TPP-PGA). Cationized triphenylphosphonium cation or TPP was introduced to the system as a moiety to increase penetration and cellular uptake. In order to obtain TPP-PGA, the PGA was grafted with 10 mol% TPP using a carbodiimide coupling reaction. The success in grafting of TPP along the polymer backbone was confirmed via Fourier-transform infrared spectroscopy (FT-IR) and Nuclear magnetic resonance (NMR) spectra. To prepare the NPs, nanoprecipitation method was used. The fluorescence probe, rhodamine B and coumarin-6 were used to represents hydrophilic and lipophilic drug molecules, respectively. Five ratios of blended PLGA and TPP-PGA (PLGA:TPP-PGA) polymers were prepared at the ratio of (70:30), (80:20), (90:10) and (100:0). It is worth to note that PLGA:TPP-PGA(100:0) NPs were the NPs prepared solely by PLGA. The hydrodynamic diameter and zeta potential of prepared NPs were observed using a Zetasizer nano ZS. Particle morphology was observed using Scanning Electron Microscopy (SEM). The NPs diameters were in the range between 117-215 nm with low polydispersity index. The smallest size of NPs was prepared using PLGA:TPP-PGA(100:0) blended ratio. According to the surface charge, PLGA:TPP-PGA(100:0) NPs had negative surface charge. When the ratio of TPP-PGA in blended polymers was increased, NPs with the positive surface charge were obtained. The cellular uptake (in vitro) was conducted in SaOS-2 cells using flow cytometry and confocal microscopy. Cytotoxicity test was conducted using MTT. Increasing ratio of TPP-PGA in blended polymers resulted in an increase in the cellular uptake. NPs made from PLGA:TPP-PGA(70:30) showed highest cellular uptake nevertheless these NPs also showed the highest cell toxicity. In this study, a new NPs system made by blending PLGA with TPP-PGA was more readily taken up by SaOS-2 cells. These particles have potential to be used as a prototype for targeting delivery in cancer therapy.