Effects of Surface Charge of Hyperbranched Polymers on Cytotoxicity, Dynamic Cellular Uptake and Localization, Hemotoxicity, and Pharmacokinetics in Mice

Abstract

Nanoscaled polymeric materials are increasingly being investigated as pharmaceutical products, drug/gene delivery vectors, or health-monitoring devices. Surface charge is one of the dominant parameters that regulates nanomaterial behavior in vivo. In this paper, we demonstrated how control over chemical synthesis allowed manipulation of nanoparticle surface charge, which in turn greatly influenced the in vivo behavior. Three methacrylate/methacrylamide-based monomers were used to synthesize well-defined hyperbranched polymers (HBP) by reversible addition-fragmentation chain transfer (RAFT) polymerization. Each HBP had a hydrodynamic diameter of approximately 5 nm as determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Incorporation of a fluorescent moiety within the polymeric nanoparticles allowed determination of how charge affected the in vivo pharmacokinetic behavior of the nanomaterials and the biological response to them. A direct correlation between surface charge, cellular uptake, and cytotoxicity was observed, with cationic HBPs exhibiting higher cellular uptake and cytotoxicity than their neutral and anionic counterparts. Evaluation of the distribution of the differently charged HBPs within macrophages showed that all HBPs accumulated in the cytoplasm, but cationic HBPs also trafficked to, and accumulated within, the nucleus. Although cationic HBPs caused slight hemolysis, this was generally below accepted levels for in vivo safety. Analysis of pharmacokinetic behavior showed that cationic and anionic HBPs had short blood half-lives of 1.82 ± 0.51 and 2.34 ± 0.93 h respectively, compared with 5.99 ± 2.30 h for neutral HBPs. This was attributed to the fact that positively charged surfaces are more readily covered with opsonin proteins and thus more visible to phagocytic cells. This was supported by in vitro flow cytometric and qualitative live cell imaging studies, which showed that cationic HBPs tended to be taken up by macrophages more effectively and rapidly than neutral and anionic particles.

Investigation of the Therapeutic Potential of a Synergistic Delivery System through Dual Controlled Release of Camptothecin–Doxorubicin

“…[ 47 ] For example, less than 10% of CPT was released from HBP/CPT/DOX after 108 h at 2 × 10 −6 m GSH, which based on known pharmacokinetic profiles of similar nanomedicines indicates that release of CPT during blood circulation should be minimal under these conditions. [ 48,49 ] When the concentration of GSH was increased to 10 × 10 −3 or 40 × 10 −3 m , the rate of release of CPT from HBP/CPT/DOX significantly increased to be almost quantitative for the higher GSH concentration at 108 h.…”

“…Similar results were also reported for mixture of free DOX and free CPT, [ 11,54 ] and for ester/amide conjugates of DOX and CPT to hyaluronic acid. [ 48 ] The use of a combination of hydrolytic and redox release mechanisms for the drugs may provide more control over the release profile of drugs in the systems reported here owing to the chemistry used in these systems (compared to ester/amide linkages). To better understand the synergy of these treatments, drug combination isoboles for CPT‐HBP and DOX‐HBP were developed based on the ED50 values derived from Figure 2 as described by Tallarida, [ 55 ] and are reported in Figure S8 in the Supporting Information.…”

Lower-Sized Chitosan Nanocapsules for Transcutaneous Antigen Delivery

“…It is possible that the positive charge of this formulation has a bigger effect on cell viability than the negative charge of the NEs. It should be noted that this same charge gives CSNCs its adjuvant properties, and increases its cellular penetration and bioadhesiveness [ 43 ]. At 27.23 mg/mL both formulations showed lower viability on RAW 264.7, however, these high concentrations do not usually occur in in vivo conditions.…”

Recent advances on synthesis and biomaterials applications of hyperbranched polymers

“…Crosslinker 1 (Chen, Simpson, Fuchs, Rolfe, & Thurecht, 2017;Liu, Kazlauciunas, Guthrie, & Perrier, 2005) Crosslinker 2 (Gao, Tsarevsky, & Matyjaszewski, 2005) S C H E M E 1 Hyperbranched polymer architecture…”