Improving the therapeutic efficacy and reducing systemic side effects of drugs is an important aspect in chemotherapy. The strategy presented here is the use of cisplatin loaded, temperature-sensitive, hydrogel nanoparticles (CisPt-NPs) and their ability to deliver and release chemodrugs selectively, based on thermal stimuli. The specially synthesized CisPt-NPs show a temperature-dependent increase of cisplatin release, at neutral pH (as in blood and normal tissue), in both the presence and absence of common metallic ions, as well as at the low pH found in lysosomes, where endocytosed NPs often localize. These CisPt-NPs were uptaken by breast cancer MDA-MB-435 cells, via endocytosis, and then mostly localized in the lysosomes. The in vitro cytotoxicity tests show that these CisPt-NPs have a significantly better efficacy at the slightly elevated temperatures. Potential applications are discussed.

Addition of polyethylenimine into drug loaded hydrogel nanoparticle leads to enhanced cellular uptake, better ability to control drug release and deliver drugs to the cytosol, while evading the endosomes.

The use of a nanoparticle (NP)-based antitumor drug carrier has been an emerging strategy for selectively delivering the drugs to the tumor area and, thus, reducing the side effects that are associated with a high systemic dose of antitumor drugs. Precise control of drug loading and release is critical so as to maximize the therapeutic index of the NPs. Here, we propose a simple method of synthesizing NPs with tunable drug release while maintaining their loading ability, by varying the polymer matrix density of amine- or carboxyl-functionalized hydrogel NPs. We find that the NPs with a loose matrix released more cisplatin, with up to a 33 times faster rate. Also, carboxyl-functionalized NPs loaded more cisplatin and released it at a faster rate than amine-functionalized NPs. We performed detailed Monte Carlo computer simulations that elucidate the relation between the matrix density and drug release kinetics. We found good agreement between the simulation model and the experimental results for drug release as a function of time. Also, we compared the cellular uptake between amine-functionalized NPs and carboxyl-functionalized NPs, as a higher cellular uptake of NPs leads to improved cisplatin delivery. The amine-functionalized NPs can deliver 3.5 times more cisplatin into cells than the carboxyl-functionalized NPs. The cytotoxic efficacy of both the amine-functionalized NPs and the carboxyl-functionalized NPs showed a strong correlation with the cisplatin release profile, and the latter showed a strong correlation with the NP matrix density.