Cationic versus anionic core-shell nanogels for transport of cisplatin to lung cancer cells

Stimuli-responsive polymeric nanogels have been proposed as nanocarriers of cisplatin to maximize its effect for cancer treatment. In this work, a comparative study between anionic core nanogels (ACN) and cationic core nanogels (CCN), both with PEGylated shells, has been performed. The nanogels were synthesized with different cross-linked cores: CCN with poly(N,N-diethylaminoethyl methacrylate) (PDEAEMA) and ACN with poly(2-methacryloyloxi benzoic acid) (P2MBA). Cisplatin chelate formation with carboxylic acids (ACN) or metal coordination with the amine groups (CCN) leads to a high loading of cisplatin into the nanocarriers. The nanocarriers ability to contain and modulate the supply of cisplatin was tested according to the pH of the medium, in which ACN efficiently released the drug at a typical pH value of a tumor tissue (pH = 6.8) while CCN only releases the drug at more acidic, endosome like, conditions (pH = 5). The effect of drug-free nanogels on cell lines NCI-H1437 (non-small cell lung carcinoma) was evaluated, showing biocompatibility at all concentrations studied (30-400 μg/mL) for both ACN and CCN. However, the survival percentage of the cells in contact with cisplatin-loaded nanogels were dependent on the dose, the time of contact and the type of nanogel. Cisplatin loaded CCN induced lower cell viability after 48 h of contact. Fluorescence microscopy showed a viable internalization of the CCN nanogels, this was confirmed by flow cytometry in which 37.8% of cells contained drug loaded CCNs after 30 min of contact, representing a more effective nanocarrier for cisplatin to this cell-line.