Double Imprinted Nanoparticles for Sequential Membrane-to-Nuclear Drug Delivery

Nanoparticles functionalized with specific receptors (e.g., antibodies, peptides) are used for targeted drug delivery of anti-cancer agents but their side effects include hypersensitivity reactions, toxicity, inflammation, and life-threatening allergic reactions (Anaphylaxis) [1,2]. Consequently, double imprinted molecularly imprinted nanoparticles (nanoMIPs) against a linear epitope of breast cancer cell receptor estrogen alpha (ERα) and loaded with an anti-cancer agent (doxorubicin, DOX) are synthesized via a solid-phase approach. Surface plasmon resonance (SPR) measurements reveal that the produced nanoMIPs exhibit KD values of 19 nM (against the epitope used for imprinting) and 10 nM (ERα receptor), and thus rival the affinity of nanoparticles decorated with natural affinity reagents (e.g., antibodies, peptides), whilst offering the advantages of low-cost and enhanced cellular uptake due to the receptor mediated endocytosis. We present the results of in vitro flow cytometry that DOX loaded nanoMIPs can preferentially bind to MCF-7 (ERα positive) breast cancer (BC) cells vs MDA-MB-231 (ERα negative) BC cells. Confocal imaging witnessed the above results and showed the sequential movement of the DOX loaded nanoMIPs from membrane to the nucleus of MCF-7 BC cells and achieve delivery of DOX once internalised in the cells (directly to the nucleus). As a result, enhanced cell toxicity in MCF-7 cells (∼80%) as compared to MDA-MB-231 cells (∼15%) is observed via MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) cytotoxicity assay in a time dependent manner. Overall, this study provides a promising approach for the targeted drug delivery of chemotherapeutic drugs to breast cancer cells, which has the potential to significantly improve patient outcome whilst also reducing debilitating side effects of current treatment.