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Conventional therapy regimens for pancreatic cancer (PC) are surgical resection and systemic gemcitabine based chemotherapy. Recent studies showed that curcumin could potentiate the anticancer effect of gemcitabine in PC. However, due to its poor water solubility, effective bioavailability of curcumin is insufficient, resulting in poor efficacy. To address this issue, mesoporous silica nanoparticles (MSN) were prepared by the sol–gel method, then loaded with curcumin (Cur), coated with polyethylene glycol (PEG), and finally conjugated with the targeting moiety transferrin (Tf) to target human PC cells. TEM analysis revealed that uniform sized spherical MSN formed with an average size of 100 nm, which increased to 120 nm after PEG coating on MSN surface. Confocal microscopy proved that curcumin uptake being seven-times higher for MSN–NH2–Cur–PEG–Tf, when compared to free curcumin. The in vitro cytotoxicity study on MIA PaCa-2 cells showed that MSN–NH2–Cur–PEG–Tf exhibited three-fold higher cytotoxicity than free curcumin. On the basis of the encouraging in vitro cytotoxicity results obtained, preclinical assessment of antitumor efficacy in MIA PaCa-2 subcutaneous xenograft model proves that both MSN–NH2–Cur–PEG and MSN–NH2–Cur–PEG–Tf inhibit tumor growth and minimize distant metastasis to major organ sites. The in vitro studies also proved that nanoparticles can enhance the sensitization effect, caused by curcumin on cancer cells, which help the gemcitabine to kill a higher percentage of cancer cells. Hence, we propose that transferrin targeted, PEGylated, mesoporous silica nanoparticles can be used as a carrier to deliver curcumin, and used in addition to gemcitabine to reduce disease burden significantly for pancreatic cancer patients.

Superior delivery of anticancer drug gemcitabine has been achieved with mesoporous silica nanoparticles (MSN), by addressing three challenges in MSN synthesis: (i) MSN was synthesized with particle diameter between 42 to 64 nm, to utilize enhanced permeability and retention effect of small particles, (ii) MSN of larger internal pore diameter (2.5–5.2 nm) was made as a tunable morphological parameter to optimize both drug loading and its release rate, in a controlled, differential manner and (iii) higher drug release at extracellular cancer-cell pH (5.5) was achieved, compared to physiological pH (7.4) of healthy cells. MSN with above features was made by the sol–gel route, with trimethylmethoxysilane as a size-quencher and hexane or decane as a pore expander. Highest gemcitabine loading of 14.92% and a cumulative release of 58% at pH 5.5 could be obtained with the optimum sample having pore diameter of 5.2 nm, in comparison to the desirably low 22% release at pH 7.4. Consequently, we obtained 60% cell growth-inhibition of pancreatic cancer cell-line (MIA Paca-2), via gemcitabine loaded MSN. This was possible because of increased gemcitabine release from MSN with larger pore diameter of 5.2 nm, simultaneously demonstrating good target-selectivity of MSN as a drug-carrier, due to engineering of its pore-size.

Localized binding of nanoparticulate formulation, actively targeting the receptors present on the cell surface.

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