10-Hydroxycamptothecin （HCPT） is a broad-spectrum anticancer drug, while its low solubility and instability severely limit its application. In this study, HCPT nanosuspension （HCPT-NSP）, also known as nanocrystal, was prepared by micro-precipitation combined with high-pressure homogenization method. This nanosuspension was characterized by size, shape, zeta potential, drug loading efficiency and in vitro drug release behavior. Preferred formulation and process showed that particle size was （129.8±13.9） nm, PDI was 0.20±0.07, and drug loading efficiency was 36.5%±9.5%. Moreover, HCPT nanocrystal concentration reached （1.35±0.2） mg/mL in HCPT-NSP, which was more than 1000-fold higher than that of HCPT. Transmission electron microscopy （TEM） results showed that the nanosuspension was short rod in shape. X-ray powder diffraction （XRD）, thermogravimetric analysis （TGA）, derivative thermogravimetric analysis （DTA） and differential scanning calorimetry （DSC） further elaborated the crystal state of the HCPT. The drug concentration-time curve of HCPT-NSP in rats was in accordance with the three-compartment model, showing prolonged half-life. Taken together, our data suggested that HCPT-NSP was a promising drug delivery system.
The epidemiological statistics reveals the striking patterns of cancer in women and highlights the need for novel therapeutic strategies. In this work, mesoporous silica nanoparticles（MSNs） as representative of inorganic nanoparticles were prepared for loading si RNA that plays a role of gene silencing to treat breast carcinoma（MCF-7） cells. The critical processes of synthesis were optimized for the nanoparticles with desired quality attributes that have the enlarged pores for elevated loading capacity. After si RNA loading into mesoporous, crosslinked-polyethylenimine was employed as the cap to coat the enlarged MSN pores and protect the cargo from leakage. The elevated quantity of si RNA（35 μg si RNA/mg MSNs） were loaded in the MSNs. The as-synthesized MSNs were further evaluated on MCF-7 cells in vitro and shown negligible cytotoxicity. As expected, the si RNA loaded in the as-synthesized MSNs was readily internalized into MCF-7 cells and displayed 420 times higher intake than that of naked si RNA. The MSNs may be exploited to become an effective si RNA cell delivery strategy and further studied for the anti-tumor efficacy.
Multidrug resistance （MDR） operated by P-glycoprotein （P-gp） is one of the major causes in the treatment failure of cancers. In this work, docetaxel-loaded mixed micelles comprised of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy （polyethylene-glycol）2000 （DSPE-PEG2000）, D-α-Tocopherylpolyethylene glycol 1000 succinate （TPGSIooo） and DSPE-PEG2000-folate were developed to overcome MDR and reduce the side effect of docetaxel in cancer therapy. The diameters of micelles ranged from 13 to 26 nm and the encapsulation efficiencies were all above 85%. The influences of DSPE-PEG2000 and TPGSIooo ratios on the micellar characteristics and anti-resistant tumors effects were evaluated. Micelles with high TPGS1000 amount showed an increased cellular uptake and stronger cytotoxicity against MDR KBv cells. Moreover, the micelles modified by targeting ligand of folic acid exhibited better antitumor effect on folate receptor over-expressing KBv cells. The study provides a method for overcoming MDR in cancer therapy.
