The fluorescence intensity of the ECCNSs and etoposide is in agreement with the results from CLSM images. Figure 10 SGC- 7901 cells were treated with 30 μg /mL etoposide in two forms of ECCNSs (f, g, and h) and void etoposide (b, c, and d). As the plots show, the number of events (y-axis) with high fluorescence intensity (x-axis) increases

by 4-h incubation with ECCNSs but without any evident change for void etoposide. Negative control (a and e) includes nontreated cells to set their auto-fluorescence as ‘0’ value. Controlled FK228 ic50 delivery of drug using carrier materials is based on two strategies: active and passive targeting. The former is technical sophisticated and suffering from many difficulties. Otherwise, the latter is easier to implement practically [46]. Many formulations have been used in the representative passive-targeting strategies based on the EPR effect [47]. Tumor vessels are often dilated and fenestrated due to rapid formation of vessels that can serve the fast-growing tumor while normal tissues contain capillaries with tight junctions

that are less permeable to nanosized particle [11, 48]. The EPR effect is that macromolecules can accumulate in the tumor at concentrations five to ten times higher than in normal tissue within 1 to SCH727965 purchase 2 days [49]. Besides, biomaterials with diameters more than 100 nm tend to migrate toward the cancer vessel walls [50]. Therefore, the EPR effect enables ECCNSs Vildagliptin (secondary nanoparticles) to permeate the tumor vasculature through the leaky endothelial tissue and then accumulate in solid tumors. On one hand, the uptake of ECCNSs by tumor cells can lead to the direct release of etoposide into intracellular environment to kill tumor cells.

On the other hand, the pH-sensitive drug release behavior for ECCNSs may lead to the low release of etoposide from ECCNSs in pH neutral blood, and the rapid release of the drug in relatively acidic extracellular fluids in the tumor. In this way, the targeted delivery of etoposide to tumor tissues may be possible by ECCNSs. Referring to some previous reports [51, 52], the possible mechanism for the targeted delivery of the ECCNSs is illustrated in Figure 11. Most of the biodegradable ECCNSs decompose into the secondary nanoparticles in the vicinity of the tumor endothelium, with the release of epotoside. The small therapeutic nanoparticles and drugs readily pass through the endothelia into tumor tissues for efficient permeability [53]. The degradation of the materials in the endosomes or lysosomes of tumor cells may determine the almost exclusive internalization along clathrin-coated pits pathway. The multistage decomposition of ECCNSs in blood vessels or tumor tissue is likely to play a key role in determining their targeting and biological activity [54]. Figure 11 A representative illustration of ECCNSs targeting.