Towards a Multi-Stage Drug Delivery System

Towards a Multi-Stage Drug Delivery System 

Recent studies have shown that the hemodynamics within cancer lesions constitutes another type of barrier to particle localization [21]. Delivery vehicles of different shapes and sizes can offer a dramatic increase in therapeutic index, by optimizing their properties of margination, extravasation, firm adhesion to the vascular endothelium and control of phagocytic uptake. 

Figu re n.15 (a) pH-responsive particles (blue) retain their payload while in the normal circulation. At the site of the tumor lesion, the characteristic enlarged fenestrations (leaky vessels) favor extravasation of the particles into the tumor tissues. After diffusion and penetration into the tumor mass, the 

The nature of these biological barriers is sequential, and a delivery vector requires 

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