Sheddable Coatings for Long-Circulating Nanoparticles

Nanoparticles, such as liposomes, polymeric micelles, lipoplexes and polyplexes are frequently studied as targeted drug carrier systems. The ability of these particles to circulate in the bloodstream for a prolonged period of time is often a prerequisite for successful targeted delivery. To achieve this, hydrophilic ‘stealth’ polymers, such as poly(ethylene glycol) (PEG), are used as coating materials. Such polymers shield the particle surface and thereby reduce opsonization by blood proteins and uptake by macrophages of the mononuclear phagocyte system. Yet, after localizing in the pathological site, nanoparticles should deliver their contents in an efficient manner to achieve a sufficient therapeutic response. The polymer coating, however, may hinder drug release and target cell interaction and can therefore be an obstacle in the realization of the therapeutic response. Attempts have been made to enhance the therapeutic efficacy of sterically stabilized nanoparticles by means of shedding, i.e. a loss of the coating after arrival at the target site. Such an ‘unmasking’ process may facilitate drug release and/or target cell interaction processes. This review presents an overview of the literature regarding different shedding strategies that have been investigated for the preparation of sterically stabilized nanoparticulates. Detach mechanisms and stimuli that have been used are described

Dynamic Scoring through Creative Destruction

Abstract: We examine the dynamic feedback effects of fiscal policies on the government budget and economy activity in a calibrated general equilibrium framework featuring endogenous growth through creative destruction. For several European countries, we find that making tax incentives with respect to research effort more generous is the least costly way, in terms of the impact on the government budget, to promote economic growth. It is almost three times as cost effective as lowering the tax rate on capital income. When non-distorting financing options are excluded, adjusting the consumption tax to finance more generous tax incentives for research effort leads to the smallest loss in economic efficiency and the largest welfare gain.