Stealth characteristics

Nanoparticles are able to cross the Reticuloendothelial system (RES) due to their stealth characteristic that enhances the Enhanced Permeability and Retention (EPR) effect. An increased EPR aids in treating cancers and tumors. The nanocarriers produced by the nanoprecipitation technique had PACA core, stealth... 

The B-2 stealth bomber in Figure 1-38 is made by Northrop Grumman. Virtually all external parts are made of various composite materials because of their radar-absorption characteristics and/or their capability to be formed to shapes that naturally lower the radar cross section of the plane. However, the details are not publicly available, nor are they for the Lockheed Martin F-117A stealth fighter. 

Hydrophobically modified HA derivatives,91 obtained through the partial esterification of the HA carboxyl groups with methylprednisolone (45% in HYCp45 and 60% in HYCp60),92 have been deeply studied 93 A key point prior to any in vivo study of the biomaterial is the assessment of the so-called "stealth character" of the species itself. Such characteristic corresponds to be invisible towards the immune system, so that colloids are not recognized as foreign objects by body fluid components, as plasma proteins fibrinogen, BSA and lipidic components.94,95... 

In modern construction materials, such as the advanced composites from which the American Stealth bomber has been built, the subterfuge of invisibility is achieved in a different way. fl he characteristics of these materials permit the virtual elimination of an electronic signature resulting in near absence of a radar screen image. Coupled with extreme high speed and low altitude heneath-radar manoeuvrability, such vehicles can operate unseen. 

B. Shi, C. Fang, M. X. You, Y. Zhang, S. Fu and Y. Pei, Stealth MePEG-PCL micelles Effects of polymer composition on micelle physicochemical characteristics, in vitro drug release, in vivo pharmacokinetics in rats and biodistribution in S180 tumor bearing mice. Colloid Polym. Sci, 283, 954-967 (2005). 

As stated previously, pSi particles are targets for internalization by cells of the mononuclear phagocyte system, and stealthing with PEG delays their uptake. For third-generation delivery systems, the first level of targeting for intravascularly administered particulates is the vascular endothehum. In vitro, vascular endothelial cells are able to internalize micron-sized pSi particles by phagocytosis and macropinocytosis (R.E. Serda et al, unpublished results). This is more compHcated in vivo, where serum opsonization coats the microparticles and alters their ability to adhere to the vascular wall. In this section we describe cellular uptake of pSi nanoparticles and microparticles, and examine the characteristics of pSi microparticles which alter this phenomenon. 

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