The formulation of hybrid nanoparticles based on synthetic polymer-protein hybrid matrices for the targeted release of proteic drugs with antiviral activity such as a-interferon was investigated. Human serum albumin, alone, or in combination with myoglobin, and the hemiesters of alternating copolymers of maleic anhydride/alkyl vinyl ethers of oligo(ethylene glycol) were selected as proteic and synthetic components, respectively. Digalactosyl diacyl gycerol, a natural glycolipid selectively recognized by the asialofetuin receptor was used for the active targeting of liver hepatocytes. Nanoparticle suspensions were prepared either by slow solvent evaporation from biphase and triphase emulsions or by controlled coprecipitation. Nanoparticles, 0.1-0.3 gm in diameter, were obtained by the latter method, whereas the former one afforded heterogeneous micro and nanoparticle mixtures. Several techniques were tested to separate the nanoparticle dispersions from the suspending solution. The best results, in terms of a homogeneous distribution of mostly spherical nanoparticles, were obtained by centrifugation in the presence of modified cyclodextrins. After lyophilization of supernatant, the resulting fluffy powder was easily resuspendable in water.
Significant efforts are being devoted to develop nanotechnology for drug delivery, mainly because of the distinct advantages offered by nanometer-size polymeric systems. Moreover, targeted drug delivery can be obtained by polymer conjugation to biospecific ligands. The present investigation was aimed mainly at determining the targeting ability of hybrid nanoparticles based on synthetic polymer/protein hybrid matrices. These nanoparticles were designed for liver targeted release of proteic drugs with antiviral activity, such as alpha-interferon. Human serum albumin and the monoesters of alternating copolymers of maleic anhydride/alkyl vinyl ethers of oligo(ethylene glycol) were selected as proteic and synthetic components, respectively. Digalactosyl diacyl glycerol, a natural glycolipid selectively recognized by the asialofetuin receptor present on liver hepatocytes was used as active targeting agent. Nanoparticles of 100-300 nm average size were obtained by controlled coprecipitation method. Investigation of nanoparticle surface properties by spectroscopic analysis and by biological tests indicated that the synthesized nanoparticles do expose on their surface targeting moieties that selectively interact with liver hepatocytes receptors.
Aus den optisch aktiven Alkoholen (I) erhält man durch Reaktion mit PBr3/Pyridin die Alkylbromide (II), die mit Thioharnstoff (III) in Wasser zu den Isothiuroniumsalzen (IV) reagieren.
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