8/2/2012 · Citrate Synthesis of Gold ..
since small nanoparticles of gold are red
Targeting moieties are classified as proteins (mainly antibodies and their fragments), peptides, nucleic acids (aptamers), small molecules, or others (vitamins or carbohydrates). Although monoclonal antibodies (mAbs) have been widely used as escort molecules for the targeted delivery of nanoparticles, several limitations including large size and difficulty in conjugation to nanoparticles have hampered their uses. Thus, other smaller-sized ligands including peptides have attracted greater attention these days. This section will discuss the types of targeting moieties that may be used for decorating multifunctional nanoparticles, as well as their potential benefits and drawbacks.
Small Gold Nanoparticles Synthesized with Sodium Citrate ..
Wei and Gao used a single chain anti-prostate stem cell antigen (PSCA) antibody (scAbPSCA) as a specific 'address tag' for prostate cancer targeted imaging and therapy . Prostate stem cell antigen is a prostate-specific glycosyl phosphatidylinositol-anchored glycoprotein that is marginally expressed in normal prostate and overexpressed in prostate cancer tissues . As shown in Figure A, the scAbPSCA was prepared by cleaving intact AbPSCA with mercaptoethylamine (MEA), followed by linking to maleimide-PEG-carboxyl (MAL-PEG-COOH) and covalent conjugation to multifunctional polymeric vesicles that had been formed by the entrapping of superparamagnetic iron oxide (SPIO) nanoparticles and docetaxel (Dtxl) by amine-terminated poly(lactic-co-glycolic) acid. The scAbPSCA-Dtxl/SPIO-NPs were 147 nm in size, as determined by dynamic light scattering (DLS), and the amounts of SPIOs and Dtxl in the polymer matrix were 23 wt% and 6.02 wt%, respectively. The high drug encapsulation efficiency was due to partitioning of Dtxl into the oleic acid and oleylamine shell of the SPIOs, which acted as a drug reservoir, thereby exhibiting a triphasic drug release pattern rather than the common two-phase kinetic release pattern, including burst effects of an initial release stage, as observed in vesicles without SPIOs. An cytotoxicity study demonstrated the antiproliferative effects of the multifunctional vesicles toward prostate cancer cells. As indicated in Figures B and C, PC3 cells incubated with scAbPSCA-Dtxl/SPIO-NPs produced distinct darkened regions in the T2-weighted MRI compared to the polymeric vesicles without scAbPSCA or Endorem® (a commercial contrast, Guerbet, France). This result demonstrated that the scAbPSCA-Dtxl/SPIO-NPs could be used as MRI contrast agents for prostate-targeted imaging and real-time monitoring of therapeutic effects.