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Abstract: One barrier to the application of current tri-octylphosphine oxide (TOPO) based quantum dots (QDs) for biomedical imaging is that the TOPO on TOPO-QDs can be replaced by the proteins in living system, which may cause the degradation of QDs and/or deactivation of protein. In order to develop biocompatible optical imaging agents, a novel triblock copolymer, designed as a multidentate ligand, was synthesized to coat quantum dot nanocrystals (QDs). The copolymer consists of a polycarboxylic acid block at one end and a polythiol block at the other end with an intervening cross-linked poly(styrene-co-divinylbenzene) block bridging the ends. The multiple mercapto groups from the polythiol block act as multidentate ligands to stabilize QDs, while the polycarboxylic acid block improves the water solubility of QDs and offers reaction sites for surface modification or conjugation with bimolecules. The cross-linked poly(styrene-co-divinylbenzene) block provides a densely compacted hydrophobic shell. This shell will act as a barrier to inhibit the degradation of QDs by preventing the diffusion of ions and small molecules into the core of QDs. This new multidentate polymer coating facilitates the transfer of QDs from organic solvent into aqueous phase. The QDs directly bound to multidentate mercapto groups instead of TOPO are less likely to be affected by the mercapto or disulfide groups within proteins or other biomolecules. Therefore, this research will provide an alternative coating material instead of TOPO to produce QDs which could be more suitable for in vivo use under complex physiological conditions. [ABSTRACT FROM AUTHOR]

5-(N-pyrrolyl)pentanethiol modified monolayer protected gold clusters (PPT-MPCs) have been synthesized and characterized by FT-IR, 1H-NMR, UV–vis spectra, Transmission electron microscopy (TEM), elemental analysis, XPS, cyclic voltammetry, and TGA. PPT-MPCs have been successfully cross-linked by chemical oxidation of the pyrrole units that confined to the surface of gold nanoparticles in the solution as well as in the form of monolayer. In comparison with as-prepared PPT-MPCs, oxidized PPT-MPCs from solution shows different mass loss behavior and electrical conductivity. The oxidation PPT-MPCs monolayer performed in the LB trough results in a red shift of surface plasmon absorption (∼10 nm) by comparing with that of the PPT-MPCs monolayer. [Copyright &y& Elsevier]