Surface initiated polymerizations yield covalently bonded polymer on the substrate. The properties of such nanoparticles are unique finding a wide range of applications. This article reviews the different techniques of synthesis of these hybrid nanoparticles and their mechanistic approach presented in literature.

A novel reversible addition fragmentation technique chain transfer agent (RAFT CTA) was synthesized which permits the possibility of using RAFT polymerization and click chemistry together for surface modification. Using this RAFT CTA, the surface of silica nanoparticles was modified with polystyrene and polyacrylamide brushes via the "grafting to" approach. A click reaction was used to attach polymers onto the surface which produced relatively high grafting density. Both tethered polystyrene and polyacrylamide chains were found in the brush regime. The combination of ATRP and click chemistry was also explored for surface modification. To our knowledge, this is first report of RAFT polymerization and click chemistry together for surface modification.

Highlights d Sister chromatids contain asymmetric levels of CID in male Drosophila GSCs d Mother and daughter centrosomes sequentially nucleate microtubules d Asymmetric centrosomes preferentially attach to microtubules (MTs) d Centromeres and MTs coordinate to mediate non-random sister chromatid segregation

PS grafted silica nanoparticles have been prepared by a tandem process that simultaneously employs RAFT polymerization and click chemistry. In a single pot procedure, azide‐modified silica, an alkyne functionalized RAFT agent and styrene are combined to produce the desired product. As deduced by thermal gravimetric and elemental analysis, the grafting density of PS on the silica in the tandem process is intermediate between analogous “grafting to” and “grafting from” techniques for preparing PS brushes on silica. Relative rates of RAFT polymerization and click reaction can be altered to control grafting density.magnified image

SUMMARY Many stem cells undergo asymmetric division to produce a self-renewing stem cell and a differentiating daughter cell. Here we show that, similarly to H3, histone H4 is inherited asymmetrically in Drosophila melanogaster male germline stem cells undergoing asymmetric division. In contrast, both H2A and H2B are inherited symmetrically. By combining superresolution microscopy and chromatin fiber analyses with proximity ligation assays on intact nuclei, we find that old H3 is preferentially incorporated by the leading strand whereas newly synthesized H3 is enriched on the lagging strand. Using a sequential nucleoside analog incorporation assay, we detect a high incidence of unidirectional replication fork movement in testes-derived chromatin and DNA fibers. Biased fork movement coupled with a strand preference in histone incorporation would explain how asymmetric old and new H3 and H4 are established during replication. These results suggest a role for DNA replication in patterning epigenetic information in asymmetrically dividing cells in multicellular organisms.