The capability of our newly developed DNA-machine-driven strategy in tuning the association rate of DNA-AuNPs was compared with that of linker-addition strategy which has potential practical applications in different fields. The new established strategy shows its superiority to the linker-addition strategy in tuning the association rate of DNA-AuNPs in both pre-incubation treatment and non-incubation treatment conditions since its two components (a complex and a catalyst-oligonucleotide) can be individually optimized to make the machine run at an optimal rate. This strategy will provide a more convenient and flexible option in designing an oligonucleotide detection system and building a complex and versatile device.
Reaction pathways for the formation of thiolate-gold nanoparticles are investigated by density functional theory(DFT) and a new mechanism upon solvent polarity and tetraalkylammonium is obtained. In solvents with high polarities, [Au(I)SR]n polymers can be formed as the precursor of metal ions prior to the addition of a reducing agent; while a product of [Cl···AuCl(HSR)] is identified as the precursor in solvents with low polarities, such as toluene and chloroform.In addition, tetraalkylammonium also has an obvious effect on the reactions when it is used as a phase transfer agent in the two-phase synthesis. These findings offer a systematic analysis on the pathways to thiolate-stabilized nanoparticles and give a favorable explanation by comparison with those in an experimental system.
By controlling the feed ratio of CMS/styrene and the polymerization time, a series of hyperbranched copolystyrenes(HBCPS) were synthesized with comparable weight-averaged molecular weights(Mw) but different degree of branching(DB) through atom transfer radical self-condensing vinyl copolymerization(ATR-SCVCP) with Cu Br/2,2?-bipyridyl as the catalyst. The resulting HBCPS samples were used to investigate the effect of branching architecture on their glass transition behavior. With the DB increased, the glass transition temperatures(Tg) of HBCPS samples measured by DMA and DSC both decreased. Their spin-lattice relaxation times(1H T1r) of protons displayed the same downtrend with increasing DB. Besides, a correlation between the Tgs and the DB was well established by all-atom molecular dynamics(MD) simulations. The values of MD-determined Tgs are little higher than the corresponding experimental ones. However, the dependence of Tgs on DB is in good agreement with the experimental results, i.e., Tg decreases both in experiments and simulations with increasing DB.
