Self-assembly of Gold Nanoparticle Chains between Nanoelectrodes

A novel strategy has been developed for construction of nanoparticle chains between nanoelectrodes with bifunctional molecules by taking advantage of linear aggregation of colloidal particles in organis solvents. As confirmed by scanning electron microscopy （SEM）,an individual nanoparticle chain bridged the electrode pair. The present approach makes this technique to be cheap and may be applicable in microelectronic industry.

A facile one-pot method to fabricate gold nanoparticle chains with dextran

A biocompatible water-soluble dextran has been used for controllable one-dimensional assembly of gold nanoparticles via a one-pot method. Long gold nanoparticle chains with good dispersion in water could be easily obtained after adding dextran in- to the mixture of HAuC14 and sodium citrate. The measurements of scanning electron microscopy （SEM） and dynamic light scattering （DLS） confirmed the formation of gold nanoparticle chains. The morphology and dispersion properties of gold na- noparticle chains could be tuned by adjustment of the reagent ratio, stirring speed, and reaction time.

Construction of CdS Nanoparticle Chain on DNA Template

Salmon sperm DNA was used as template to assembly and nucleate CdS nanoparticles. Transmission electron microscopy (TEM) images showed that the CdS nanoparticles formed unique nanostructure which present regular and parallel chains along DNA molecular chain. The width of every chain was about 3 nm. Raman and X ray photoelectron energy spectroscopy (XPS) confirmed that the nucleation sites of CdS nanoparticles were phosphate acid groups of DNA.

Superparticles Formed by Amphiphilic Tadpole-like Single Chain Polymeric Nanoparticles and Their Application as an Ultrasonic Responsive Drug Carrier

Herein, we report self-assembly of tadpole-like single chain polymeric nanoparticles （TPPs） and the ultrasonic response of the resultant superparticles. The TPPs are with an intramolecularly crosslinked poly（2-（methacryloyloxy）ethyl pent-4-ynoate）-rpoly（hydroxyethyl methacrylate） （PMAEP-r-PHEMA） chain as the ＂head＂ and a poly（2- （dimethylamino）ethyl methacrylate （PDMAEMA） linear chain as the ＂tail＂, and are pre- pared simply and emciently by Glaser-coupling of the pendant alkynes in the PMAEP-r- PHEMA block in the common solvent methanol. The formation of the TPPs was confirmed by gel permeation chromatograph, nuclear magnetic resonance spectroscopy, dynamic light scattering, static dynamic scattering, and transmission electron microscopy. In aqueous solution, the amphiphilic TPPs could self-assemble into regular superparticles, driven by aggregation of the hydrophobic ＂heads＂. Since in the structure there is no chain entanglement and the embedding of PDMAEMA chains disturb close-packing of the ＂heads＂, the superpartieles are responsive to a low-energy ultrasonic vibration, as evidenced by greatly enhanced release of the functional molecules from the superparticles by treatment of a low-energy ultrasound. Therefore, the superparticles should be very promising in the use as the drug carriers that can be manipulated from a long distance, considering that ultrasonic energy can be focused at a small area in a relatively long distance from the ultrasound-radiating source.

Merging non-covalent and covalent crosslinking:En route to single chain nanoparticles

Single-chain nanoparticles represent an emerging class of nanomaterials designed to mimic protein's folding paradigm.Intrachain covalent crosslinking toward the formation of single-chain nanoparticles encounters complex energy landscapes,leading to the potential occurrence of misfolding issues.While noncovalent crosslinking can circumvent this issue,the resulting single-chain nanoparticles exhibit lower structural stability compared to their covalently crosslinked counterparts.In this study,we present a novel approach for the synthesis of single-chain nanoparticles,achieved through the combination of non-covalent and covalent intramolecular crosslinking.Cyanostilbenes grafted onto the linear polymer form intrachain non-covalent stacks aided by hydrogen bonds,leading to the formation of non-covalently crosslinked single-chain nanoparticles.These nanoparticles undergo conversion to covalently crosslinked nanostructures through subsequent photo-irradiation using[2+2]photocycloaddition,a process facilitated by the supramolecular confinement effect.Consequently,the resulting single-chain nanoparticles demonstrate both intrachain folding efficiency and substantial stability,offering significant potential for advancing applications across diverse fields.

Hybridization chain reaction triggered controllable one-dimensional assembly of gold nanoparticles

Assembling and ordering nanomaterials into desirable patterns are considerably significant,since the properties of nanomaterials depend not only on the size and shape,but also on the spatial arrangement among the collective building blocks.In this work,the DNA self-assembly technology of hybridization chain reaction(HCR) provided a convenient method to yield long double-strand DNA(dsDNA) to install gold nanoparticles(AuNPs) into one dimensional assembly along the skeleton of dsDNA.Interestingly,the tunable length of AuNPs assemblies along dsDNA chain could be achieved by adjusting the reaction time of HCR,which is based on the formation of covalent bond between Au and the-SH group of DNA.Compared with weak light scattering of single AuNP,these AuNPs assemblies could be clearly imaged under the dark field microscopy,indicating that the light scattering was greatly improved after assembling.

Preparing cyclic polymers at high concentrations via self-folding cyclization technique by adjusting the contents of hydrophilic units in linear precursors

Cyclic polymers are a class of polymers that feature endless topology,and the synthesis of cyclic polymers has attracted the attention of many researchers.Herein,cyclic polymers were efficiently constructed by self-folding cyclization technique at high concentrations.Linear poly((oligo(ethylene glycol)acrylate)-co-(dodecyl acrylate))(P(OEGA-co-DDA))precursors with different ratios of hydrophilic and hydrophobic moieties were synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization using a bifunctional chain transfer agent with two anthryl end groups.The amphiphilic linear precursors underwent the self-folding process to generate polymeric nanoparticles in water.By irradiating the aqueous solution of the nanoparticles with 365 nm UV light,cyclic polymers were synthesized successfully via coupling of anthryl groups.The effects of the ratios of hydrophilic and hydrophobic moieties in linear P(OEGA-co-DDA)copolymers and polymer concentration on the purity of the obtained cyclic polymers were explored in detail via ^(1)H nuclear magnetic resonance(^(1)H NMR),dynamic light scattering(DLS),UV‒visible(vis)analysis,three-detection size exclusion chromatography(TD-SEC)and transmission electron microscopy(TEM).It was found that by adjusting the content of the hydrophilic segments in linear precursors,single chain polymeric nanoparticles(SCPNs)can be generated at high polymer concentrations.Therefore,cyclic polymers with high purity can be constructed efficiently.This method overcomes the limitation of traditional ring-closure method,which is typically conducted in highly dilute conditions,providing an efficient method for the scalable preparation of cyclic polymers.