Self-assembly of semiconductor nanoparticles toward emergent behaviors on fluorescence

Due to the unique fluorescence characteristics,superstructures from self-assembly of semiconductor nanoparticles have become essential components of material and chemical science,and thus it has broad application potential in displays,single-photon source,sensing,biological tagging and emerging quantum technologies.Superstructure refers to an artificial functional architecture whose length scale is between the quantum scale and the macroscale.When solely treating this complicated stage fitted from less complicated pieces together(basic nanoparticles)and pile speculation on speculation,we must understand the fundamental questions,that is,what the hierarchy or specialization of function is at the stage.The uniqueness of this stage is not the collection of basic nanoparticles,but the behavior that emerges on fluorescence-basically a new type of behavior.Under the angle of view,this study reviews the advances in the fluorescence of individual semiconductor nanoparticles,inter-nanoparticles coupling and thus emergent fluorescence behaviors of assemblies.We also try to present the methodology for seeking emergent behaviors on fluorescence.

A facile route to the hierarchical assembly of Au nanoparticles on carbon nanotubes through Cu^(2＋) coordination for surface-enhanced Raman scattering

We report the hierarchical assembly of Au nanoparticles on carboxylized carbon nanotubes（c-CNTs）through Cu^（2＋） coordination. This route is facile and green, and can easily control the loading density of Au nanoparticles. The c-CNT matrix ensures uniform distribution of Au nanoparticles, which is particularly important for the enrichment of hot spots while preventing their serious agglomeration. Moreover, the cCNT matrix also contributes to the electromagnetic enhancement due to its surface plasmon resonance,and the chemical enhancement due to the adsorption of the target molecules. The resulting Au@c-CNT nanohybrids exhibit a remarkable synergy in SERS compared to neat Au nanoparticles.

Assembly of charged aerosols on non-conducting substrates via ion-assisted aerosol lithography （IAAL）

The development of ion-assisted aerosol lithography （IAAL） has enabled fabrication of complex three- dimensional nanoparticle （NP） structures on conducting substrates. In this work, the applicability of the IAAL technique was investigated on non-conducting substrates. The NP structure growth process on a non-conducting substrate was found to self-terminate and the structures subsequently repel incoming charged NPs and scatter them away. Electric field calculations supported the experimental findings and confirmed that the electric field distortions owing to charge build-up within the structures prevented additional NP deposition thereon. To regulate the charge build-up without compromising the number of NPs available for assembly, a corona discharger and an ion trap were implemented. By varying the number of ions available in the assembly process, an optimum level of ion injection was found that allowed for a prolonged （〉120 rain） assembly of NP structures on non-conducting substrates without the unwanted scattering of NPs.

Gold nanoparticles functionalized with supramolecular macrocycles

Gold nanoparticles （AuNPs） functionalized with supramolecular macrocycles are versatile and diverse hybrid nanomaterials, which combine and enhance the characteristics of the two components. In this mini-review, we summarize the recent research progress on the synthesis and assembly of AuNPs functionalized with different supramolecular macrocyclic compounds, i.e., crown ethers, cyclophanes, cyclodextrins （CDs）, cucurbit[n]urils （CB[n]）, calix[n]arenes, and pillar[n]arenes （PIn]A）. Meanwhile, applications of these supramolecular hybrid nanomaterials in the fields of sensors, biomedicine and plasmonic devices are also presented.

Simulation Modelling Study of Self-Assembled Nanoparticle Coatings for Retinal Implants

The electrode resolution of current retinal prostheses is still far from matching the densities of retinal neurons. Decreasing electrode diameter increases impedance levels thus deterring effective stimulation of neurons. One solution is to increase the surface roughness of electrodes, which can be done via nanoparticle coatings. This paper explores a Lattice Gas Model of the drying-mediated self-assembly of nanoparticle mixtures. The model includes representations for different types of nanoparti- cles, solvent, vapour, substrate and the energetic relationships between these elements. The dynamical aspect of the model is determined by energy minimization, stochastic fluctuations and physical constraints. The model attempts to unravel the rela- tionships between different experimental conditions （e.g. evaporation rate, substrate characteristics and solvent viscosity） and the surface roughness of resulting assemblies. Some of the main results include the facts that the assemblies formed by nanoparticles of different sizes can boost roughness in specific circumstances and that the optimized assemblies can exhibit walled or stalagmite structures. This study provides a set of simulation modelling experiments that if confirmed in the laboratory may result in new and useful materials.

Flexible synthesis of high-purity plasmonic assemblies

The self-assembly of nanoparticles has attracted a vast amount of attention due to the ability of the nanostructure to control light at the sub-wavelength scale,along with consequent strong electromagnetic field enhancement.However,most approaches developed for the formation of discrete assemblies are limited to a single and homogeneous system,and incorporation of larger or asymmetrical nanoparticles into assemblies with high purity remains a key challenge.Here,a simple and versatile approach to assemble nanoparticles of different sizes,shapes,and materials into various discrete homo-or hetero-structures using only two complementary deoxyribonucleic acid(DNA)strands is presented.First,surface functionalisation using DNA and alkyl-polyethylene glycol(PEG)enables transformation of as-synthesised nanoparticles into readily usable plasmonic building blocks for self-assembly.Optimisation of the DNA coverage enables the production of different assembly types,such as homo-and hetero-dimers,trimers and tetramers and core-satellite structures,which are produced in high purity using electrophoresis purification.The approach is extended from purely plasmonic structures to incorporate(luminescent)semiconductor nanoparticles for formation of hybrid assemblies.The deposited assemblies form a high yield of specific geometrical arrangements,attributed to the van der Waals attraction between particles.This method will enable the development of new complex colloidal nanoassemblies for biological and optical applications.