Size-selective separation of DNA fragments by using lysine-functionalized silica particles.

In this work, a facile and efficient approach has been demonstrated for size-selective separation of DNA fragments by using lysine-functionalized silica particles. At a given pH, the environmental ionic strength can be utilized to alter the electrostatic interactions of lysine-functionalized silica particles with DNA fragments and in turn the DNA fragments on the silica particle surfaces, which exhibits a clear dependence on the DNA fragment sizes. By carefully adjusting the environmental pH and salt concentration, therefore, the use of the lysine-functionalized silica particles allows effective separation of binary and ternary DNA mixtures, for example, two different DNA fragments with sizes of 101 and 1073 bp, 101 and 745 bp, 101 and 408 bp, respectively, and three different DNA fragments with sizes of 101, 408 and 1073 bp.

Facile deposition of continuous gold shells on Tween-20 modified FeO superparticles.

A facile method to deposit continuous Au shells on FeO colloidal superparticles was developed by introducing Tween-20 as a surface modification agent to maintain the colloidal stability of the FeO superparticles and provide nucleation and growth sites for the Au shells. The FeO-Au core-shell particles showed excellent chemical stability, superparamagnetic properties and efficient photothermal conversion performance under laser irradiation at 808 nm, and were expected to be a useful material for biodetection and cancer therapy.

Colloidal superparticles from nanoparticle assembly.

Colloidal superparticles are size- and shape-controlled nanoparticle assemblies in the form of colloidal particles. Because these superparticles can exhibit physical and chemical properties different from both individual nanoparticles and their bulk assemblies, the development of superparticle synthesis has attracted significant research attention and is emerging as a new frontier in the field of nanotechnology. In this review, we discuss theoretical considerations on the nucleation and growth of colloidal superparticles.

Self-assembled colloidal superparticles from nanorods.

Colloidal superparticles are nanoparticle assemblies in the form of colloidal particles. The assembly of nanoscopic objects into mesoscopic or macroscopic complex architectures allows bottom-up fabrication of functional materials. We report that the self-assembly of cadmium selenide-cadmium sulfide (CdSe-CdS) core-shell semiconductor nanorods, mediated by shape and structural anisotropy, produces mesoscopic colloidal superparticles having multiple well-defined supercrystalline domains.

Formation of heterodimer nanocrystals: UO2/In2O3 and FePt/In2O3.

This Article reports a mechanistic study on the formation of colloidal UO(2)/In(2)O(3) and FePt/In(2)O(3) heterodimer nanocrystals. These dimer nanocrystals were synthesized via the growth of In(2)O(3) as the epitaxial material onto the seed nanocrystals of UO(2) or FePt. The resulting dimer nanocrystals were characterized using X-ray powder diffraction (XRD), energy dispersion spectroscopy, transmission electron microscopy (TEM), scanning transmission electron microscopy, and high-resolution TEM (HRTEM).

Gas-bubble effects on the formation of colloidal iron oxide nanocrystals.

This paper reports that gas bubbles can be used to tailor the kinetics of the nucleation and growth of inorganic-nanocrystals in a colloidal synthesis. We conducted a mechanistic study of the synthesis of colloidal iron oxide nanocrystals using gas bubbles generated by boiling solvents or artificial Ar bubbling. We identified that bubbling effects take place through absorbing local latent heat released from the exothermic reactions involved in the nucleation and growth of iron oxide nanocrystals.

Carboxyl-functionalized superparamagnetic Fe3O4/poly(St-co-MPS)/SiO2 composite particles for rapid and sensitive immunoassay.

Superparamagnetic Fe3O4/poly(St-co-MPS)/SiO2 composite particles with the average size of 140 nm were functionalized with carboxyl group by emulsion polymerization. Functionalized particles with carboxyl contents of 13.6 and 136 micromol/mL were prepared by changing the amount of acrylic acid monomer used in the polymerization.

Synthesis of water-soluble 2,2'-diphenyl-1-picrylhydrazyl nanoparticles: a new standard for electron paramagnetic resonance spectroscopy.

This communication reports a size-controlled synthesis of water-soluble 2,2'-diphenyl-1-picrylhydrazyl (DPPH) nanoparticles (NPs). These nanoparticles exhibit size-dependent absorption spectra and fast spin exchange-narrowed single-line EPR spectra. The linewidths of the EPR spectra of these water-soluble nanoparticles are approximately 1.

Cylindrical superparticles from semiconductor nanorods.

In this communication, we report a synthesis of anisotropic colloidal superparticles (SPs) from CdSe/CdS semiconductor nanorods. These anisotropic SPs are cylindrical disks or stacked-disk arrays. We attribute the major driving forces controlling the SP shape to interparticle interactions between nanorods and solvophobic interactions between a superparticle and its surrounding solvent.