A facile method for the detection of DNA by using gold nanoparticle probes coupled with dynamic light scattering.

In this paper, we present a simple and rapid method for deoxyribonucleic acid (DNA) detection using gold nanoparticle probes coupled with dynamic light scattering (DLS) analysis. The redox agent 1,4-dithio-dl-threitol cross-links the gold nanoparticles (AuNPs) to form clusters, while the monothiol DNA could terminate the formation and stabilize the assembled clusters by their negatively charge-based repulsions. By varying the concentration of DNA, the different sizes of DNA-AuNP clusters can be obtained. The sizes of the DNA-AuNP clusters were determined by DLS. A linear correlation was obtained between the sizes and the logarithm of DNA concentration from 2 nM to 5 µM with a detection limit of 1 nM (S/N = 3).

Functionalized halloysite nanotube-based carrier for intracellular delivery of antisense oligonucleotides.

Halloysites are cheap, abundantly available, and natural with high mechanical strength and biocompatibility. In this paper, a novel halloysite nanotube [HNT]-based gene delivery system was explored for loading and intracellular delivery of antisense oligodeoxynucleotides [ASODNs], in which functionalized HNTs [f-HNTs] were used as carriers and ASODNs as a therapeutic gene for targeting survivin. HNTs were firstly surface-modified with γ-aminopropyltriethoxysilane in order to facilitate further biofunctionalization. The f-HNTs and the assembled f-HNT-ASODN complexes were characterized by transmission electron microscopy [TEM], dynamic light scattering, UV-visible spectroscopy, and fluorescence spectrophotometry. The intracellular uptake and delivery efficiency of the complexes were effectively investigated by TEM, confocal microscopy, and flow cytometry. In vitro cytotoxicity studies of the complexes using MTT assay exhibited a significant enhancement in the cytotoxic capability. The results exhibited that f-HNT complexes could efficiently improve intracellular delivery and enhance antitumor activity of ASODNs by the nanotube carrier and could be used as novel promising vectors for gene therapy applications, which is attributed to their advantages over structures and features including a unique tubular structure, large aspect ratio, natural availability, rich functionality, good biocompatibility, and high mechanical strength.

Synthesis of NaYF4:Yb3+, Er3+ upconversion nanoparticles in normal microemulsions.

An interface-controlled reaction in normal microemulsions (water/ethanol/sodium oleate/oleic acid/n-hexane) was designed to prepare NaYF4:Yb3+, Er3+ upconversion nanoparticles. The phase diagram of the system was first studied to obtain the appropriate oil-in-water microemulsions. Transmission electron microscopy and X-ray powder diffractometer measurements revealed that the as-prepared nanoparticles were spherical, monodisperse with a uniform size of 20 nm, and of cubic phase with good crystallinity. Furthermore, these nanoparticles have good dispersibility in nonpolar organic solvents and exhibit visible upconversion luminescence of orange color under continuous excitation at 980 nm. Then, a thermal treatment for the products was found to enhance the luminescence intensity. In addition, because of its inherent merit in high yielding and being economical, this synthetic method could be utilized for preparation of the UCNPs on a large scale.

Metal sulfide coated multiwalled carbon nanotubes synthesized by an in situ method and their optical limiting properties.

A metal sulfide such as ZnS, CdS, Ag(2)S or PbS was coated on the sidewall of multiwalled carbon nanotubes (MWCNTs) by an in situ wet chemical synthesis approach via noncovalent functionalization of MWCNTs with a polyelectrolyte (polyethylenimine or poly(diallyldimethylammonium chloride)) without causing significant electronic and structural modification of the carbon nanotubes. Extensive characterizations of the fabricated nanocomposites have been performed using x-ray diffraction, transmission electron microscopy (TEM), high resolution TEM, energy dispersive x-ray spectroscopy, selected area electron diffraction, thermal gravimetric analysis, Fourier transform IR spectra, UV-vis spectra and x-ray photoelectron spectroscopy. The coating layers were composed of metal sulfide nanoparticles with a mean size of less than 10 nm. The optical limiting property measurements for some metal sulfide coated MWCNTs were carried out by the open-aperture z-scan technique. The results demonstrate that the samples suspended in water showed optical limiting behavior better than that of purified MWCNTs.

Magnetic force microscopy analysis of apoptosis of HL-60 cells induced by complex of antisense oligonucleotides and magnetic nanoparticles.

Magnetic force microscopy (MFM) has been employed to observe antisense oligonucleotides (ASOs)-coupled silica-coated magnetic iron oxide nanoparticles (SMNPs) internalized into human leukemia (HL-60) cells. The experiment demonstrated that the ASOs-coupled SMNPs delivery into the cells really occurred. The nanoparticles were internalized into the cells and the apoptotic topography can be directly visualized simultaneously with MFM technology. These present observations offer direct morphology evidence on studying the apoptosis of tumor cells and provide useful information for better design of new diagnostic and therapeutic tools in tumor treatment.