Synthesis, Stability, Cellular Uptake, and Blood Circulation Time of Carboxymethyl-Inulin Coated Magnetic Nanoparticles.

Iron oxide nanoparticles were coated with the biocompatible, biodegradable, non-immunogenic polysaccharide inulin by introduction of carboxyl groups into the inulin structure and conjugation with amine groups on the surface of iron oxide nanoparticles grafted with 3-aminopropyltriethoxysilane. The resulting nanoparticles were characterized by FT-IR spectroscopy, transmission electron microscopy, dynamic light scattering, zeta potential, SQUID magnetometry, and with respect to their energy dissipation rate in applied alternating magnetic fields. The nanoparticles had a hydrodynamic diameter in the range of 70 ± 10 nm and were superparamagnetic, with energy dissipation rates in the range of 58-175 W/g for an applied field frequency of 233 kHz and an applied field amplitude in the range of 20-48 kA/m. The nanoparticles were stable in a range of pH, at temperatures between 23°C and 53°C, and in short term storage in water, PBS, and culture media. The particles were non-cytotoxic to the immortalized human cancer cell lines Hey A8 FDR, A2780, MDA 468, MCF-7 and Caco-2. The nanoparticles were readily taken up by Caco-2 cells in a time and concentration dependent fashion, and were found to have a pharmacokinetic time constant of 47 ± 3 min. The small size, non-cytotoxicity, and efficient energy dissipation of the particles could make them useful for biomedical applications such as magnetic fluid hyperthermia.

DNA-functionalized carbon nanotubes for biosensing applications.

Carbon nanotubes (CNTs) have been broadly studied due to their exceptional structural, electronic and mechanical properties, and their use have been proposed for many applications. The number of biosensing applications of CNTs has increased in the past few years. Nevertheless, in order to use CNTs as standard materials in the biosensing field and to take full advantage of their unique properties, several problems must be solved. For example, the solubility of CNTs, especially in aqueous solvents, needs to be improved. Furthermore, reliable methodologies for the easy, reproducible and efficient incorporation of CNTs into solid substrates must be developed. Chemical functionalization of CNTs with biomolecules, and specifically with DNA, provides an alternative to the previous challenges. This review will present a brief overview of the methods available for the chemical functionalization of CNTs with DNA by either covalent or non-covalent means. Moreover, the main scope will be on describing the use of DNA-CNT complexes in biosensing applications. Detection of ions, glucose, peroxide and DNA hybridization using the DNA-CNT hybrids will be discussed.

Bioelectrochemical sensing based on single stranded deoxyribonucleic acid-carbon nanotubes covalently attached on gold electrodes.

A biosensor based on single-stranded deoxyribonucleic acid-functionalized carbon nanotubes covalently attached to a self-assembled monolayer of 11-amino-1-undecanethiol on gold has been prepared. The preparation of the deoxyribonucleic acid sensor was followed using cyclic voltammetry. Single-walled carbon nanotubes, covalently attached to the gold surface present a nanoelectrode array behavior. To confirm the hybridization step between the probe and the target deoxyribonucleic acid, we used methylene blue, which is an indicator capable of distinguishing between single-stranded deoxyribonucleic acid and double-stranded deoxyribonucleic acid. Our results demonstrate that the modification of gold with single-walled carbon nanotubes and single-stranded deoxyribonucleic acid can be used for deoxyribonucleic acid hybridization detection.