Combination of viral biology and nanotechnology: new applications in nanomedicine.

Viruses are well known for their ability to cause disease, but their beneficial usefulness as vectors for gene therapy have been noted as well. As an extension of their use in a gene therapy context, their combination with nanotechnology is starting to benefit many areas of science and medicine. These include nanofabrication and medical diagnostics, to name a few, as well as viro-nanotherapy, here defined as the combination of viral biology with nanotechnology to create new therapeutic avenues to treat disease. This review provides examples of areas wherein viruses in combination with nanotechnology are being used to either advance scientific knowledge or accelerate the development of new diagnostics and therapeutics for human pathological conditions.

Numerical study on the multi-region bio-heat equation to model magnetic fluid hyperthermia (MFH) using low Curie temperature nanoparticles.

This study develops and solves two-dimensional convective-conductive coupled partial differential equations based on Pennes' bio-heat transfer model using low Curie temperature nanoparticles (LCTNPs) to illustrate thermal behavior quantitatively within tumor-normal composite tissue by establishing a multi-region finite difference algorithm. The model combines NEel relaxation and temperature-variant saturation magnetization derived from Brillouin Equation and Curie-Weiss Law. The numerical results indicate that different deposition patterns of LCTNP and boundary conditions directly effect the steady state temperature distribution. Compared with high Curie temperature nanoparticles (HCTNPs), optimized distributions of LCTNPs within tumorous tissue can be used to control the temperature increase in tumors for hyperthermia treatment using an external magnetic field while healthy tissue surrounding a tumor can be kept closer to normal body tissue, reducing the side effects observed in whole body and regional hyperthermia therapy.

Understanding mercapto ligand exchange on the surface of FePt nanoparticles.

Tailoring the surface of nanoparticles is essential for biological applications of magnetic nanoparticles. FePt nanoparticles are interesting candidates owing to their high magnetic moment. Established procedures to make FePt nanoparticles use oleic acid and oleylamine as the surfactants, which make them dispersed in nonpolar solvents such as hexane. As a model study to demonstrate the modification of the surface chemistry, stable aqueous dispersions of FePt nanoparticles were synthesized after ligand exchange with mercaptoalkanoic acids. This report focuses on understanding the surface chemistry of FePt upon ligand exchange with mercapto compounds by conducting X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) studies. It was found that the mercapto end displaces oleylamine on the Pt atoms and the carboxylic acid end displaces the oleic acid on the Fe atoms, thus exposing carboxylate and thiolate groups on the surface that provide the necessary electrostatic repulsion to form stable aqueous dispersions of FePt nanoparticles.

Covalently linked Au nanoparticles to a viral vector: potential for combined photothermal and gene cancer therapy.

Hyperthermia can be produced by near-infrared laser irradiation of gold nanoparticles present in tumors and thus induce tumor cell killing via a bystander effect. To be clinically relevant, however, several problems still need to be resolved. In particular, selective delivery and physical targeting of gold nanoparticles to tumor cells are necessary to improve therapeutic selectivity. Considerable progress has been made with respect to retargeting adenoviral vectors for cancer gene therapy. We therefore hypothesized that covalent coupling of gold nanoparticles to retargeted adenoviral vectors would allow selective delivery of the nanoparticles to tumor cells, thus feasibilizing hyperthermia and gene therapy as a combinatorial therapeutic approach. For this, sulfo-N-hydroxysuccinimide labeled gold nanoparticles were reacted to adenoviral vectors encoding a luciferase reporter gene driven by the cytomegalovirus promoter (AdCMVLuc). We herein demonstrate that covalent coupling could be achieved, while retaining virus infectivity and ability to retarget tumor-associated antigens. These results indicate the possibility of using adenoviral vectors as carriers for gold nanoparticles.

Adsorption of acicular particles at liquid-fluid interfaces and the influence of the line tension.

In this paper, the adsorption energy of an acicular (prolate and cylindrical) particle onto a liquid-fluid interface and the effect of the line tension are investigated. The results show that, without line tension, acicular particles always prefer to lie flat in the plane of the interface. However, line tension plays a significant role in determining the adsorption of an acicular particle. First, the line tension creates an energy barrier for the adsorption of particles onto an interface. The planar configuration has a larger energy barrier due to the longer contact line. Therefore, the particles prefer to enter the interface in a homeotropic configuration and then rearrange to a planar configuration or an oblique configuration with a small tilt angle. Second, for prolate particles, an energy maximum occurs at some tilt angles when the line tension is large. Therefore, once the prolate particle is adsorbed on the interface in a homeotropic configuration or with a larger tilt angle, it must conquer an energy barrier to rearrange to a planar configuration. For cylindrical particles, when the line tension is higher, the planar configuration will not be the most energy-favorable configuration. The cylindrical particles prefer to stay in the interface with a small tilt angle.