Sub-Wavelength Focusing in Inhomogeneous Media with a Metasurface Near Field Plate

Overcoming the diffraction limit, which enables focusing much less than the wavelength, requires tailoring the evanescent spectrum of an aperture’s field distribution. We model and simulate a corrugated near field plate, which can generate a sub-wavelength focus in inhomogeneous background media. All reactive coupling, between the metasurface near field plate and the focusing domain and among the corrugations in the metasurface, is taken into consideration with the finite element method, which we solve in combination with a constraint to generate a desired focus. Various geometries for the near field plate are considered and we demonstrate that the proposed method can effectively create a deeply sub-wavelength focus within a layered medium having properties resembling brain tissue. Such a device could find use as a detector of biological signals or for hyperthermic treatment near the skin surface.

Potential role of heat shock protein 90 in regulation of hyperthermia-driven differentiation of neural stem cells

ObjectiveOur previous studies indicated that hyperthermia may play a role in differentiation of neural stem cells and that hypoxia inducible factor-1(HIF-1) was critical in this process. Heat shock protein 90 (Hsp90) is one of the most common heat-related proteins and involved in HIF-1 expression by regulating its activity and stabilization. Here, we hypothesized that HSP90 may be involved in regulation of hyperthermia-driven differentiation of neural stem cells(NSCs). We also investigated whether the HSP90 activity exert its regulatory action via HIF-1 pathway and the transcriptional level of the target genes of HIF-1.MethodThe cultured NSCs were divided into three groups: an hyperthermic treatment group(40NSC) which NSCs was induced under 40°C temperature; a control group(37NSC) which NSCs was induced under 37°C temperature; an hyperthermic treatment and HSP90-inhibited group(40NSC+GA) which NSCs was induced with 0.5μM HSP90 inhibitor Geldanamycin(GA) under 40°C temperature. We examined cells HSPa and HIF-1a expression during a time window of 5 days(12h, 1d, 3d, 5d) post-differentiation. The expression HSPα, HIF-1α, VEGF (vascular endothelial growth factor) and erythmpoietin(EPO) of during a time window was evaluated by RT-qPCR. The proportion of Tuj-1 positive differentiated cells were observed by flow cytometry.ResultHyperthermia promoted neuronal differentiation of NSC, and this effect could be blocked by HSP90 inhibitor GA. We observed the up-regulation of HSP90 during hyperthermia treatment, and that the protein levels of HIF-1α changed depending of the GA treatment. GA could not inhibited HSP90α expression but suppressed HSP activity and decreased the expression HIF-1α protein. Inhibition of HIF-1α expression by GA could consequently affect expression of its targeted genes such as VEGF and EPO.ConclusionHyperthermia promote differentiation of NSCs into neurons. HSP90 involved in the regulation of hyperthermia-driven differentiation of NSC, and the mechanism is related to HIF-1α and its downstream gene activation.

Optimized PAMAM coated magnetic nanoparticles for simultaneous hyperthermic treatment and contrast enhanced MRI diagnosis

We report the synthesis and characterization of multi-functional monodisperse superparamagnetic Magnetic NanoParticles, MNPs, able to act as contrast agents for magnetic resonance and Magnetic Fluid Hyperthermia (MFH) mediators.