Swim Ireland

This study presents an analytical method for the extraction of the complex relative permittivity of multi‐layered dielectric substrates that are used to construct thin film microstrip lines (TFMLs). The proposed approach is based on the analysis of an equivalent parallel plate waveguide filled with a dielectric material whose relative dielectric permittivity is the effective dielectric permittivity of the corresponding TFML. The extraction technique relies only on the knowledge of the complex propagation constant obtained from S‐parameter measurements and is applicable to a wide range of line dimensions and dielectric permittivity values. For experimental verification, several TFMLs were fabricated, and from the measured scattering parameters, the complex dielectric characteristics of each device are extracted. The extracted relative permittivity and loss tangent values are then compared with the dielectric parameters obtained from a numerical technique based on full wave analyses. The accuracy of the proposed analytical method is shown to be approximately 15 and 5% for the fabricated TFMLs with ratios of the microstrip line width (W) to dielectric thickness (H), (W/H) of 4 and 80, respectively.

Achieving targeted delivery of gene medicines is desirable to maximise activity. Here, galactosylated amphiphilic cyclodextrins (CDs) are examined in terms of their ability to transfect asialoglycoprotein receptor-bearing HepG2 cells. Cationic amphiphilic CDs were synthesised as well as amphiphilic CDs bearing galactose-targeting ligands with different linker lengths. Binding of galactosylated CDs to a galactose-specific lectin was examined by surface plasmon resonance. CDs were formulated with and without the helper lipid DOPE and complexed with plasmid DNA. Transfection was evaluated by luciferase assay. Intracellular trafficking was assessed by confocal microscopy. Binding of targeted CDs to a galactose-specific lectin was achieved. Binding decreased with linker length between the galactosyl group and the CD core. Contrary to the lectin binding results, transfection levels increased with an increase in linker length from 7 atoms to 15. Compared to non-targeted formulations, a significant increase in transfection was observed only in the presence of the helper lipid DOPE. Confocal microscopy revealed that DOPE caused a pronounced effect on cellular distribution. The galactose-targeting ligand induced substantial increases in transfection over non-targeted formulations when DOPE was included, indicating the potential for targeted gene delivery using CD-based delivery systems.

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