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Gene therapy poses a great promise in treatment and prevention of a variety of diseases. However, crucial to studying and the development of this therapeutic approach is a reliable and efficient technique of gene and drug delivery into primary cell types. These cells, freshly derived from an organ or tissue, mimic more closely the in vivo state and present more physiologically relevant information compared to cultured cell lines. However, primary cells are known to be difficult to transfect and are typically transfected using viral methods, which are not only questionable in the context of an in vivo application but rely on time consuming vector construction and may also result in cell de-differentiation and loss of functionality. At the same time, well established non-viral methods do not guarantee satisfactory efficiency and viability. Recently, optical laser mediated poration of cell membrane has received interest as a viable gene and drug delivery technique. It has been shown to deliver a variety of biomolecules and genes into cultured mammalian cells; however, its applicability to primary cells remains to be proven. We demonstrate how optical transfection can be an enabling technique in research areas, such as neuropathic pain, neurodegenerative diseases, heart failure and immune or inflammatory-related diseases. Several primary cell types are used in this study, namely cardiomyocytes, dendritic cells, and neurons. We present our recent progress in optimizing this technique's efficiency and post-treatment cell viability for these types of cells and discuss future directions towards in vivo applications.

We discuss the phase and group modal birefringence in photonic crystal fibres (PCFs) with an elongated core. Owing to large form birefringence, these two types of birefringence in such PCFs may not only have opposite signs, but their absolute value can also differ by several orders of magnitude. We also show that PCFs offer the unique possibility of having a large phase birefringence and a negligible polarization mode dispersion at the same time. Using a fully vectorial mode solver, we show how these parameters can be tailored by a proper choice of the geometry of the PCF. We demonstrate both numerically and experimentally the strong wavelength dependence of phase and group modal birefringence in triple-defect photonic crystal fibres (PCFs).