Tailoring optical fibers for cell transfection

Abstract

Optical transfection is a promising technique for the delivery of foreign genetic material into cells by transiently changing the permeability of the cell membrane. Of the different optical light sources that have been used, femtosecond laser based transfection has been one of the most effective methods for optical transfection, which is generally implemented using a free-space bulk optical setup. Here in this thesis, a few novel fabrication methods are devised to obtain easy and inexpensive fabrication of microlensed optical fibers, which can be used to replace traditional optical setups and perform femtosecond optical transfection. These fabrication methods offer the flexibility to fabricate a microlens which can focus femtosecond laser pulses at 800 nm to a small focal spot whilst keeping a relatively large working distance. In conventional optical transfection methods the foreign genetic material to be transfected is homogenously mixed in the medium. This thesis reports the first realization of an integrated optical transfection system which can achieve transfection along with localized drug delivery by combining lensed fiber based optical transfection system with a micro-capillary based microfluidic system. Finally, based on an imaging fiber, (coherent optical fiber bundle), the first endoscope-like integrated system for optical transfection with subcellular resolution epifluorescence imaging was built. The transfection efficiency of these fiber based systems is comparable to that of a standard free-space transfection system. Also the use of an integrated system for localized gene delivery resulted in a reduction of the required amount of genetic material for transfection. The miniaturized, integrated design opens a range of exciting experimental possibilities, such as the dosing of tissue slices to study neuron activities, targeted drug delivery, and in particular for using endoscope-like integrated systems for targeted in vivo optical microsurgery.