Development of multifunctional nano-probes for neuroscience research

Abstract

The contribution of nanotechnology to the field of Neuroscience is increasing exponentially. In order to understand the relationship of structure to function at the cellular level, and to decipher the mysteries of nervous system, development of new tools to manipulate and measure cellular function at a local level is necessary. It is a continuing challenge to develop easily fabricated, multipurpose nano-probes which are able to target neural nanostructures for the local manipulation and measurement of functional responses. This thesis is focused on the fabrication, characterisation and implementation of a nano-pipette on a Scanning Ion Conductance Microscopy (SICM). The nano-pipette mounted on a SICM set-up acts as a proximity sensor for non-contact imaging of cellular features. SICM platform to accommodate electrochemical experiments is discussed. In particular, the development of a novel electrochemical probe, fabricated by pyrolytic decomposition of carbon within a quartz nano-pipette is discussed. This method is simple and carbon nano-electrodes of variable size can be fabricated in a single step. The nano-pipette‘s distance controlled feedback system was exploited for local delivery of chemicals to neuronal structures. Experimental and theoretical data are compared in order to calculate the concentration of molecules at the tip of the nano-pipette as a function of the driving force (voltage or pressure) and distance. The quantitative delivery of molecules from a 100 nm nano-pipette is demonstrated. In particular capsaicin-filled nano-pipette is used to trigger capsaicin-sensitive TRPV1 receptors in sensory neurons and transfected cells. Finally some preliminary results for the future development and potential application of nano-pipettes are shown. The nano-pipette is easily fabricated and is shown to be multi-functional. It provides an invaluable tool in the investigation of the nano-physiology of neurons. The SICM multipoint delivery competence can contribute to the various endeavours in drug discovery and to the yield of in vitro pharmacological assays.