Making Carbon-Fibre Microelectrode (CFM) for electrochemical recordings of monoamines in ex vivo mouse brain slices
Stephanie J Cragg, Katherine Brimblecombe
Abstract
This protocol is to make carbon-fibre microelectrode (CFM) for electrochemical recordings of monoamines in ex-vivo mouse brain slices. This protocol is optimised for the detection of dopamine from 300 µm coronal striatal sections, using a Miller voltammeter.
Steps
Threading Carbon Fibre
Fill test tube with acetone (flammables cupboard) and add capillary tubes.
Stick test tube to light box with Blu Tack.
Select a single carbon fibre using rubber tipped forceps.
Thread carbon fibre down capillary tube.
Lift the tube out of the acetone and allow acetone to evaporate.
Pulling Carbon Fibre
Place capillary tube into puller.
Tighten holder “finger-tight” and raise tube for 3 clicks and secure in place “finger tight”.
Settings:
- Magnet: off
- Heat: ~6.7
Check which end of the tube the carbon is in and carefully remove from puller.
Trim excess exposed fibre with fine scissors to stop waving extended fibre from stressing the glass seal.
Cutting Carbon Fibre
Carefully place electrode between capillary tubes on cutting block.
Approximately line up seal with cut ridge.
Make a cut at ~ 300 µm from seal, by running scalpel down cut ridge, mark this as 0 on the graticule.
Move electrode so there is 50-100 µm exposed carbon fibre and run scalpel down cut ridge.
Carefully remove electrode from cutting block.
Wiring Electrode
Cut wire to slightly longer than your capillary tube.
Strip off ~1cm of the plastic coating from each end.
On one end trim exposed wires so only 1 is sticking out.
Dip this end in the conductive silver paint and gently thread down the capillary so the paint makes contact with the carbon fibre.
Glue exposed end of wire in place by dripping glue down capillary tube, exposed wire can be connected to voltammetry head-stage using croc-clip.
Allow to set overnight before use.
