title: Silicon/SU8 multi-electrode micro-needle for in vivo neurochemical monitoring.
abstract: Simultaneous monitoring of glucose and lactate is an important challenge for understanding brain energetics in physiological or pathological states. We demonstrate here a versatile method based on a minimally invasive single implantation in the rat brain. A silicon/SU8-polymer multi-sensing needle-shaped biosensor, was fabricated and tested. The multi-electrode array design comprises three platinum planar microelectrodes with a surface area of 40 × 200 µm(2) and a spacing of 200 µm, which were micromachined on a single 3mm long micro-needle having a 100 × 50 µm(2) cross-section for reduced tissue damage during implantation. Platinum micro-electrodes were aligned at the bottom of micro-wells obtained by photolithography on a SU8 photoresist layer. After clean room processing, each micro-electrode was functionalized inside the micro-wells by means of a micro-dispensing device, either with glucose oxidase or with lactate oxidase, which were cross-linked on the platinum electrodes. The third electrode covered with Bovine Serum Albumin (BSA) was used for the control of non-specific currents. The thick SU8 photoresist layer has revealed excellent electrical insulation of the micro-electrodes and between interconnection lines, and ensured a precise localization and packaging of the sensing enzymes on platinum micro-electrodes. During in vitro calibration with concentrations of analytes in the mM range, the micro-wells patterned in the SU8 photoresist proved to be highly effective in eliminating cross-talk signals, caused by H2O2 diffusion from closely spaced micro-electrodes. Moreover, our biosensor was successfully assayed in the rat cortex for simultaneous monitoring of both glucose and lactate during insulin and glucose administration.
authors.affiliation: Lyon Institute of Nanotechnologies, CNRS UMR 5270, INSA de Lyon, 7, avenue Jean Capelle, 69621 Villeurbanne Cedex, France; INSERM U1028, CNRS UMR 5292, Lyon Neuroscience Research Center, Team WAKING, 8 avenue Rockefeller, University Claude Bernard Lyon 1, 69373 Lyon Cedex 08, France.
authors.forename: Natalia
authors.initials: N
authors.lastname: Vasylieva
authors.affiliation: INSERM U1028, CNRS UMR 5292, Lyon Neuroscience Research Center, Team WAKING, 8 avenue Rockefeller, University Claude Bernard Lyon 1, 69373 Lyon Cedex 08, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Marinesco
authors.affiliation: Lyon Institute of Nanotechnologies, CNRS UMR 5270, INSA de Lyon, 7, avenue Jean Capelle, 69621 Villeurbanne Cedex, France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Barbier
authors.affiliation: Lyon Institute of Nanotechnologies, CNRS UMR 5270, INSA de Lyon, 7, avenue Jean Capelle, 69621 Villeurbanne Cedex, France. Electronic address: andrei.sabac@insa-lyon.fr.
authors.forename: Andrei
authors.initials: A
authors.lastname: Sabac
mesh_terms: D000818:Animals; D001234:Aspergillus niger / Q000201:enzymology; D015374:Biosensing Techniques / Q000295:instrumentation*; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D002417:Cattle; D004567:Electrodes, Implanted; D004800:Enzymes, Immobilized / Q000378:metabolism; D004867:Equipment Design; D005947:Glucose / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism*; D005949:Glucose Oxidase / Q000378:metabolism; D007328:Insulin / Q000008:administration & dosage; D019344:Lactic Acid / Q000032:analysis / Q000378:metabolism*; D008297:Male; D008839:Microelectrodes; D006899:Mixed Function Oxygenases / Q000378:metabolism; D009339:Needles; D010376:Pediococcus / Q000201:enzymology; D011108:Polymers / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D012825:Silicon / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D007328:Insulin; D011108:Polymers; D019344:Lactic Acid; D006899:Mixed Function Oxygenases; D005949:Glucose Oxidase; C021497:lactate 2-monooxygenase; D005947:Glucose; D012825:Silicon
keywords: Enzymatic biosensor; Glucose; Lactate; Microfabrication; Rat brain; bioMEMS