Creating Ultrafast Biosensors for Neuroscience
Doctoral thesis, 2019
In Paper I, an acetylcholine sensor was designed and fabricated by modifying the sensor surface with gold nanoparticles (AuNPs) and two sequential enzymes, where the enzyme coating was limited to a monolayer in thickness to minimize enzyme product diffusion distance to be detected by the electrode surface. This novel sensor provided the first proof of concept to improving enzyme-based sensors speed by 2 orders of magnitude compared to existing technology and was fast enough to temporally resolve single millisecond vesicle release events of acetylcholine from an artificial cell model that mimics exocytosis.
In Paper II, a new and analytical method was introduced that provided a significantly faster and a non-toxic way to quantify AuNP immobilized enzymes during sensor surface characterization in comparison to the previous method used in Paper I that involved using toxic cyanide solutions. This method was based on electrochemical stripping of AuNPs from the electrode surface after enzymes were attached, followed by quantifying the number of enzymes released, to determine the average number of enzymes attached to each single nanoparticle.
In Paper III, an ultrafast glutamate sensor was developed by careful characterization of the conditions for controlling the enzyme coverage on a AuNP decorated electrode surface to a monolayer. By placing this novel sensor in the Nucleus Accumbens of rodent brain slice, recording of spontaneous glutamate activity and various isolated dynamic current transients from single exocytotic events on the sub-millisecond timescale were captured.
In Paper IV, the conjugation of enzyme glucose oxidase (GOx) to AuNP surfaces was used to study how physical crowding affects enzyme stability and activity when immobilized at a highly curved nanoparticle surface. This work showed that by crowding a gold nanoparticle surface with its maximum number of enzymes that can theoretically fit, while maintaining a monolayer coverage, the retained enzymatic activity of immobilized enzyme improved 300% compared to GOx free in solution. Implementing these findings to a nanostructured electrochemical biosensor for glucose confirmed a recording speed for glucose on the millisecond timescale
In Paper V, using our novel ultrafast glutamate sensor, a novel method was developed for quantification of the quantal glutamate content in single synaptic vesicles, and quantification of the quantal amount glutamate released from single exocytosis events in rodent brain tissue.
Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry
Amperometric Detection of Single Vesicle Acetylcholine Release Events from an Artificial Cell
ACS Chemical Neuroscience,; Vol. 6(2015)p. 181-188
Counting the number of enzymes immobilized onto a nanoparticle-coated electrode
Analytical and Bioanalytical Chemistry,; Vol. 410(2018)p. 1775-1783
Ultrafast Glutamate Biosensor Recordings in Brain Slices Reveal Complex Single Exocytosis Transients
ACS Chemical Neuroscience,; Vol. 10(2019)p. 1744-1752
Molecular Crowding and a Minimal Footprint at a Gold Nanoparticle Support Stabilize Glucose Oxidase and Boost Its Activity
Langmuir,; Vol. 36(2020)p. 37-46
Counting the Number of Glutamate Molecules in Single Synaptic Vesicles
Journal of the American Chemical Society,; Vol. 141(2019)p. 17507-17511
Innovation and entrepreneurship
Areas of Advance
Nanoscience and Nanotechnology (2010-2017)
Other Chemistry Topics
Chalmers Materials Analysis Laboratory
Learning and teaching
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4617
Chalmers University of Technology
Opponent: Martin Jönsson Niedziolka, Department of Physical Chemistry, The Polish Academy of Science, Warsaw, Poland