Single-molecule spectroelectrochemical cross-correlation during redox cycling in recessed dual ring electrode zero-mode waveguides
Year: 2017
Type: article
Abstract: The ability of zero-mode waveguides (ZMW) to guide light into subwavelength-diameter nanoapertures has been exploited for studying electron transfer dynamics in zeptoliter-volume nanopores under single-molecule occupancy conditions. In this work, we report the spectroelectrochemical detection of individual molecules of the redox-active, fluorogenic molecule flavin mononucleotide (FMN) freely diffusing in solution. Our approach is based on an array of nanopore-confined recessed dual ring electrodes, wherein repeated reduction and oxidation of a single molecule at two closely spaced annular working electrodes yields amplified electrochemical signals. We have articulated these structures with an optically transparent bottom, so that the nanopores are bifunctional, exhibiting both nanophotonic and nanoelectrochemical behaviors allowing the coupling between electron transfer and fluorescence dynamics to be studied under redox cycling conditions. We also investigated the electric field intensity in electrochemical ZMWs (E-ZMW) through finite-element simulations, and the amplification of fluorescence by redox cycling agrees well with predictions based on optical confinement effects inside the E-ZMW. Proof-of-principle experiments are conducted showing that electrochemical and fluorescence signals may be correlated to reveal single molecule fluctuations in the array population. Cross-correlation of single molecule fluctuations in amperometric response and single photon emission provides unequivocal evidence of single molecule sensitivity.
Source: Chemical Science
DOI: 10.1039/c7sc02250f
Institution: University of Notre Dame
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: diamond
Awards: G2506193346, G2508191047, IN THIS PROPOSAL THE FUNDAMENTAL QUANTUM AND PHOTONIC INTERACTIONS OF BIMETALLIC ATOMIC-SCALE JUNCTIONS (ASJS) WILL BE EXPLORED WITH THREE MAJOR SPACE TECHNOLOGY-RELATED APPLICATIONS IN FOCUS: 1)CHEMICAL SENSING 2)SMART/METAMATERIALS AND 3)MEMRISTORBASED COMPUTING. AN ASJ IS A TYPE OF QUANTUM-POINT CONTACT CREATED BY ELECTROCHEMICALLY DEPOSITING SILVER BETWEEN TWO NANOSCALE ELECTRODES. THIS CONNECTION CAN BE FORMED AND DESTROYED BY APPLYING THE APPROPRIATE VOLTAGE POTENTIAL ACROSS THE ELECTRODES AND THUS CONTROLLED TO THE POINT WHERE THE JUNCTION NARROWS TO THE WIDTH OF A SINGLE ATOM. AT THIS POINT THE JUNCTION CAN EXHIBIT A PHENOMENON KNOWN AS QUANTIZED CONDUCTANCE. IN THIS REGION THE JUNCTION IS ESPECIALLY SENSITIVE TO DISTURBANCES IN THE SURROUNDING ENVIRONMENT. PREVIOUS RESEARCH HAS DEMONSTRATED THE POTENTIAL OF A SINGLE ASJ IN SENSING CHEMICALS BOUND TO THE JUNCTION AT THIS NARROWEST SECTION; THIS PROPOSAL WILL EXTEND ON THAT WORK BY EXAMINING PARALLEL AND SERIAL ARRAYS OF ASJS FOR CHEMICAL SENSING AND MEMRISTIVE COMPUTING AS WELL AS THE INTERACTION OF THE JUNCTIONS IN 3-DIMENSIONAL CONFIGURATIONS WITH LIGHT FOR METAMATERIALS. THE OBJECTIVES OF THIS PROJECT ARE TO ESTABLISH CONTROL OVER JUNCTION GROWTH IN MASSIVELY PARALLEL ARRAYS BOTH THROUGH DIRECT ELECTRICAL CONTACT AND WITH PHOTO-INDUCED CHARGING THEN UTILIZE THIS CONTROL TO EXAMINE THE POTENTIAL APPLICATION OF THESE JUNCTIONS IN THE AREAS DESCRIBED ABOVE. JUNCTIONS WILL BE CREATED USING ELECTROCHEMICAL DEPOSITION BETWEEN CONDUCTIVE ELECTRODES WHICH MAY BE LITHOGRAPHICALLY-DEFINED MACROSCALE ELECTRODES ON A WAFER A CONDUCTIVE AFM TIP OR NANOPARTICLES STIMULATED WITH FOCUSED LASERS. ACHIEVING THESE OBJECTIVES WOULD BE HIGHLY SIGNIFICANT TO BOTH NASA AND THE COMMUNITY AT LARGE. DUE TO THE JUNCTIONS SMALL SPACE AND WEIGHT A MASSIVELY PARALLEL ARRAY OF JUNCTIONS WOULD NOT TAKE UP MORE THAN A FEW SQUARE MILLIMETERS OF AREA ON A SILICON WAFER YET COULD PERFORM A WIDE ARRAY OF FUNCTIONS; THUS THEY ARE IDEALLY SUITED TO THE TIGHT WEIGHT AND SIZE REQUIREMENTS OF TERRESTRIALLYLAUNCHED SPACE MISSIONS. THE APPLICATIONS OF ASJS IN CHEMICAL SENSING AND MEMRISTOR-BASED NEURAL NETWORK APPLICATIONS COULD ALLOW FOR NEW EXPERIMENTS AND DATA ANALYSIS NOT POSSIBLE WITH EXISTING TECHNOLOGY. IN ADDITION THE FUNDAMENTAL INSIGHTS INTO QUANTUM AND PHOTONIC PHENOMENA GAINED BY DEVICES THAT OPERATE AT ROOM-TEMPERATURE AND UNDER SIMPLE CONDITIONS WOULD ALSO GREATLY BENEFIT THE SCIENTIFIC COMMUNITY AND SCIENCE EDUCATION., Coupled Transport and Reactions in Low-Dimensional Nanofluidic Structures for Enhanced Chemical Measurements
OpenAlex ID: W2677208376