Capture of Single Silver Nanoparticles in Nanopore Arrays Detected by Simultaneous Amperometry and Surface-Enhanced Raman Scattering
Year: 2019
Type: article
Abstract: The attoliter volumes and confinement abilities of zero-dimensional nanopore-electrode arrays (NEAs) hold considerable promise for examining the behavior of single nanoparticles. In this work, we use surface-enhanced Raman scattering (SERS) in tandem with amperometry in order to monitor single Ag Raman-sentinel nanoparticles transported to and captured in single nanopores. To that end, highly ordered solid-state NEAs were fabricated to contain periodic arrays of nanopores, each housing a single recessed Au-ring electrode. These were used to electrostatically capture and trap single silver nanoparticles (AgNPs) functionalized with the electrochemically stable Raman reporter, 1,4-bis(2-methylstyryl)benzene (bis-MSB). Transport and capture of the bis-MSB-tagged AgNPs in the nanopores was followed by simultaneous amperometry and SERS signals characteristic of AgNP oxidation and enhanced Raman scattering by bis-MSB at silver-gold hot spots, respectively. The frequency and magnitude of oxidation-current spikes increased with stepwise increases in DC voltage, and characteristic bis-MSB SERS spectra were observed. Under AC excitation, on the other hand, two distinctly different types of SERS signals were observed, independent of frequency and amplitude: (1) strong, transient (<10 s) spectra and (2) slow (>100 s) monotonically diminishing spectra. We hypothesize that the former behavior results from AgNP aggregates, whereas the latter occurs as a result of multiple incomplete AgNP-oxidation events in succession. These results show that attoliter-volume NEAs are competent for acquiring concurrent SERS spectra and for amperometry of single nanoparticles and that together these measurements can illuminate the collision dynamics of nanoparticles in confined environments.
Source: Analytical Chemistry
Institutions: University of Notre Dame, Catholic University of Korea
Language: English
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Awards: MOLECULAR ASPECTS OF TRANSPORT IN THIN FILMS OF CONTROLLLED ARCHITECTURE, G222768804, G4979838128, G6328961138, MOLECULAR ASPECTS OF TRANSPORT IN THIN FILMS OF CONTROLLLED ARCHITECTURE, 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., MOLECULAR ASPECTS OF TRANSPORT IN THIN FILMS OF CONTROLLLED ARCHITECTURE
OpenAlex ID: W2922193531