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Femtomolar Detection of Silver Nanoparticles by Flow-EnhancedDirect-Impact Voltammetry at a Microelectrode Array

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ABSTRACT

20142014: Wereport the femtomolar detection of silver (Ag) nanoparticlesby direct-impact voltammetry. This is achieved through the use ofa random array of microelectrodes (RAM) integrated into a purpose-builtflow cell, allowing combined diffusion and convection to the electrodesurface. A coupled RAM-flow cell system is implemented and is shownto give reproducible wall-jet type flow characteristics, using potassiumferrocyanide as a molecular redox species. The calibrated flow systemis then used to detect and quantitatively size Ag nanoparticles atfemtomolar concentrations. Under flow conditions, it is found thenanoparticle impact frequency increases linearly with the volumetricflow rate. The resulting limit of detection is more than 2 ordersof magnitude smaller than the previous detection limit for direct-impact voltammetry (900 fM) [J. Ellison et al. Sens. Actuators, B, 200, 47], and is more than 30 times smaller than the previous detectionlimit for mediated-impact voltammetry (83 fM) [T.M. Alligrant et al. Langmuir, 30, 13462].

No MeSH data available.


Expandedand cross-sectional views of the home-built flow cell.Full schematics are reported in the Supporting Information.
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fig1: Expandedand cross-sectional views of the home-built flow cell.Full schematics are reported in the Supporting Information.

Mentions: The flow cell was designedand built in-house. It allows the interchange of working electrodes,with a washer allowing control over the inlet–working electrodedistance. A schematic design is shown in Figure 1, and full schematics are reported in the Supporting Information. Figure 1 shows the demountable flow cell system,which is built from three separate sections that are bolted together.The three main cell components were manufactured from polyether etherketone (PEEK), with Delrin used for the reference and working electrodeholder. During operation, solution is flowed through the cell, usinga computer-controlled Fusion 100 Chemyx syringe pump (USA), and isinjected onto the electrode surface through a 0.5-mm-diameter inlethole. The inlet–electrode distance can be altered by usingdifferent washer thicknesses; however, the distance was maintainedat 2 mm for all experiments conducted herein. The flow is then strainedby the central component through 8 pores, each 0.5 mm in diameter,before passing into a pressure-equalizing well containing the counterand reference electrodes. The positioning of the electrodes in thiscell ensures that the electroactive solution components cannot beaffected by the counter electrode before reaching the working electrode.


Femtomolar Detection of Silver Nanoparticles by Flow-EnhancedDirect-Impact Voltammetry at a Microelectrode Array
Expandedand cross-sectional views of the home-built flow cell.Full schematics are reported in the Supporting Information.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5015217&req=5

fig1: Expandedand cross-sectional views of the home-built flow cell.Full schematics are reported in the Supporting Information.
Mentions: The flow cell was designedand built in-house. It allows the interchange of working electrodes,with a washer allowing control over the inlet–working electrodedistance. A schematic design is shown in Figure 1, and full schematics are reported in the Supporting Information. Figure 1 shows the demountable flow cell system,which is built from three separate sections that are bolted together.The three main cell components were manufactured from polyether etherketone (PEEK), with Delrin used for the reference and working electrodeholder. During operation, solution is flowed through the cell, usinga computer-controlled Fusion 100 Chemyx syringe pump (USA), and isinjected onto the electrode surface through a 0.5-mm-diameter inlethole. The inlet–electrode distance can be altered by usingdifferent washer thicknesses; however, the distance was maintainedat 2 mm for all experiments conducted herein. The flow is then strainedby the central component through 8 pores, each 0.5 mm in diameter,before passing into a pressure-equalizing well containing the counterand reference electrodes. The positioning of the electrodes in thiscell ensures that the electroactive solution components cannot beaffected by the counter electrode before reaching the working electrode.

View Article: PubMed Central - PubMed

ABSTRACT

20142014: Wereport the femtomolar detection of silver (Ag) nanoparticlesby direct-impact voltammetry. This is achieved through the use ofa random array of microelectrodes (RAM) integrated into a purpose-builtflow cell, allowing combined diffusion and convection to the electrodesurface. A coupled RAM-flow cell system is implemented and is shownto give reproducible wall-jet type flow characteristics, using potassiumferrocyanide as a molecular redox species. The calibrated flow systemis then used to detect and quantitatively size Ag nanoparticles atfemtomolar concentrations. Under flow conditions, it is found thenanoparticle impact frequency increases linearly with the volumetricflow rate. The resulting limit of detection is more than 2 ordersof magnitude smaller than the previous detection limit for direct-impact voltammetry (900 fM) [J. Ellison et al. Sens. Actuators, B, 200, 47], and is more than 30 times smaller than the previous detectionlimit for mediated-impact voltammetry (83 fM) [T.M. Alligrant et al. Langmuir, 30, 13462].

No MeSH data available.