Highly Sensitive Detection of Exocytotic Dopamine Release Using a Gold-Nanoparticle-Network Microelectrode

Abstract

Here we report a new type of microelectrode sensor for single-cell exocytotic dopamine release. The new microsensor is built by forming a gold-nanoparticle (AuNP) network on a carbon fiber microelectrode. First a gold surface is obtained on a carbon fiber microdisk electrode by partially etching away the carbon followed by electrochemical deposition of gold into the pore. The gold surface is chemically functionalized with a sol-gel silicate network derived from (3-mercaptopropyl)trimethoxysilane (MPTS). A AuNP network is formed by immobilizing Au nanoparticles onto the thiol groups in the sol-gel silicate network. The AuNP-network microelectrode has been characterized by scanning electron microscopy (SEM) and steady-state voltammetry. The AuNP-network microelectrode has been used for amperometric detection of exocytotic dopamine secretion from individual pheochromocytoma (PC12) cells. The results show significant differences in the kinetic peak parameters including shorter rise time, decay time, and half-width as compared to a bare carbon fiber electrode equivalent. These results indicate AuNP-network microelectrodes possess an excellent sensing activity for single-cell exocytotic catecholamine release, specifically dopamine. Moreover, key advantageous properties inherent to bare carbon fiber microelectrodes (i.e., rigidity, flexibility, and small size) are maintained in addition to an observed prolonged shelf life stability and resistance to cellular debris fouling and dopamine polymerization.

Coupled Electrochemical Reactions at Bipolar Microelectrodes and Nanoelectrodes

“…CFEs were fabricated following our previously reported procedures. 22 Briefly, an isolated carbon fiber (5 μm diameter) was aspirated into a borosilicate glass capillary (1.2 mm o.d., 0.69 mm i.d., Sutter). Capillaries were subsequently pulled with a P-97micropipet puller (Sutter) and sealed with epoxy (Epoxy Technology) and beveled to 45°or further sealed in epoxy and polished at 90°as noted.…”

Redox‐Filled Carbon‐Fiber Microelectrodes for Single‐Cell Exocytosis

“…9 Briefly, a 5-μm-diameter carbon fiber was aspirated into a borosilicate glass capillary (o. d. = 1.2 mm, i. d. = 0.69 mm, Sutter Instrument Co.) and pulled with a micropipette puller (Model P-97, Sutter Instrument Co.). The pulled tip was sealed with epoxy (EPO-TEK 301-2, Epoxy Technology) and beveled (Model BV-10, Sutter Instrument Co.) to 45°.…”

“…9 Amperometric recordings at single cells were made on an inverted microscope (IX-71, Olympus) inside a home-built Faraday cage with culture dishes kept at 37 ± 1 °C. A CFE was positioned onto a cell by lowering the electrode tip until a slight deformation in the outline of the cell was observed.…”

Gold nanoparticle-based sensing platform of hydrazine, sulfite, and nitrite for food safety and environmental monitoring

“…In the 1980s, the sol-gel chemistry has been utilized for the fabrication of the modified metal such as gold (Au), platinum (Pt), and silver (Ag) interfaces (Gong et al 2014, Jena and Raj 2015, Sampath and Lev 1996. Numerous sensor platforms based on metal nanoparticles dispersed silicate matrices have been reported for environmental and biomedical applications (Adams et al 2011;Jena and Raj 2007;Matsuhisa et al 2013).…”