Electrochemical attosyringe

Abstract

The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In cell biology, it is often necessary to inject material of high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable to such molecules. All techniques currently used for microinjection are plagued by two common problems: the relatively large injector size and volume of injected fluid, and poor control of the amount of injected material. Here we demonstrate the possibility of electrochemical control of the fluid motion that allows one to sample and dispense attoliter-to-picoliter (10 ؊18 to 10 ؊12 liter) volumes of either aqueous or nonaqueous solutions. By changing the voltage applied across the liquid/liquid interface, one can produce a sufficient force to draw solution inside a nanopipette and then inject it into an immobilized biological cell. A high success rate was achieved in injections of fluorescent dyes into cultured human breast cells. The injection of femtoliter-range volumes can be monitored by video microscopy, and current/resistance-based approaches can be used to control injections from very small pipettes. Other potential applications of the electrochemical syringe include fluid dispensing in nanolithography and pumping in microfluidic systems.liquid/liquid interface ͉ microinjection ͉ nanopipette ͉ fluid delivery ͉ nanopump

Nanokit for single-cell electrochemical analyses

“…In this process, the physiological buffer (10 mM PBS, pH 7.4) with glucose oxidase was added to the capillary to detect the aqueous glucose levels. Based on previously reported conditions (22), a voltage of 1.0 V was applied to the capillary for 2 s for the initial egress of glucose oxidase. The charge curve in Fig.…”

“…A single injection of a femtoliter of solution was required to reduce the volume of the solution injected into the cell and produce minimal interruptions of cellular activity, which could not be achieved using mechanical pumping. Recently, an electrochemical attosyringe using electrochemical control of the fluid motion was reported to dispense attoliter to picoliter volumes of aqueous solutions into the cell, which was adapted into our nanokit for the flow of the kit components (22). As a result, electrochemical pumping was integrated into the nanokit to control the fluid flow and initiate the kit reaction at the tip.…”

Self‐assembled organic nanotubes: Toward attoliter chemistry

“…To manipulate still ultrasmaller volumes of liquids in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography, one needs a better understanding of fluid behavior confined in attoliter volume. [1][2][3][4][5][6][7] Indeed, water in nanometer-sized restricted geometries, such as micelles and microemulsions, 8,9 nanometer films, 10,11 and nanoporous silica, 12 often shows different and sometimes unexpected features in comparison to bulk water. The trend of miniaturization in conventional microchip devices consisting of poly(dimethylsiloxane), silicone, and glass has thus directed growing attention to new femtoliter (fL ¼ 10 À15 L) or attoliter (aL ¼ 10 À18 L) vessels like carbon 13 and silica nanotubes.…”

Label-free biosensing with functionalized nanopipette probes

“…By pulling a single glass capillary, one can easily and cost-effectively create a pair of nanopipettes that can be used for molecular deposition onto a solid surface (1,2), for delivery to the surface of a single cell (3) and its inner compartments (4,5), or for biomolecular sensing as described hereafter. These applications can be optimized by an enhanced understanding of the physical and chemical interactions at the pore region, which has been a subject of theoretical studies (6).…”