Direct Detection of Low-Concentration NO in Physiological Solutions by a New GaAs-Based Sensor

Abstract

Nitric oxide (NO) acts as a signal molecule in the nervous system, as a defense against infections, as a regulator of blood pressure, and as a gate keeper of blood flow to different organs. In vivo, it is thought to have a lifetime of a few seconds. Therefore, its direct detection at low concentrations is difficult. We report on a new type of hybrid, organic-semiconductor, electronic sensor that makes detection of nitric oxide in physiological solution possible. The mode of action of the device is described to explain how its electrical resistivity changes as a result of NO binding to a layer of native hemin molecules. These molecules are self-assembled on a GaAs surface to which they are attached through a carboxylate binding group. The new sensor provides a fast and simple method for directly detecting NO at concentrations down to 1 microM in physiological aqueous (pH=7.4) solution at room temperature.

Real-time electrical detection of nitric oxide in biological systems with sub-nanomolar sensitivity

“…NO solution was prepared by dissolving an NO precursor (diethylamine NONOate sodium salt) into 10 mM NaOH solution followed by dilution with 10 mM PBS (pH ¼ 7.4), following a protocol developed in previous NO sensor studies 15 . All NaOH and PBS solutions were pre-bubbled with N 2 for 2 h to remove the dissolved oxygen.…”

“…With specific molecular functionalization, semiconductor (for example, GaAs)-based field-effect transistors (FETs) can be configured as NO sensors with reduced dimension for real-time detection of NO in physiological solutions 15 . However, the sensitivity of such sensors reported to date is typically limited to the micromolar regime, unsuitable for practical monitoring of biological NO levels that are typically in the nanomolar regime.…”

Computational insights into charge transfer across functionalized semiconductor surfaces

“…Surface modification is commonly used in PEC cells [31,32] as well as a variety of additional applications such as electronic devices [16][17][18][19][20][21], data storage [22], chemical sensing [23][24][25], molecular nanopatterning [26], and bioengineering [27][28][29][30]. In PEC applications, chemical attachment of organic molecules is a versatile technique used to enhance the stability of low-gap semiconductors while controlling the physiochemical properties of the surface [33].…”

The Cooperative Molecular Field Effect

“…They can cover existing surfaces conformally and modify them functionally, yielding surfaces with new (opto)electronic properties, [2±6] and leading to new elements in electronic devices, [7±10] including light-emitting diodes [11] and sensors. [12] In the following we will discuss the unique electronic properties of 2D close-packed molecular layers that lead to the COMFE and then describe several applications which are based on these properties. David Cahen completed his B.Sc.…”