NITRIC OXIDE RELEASE

Nitric oxide (NO) release has been a major issue for precise NO sensor and AND gate testing. NO is a unstable species which degrades quickly in an aqueous medium. It is produced using the DETA/NO release mechanism. DETA was chosen because its half life is about 20 h, meaning it produces a slow and regular release, ensuring an almost constant concentration for a long duration.

DETA/NO is unstable in acid solvants. In aqueous solutions, the protein is destabilized by a proton transfer and releases 2 mol NO for 1 mol DETA/NO. Under aerobic conditions, NO oxidises to NO$_{2}$.

GOALS

Modelling the NO release from the DETA/NO system to identify the required DETA/NO concentration for testing our NO sensor and AND gate
Since it was not feasable for us to measure a calibration curve experimentally, we decided to simulate the NO release based on physical parameters

ASSUMPTIONS

The wells in which we perform the experiments involving nitric oxide are sealed, that's why we assumed that Henri's law can be applied to compute the partial pressure of oxygen on the volume containing air, and that because of the liquid-air equilibrium, the concentration of oxygen in the acqueous solution can be considered as constant. The parameters for the model were taken from literature (see Parameters).

REACTIONS

\begin{align*} DETA&\rightarrow 2 \ NO\\ 2 \ NO + O_{2}&\rightarrow 2 \ NO_{2}\\ \end{align*}

Species	Description
NO	Nitric Oxyde produced from DETA/NO reaction
DETA	Diethylenetriamine
O2	Oxygen
NO2	Nitrogen dioxyde

Parameters	Description
kox	Oxydation rate of NO into NO2 in water
kdeta	Production rate of NO from DETA

For parameter values, please check PARAMETERS

CALIBRATION CURVES

Figure 1: Calibration curve for DETA/NO release for different DETA concentrations ranging from 10 nM to 500 nM.

Figure 2: Calibration curve for DETA/NO release for DETA concentrations ranging from 1 mM to 100 mM.

RESULTS

Measuring NO in acqueous solution is fastidious, complicated, disturbs the studied system, and requires expensive material. Using the model above, we were able to estimate the amount of DETA required to test our NO sensor system. Our range of interest for the Nitric Oxide sensing is [2uM - 200 uM] which correspond to [30 uM - 100 mM] of DETA.