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. DETANO is unstable in acid solvants. In acqueous solution the protein is destabilized by a proton transfer and released 2 mol of nitric oxyde for 1 mol of DETANO. NO is also unstable in water as it is involved in oxydo-reduction reaction with the dioxygene (O2) present in water.

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

As the well on which we perform experiment involving nitric oxide release are sealed, we used henri's Law to computer the partial pressure of oxygen on the volume containing air, and make sure that the concentration of O2 insique the acqueous solution can be considered as constant, because of the liquid-air equilibrium. The parameters we are using are taken from literature.

REACTIONS

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

Species	Description
NO	Nitric Oxyde produced from DETA/NO reaction
DETA	DiethylenetriamineE. coli cells
O2	OxygenE. coli cells
NO2	Nitrogen dioxydeE. coli cells

Parameters	Description
kox	Oxydation rate of NO into NO2 in water
kdeta	production rate of NO from DETAE. coli cells

Parameters Values

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.