Novel Solid State Nitric Oxide Sensor Using Siloxane-Poly(Oxypropylene) (PPO)

Abstract

In this paper, a novel solid state Nitric Oxide (NO) sensor made of a spin trap (iron(II)-diethyldithiocarbamate complex, FeDETC) encapsulated in a siloxane-poly(oxypropylene) (PPO) matrix was developed. Nitric oxide (NO), a free radical molecule, has numerous roles in various physiological functions, such as the regulation of blood pressure, immune response to bacterial infection, and nervous systems. Siloxane-polyether hybrid materials, for example siloxanepoly(oxypropylene) (PPO), are easy to prepare, transparent and flexible. The combination of all these characteristics in a unique material allows it to be used in several scientific and technological areas, including human health. NO radical is trapped in FeDETC, which allows its detection by electron paramagnetic resonance (EPR). FeDETC was added while PPO was a sol, which was then left in air for gelation. The novel sensor was dived directly into a solution of NO, when the NO-FeDETC complex was formed. Our results show that the novel sensor responds to NO, with similar sensitivity as previously published sensors. PPO sensors present a strong EPR signal and a high stability, keeping its signal for 45 days. We have studied ways to accelerate the NO release from the sensor, in order to study its potential as a drug delivery system. We observed an acceleration in NO release by using a modulated magnetic field of 40 G at 100 kHz; as well as by UV irradiation. Thermal induced NO release was also tested by heating NO-FeDETC PPO up to 50˚C, with good results.

Drug Delivery Systems Obtained from Silica Based Organic-Inorganic Hybrids

“…Herculano et al [ 74 ] showed that the release of nitric oxide (NO) could be improved when incorporated in ureasil-PPO ( M w 400 g·mol −1 ). NO is a free radical indicated for the treatment of blood vessel protection.…”

“…Thus, the authors use encapsulation of iron(II)-diethyldithiocarbamate (FeDETC) in various matrices for either the measurement of NO or its release due to the affinity between NO and the iron complexes, allowing the use of electron paramagnetic resonance (EPR) to radical detection [ 77 ]. The studies showed that it was possible to detect the release of NO after 40 days [ 74 ]. This system is an important advance in the development of DDS containing NO for the treatment of heart diseases.…”