Selective and enhanced nitric oxide detection using hemoprotein/silica hybrids

We have attempted to detect nitric oxide (NO) in a gaseous state using soluble guanylyl cyclase (sGC), a NO specific hemoprotein, entrapped in a mesoporous silica network. Quartz crystal microbalance (QCM) carrying the above sensing matrix is used to monitor the NO response. The mesoporous silica film is prepared by a sol–gel process using polyethylene glycol with a molecular weight of 400 as an organic template to generate the porous structure. sGC is entrapped in the mesoporous silica network through physisorption. The frequency response of the QCM to NO is enhanced by the introduction of the mesoporous silica film on the QCM electrodes, and a detection sensitivity of ∼15 ppb/Hz is obtained. Owing to the strong affinity between the ferrous heme(s) of sGC and NO, we have demonstrated that other species such as nitrogen dioxide (NO2) and carbon monoxide (CO) exhibit minimal interferences on the sensor response and as such a selective NO detection is achieved.