In the last years, we have been interested in replicating the behavior of QMB sensor arrays with other transduction principle which enables a more simple sensor system design and even the integration of sensors in wearable supports. To this regard the simplest sensor is that based on electric impedance variation. For this scope porphyrins have been grafted onto the surface of nanostructures that can provide a change of impedance as a result of the chemical interaction between porphyrinoids and volatile compounds. For instance, layers of porphyrinoids coated ZnO nanoparticles shown sensitivity towards a large spectra of compounds [5]. Exploiting the optical properties of porphyrins, the sensitivity of this sensors can be triggered by light. As a result, these devices show a negative sensitivity to electron donor compounds (e.g. amines) and a positive sensitivity respect to other compounds. This property can be fruitfully exploited in sensor arrays configuration to classify complex samples such as foods and furthermore to detect spoilage processes. Another example is provided by porphyrnoids coated silica nanoparticles. In this case, the dielectric properties of silica are exploited to develop capacitive sensors whose capacitance is modulated by the absorption of volatile compounds. These sensors retains the chemical sensitivity properties of porphyrins allowing for instance to reproduce the results of the QMB sensors in the identification of COVID-19 blood serum sample.
References
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[2] R. Gasparri, M. Santonico, C. Valentini, G. Sedda, A. Borri, F. Petrella, P. Maisonneuve, G. Pennazza, A. D’Amico, C. Di Natale, R. Paolesse, L. Spaggiari, Volatile signature for the early diagnosis of lung cancer, J. Breath Res. 10 (2016).
[3] M. Murdocca, F. Torino, S. Pucci, M. Costantini, R. Capuano, C. Greggi, C. Polidoro, G. Somma, V. Pasqualetti, Y.K. Mougang, C. Di Natale, F.C. Sangiuolo, Urine lox-1 and volatilome as promising tools towards the early detection of renal cancer, Cancers. 13 (2021).
[4] Y.K. Mougang, L. Di Zazzo, M. Minieri, R. Capuano, A. Catini, J.M. Legramante, R. Paolesse, S. Bernardini, C. Di Natale, Sensor array and gas chromatographic detection of the blood serum volatolomic signature of COVID-19, IScience. 24 (2021) 102851.
[5] G. Magna, M. Muduganti, M. Stefanelli, Y. Sivalingam, F. Zurlo, E. Di Bartolomeo, A. Catini, E. Martinelli, R. Paolesse, C. Di Natale, Light-Activated Porphyrinoid-Capped Nanoparticles for Gas Sensing, ACS Appl. Nano Mater. 4 (2021) 414–424.