Process control and safety assessment in fermentation industry are currently assured using highly sophisticated (and expensive) analytical methods, often performed off-line and characterized by a delay not compatible with the timing of the process. Therefore, there is an urgent need to develop new industrial technologies based on simple, low-cost electrochemical sensors for on-line monitoring and safety in fermentation processes [1]. Modern fermentation industry requires quick solutions for in-process control and monitoring as many parameters as possible. While most bioprocesses are controlled by measuring traditional parameters (pH, temperature, CO2 and O2 concentrations), a demanding issue is to follow on-line the concentrations of raw substrates and fermentation products. The direct monitoring of chemical species (e.g. glucose, ethanol which could be tracers in the process) may strongly improve the bioprocess performances. In this contribution we report the development of an enzyme-free glucose and ethanol electrochemical sensor based on Au nano-particles (NPs) dispersed on titania. In order to obtain Au NPs with different dimensions, ranging from 2 to 40 nm, we started with the synthesis of colloidal solutions of Au NPs by reduction of an aqueous solution of HAuCl4 performed with different reducing agents. By varying some parameters, such as the i) nature of reducing/capping agent, ii) ratio of gold ion concentration to stabilizer/reductant and iii) reaction temperature, a high grade of control on size distribution has been obtained. In a second step an appropriate volume of Au colloidal solution was contacted with TiO2 powder (P25 Degussa), in order to have an Au loading of 0.5 wt. % by wet impregnation. Then, planar electrochemical sensors for the detection of glucose and ethanol were fabricated by casting the Au TiO2 powder on the working electrode. The evaluation of the electrochemical performances of those sensors showed their promising properties in the simultaneous determination of both glucose and ethanol. Blank tests with bare titania did not give any activity, indicating the importance to have small NPs well dispersed on the surface of TiO2. The electrocatalytic activity of Au TiO2 can be ascribed to the large surface area of Au NPs on the TiO2. Furthermore, titania stabilizes Au NPs and new catalytic sites are formed at the interface between Au and TiO2. This joint effect significantly enhances the electrocatalytic activity towards the oxidation of glucose and ethanol, allowing monitoring of both these substances by using only one sensor. In conclusion, the development of a novel industrial technology for fermentation process monitoring and safety based on inexpensive sensors is very actual, since it intends to solve a global industrial issue. Work is in progress to deposit Au NPs on different kinds of titania, as nano-structured TiO2 arrays prepared by anodic oxidation [2] to further improve the electrocatalytic responses of our sensors. References [1] S. G. Leonardi, N. Donato, D. Aloisio, L. Lombardo, E. Patti, M Latino, G. Neri. Novel Nanomaterials for (bio)sensors, La Chimica e l'Industria, 94 (9) (2012), 122-125. [2] R. Passalacqua, C. Ampelli, S. Perathoner, G. Centi. Anodically Formed TiO2 Thin Films: Evidence for a Multiparameter Dependent Photocurrent-Structure Relantionship, Nanosci. Nanotechnol. Lett., 4 (2) (2012), 142-148.

Novel electrochemical sensors for safety and control in fermentation processes

AMPELLI, Claudio;LEONARDI, SALVATORE GIANLUCA;GENOVESE, CHIARA;LANZAFAME, PAOLA;PASSALACQUA, Rosalba;PERATHONER, Siglinda;CENTI, Gabriele;NERI, Giovanni
2014-01-01

Abstract

Process control and safety assessment in fermentation industry are currently assured using highly sophisticated (and expensive) analytical methods, often performed off-line and characterized by a delay not compatible with the timing of the process. Therefore, there is an urgent need to develop new industrial technologies based on simple, low-cost electrochemical sensors for on-line monitoring and safety in fermentation processes [1]. Modern fermentation industry requires quick solutions for in-process control and monitoring as many parameters as possible. While most bioprocesses are controlled by measuring traditional parameters (pH, temperature, CO2 and O2 concentrations), a demanding issue is to follow on-line the concentrations of raw substrates and fermentation products. The direct monitoring of chemical species (e.g. glucose, ethanol which could be tracers in the process) may strongly improve the bioprocess performances. In this contribution we report the development of an enzyme-free glucose and ethanol electrochemical sensor based on Au nano-particles (NPs) dispersed on titania. In order to obtain Au NPs with different dimensions, ranging from 2 to 40 nm, we started with the synthesis of colloidal solutions of Au NPs by reduction of an aqueous solution of HAuCl4 performed with different reducing agents. By varying some parameters, such as the i) nature of reducing/capping agent, ii) ratio of gold ion concentration to stabilizer/reductant and iii) reaction temperature, a high grade of control on size distribution has been obtained. In a second step an appropriate volume of Au colloidal solution was contacted with TiO2 powder (P25 Degussa), in order to have an Au loading of 0.5 wt. % by wet impregnation. Then, planar electrochemical sensors for the detection of glucose and ethanol were fabricated by casting the Au TiO2 powder on the working electrode. The evaluation of the electrochemical performances of those sensors showed their promising properties in the simultaneous determination of both glucose and ethanol. Blank tests with bare titania did not give any activity, indicating the importance to have small NPs well dispersed on the surface of TiO2. The electrocatalytic activity of Au TiO2 can be ascribed to the large surface area of Au NPs on the TiO2. Furthermore, titania stabilizes Au NPs and new catalytic sites are formed at the interface between Au and TiO2. This joint effect significantly enhances the electrocatalytic activity towards the oxidation of glucose and ethanol, allowing monitoring of both these substances by using only one sensor. In conclusion, the development of a novel industrial technology for fermentation process monitoring and safety based on inexpensive sensors is very actual, since it intends to solve a global industrial issue. Work is in progress to deposit Au NPs on different kinds of titania, as nano-structured TiO2 arrays prepared by anodic oxidation [2] to further improve the electrocatalytic responses of our sensors. References [1] S. G. Leonardi, N. Donato, D. Aloisio, L. Lombardo, E. Patti, M Latino, G. Neri. Novel Nanomaterials for (bio)sensors, La Chimica e l'Industria, 94 (9) (2012), 122-125. [2] R. Passalacqua, C. Ampelli, S. Perathoner, G. Centi. Anodically Formed TiO2 Thin Films: Evidence for a Multiparameter Dependent Photocurrent-Structure Relantionship, Nanosci. Nanotechnol. Lett., 4 (2) (2012), 142-148.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11570/2628968
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