3,861 research outputs found
Photo-renewable engineered sensor based on silica, silver nanoparticles and titania
No full textElectrode surface passivation and fouling are important challenges in electroanalysis when using modified electrodes in complex matrices, especially in the biomedical and environmental fields [1-2].
In order to overcome such problems, the production of highly engineered ad hoc designed devices could provide really effective sensors [2]. In particular, a reliable and reusable sensor, that could be cleaned by a simple irradiation with UV or solar light, could be perfect for this purpose.
In this context, a three-layered transparent electrode, in which silver nanoparticles are embedded between a bottom silica and a top titania layer is developed [3-4]. Such structure confers to the device multifunctional properties which can be conveniently used in the detection and quantification of some neurotransmitters: dopamine, norepinephrine and serotonin.
The sensor is thoroughly investigated by structural, morphological and electrochemical characterizations in order to understand the role of each component with the aim to improve the robustness and efficiency of the electroanalytical system. In particular, the size distribution of silver nanoparticles, the device architecture and surface homogeneity are inspected by electron microscopy. As confirmed by X-ray diffraction the overlayer is made of anatase (the active polymorph of titanium dioxide), capable of photodegrading model contaminants. Furthermore, electrochemical techniques (cyclic voltammetry and electrochemical impedance spectroscopy) revealed that a highly ordered distribution of silver nanoparticles constitutes the active analytical core of the device, allowing easier electron transfer and better quantification of the analytes.
The system presents good sensing performances, reaching low detection limits even in the presence of typical interferents such as ascorbic and uric acids. Moreover, the titania photoactive top layer allows the complete recovery of the device performance in terms of sensitivity after a fast and simple UV-A cleaning step, affordable with different UV sources. In particular, three lamps (different in terms of power and wavelength) were tested, reaching the total removal of the contaminants in 10-15 minutes [5]. This “self-cleaning” property, combined with a remarkable resistance against aging and ease of use, allows to employ the sensor also for detection in real matrixes, such as liquor and serum.
ACKNOWLEDGEMENTS
The Authors would like to thank MIUR (Ministero dell’Istruzione, dell’Università e della Ricerca) for the fundings in the framework of the PRIN 2012 Project (20128ZZS2H)
REFERENCES
[1] C.M.A. Brett, Pure Appl. Chem. 73, 2001, pp 1969–1977.
[2] C.M. Welch, R.G. Compton, Anal. Bioanal. Chem. 384, 2006, pp 601–619.
[3] G. Maino, D. Meroni, V. Pifferi, L. Falciola, G. Soliveri, G. Cappelletti, S. Ardizzone, J. Nanoparticle Res. 15, 2013, pp 2087.
[4] G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, L. Falciola, Analyst 140, 2015, 1486-1494.
[5] V. Pifferi, G. Soliveri, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, L. Falciola, RSC Advances, 5, 2015, 71210-71214
Self-cleaning properties of a silica/silver nanoparticles/titania sandwich sensor
No full textOne of the main challenges faced during electroanalysis of complex matrices is represented by fouling and passivation of the electrode surface, especially in the fields of biomedical and environmental trace analysis [1], where sophisticated and highly engineered sensors have to be used in order to increase sensitivity and lower detection limits. These sensors can not be cleaned by conventional mechanical or electrochemical procedures, since these methods could affect the integrity of the active layer. In order to overcome these problems, the production of highly engineered reliable and reusable devices, designed ad hoc for specific applications, which could be simply cleaned by irradiation with UV light, would be an interesting step beyond the current state of the art.
In this context, a three-layered transparent electrode, in which silver nanoparticles are embedded between a bottom silica and a top titania layer [2, 3] was designed, prepared and characterized. The device structure is meant to confer multifunctional properties for a complex biomedical challenge: the detection and quantification of catecholamine neurotransmitters. The key role of each component of the device was thoroughly investigated to demonstrate the robustness and efficiency of the final sensor. In particular, the size distribution of silver nanoparticles, the device architecture and surface homogeneity were inspected by electron microscopy. The cleaning overlayer was made of the active polymorph of titanium dioxide (anatase), as confirmed by X-ray diffraction and by model contaminants photodegradation measurements. Electrochemical techniques (cyclic voltammetry and electrochemical impedance spectroscopy) revealed that an highly ordered distribution of silver nanoparticles is the active core of the device, allowing easier electron transfer and better quantification of the analytes even in the presence of conventional interferents, e.g. ascorbic acid and uric acid in human fluids.
The high photoactivity of titania top layer allowed total recovery of the device performance in terms of sensitivity after a fast (less than 20 min) UV cleaning step, affordable with different UV-A sources. This self-cleaning property, combined with a remarkable resistance against ageing, allows to employ the sensor also in on-field and remote applications.
References
[1] C. M. Welch and R. G. Compton, Anal. Bioanal. Chem. 2006, 384, 601–619.
[2] G. Maino, D. Meroni, V. Pifferi, L. Falciola, G. Soliveri, G. Cappelletti, S. Ardizzone, J. Nanoparticle Res. 2013, 15, 2087.
[3] G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, L. Falciola, Analyst 2015, 140, 1486
Innovative engineered sensors based on silica, silver nanoparticles and titania with self-cleaning features
No full textPassivation of the electrode surface and fouling are important challenges in electroanalysis during the use of modified electrodes in complex matrices, especially in the biomedical and environmental fields (Soliveri et al., 2015). The production of highly engineered devices, ad hoc designed for specific applications, could overcome such problems, accessing really effective sensors. A performing, reliable and reusable sensor, that could be cleaned by a simple irradiation with UV or solar light, would perfectly match this goal.
In this context, a three-layered transparent electrode, in which silver nanoparticles are embedded between a bottom silica and a top titania layer (Maino et al., 2013 and Welch and Compton, 2006), was developed. Such structure confers to the device multifunctional properties for a complex biomedical challenge: the detection and quantification of catecholamine neurotransmitters. The sensor was thoroughly investigated in order to understand the role of each component with the aim of making the device a robust and efficient electroanalytical system.
The overlayer was made of anatase (the active polymorph of titanium dioxide) as confirmed by X-ray diffraction and by measuring the photodegradation of model contaminants. The size distribution of silver nanoparticles, the device architecture and surface homogeneity were inspected by electron microscopy. Electrochemical techniques (cyclic voltammetry and electrochemical impedance spectroscopy) revealed that a highly ordered distribution of silver nanoparticles constitutes the active core of the device, allowing easier electron transfer and better quantification of the analytes even in the presence of conventional interferents, e.g. ascorbic and uric acid. Titania photoactive top layer allowed total recovery of the device performance in terms of sensitivity after a fast and simple UV-A cleaning step, affordable with different UV sources. This self-cleaning property, combined with a remarkable resistance against aging and ease of use, allows to employ the sensor also in on-field and remote applications.
Maino G., Meroni D., Pifferi V., Falciola L., Soliveri G., Cappelletti G., Ardizzone S. (2013). Electrochemically assisted deposition of transparent, mechanically robust TiO2 films for advanced applications. J. Nanoparticle Res., 15, 2087.
Soliveri G., Pifferi V., Panzarasa G., Ardizzone S., Cappelletti G., Meroni D., Sparnacci K., Falciola L. (2015). Self-cleaning properties in engineered sensors fordopamine electroanalytical detection. Analyst, 140, 1486-1494.
Welch C. M., Compton R. G. (2006). The use of nanoparticles in electroanalysis: a review. Anal. Bioanal. Chem., 384, 601–619
Self-cleaning features of an innovative engineered sensor based on silica, silver nanoparticles and titania
No full textPassivation of the electrode surface and fouling are important challenges in electroanalysis during the use of modified electrodes in complex matrices, especially in the biomedical and environmental fields [1-2].
In order to overcome such problems, the production of highly engineered ad hoc designed devices could access really effective sensors [2]. In particular, a performing, reliable and reusable sensor, that could be cleaned by a simple irradiation with UV or solar light, would be perfect for this purpose.
In this context, a three-layered transparent electrode, in which silver nanoparticles are embedded between a bottom silica and a top titania layer was developed [3-4]. Such structure confers to the device multifunctional properties for a complex biomedical challenge: the detection and quantification of catecholamine neurotransmitters. The sensor was thoroughly investigated by structural, morphological and electrochemical characterizations in order to understand the role of each component with the aim to improve the robustness and efficiency of the electroanalytical system.
The overlayer was made of anatase (the active polymorph of titanium dioxide) as confirmed by X-ray diffraction and by measuring the photodegradation of model contaminants. The size distribution of silver nanoparticles, the device architecture and surface homogeneity were inspected by electron microscopy. Electrochemical techniques (cyclic voltammetry and electrochemical impedance spectroscopy) revealed that a highly ordered distribution of silver nanoparticles constitutes the active core of the device, allowing easier electron transfer and better quantification of the analytes even in the presence of conventional interferents, e.g. ascorbic and uric acid. Titania photoactive top layer allowed total recovery of the device performance in terms of sensitivity after a fast and simple UV-A cleaning step, affordable with different UV sources. This self-cleaning property, combined with a remarkable resistance against aging and ease of use, allows to employ the sensor also in on-field and remote applications.
References
1. C.M.A. Brett, Pure Appl. Chem. 73, 2001, pp 1969–1977.
2. C.M. Welch, R.G. Compton, Anal. Bioanal. Chem. 384, 2006, pp 601–619.
3. G. Maino, D. Meroni, V. Pifferi, L. Falciola, G. Soliveri, G. Cappelletti, S. Ardizzone, J. Nanoparticle Res. 15, 2013, pp 2087.
4. G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, L. Falciola, Analyst 140, 2015, 1486-1494
Some Remarks on the Recent SRM Related Case-Law of the CJEU with Special Regard to the Meroni Doctrine
No full textThe study elaborates on the development of the Meroni doctrine, derived from the Meroni judgment of the Court of Justice of the European Coal and Steel Community under a different Founding Treaty framework and its applicability to the Banking Union under the current Treaty framework. To fulfil this aim, the author first elaborates on the Advocate General’s opinion and the Judgment of the Court of Justice in the Meroni case and then briefly introduces the evolution and the literature on the issue. After a short introduction of the Banking Union’s institutional order, the author introduces two cases in which issues related to the Meroni doctrine were raised before the General Court, as well as the appellate procedures before the Court of Justice in one of these cases
Introduzione Reaction
No full textUna introduzione ai progetti nati a Milano con il programma strategico Reaction, dedicato alla rigenerazione di quartieri di edilizia residenziale pubblica
Silver nanoparticles/nanostructured TiO2 interface: a photo-renewable “silver-ions electrode” for neurotransmitters detection
No full textSilver nanoparticles were embedded in a TiO2 (anatase polymorph) photoactive layer in a sandwich-like nanostructured electrode. [1-2]
The device was (photo)electrochemically characterized by cyclic voltammetry and electrochemical impedance spectroscopy.
In comparison with literature data on electrodes modified with silver nanoparticles [3-5], the new sensor presents a pronounced electrocatalytic effect on the silver oxidation peak together with a great increase in the current intensity.
Parallel plane-wave DFT calculations, performed using the VASP code [6], described the composite junction as a distorted bulk Ag structure, commensurate with the periodicity of the (101) face of the I41/amd TiO2 anatase polymorph. The silver atoms close to the semiconductor were found to gain a partially positive charge, quickly decreasing with the distance from the TiO2 surface.
Comparing the theoretical and experimental results it could be concluded that the device may be considered as a “positively charged silver nanoparticles-based electrode”, with positively ionized surface silver atoms protected by the titania layer, which holds a partial negative charge.
The final sensor performed efficiently in the electroanalytical determination of some neurotransmitters (e.g. dopamine, norepinephrine and serotonin) in simulated biological matrices (liquor, serum and urine). The optimized analytical methodology is not only characterized by high sensitivity and low detection limits (around 0.03 μM, which makes it appealing for clinical purposes), but also by high selectivity in the presence of high concentrations of conventional interferents (uric and ascorbic acids).
Last but not least, the fouling and passivation of the electrode surface, an unavoidable drawback during the detection of this kind of analytes, could be easily overcome by irradiating the device with UVA-light, which restored the initial sensor sensitivity. The photo-renewability allows to reactivate the sensor on site, i.e. directly in solution, to yield a system capable of working in continuous, able to be used in an integrated monitoring system.
References
[1] G. Soliveri, V. Pifferi, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, K. Sparnacci, L. Falciola, Analyst, 140, (2015), 1486 – 1494.
[2] V. Pifferi, G. Soliveri, G. Panzarasa, S. Ardizzone, G. Cappelletti, D. Meroni, L. Falciola, RSC Advances, 5, (2015), 71210 – 71214.
[3] O. S. Ivanova, F. P. Zamborini, J. Am. Chem. Soc., 132, (2010), 70–72.
[4] G. Chang, J. Zhang, M. Oyama, K. Hirao, J. Phys. Chem. B, 109, (2005), 1204-1209.
[5] S.E. Ward Jones, F.W. Campbell, R. Baron, L. Xiao, R.G. Compton, J. Phys. Chem. C, 112, (2008), 17820–17827.
[6] G. Kresse, J. Furthmüller, Phys. Rev. B, 54:11169, (1996).
Acknowledgements
This work has been supported by Fondazione Cariplo (Milano, Italy), grant no. 2014-1285. We acknowledge the CINECA and the Regione Lombardia award under the LISA initiative (grant SURGREEN) for the availability of high performance computing resources. We also thank the Chemistry Department for funding through the Development Plan of Athenaeum grant – line B1 (UNIAGI 17777)
Neuroeconomia, neuromarketing e processi decisionali
No full textIl libro copre un settore, quello della applicazione delle moderne tecniche di neuroscienze ai settori dell'economia e del marketing, di recente nascita e di grande interesse per l'opinione pubblica, per gli addetti alla pubblicità nonché agli studiosi di neuroscienze. Il libro presenta, in un linguaggio piano e non per gli esperti della materia, la struttura ed il funzionamento cerebrale (così come si conosce ad oggi) durante i processi decisionali nell'uomo. Di interesse l'analisi di come i diversi sistemi neuronali all'interno del cervello possono cooperare fra loro nel generare delle decisioni. Tutta questa semplice trattazione fisiologica è inserita nel contesto dell'analisi dell'attività cerebrale durante la visione di clip commerciali. Nello studio originale presentato in questo libro, le variabili interessate sono state quelle relative al ricordo della pubblicità televisiva in un campione di soggetti normali giovani. Questo studio è semplicemente il primo che si effettua di tale tipo in Italia e sarà destinato ad essere un punto di riferimento per i successivi studi nel settor
Thigh pain incidence at 24-months after total hip arthroplasty with the short stem Tri-Lock BPS, Gription coating : a prospective study
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