| 1. |
- Ali Malik, Muhammad, et al.
(author)
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Imaging fingerprinting of excitation emission matrices
- 2009
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In: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 635:2, s. 196-201
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Journal article (peer-reviewed)abstract
- The spectral fingerprinting of the excitation emission matrix (EEM) of fluorescent substances is demonstrated using polychromatic light sources and tri-chromatic image detectors. A model of the measured fingerprints explaining their features and classification performance, based on the polychromatic excitation of the indicators is proposed.Substantial amount of spectral information is retained in the fingerprints as corroborated by multivariate analysis and experimental conditions that favor such situation are identified.In average, for five different substances, the model shows a fitting goodness measured by the Pearsons r coefficient and the root mean square deviation of 0.8541 and 0.0247 respectively, while principal component classification patterns satisfactorily compare with the EEM spectroscopy classification and respectively explain 96% and 93% of the information in the fist two principal components.The measurements can be performed using regular computer screens as illumination and web cameras as detectors, which constitute ubiquitous and affordable platforms compatible with distributed evaluations, in contrast to regular instrumentation for EEM measurements.
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| 2. |
- Di Natale, Corrado, et al.
(author)
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Investigation of quartz microbalance and ChemFET transduction of molecular recognition events in a metalloporphyrin film
- 2009
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In: Sensors and actuators. B, Chemical. - : Elsevier BV. - 0925-4005. ; 135:2, s. 560-567
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Journal article (peer-reviewed)abstract
- Progresses of synthetic chemistry methodologies have allowed the preparation of a great variety of artificial receptors that are particularly appealing for chemical sensor development. In this paper, we investigate and compare the properties of gas sensors based on two types of devices, quartz microbalances (QMBs) and field effect transistors (FETs), which give the means to exploit the molecular recognition events occurring in non-conductive sensing layers formed by a thiol-modified cobalt tetraphenylporphyrin (CoTPPSH). Since QMB is sensitive to mass and FET is sensitive to electric dipoles, the resulting sensors are expected to exhibit different sensitivities and selectivities, although both based on the same sensing layer. In particular we show that the high sensitivity of CoTPPSH-coated FETs towards CO and NO is a consequence of the significant CoTPPSH electric dipole change after the gas coordination to the metal centre.
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| 3. |
- Di Natale, Corrado, et al.
(author)
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Multi-transduction of molecular recognition events in metalloporphyrin layers
- 2009
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In: Journal of Porphyrins and Phthalocyanines. - 1088-4246 .- 1099-1409. ; 13:11, s. 1123-1128
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Journal article (peer-reviewed)abstract
- Besides the design and synthesis of appropriate molecular recognition systems, the development of chemical sensors requires a careful selection of the transducer to allow conversion of the chemical interaction into an exploitable electric signal. Metalloporphyrins, which are characterized by manifold of interactions of different strength and selectivity, provide a good example of the complexity of such an issue. In this paper, an example of the different ways to capture interactions occurring in a metalloporphyrin layer is presented. In particular, the properties of mass ( quartz microbalance) and surface potential transducers (field effect transistor) are illustrated. Results suggest that field effect transistors are more suitable to preserve the interactions magnitude scale than to maintain the original selectivity of the molecular recognition system.
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| 4. |
- Dini, Francesca, et al.
(author)
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Chemical sensitivity of self-assembled porphyrin nano-aggregates
- 2009
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In: NANOTECHNOLOGY. - : IOP Publishing. - 0957-4484 .- 1361-6528. ; 20:5, s. 055502-
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Journal article (peer-reviewed)abstract
- Nanostructured molecular assemblies may provide additional sensing properties not found in other arrangements of the same basic constituents. Among three-dimensional structures, nanotubes are particularly appealing for applications as chemical sensors, because of the potential inclusion of different guests inside the cavity or the induced modification of the skeletal interaction after analyte binding. Porphyrins are a class of compounds characterized by brilliant sensing properties, appearing also in non-ordered solid-state aggregates. In recent years, it was reported that aggregation of oppositely charged porphyrins led to the formation of self-assembled nanotubes and in this paper their sensing properties, both in solution and in the solid state, have been investigated. The interactions of porphyrin nanotubes with guest molecules have been monitored by following the changes in their UV-vis spectra. The results obtained have been exploited to build up a sensing platform based on a computer screen as a light source and a digital camera as detector. Porphyrin nanostructures exhibited an enhanced sensitivity to different compounds with respect to those shown by single porphyrin subunits. The reason for the increased sensitivity may be likely found in an additional sensing mechanism related to the modulation of the strength of the forces that keep the supramolecular ensemble together.
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| 5. |
- Filippini, Daniel, et al.
(author)
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Spectral fingerprinting of porphyrins for distributed chemical sensing
- 2009
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In: JOURNAL OF PORPHYRINS AND PHTHALOCYANINES. - 1088-4246. ; 13:1, s. 77-83
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Journal article (peer-reviewed)abstract
- Recent progress in spectral fingerprinting of fluorescent indicators using distributed instrumentation based on consumer electronic devices is reviewed. In particular, the evaluation of disposable assays using a computer screen photo-assisted technique (CSPT) is discussed. Sample identification and optimization strategies are analyzed as well as the underlying theoretical background for polychromatic spectral fingerprinting.
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| 6. |
- Macken, Stephen, et al.
(author)
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Towards integrated devices for computer screen photo-assisted multi-parameter sensing
- 2009
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In: Analytica Chimica Acta. - : Elsevier BV. - 0003-2670 .- 1873-4324. ; 632:1, s. 143-147
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Journal article (peer-reviewed)abstract
- The computer screen photo-assisted technique (CSPT) utilizes consumer electronic devices such as computer screens and web cameras for distributed chemical sensing. Key to this method is the development of small and disposable sensing assays able to aid the CSPT optical detection, and the evaluation of multiple indicators. Here we demonstrate CSPT identification of fluorescent indicators from individual 100 mu m SU-8 (10) pillars covering an area of 4 mm x 4 mm with a density of 47 elements mm-2. The extraction of distinctive spectral fingerprints is aided by the exploitation of a three-band Moire interference that enables the partial Bayer decoding of the CSPT images.
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| 7. |
- Tortora, Luca, et al.
(author)
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The hyphenated CSPT-potentiometric analytical system : An application for vegetable oil quality control
- 2009
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In: SENSORS AND ACTUATORS B-CHEMICAL. - : Elsevier BV. - 0925-4005. ; 142:2, s. 457-463
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Journal article (peer-reviewed)abstract
- The computer screen photo assisted technique (CSPT) has been used to develop a hyphenated optical-potentiometric sensing at-ray, based on porphyrinoid materials dispersed into PVC membranes. Sensing layers have been deposited onto indium tin oxide (ITO) glass slides, which were exploited as electrodes, for potentiometric measurements, and chromophore spots, to obtain CSPT data. Both measurements were contemporaneously carried out in the hyphenated sensing platform. The performances of the hyphenated sensing array were first tested for the detection of model analytes, characteristics of vegetable oil matrices, and then evaluated in the discrimination of real samples of olive and seed oils. The results obtained demonstrated that the hyphenated system affords a significant improvement of information and oils classification with respect to the individual potentiometric and optical components.
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