What is it about?
Porous materials offer a large surface to which molecules can bind. Thus, ideally, they can increase the sensitivity of detection schemes even by order of magnitudes. Yet a large surface constrained into a small volume implies that unwanted molecules might be trapped within the sensor during the analysis and give rise to a false positive signal. This signal is called unspecific signal and it is due to species that were not the target of the measurement but which still induec a sensor reponse. This article describes and quantifies how strong the effect is in nanoporous material optical sensors and demonstrate that the non specific signal might completely hidden the specific one, unless the surface is properly rinsed using a flow-through approach.
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Why is it important?
Ultra high sensitivity is often obtained only in laboratory using model samples (aka samples that contained dilutied solution of only the target molecule). In real applications several species are rpesent and interact with the sensor. One of the main factor that increase the minimum detectable concentration is the non specific signal. Thus it is of paramount importance to understand this interactions (which are specific for each type of sensors) in order to minimize them and reduce the limit of detection.
Perspectives
In this article we demonstrate that non specific signal can be of the same order of magnitude of the specific one and that it can completely mimic a specific signal (even the linear -expected- sensor calibration curve). Thus the results of a sensing measurements done on porous material can be completely flawed by the non specific effect. The article compares flow oVer and flow through appraoches and shows that only the latter can reduce the non specific signal.
Dr Paolo Bettotti
university of Trento
Read the Original
This page is a summary of: Investigation of non-specific signals in nanoporous flow-through and flow-over based sensors, The Analyst, January 2014, Royal Society of Chemistry,
DOI: 10.1039/c3an01996a.
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