Correlated imaging – a grand challenge in chemical analysis

Abstract

Correlated chemical imaging is an emerging strategy for acquisition of images by combining information from multiplexed measurement platforms to track, visualize, and interpret in situ changes in the structure, organization, and activities of interesting chemical systems, frequently spanning multiple decades in space and time. Acquiring and correlating information from complementary imaging experiments has the potential to expose complex chemical behavior in ways that are simply not available from single methods applied in isolation, thereby greatly amplifying the information gathering power of imaging experiments. However, in order to correlate image information across platforms, a number of issues must be addressed. First, signals are obtained from disparate experiments with fundamentally different figures of merit, including pixel size, spatial resolution, dynamic range, and acquisition rates. In addition, images are often acquired on different instruments in different locations, so the sample must be registered spatially so that the same area of the sample landscape is addressed. The signals acquired must be correlated in both spatial and temporal domains, and the resulting information has to be presented in a way that is readily understood. These requirements pose special challenges for image cross-correlation that go well beyond those posed in single technique imaging approaches. The special opportunities and challenges that attend correlated imaging are explored by specific reference to correlated mass spectrometric and Raman imaging, a topic of substantial and growing interest.

Spatially dependent alkyl quinolone signaling responses to antibiotics in Pseudomonas aeruginosa swarms

“…We utilized two chemically information rich imaging approaches, secondary ion mass spectrometry (SIMS) and confocal Raman microscopy (CRM) (31)(32)(33), to analyze the relative abundance and spatial distribution of AQs within 2D intact P. aeruginosa swarm communities both with and without antibiotic challenges. In the absence of antibiotics, our in situ observations of P. aeruginosa swarms revealed that the PQS and AQNO subclasses act on different spatial scales within plateassay pre-biofilm swarm communities.…”

Label-free molecular imaging of bacterial communities of the opportunistic pathogen Pseudomonas aeruginosa

“…11–12 The use of CRM provides sub-micron (diffraction limited) spatial resolution for constructing 3D chemical maps of the biological sample under study. 13–14 For example, CRM imaging has been employed extensively in the biomedical sciences for studying the distribution of biomolecules within living cells, the diagnosis of cancer in vivo and identification of cancer biomarkers. 15–18 Furthermore, compared to normal Raman spectroscopy, surface enhanced Raman spectroscopy (SERS) provides higher sensitivity along with the ability to probe biological samples exhibiting high auto-fluorescence.…”

Mass Spectrometry Imaging of Biomolecular Information

“…Combining information from mass spectrometry with information from other analytical methods is a topic of high interest in life sciences 101 . Besides comparing MS methods such as MALDI and SIMS, much has been done to co-register MS data with microscopic, histological or in-vivo analytical studies.…”