Targeted multiplex imaging mass spectrometry with single chain fragment variable (scfv) recombinant antibodies

Conjugating immunoassays to mass spectrometry: Solutions to contemporary challenges in clinical diagnostics

Developments in immunoassays and mass spectrometry have independently influenced diagnostic technology. However, both techniques possess unique strengths and limitations, which define their ability to meet evolving requirements for faster, more affordable and more accurate clinical tests. In response, hybrid techniques, which combine the accessibility and ease-of-use of immunoassays with the sensitivity, high throughput and multiplexing capabilities of mass spectrometry are continually being explored. Developments in antibody conjugation methodology have expanded the role of these biomolecules to applications outside of conventional colorimetric assays and histology. Furthermore, the range of different mass spectrometry ionisation and analysis technologies has enabled its successful adaptation as a detection method for numerous clinically relevant immunological assays. Several recent examples of combined mass spectrometry-immunoassay techniques demonstrate the potential of these methods as improved diagnostic tests for several important human diseases. The present challenges are to continue technological advancements in mass spectrometry instrumentation and develop improved bioconjugation methods, which can overcome their existing limitations and demonstrate the clinical significance of these hybrid approaches.

Targeted imaging of integrins in cancer tissues using photocleavable Ru(ii) polypyridine complexes as mass-tags

Targeted epitope-based mass spectrometry imaging (MSI) utilizes laser cleavable mass-tags bound to targeting moieties for detecting proteins in tissue sections. Our work constitutes the first proof-of-concept of a novel laser desorption ionization (LDI)-MSI strategy using photocleavable Ru(ii) polypyridine complexes as mass-tags for imaging of integrins αvβ3 in human cancer tissues.

A triphenylcyclopropenylium mass tag: synthesis and application to ultrasensitive LC/MS analysis of amines

Thiol adducts of triphenylcyclopropenylium undergo efficient heterolytic dissociation in electrospray (ESI) or laser desorption ionization (LDI) mass spectrometry giving rise to a prominent signal of an aromatic C₃Ph₃⁺ cation.

Pharmacokinetic studies of protein drugs: past, present and future

Among the growing number of therapeutic proteins on the market, there is an emergence of biotherapeutics designed from our comprehension of the physiological mechanisms responsible for their peripheral and tissue pharmacokinetics. Most of them have been optimized to increase their half-life through glycosylation engineering, polyethylene glycol conjugation or Fc fusion. However, our understanding of biological drug behaviors is still its infancy compared to the huge amount of data regarding small molecular weight drugs accumulated over half a century. Unfortunately, therapeutic proteins share few resemblances with these drugs. For instance drug-targeted-mediated disposition, binding to glycoreceptors, lysosomal recycling, large hydrodynamic volume and electrostatic charge are typical critical characteristics that cannot be derived from our anterior knowledge of classical drugs. However, the numerous discoveries made in the two last decades have driven and will continue to drive new options in biochemical engineering and support the design of complex delivery systems. Most of these new developments will be supported by novel analytical methods for assessing in vitro or in vivo metabolism parameters.

Matrix-assisted laser desorption ionization imaging mass spectrometry: in situ molecular mapping

Matrix-assisted laser desorption ionization imaging mass spectrometry (IMS) is a relatively new imaging modality that allows mapping of a wide range of biomolecules within a thin tissue section. The technology uses a laser beam to directly desorb and ionize molecules from discrete locations on the tissue that are subsequently recorded in a mass spectrometer. IMS is distinguished by the ability to directly measure molecules in situ ranging from small metabolites to proteins, reporting hundreds to thousands of expression patterns from a single imaging experiment. This article reviews recent advances in IMS technology, applications, and experimental strategies that allow it to significantly aid in the discovery and understanding of molecular processes in biological and clinical samples.

Targeted multiplex imaging mass spectrometry in transmission geometry for subcellular spatial resolution

Targeted multiplex imaging mass spectrometry utilizes several different antigen-specific primary antibodies, each directly labeled with a unique photocleavable mass tag, to detect multiple antigens in a single tissue section. Each photocleavable mass tag bound to an antibody has a unique molecular weight and can be readily ionized by laser desorption ionization mass spectrometry. This article describes a mass spectrometry method that allows imaging of targeted single cells within tissue using transmission geometry laser desorption ionization mass spectrometry. Transmission geometry focuses the laser beam on the back side of the tissue placed on a glass slide, providing a 2 μm diameter laser spot irradiating the biological specimen. This matrix-free method enables simultaneous localization at the sub-cellular level of multiple antigens using specific tagged antibodies. We have used this technology to visualize the co-expression of synaptophysin and two major hormones peptides, insulin and somatostatin, in duplex assays in beta and delta cells contained in a human pancreatic islet.

Mass spectrometry based imaging techniques for spatially resolved analysis of molecules

Higher plants are composed of a multitude of tissues with specific functions, reflected by distinct profiles for transcripts, proteins, and metabolites. Comprehensive analysis of metabolites and proteins has advanced tremendously within recent years, and this progress has been driven by the rapid development of sophisticated mass spectrometric techniques. In most of the current "omics"-studies, analysis is performed on whole organ or whole plant extracts, rendering to the loss of spatial information. Mass spectrometry imaging (MSI) techniques have opened a new avenue to obtain information on the spatial distribution of metabolites and of proteins. Pioneered in the field of medicine, the approaches are now applied to study the spatial profiles of molecules in plant systems. A range of different plant organs and tissues have been successfully analyzed by MSI, and patterns of various classes of metabolites from primary and secondary metabolism could be obtained. It can be envisaged that MSI approaches will substantially contribute to build spatially resolved biochemical networks.