Surface plasmon resonance imaging in arrays coupled with mass spectrometry (SUPRA–MS): proof of concept of on-chip characterization of a potential breast cancer marker in human plasma

Abstract

Protein biomarker discovery and validation are crucial for diagnosis, prognosis, and theranostics of human pathologies; "omics" approaches bring new insights in this field. In particular, the combination of immuno-sensors in array format with mass spectrometry efficiently extends the classical immunoassay format and includes molecular characterization. Here, we coupled surface plasmon resonance imaging (SPRi) with MALDI-TOF mass spectrometry in a hyphenated technique which enables multiplexed quantification of binding by SPRi and molecular characterization of interacting partners by subsequent MS analysis. This adds specificity, because MS enables differentiation of molecules that are difficult to distinguish by use of antibodies, for example truncation variants or protein isoforms. Proof of concept was established for detection, identification, and characterization of a potential breast cancer marker, the LAG3 protein, at ~1 μg mL(-1), added to human plasma. The analytical performance of this new method, dubbed "SUPRA-MS", was established, particularly its specificity (S/N > 10) and reliability (100 % LAG3 identification with high significant mascot score >87.9). The adjusted format for rapid, collective, and automated on-chip MALDI-MS analysis is robust at the femtomole level and has numerous potential applications in proteomics.

Limit of detection comparison for surface wave biosensors

“…Obviously the assumptions taken for noise analysis as well as detector pixel number are debatable, so the absolute LoD thickness is debatable as well. But the optimum wavelength range derived corresponds to the choices of commercial systems [13][14][15] . So the results obtained allow a comparison to BSW as plasmon-like sensing principle when assuming a similar detector and angular imaging system.…”

Early Lung Cancer Diagnosis by Biosensors

“…Three model biomarkers, α-fetoprotein, carcinoembryonic antigen, and hepatitis B surface antigen were simultaneously detected in human serum samples by a SPRi chip, showing detection limits of 50, 20, and 100 ng/mL, respectively [119]. SPRi and MALDI-TOF mass spectrometry were coupled in a hyphenated technique which enabled multiplexed quantification of binding by SPRi and molecular characterization of interacting partners by subsequent MS analysis [82]. …”

Single-Multiplex Detection of Organ Injury Biomarkers using SPRi based Nano-Immunosensor

“…For example, the immobilization of antibodies in immunoassays can be performed by the amine coupling of lysine residues in antibodies to the surface linked carboxylic acid groups through an EDC/NHS intermediate activation step. This surface chemistry has been widely used and successful in many previous works181920; however, we found this strategy not to be suitable for our specific experimental setup. It resulted in inconsistency of surface uniformity from one experiment to the other as shown in Fig.…”