title: Design of buffer exchange surfaces and sensor chips for biosensor chip mass spectrometry.
abstract: The feasibility of buffer exchange in biosensor chip mass spectrometry, along with the construction of base sensor chips and use of alternative chip chemistries, is demonstrated in this work. Beta-2-microglobulin (beta2m) was used as an analyte and captured in the first flow cell (FC1) on the sensor chip surface by an immobilized anti-beta2m antibody. Low pH buffer was then used to elute the captured analyte from the flow cell and route it to a second flow cell (FC2) downstream that served as a cation exchanger that retains the analyte. Following additional washes in FC1, the analyte present in FC2 was either eluted with a higher pH buffer (to demonstrate the possibility of elution into a downstream trypsin flow cell), or it was subjected to matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry analysis to verify its presence in FC2. In a separate experiment, a gold-sputtered glass slide (base chip) was activated through a formation of 11-mercaptoundecanoic acid self-assembled monolayer and via reaction with 1,1"-carbonyldiimidazole. The activated chip was placed manually into the biosensor and two surfaces (flow cells) were derivatized with antibodies to beta2m and cystatin C (cysC). To evaluate the chip performance, diluted human urine aliquot was injected over the flow cells. Following the surface plasmon resonance analysis, the chip was MALDI-TOF MS analyzed, yielding signals from beta2m and cysC from their respective flow cells. Artifacts arising from the surface chemistries were not observed in the analysis.
authors.affiliation: Intrinsic Bioprobes Inc., Tempe, AZ 85281, USA. dnedelkov@intrinsicbio.com
authors.forename: Dobrin
authors.initials: D
authors.lastname: Nedelkov
authors.forename: Kemmons A
authors.initials: KA
authors.lastname: Tubbs
authors.forename: Randall W
authors.initials: RW
authors.lastname: Nelson
mesh_terms: D002021:Buffers; D006801:Humans; D040081:Protein Array Analysis / Q000295:instrumentation / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000295:instrumentation* / Q000379:methods*; D013499:Surface Properties; D014556:Urine / Q000737:chemistry; D001613:beta 2-Microglobulin / Q000032:analysis
chemical_list: D002021:Buffers; D001613:beta 2-Microglobulin