Imaging and chemical surface analysis of biomolecular functionalization of monolithically integrated on silicon Mach-Zehnder interferometric immunosensors

Controlling orientation, conformation, and biorecognition of proteins on silane monolayers, conjugate polymers, and thermo-responsive polymer brushes: investigations using TOF-SIMS and principal component analysis

“…Silicon surfaces are activated with silane selfassembled monolayers prior to their biofunctionalization [97]. Therefore, surface analysis methods including TOF-SIMS have been applied to examine the antibodies, antigens, and blocking proteins adsorbed and covalently attached to silicon surfaces functionalized with organo-silanes for silicon-based biosensors [34,74,[98][99][100]. In the following section, we discuss the TOF-SIMS examination of the factors affecting antibodies orientation, with focus on the surfaces modified with self-assembled monolayers, in particular the organo-silanes on silicon surfaces.…”

Using a lactadherin-immobilized silicon surface for capturing and monitoring plasma microvesicles as a foundation for diagnostic device development

“…Additionally, the binding of PMVs to the control sample blocked with BSA was tested (white columns). Error bars are standard deviations from 10 ToF-SIMS measurements of the same sample molecular composition even in complex layers of several different proteins [33,35] and PMVs.…”

Protein adsorption/desorption and antibody binding stoichiometry on silicon interferometric biosensors examined with TOF-SIMS

“…Firstly, the silicon chips surface was cleaned and hydrophilized with oxygen plasma. Then, the surfaces were silanized (1) through immersion in a 0.5% (v/v) aqueous APTES solution for 2 min, For the immunoassay, the functionalized chips were covered with the fluidic module and placed on the docking station of the measuring apparatus that provides for both the electrical and fluidic connections [19,24]. Firstly, the chip is equilibrated by running assay buffer (50 mM Tris-HCl buffer, pH 7.8, containing 9 g/L NaCl and 5g/L BSA).…”

“…Recently, Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) has been recognized as a powerful technique to analyze biomolecular overlayers on solid supports [17], including biosensor surfaces, due to chemical specificity and surface sensitivity it exhibits. Indeed, TOF-SIMS has been successfully employed to discriminate between different molecules immobilized on the different surfaces and in particular to detect different proteins based in differences in their amino acids composition [14,[18][19][20][21][22][23]. Among the reported applications of TOF-SIMS technique for biosensor surface analysis the examination of microstructured interferometric biosensors based on Mach-Zehnder interferometers monolithically integrated on silicon chips modified following a multi-step protocol has been demonstrated [19].…”

“…Here, such a step-by-step TOF-SIMS inspection of Mach-Zehnder interferometers (MZIs) monolithically integrated on silicon chips [19] is extended to an indirect competitive immunoassay for the determination of Ochratoxin A (OTA). The assay is performed on MZIs modified with protein-analyte conjugate after blocking of the surface by introducing a mixture of analyte-specific (primary) antibody with calibrators, and it is followed by reaction with a secondary antibody for signal enhancement.…”