Combination of aptamer amplifier and antigen-binding fragment probe as a novel strategy to improve detection limit of silicon nanowire field-effect transistor immunosensors

Cao An Vu, Pin Hsien Pan, Yuh Shyong Yang, Hardy Wai Hong Chan, Yoichi Kumada, Wen Yih Chen*

*Corresponding author for this work

Research output: Contribution to journalLetterpeer-review

4 Scopus citations

Abstract

Detecting proteins at low concentrations in high-ionic-strength conditions by silicon nanowire field-effect transistors (SiNWFETs) is severely hindered due to the weakened signal, primarily caused by screening effects. In this study, aptamer as a signal amplifier, which has already been reported by our group, is integrated into SiNWFET immunosensors employing antigen-binding fragments (Fab) as the receptors to improve its detection limit for the first time. The Fab-SiNWFET immunosensors were developed by immobilizing Fab onto Si surfaces modified with either 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA) (Fab/APTES-SiNWFETs), or mixed self-assembled monolayers (mSAMs) of polyethylene glycol (PEG) and GA (Fab/PEG-SiNWFETs), to detect the rabbit IgG at different concentrations in a high-ionic-strength environment (150 mM Bis-Tris Propane) followed by incubation with R18, an aptamer which can specifically target rabbit IgG, for signal enhancement. Empirical results revealed that the signal produced by the sensors with Fab probes was greatly enhanced compared to the ones with whole antibody (Wab) after detecting similar concentrations of rabbit IgG. The Fab/PEG-SiNWFET immunosensors exhibited an especially improved limit of detection to determine the IgG level down to 1 pg/mL, which has not been achieved by the Wab/PEG-SiNWFET immunosensors.

Original languageEnglish
Article number650
Pages (from-to)1-12
Number of pages12
JournalSensors (Switzerland)
Volume21
Issue number2
DOIs
StatePublished - 2 Jan 2021

Keywords

  • Aptamer
  • ELISA
  • Fab
  • Mixed self-assembled monolayer
  • Signal enhancement
  • Silicon nanowire field-effect transistor biosensor

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