Modification and characterization of an aptamer-based surface plasmon resonance sensor chip

Abstract

Abstract. Recently, aptamer-based surface plasmon resonance (SPR) sensors have become increasingly popular due to their high specificity, high sensitivity, real-time detection capabilities, and label-free features. The core component of an aptamer-based SPR sensor is a chip. This paper presents the modification steps and the characterization results of a sensor chip for the construction of a 2, 4, 6-trinitrotoluene-targeted, aptamer-based, SPR sensor. After cleaning the aptamer-based SPR sensor chip, polyethylene glycol (PEG) with functional thiol groups at one end was added to the chip surface by Au-S covalent bonds to form a selfassembled film. Then, the carboxyl groups at the other end of PEG and the carboxyl groups of trinitrophenyl-glycine (TNP-Gly) were activated and connected via ethylenediamine (EDA). This effectively completed the chip's modification. During the modification process, relevant experimental conditions were optimized. The chip's surface elements, as well as their chemical states, were characterized by X-ray photoelectron spectroscopy (XPS). The results, outlined in the following study, demonstrate that this modification of an aptamer-based SPR sensor chip adhered to normative expectations. Thus, the modification process proposed here establishes an important foundation for subsequent study of TNT detection.

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“…Figure b shows the X-ray photoelectron spectroscopy (XPS) spectra of the different modification layers. High-resolution C 1s XPS spectra of the dextran polymer and Cas13a RNPs demonstrated the different immobilization steps by revealing C–O–C and CO bonds, and a peak at about 284.8 eV was attributed to the C–C bond . As Cas13a RNPs were introduced, two new peaks appeared at high-resolution N 1s and P 2p XPS spectra.…”

“…High-resolution C 1s XPS spectra of the dextran polymer and Cas13a RNPs demonstrated the different immobilization steps by revealing C–O–C and C=O bonds, and a peak at about 284.8 eV was attributed to the C–C bond. 32 As Cas13a RNPs were introduced, two new peaks appeared at high-resolution N 1s and P 2p XPS spectra. They were attributed to the C–NH 2 and −PO 4– – bonds from nucleobase, amino acid, and backbone, respectively.…”