Immobilized aptamer paper spray ionization source for ion mobility spectrometry

Abstract

A selective thin-film microextraction based on aptamer immobilized on cellulose paper was used as a paper spray ionization source for ion mobility spectrometry (PSI-IMS), for the first time. In this method, the paper is not only used as an ionization source but also it is utilized for the selective extraction of analyte, based on immobilized aptamer. This combination integrates both sample preparation and analyte ionization in a Whatman paper. To that end, an appropriate sample introduction system with a novel design was constructed for the paper spray ionization source. Using this system, a continuous solvent flow works as an elution and spray solvent simultaneously. In this method, analyte is adsorbed on a triangular paper with immobilized aptamer and then it is desorbed and ionized by elution solvent and applied high voltage on paper, respectively. The effects of different experimental parameters such as applied voltage, angle of paper tip, distance between paper tip and counter electrode, elution solvent type, and solvent flow rate were optimized. The proposed method was exhaustively validated in terms of sensitivity and reproducibility by analyzing the standard solutions of codeine and acetamiprid. The analytical results obtained are promising enough to ensure the use of immobilized aptamer paper-spray as both the extraction and ionization techniques in IMS for direct analysis of biomedicine.

Aptamer-based and immunosorbents

“…This example shows the need to study the effect of different cations to determine the optimal conditions for a strong binding of the target on the OS during the extraction step. Some parameters such as temperature (20)(21)(22)(23)(24), ionic strength and pH (20) also strongly affect the conformation of aptamers. These parameters must be controlled and adapted to ensure high extraction recoveries or favor the elution (25).…”

Paper spray ionization mass spectrometry: recent advances and clinical applications

“…Combinations of several modifications have been studied, where an aptamer-modified carbon nanotube paper spray was used to improve detection of methamphetamine [34]. Carbon nanotubes have shown improved ionization due to generation of high electric fields[35], while aptamer-modifications have demonstrated selective extraction in complex matrices[36,37]. The combination of both modifications showed improved sensitivity and selectivity, reporting LODs of 0.45 ng/mL in plasma and saliva.…”

Integration of paper spray ionization high‐field asymmetric waveform ion mobility spectrometry for forensic applications

“…An ion mobility device could serve as a filter and only allow the transmission of the ions of interest. While there are other reports on the combination of PSI with ion separation methods, here we evaluate the use of high‐field asymmetric waveform ion mobility spectrometry (FAIMS) to reduce background ion interference, while attempting to maximize information about the analytes in the samples.…”