{"title":"High Stability Hydrogel Magnetic Relaxation Switch Sensor Driven by pH for the Sensitive Detection of Cd2+","authors":"Xingyu Yang, Li Yao, Shaoyi Yu, Tong Mu, Yudie Hu, Xiaohong He, Yunhui Cheng, Zhou Xu","doi":"10.1021/acs.analchem.4c02349","DOIUrl":null,"url":null,"abstract":"The traditional magnetic relaxation switching (MRS) sensors have excellent sensitivity, but their stability is poor because the magnetic relaxation signal is easily affected by the external magnetic field or environmental oxidation. In this study, a highly stable hydrogel bead-based MRS (Gel-MRS) sensor was established for the accurate and sensitive detection of Cd<sup>2+</sup> in rice. A pH-responsive hydrogel bead was applied as a core element for the target stimulus and transverse relaxation signal transduction. The stability experiments showed that the transverse relaxation time (<i>T</i><sub>2</sub>) change of the Gel-MRS sensor was one-seventh that of traditional magnetic nanoparticles under an external magnetic field and less than a fifth that of Fe<sup>2+</sup>/Fe<sup>3+</sup> conversion in air. The excellent stability was due to the fact that <i>T</i><sub>2</sub> of the Gel-MRS sensor came from the swelling system mediated by pH rather than the traditional aggregation/dispersion or Fe<sup>2+</sup>/Fe<sup>3+</sup> conversion of magnetic nanoparticles. In addition, the target Cd<sup>2+</sup> could exclusively trigger a pH response of the hydrogel beads, altering the <i>T</i><sub>2</sub>, thus resulting in excellent relaxation properties (R<sub>2</sub> = 56.89) and pH responsiveness of the Gel-MRS sensor. The swelling process of the hydrogel beads followed quasi-second-order dynamics. The Gel-MRS sensor demonstrated a remarkable limit of detection as low as 0.009 ng/mL for Cd<sup>2+</sup>, with a linear range of 0.01–5 ng/mL. The excellent stability and sensitivity made the Gel-MRS sensor have great application potential in food and environmental detection.","PeriodicalId":27,"journal":{"name":"Analytical Chemistry","volume":null,"pages":null},"PeriodicalIF":6.7000,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Analytical Chemistry","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/acs.analchem.4c02349","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, ANALYTICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The traditional magnetic relaxation switching (MRS) sensors have excellent sensitivity, but their stability is poor because the magnetic relaxation signal is easily affected by the external magnetic field or environmental oxidation. In this study, a highly stable hydrogel bead-based MRS (Gel-MRS) sensor was established for the accurate and sensitive detection of Cd2+ in rice. A pH-responsive hydrogel bead was applied as a core element for the target stimulus and transverse relaxation signal transduction. The stability experiments showed that the transverse relaxation time (T2) change of the Gel-MRS sensor was one-seventh that of traditional magnetic nanoparticles under an external magnetic field and less than a fifth that of Fe2+/Fe3+ conversion in air. The excellent stability was due to the fact that T2 of the Gel-MRS sensor came from the swelling system mediated by pH rather than the traditional aggregation/dispersion or Fe2+/Fe3+ conversion of magnetic nanoparticles. In addition, the target Cd2+ could exclusively trigger a pH response of the hydrogel beads, altering the T2, thus resulting in excellent relaxation properties (R2 = 56.89) and pH responsiveness of the Gel-MRS sensor. The swelling process of the hydrogel beads followed quasi-second-order dynamics. The Gel-MRS sensor demonstrated a remarkable limit of detection as low as 0.009 ng/mL for Cd2+, with a linear range of 0.01–5 ng/mL. The excellent stability and sensitivity made the Gel-MRS sensor have great application potential in food and environmental detection.
期刊介绍:
Analytical Chemistry, a peer-reviewed research journal, focuses on disseminating new and original knowledge across all branches of analytical chemistry. Fundamental articles may explore general principles of chemical measurement science and need not directly address existing or potential analytical methodology. They can be entirely theoretical or report experimental results. Contributions may cover various phases of analytical operations, including sampling, bioanalysis, electrochemistry, mass spectrometry, microscale and nanoscale systems, environmental analysis, separations, spectroscopy, chemical reactions and selectivity, instrumentation, imaging, surface analysis, and data processing. Papers discussing known analytical methods should present a significant, original application of the method, a notable improvement, or results on an important analyte.