Highly selective paper-based and colorimetric detection for arsenic(V) with methylene blue-functionalized gold nanoparticles

Paper-strip-type methylene blue (MB)-functionalized gold nanoparticles (AuNPs@MB) were developed and tested as colorimetric sensors for arsenic in this study. The valence state of arsenic speciation was pH-dependent, with arsenate (As(V)) exhibiting the HAsO42- form over the pH range of 7-11. When exposed to arsenic ions, AuNPs@MB exhibited significant agglomeration between nanoparticles via an ion-pairing mechanism between MB+ and As(V), resulting in a color shift from red to blue. The amount of MB loading on the AuNPs and the pH were adjusted to optimize the colorimetric sensing efficiency. AuNPs@MB-0.9 and AuNPs@MB-1.1 were employed as colorimetric sensors at low (0-30 ppb) and high (1-100 ppb) concentrations of As(V), respectively. To confirm the feasibility of using the AuNPs@MB sensor for As(V) detection, a selectivity test was conducted in the presence of 16 cations and 5 anions. This test demonstrated the practicality of the AuNPs@MB sensor for As(V) and showed that AuNPs@MB had a very high selectivity for As(V) compared to other cations and anions. Further, a solid-state colorimetric sensor based on a cellulose paper strip was developed for arsenic detection. The results of the paperbased colorimetric sensor with AuNPs@MB were the same as those of the solution-based colorimetric sensor.(c) 2023 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

Paper-strip-type methylene blue (MB)-functionalized gold nanoparticles (AuNPs@MB) were developed and tested as colorimetric sensors for arsenic. The valence state of arsenic speciation was pH-dependent. AuNPs@MB exhibited significant agglomeration between nanoparticles via an ion-pairing mechanism with As(V), resulting in a color shift from red to blue. The AuNPs@MB sensor showed high selectivity for As(V) and a solid-state colorimetric sensor based on a cellulose paper strip was also developed.