Published in 12/12/2023 - ISBN: 978-65-272-0088-8

Paper Title
  • Pablo Cesar Serrano Arambulo
  • Renê Santos de Amorim
  • Gisele Elias Nunes
  • Ivan H Bechtold
Subject area
Biossensores / Biomoléculas
Publishing Date
Country of Publishing
Language of Publishing
Paper Page
Biosensor, Aptamer, Saxitoxin, Electrochemical impedance
Since their development, aptamers (APTs) have become a very attractive type of molecular recognition probes, being much in demand in various fields such as environmental monitoring, biological analysis and food safety. APTs can be immobilized on electrodes to develop electrochemical aptasensors that are advantageous analytical devices for sensitive, continuous, real-time detection [1]. Specifically, impedimetric aptasensors use electrochemical impedance spectroscopy (EIS), which is a non-invasive technique, as they do not disturb the sample under study because of low-amplitude electrical signals, these aptasensors offer a low cost, portability, miniaturization capability and fast detection times using minimal amounts of sample volumes [2]. Saxitoxin (STX) is a neurotoxin that consumed in high concentrations can cause death in humans and animals. Since 1994, STX has been observed in Peri Lagoon, Florianópolis/SC – Brazil, despite this, the lagoon supplies drinking water, after treatment, to more than 100 thousand inhabitants [3]. In this context, the STX-specific aptamer M-30f [4] was functionalized with thiol to be immobilized by drop-casting on a gold electrode. The antifouling 6-mercaptohexanol (MCH) was adhered by self-assembly to fill the empty spaces left by the M-30f immobilization. The electrochemical characterization in each step of the aptasensor was by EIS using an electrolyte solution. In the M-30f immobilization and MCH adhesion stages, a decrease in Faradaic current and an increase in charge transfer resistance (R_ct ) were observed. In the detection of STX, the opposite happened, ie, an increase in the Faradaic current and a decrease ??R?_ct. This last decrease in R_ct was used for the detection of STX, observing a decrease in R_ct proportional to the increase in STX concentration. The electrochemical aptasensor detected STX in the range of concentrations between 0.3- 30 µg/L, from this data, a calibration curve for the detection of STX was made, observing that a ??R?_ct decrement of 30% corresponds to the concentration limit of 3 µg/L in drinking water and that the detection limit obtained by the aptasensor was 0.3 µg/L, corresponding to 10% of the limit concentration of STX [5]. Furthermore, the biosensor proved to be selective in negative control experiments with microcystin-LR (MCLR), another cyanotoxin, indicating that there is no significant change in the decrease in ??R?_ct in the presence of MCLR when compared to STX, demonstrating be a promising alternative for the detection of STX in water. As a prospective application, the aptasensor can be tested in real water samples from Peri Lake, using the calibration curve obtained in this work as a reference. Acknowledgements: INCT/INEO, Capes, CNPq, FAPESC. [1] Mishra G, Sharma V, Mishra R. Electrochemical Aptasensors for Food and Environmental Safeguarding: A Review. Biosensors 2018; 8: 28. [2] Brett CMA. Electrochemical Impedance Spectroscopy in the Characterisation and Application of Modified Electrodes for Electrochemical Sensors and Biosensors. Molecules 2022; 27: 1497. [3] Ramos TK, Costa LDF, Yunes JS, et al. Saxitoxins from the freshwater cyanobacterium Raphidiopsis raciborskii can contaminate marine mussels. Harmful Algae 2021; 103: 102004. [4] Zheng X, Hu B, Gao SX, et al. A saxitoxin-binding aptamer with higher affinity and inhibitory activity optimized by rational site-directed mutagenesis and truncation. Toxicon 2015; 101: 41–47. [5] Serrano PC, Nunes GE, Avila LB, et al. Electrochemical impedance biosensor for detection of saxitoxin in aqueous solution. Anal Bioanal Chem 2021; 413: 6393–6399.
Title of the Event
Workshop do INEO 2023
City of the Event
Nazaré Paulista
Title of the Proceedings of the event
Anais do Workshop INEO 2023
Name of the Publisher
Means of Dissemination
Meio Digital
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How to cite

ARAMBULO, Pablo Cesar Serrano et al.. LABEL-FREE DETECTION OF SAXITOXIN WITH AN IMPEDIMETRIC APTASENSOR.. In: Anais do workshop INEO 2023. Anais...Nazaré Paulista(SP) Hotel Estância Atibainha, 2023. Available in: https// Access in: 15/06/2024


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