University of Oulu

Celio L, Ottaviani M, Cancelliere R, Di Tinno A, Panjan P, Sesay AM and Micheli L (2021) Microfluidic Flow Injection Immunoassay System for Algal Toxins Determination: A Case of Study. Front. Chem. 9:626630. doi: 10.3389/fchem.2021.626630

Microfluidic flow injection immunoassay system for algal toxins determination : a case of study

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Author: Celio, Lorenzo1; Ottaviani, Matteo2; Cancelliere, Rocco1;
Organizations: 1Departement of Chemical Sciences and Technologies, University of Rome Tor Vergata, Rome, Italy
2Department of Analytical Chemistry, University of Turin, Turin, Italy
3Department of Electrical and Information Engineering, University of Cassino and Southern Lazio, Cassino (FR), Italy
4Measurement Technology Research Unit, Oulu University, Kajaani, Finland
5Essi Tech d.o.o., Ljubljana, Slovenia
6Wyss Institute of Bioinspired Engineering, Harvard University, Boston, MA, United States
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.5 MB)
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Language: English
Published: Frontiers Media, 2021
Publish Date: 2021-04-29


A novel flow injection microfluidic immunoassay system for continuous monitoring of saxitoxin, a lethal biotoxin, in seawater samples is presented in this article. The system consists of a preimmobilized G protein immunoaffinity column connected in line with a lab-on-chip setup. The detection of saxitoxin in seawater was carried out in two steps: an offline incubation step (competition reaction) performed between the analyte of interest (saxitoxin or Ag, as standard or seawater sample) and a tracer (an enzyme-conjugated antigen or Ag*) toward a specific polyclonal antibody. Then, the mixture was injected through a “loop” of a few μL using a six-way injection valve into a bioreactor, in line with the valve. The bioreactor consisted of a small glass column, manually filled with resin upon which G protein has been immobilized. When the mixture flowed through the bioreactor, all the antibody-antigen complex, formed during the competition step, is retained by the G protein. The tracer molecules that do not interact with the capture antibody and protein G are eluted out of the column, collected, and mixed with an enzymatic substrate directly within the microfluidic chip, via the use of two peristaltic pumps. When Ag* was present, a color change (absorbance variation, ΔAbs) of the solution is detected at a fixed wavelength (655 nm) by an optical chip docking system and registered by a computer. The amount of saxitoxin, present in the sample (or standard), that generates the variation of the intensity of the color, will be directly proportional to the concentration of the analyte in the analyzed solution. Indeed, the absorbance response increased proportionally to the enzymatic product and to the concentration of saxitoxin in the range of 3.5 × 10⁻⁷–2 × 10⁻⁵ ng ml⁻¹ with a detection limit of 1 × 10⁻⁷ ng ml⁻¹ (RSD% 15, S N⁻¹ equal to 3). The immunoanalytical system has been characterized, optimized, and tested with seawater samples. This analytical approach, combined with the transportable and small-sized instrumentation, allows for easy in situ monitoring of marine water contaminations.

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Series: Frontiers in chemistry
ISSN: 2296-2646
ISSN-E: 2296-2646
ISSN-L: 2296-2646
Volume: 9
Article number: 626630
DOI: 10.3389/fchem.2021.626630
Type of Publication: A1 Journal article – refereed
Field of Science: 116 Chemical sciences
Copyright information: © 2021 Celio, Ottaviani, Cancelliere, Di Tinno, Panjan, Sesay and Micheli. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.