Electrochemical detection of tetracycline in milk using nanocellulose/carbon nanostructure composite electrodes
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School of Electrical Engineering |
Master's thesis
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Authors
Date
2025-04-28
Department
Major/Subject
Biosensing and Bioelectronics
Mcode
Degree programme
Master's Programme in Life Science Technologies
Language
en
Pages
96
Series
Abstract
The thesis focuses on electrochemical sensing of tetracycline antibiotic molecule in phosphate buffered saline (PBS) and milk serum. The study was conducted primarily on carbon nanofiber (CNF) electrode using a modification with TEMPO-oxidized cellulose nanofibrils (TOCNF), polyethyleneimine (PEI) and single wall carbon nanotubes (SWCNT). The study includes basic characterization of electrode kinetics using ruthenium, study on the effect of scan rate, study on repeatability and reproducibility as well as analytical studies to determine linear concentration range and the limit of detection. The electrode was shown to have an electrochemically reversible electron transfer process. In low concentrations (1-10 µM) the response was governed mostly by adsorption and in high concentrations (above 25 µM) the deeper adsorption sites start to saturate. In low concentrations the electrode had limit of detection (LOD) of 0.86 µM with sensitivity of 0.82 µA/µM in PBS, and in milk serum LOD was 29.4 µM and 60.48 µM for two oxidation peaks, with sensitivities of 0.143 µA/µM and 0.137 µA/µM.Diplomityö keskittyy sähkökemialliseen sensoriin, jossa havainnoidaan tetrasykliini-antibioottimolekyylin konsentraatiota fosfaattipuskuroidussa fysiologisessa suolaliuoksessa (PBS) ja maidossa. Pääasiallisesti käytetyssä sensorissa hiilinanokuitu (CNF) elektrodin pinta on modifioitu käyttämällä nanoselluloosakuituja (TOCNF), polyeetteri-imidiä (PEI) ja hiilinanoputkia (SWCNT). Diplomityöhön sisältyi elektrodien kinetiikan sähkökemiallinen karakterisointi, elektrodien valmistuksen toistettavuus sekä analyyttiset mittaukset lineaarisen pitoisuusalueen ja havainnointirajan määrittämiseen. Elektrodin elektronin siirtymisen havaittiin olevan elektrokemiallisesti palautuva prosessi. Elektrodin havaittiin olevan adsorptio-kontrolloitu pienissä pitoisuuksissa (1-10 µM). Havainnointirajaksi (LOD) mitattiin 0.86 µM ja sensorin herkkyys oli 0.82 µA/µM PBS-liuoksessa. Maito-seerumissa havainnointiraja oli 29.4 µM ja 60.48 µM sekä sensorin herkkyys 0.143 µA/µM ja 0.137 µA/µM kahden oksidaatiohuipun avulla laskettuna. (Arvot pienissä pitoisuuksissa.)Description
Supervisor
Laurila, TomiKeywords
electrochemical detection, electrochemical sensor, tetracycline detection in milk, electrochemical antibiotics detection, cellulose nanofiber electrode, electrochemical carbon nanofiber electrode