Browsing by Author "Kontturi, Katri S"

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    Advanced Nanocellulose-Based Electrochemical Sensor for Tetracycline Monitoring
    (Elsevier Ltd, 2024-10-01) Nekoueian, Khadijeh; Kontturi, Katri S; Meinander, Kristoffer; Quliyeva, Ulviyya; Kousar, Ayesha; Durairaj, Vasuki; Tammelin, Tekla; Laurila, Tomi; Department of Electrical Engineering and Automation; Department of Bioproducts and Biosystems; Department of Applied Physics; Microsystems Technology; VTT Technical Research Centre of Finland
    Antibiotics play a pivotal role in healthcare and agriculture, but their overuse and environmental presence pose critical challenges. Developing sustainable and effective detection methodologies is crucial to mitigating antibiotic resistance and environmental contamination. This study presents a cellulosic polymer-based electrochemical sensor by integrating TEMPO-oxidized cellulose nanofibers-polyethyleneimine hybrids (TOCNFs-PEI) with single-walled carbon nanotube networks (SWCNTs). Our research focuses on (i) conducting physicochemical and electrochemical studies of multifunctional SWCNT/TOCNFs-PEI architectures, (ii) elucidating the relationships between the material's properties and their electrochemical performance, and (iii) assessing its performance in detecting tetracycline concentrations in both controlled and more complex matrices (treated wastewater effluents). The limits of detection were evaluated to be 0.180 µmol L−1 (at the potential of 0.85 V) and 0.112 µmol L−1 (at the potential of 0.65 V) in phosphate-buffered saline solution, and 2.46 µmol L−1 (at the potential of 0.82 V) and 1.5 µmol L−1 (at the potential of 0.65 V) in the undiluted membrane bioreactor effluent sample, respectively. Further, the designed cellulosic polymer-based sensing architecture is compatible with large-scale production, paving the way for a new era of green, versatile sensing devices. These developments will significantly contribute to global efforts to alleviate antibiotic resistance and environmental contamination.
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    Sustainable High Yield Route to Cellulose Nanocrystals from Bacterial Cellulose
    (AMERICAN CHEMICAL SOCIETY, 2019-08-16) Pääkkönen, Timo; Spiliopoulos, Panagiotis; Nonappa, Nonappa; Kontturi, Katri S; Penttilä, Paavo; Viljanen, Mira; Svedström, Kirsi J.; Kontturi, Eero; Department of Bioproducts and Biosystems; Department of Applied Physics; Materials Chemistry of Cellulose; Wood Material Science; VTT Technical Research Centre of Finland; University of Helsinki
    HCl gas hydrolysis of a bacterial cellulose (BC) aerogel followed by 2,2,6,6-tetramethylpiperidine-1-oxyl radical-mediated oxidation was used to produce hydrolyzed BC with carboxylate groups, which subsequently disintegrated into a stable dispersion of cellulose nanocrystals (CNCs). The degree of polymerization was successfully reduced from 2160 to 220 with a CNC yield of >80%.