High resolution portable platform for pH sensing via colorimetric fluorescence of carbon dots
Minervini, Gianluca (Institut Català de Nanociència i Nanotecnologia)
Panniello, Annamaria (Institute for Chemical and Physical Processes)
Quesada-González, Daniel (Institut Català de Nanociència i Nanotecnologia)
Maroli, Gabriel (Institut Català de Nanociència i Nanotecnologia)
Fanizza, Elisabetta (University of Bari Aldo Moro. Chemistry Department)
Striccoli, Marinella (Institute for Chemical and Physical Processes)
Álvarez Diduk, Ruslan (Institut Català de Nanociència i Nanotecnologia)
Curri, Maria Lucia (University of Bari Aldo Moro. Chemistry Department)
Merkoçi, Arben (Institut Català de Nanociència i Nanotecnologia)

Data:	2025
Resum:	Portable sensing platforms based on nanoparticles are becoming increasingly significant across diverse fields, as they enable real-time measurements in various environments without complex lab protocols. Carbon dots (CDs), known for low toxicity and intense fluorescence, can exhibit pH-dependent optical emission, generally related to proton exchange-capable surface groups. In addition, CDs' hydrophilicity, biocompatibility, and stability make them advantageous for pH sensing and, despite limited application in portable sensing devices, their full potential can be realized with precise control of chemistry and optical properties. In this study, we fabricate a portable nitrocellulose-based platform for pH sensing, expressly designed to take advantage of the fluorescence properties of resorcinol-based CDs. First, responsivity of CDs fluorescence features on pH is carefully spectroscopically characterized and linked to acid-base equilibria of polyphenols (hydroxylated polyaromatic rings) present within the CDs carbonaceous structure. Notably, this also offers a titrimetric method to estimate CD concentration. Next, nitrocellulose-based wax-printed circular pads are functionalized with CDs and integrated with a smartphone-based fluorescence colorimetric optical detection system. The developed portable device exhibits a measurement resolution of ± 0. 2 pH units (in the range between 2. 5 and 6. 7) and of ± 0. 3 pH units (in the 6. 7 - 7. 0 range), compatible with most practical pH measurement needs in biological, food and drink, wastewater sample analysis and others. Moreover, although some portable pH sensing devices are already widespread and commercially available, this platform is easy to use, it necessitates only very small sample volumes and is potentially adaptable to various environments and automated analysis processes that does not need prior-use calibrations.
Ajuts:	Agencia Estatal de Investigación CEX2021-001214-S Agència de Gestió d'Ajuts Universitaris i de Recerca 2021/SGR-01464 Agencia Estatal de Investigación PID2021-124795NB-I00
Nota:	Altres ajuts: CERCA Programme/Generalitat de Catalunya
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Llengua:	Anglès
Document:	Article ; recerca ; Versió sotmesa a revisió
Publicat a:	Chemical engineering journal (1996), Vol. 505 (February 2025) , art. 159664, ISSN 1873-3212

DOI: 10.1016/j.cej.2025.159664

Preprint 35 p, 1.4 MB

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