Photoluminescent nanopaper-based microcuvette for iodide detection in seawater

Nanopaper defined as a sheet made of cellulose nanofibers has recently attracted a growing interest in paper-based flexible and transparent sustainable transistors, electronics, devices and sensors. Use of bacterial cellulose nanopaper, particularly in optical sensing platforms, is becoming increasingly popular owing to its numerous desirable properties. Herein, we propose a carbon quantum dots-embedded paper-based sensor for selective iodide sensing. To this aim, the nanopaper was obtained by an environment-friendly approach using bacterial cellulose made of nanofibers (the diameter of nanofibers was observed as 40 ± 10 nm), which were produced by A. xylinum. Then, nitrogen-doped carbon quantum dots were embedded into nanopaper to gain photoluminescence properties. The obtained photoluminescent nanopaper was cut into circular pieces for easily handling, or rectangular pieces for use in a disposable wax-printed paper-based microcuvette which could be inserted in a common spectrofluorometer. Finally, the nanopaper pieces were used for anion sensing and we obtained a selective detection of iodide in seawater (as a model real sample media). Limit of detection (LOD) and limit of quantification (LOQ) values were respectively calculated as 48 and 144 μM (6.1 and 18.3 ppm) for microcuvette application in seawater.