Visual detection using quantum dots sensing platforms Rafael C. Castro, David S.M. Ribeiro ⇑ , João L.M. Santos ⇑ LAQV, REQUIMTE, Department of Chemical Sciences, Laboratory of Applied Chemistry, Faculty of Pharmacy, University of Porto, Rua de Jorge Viterbo Ferreira n° 228, 4050-313 Porto, Portugal article info Article history: Received 29 July 2020 Accepted 30 September 2020 Available online xxxx Keywords: Visual detection Quantum dots Naked eye Fluorescence Sensors Nanomaterials abstract Despite the ancient visual detection origins, established at the end of the XIX century and raised through the early XX century, in recent years it has acquired a renovated relevance as research has been focused on the development of fast, expeditious, cost-effective and easy to handle analytical methodologies, for on-site monitoring of distinct analytes, from pollutants, to food contaminants, pharmaceuticals, biomark- ers, pathogens, etc. This work examines fluorescence-based visual detection methods resorting to quantum dots, either alone or in combination with other molecules and nanoparticles, discussing the formats employed to implement sensing platforms, including strategies for enhanced sensitivity and selectivity, multi- analyte determinations, detection modes, sensors assembly, readout acquisition and processing, etc. The different types of quantum dots used, from binary to ternary nanocrystals, the tailoring of their sur- face chemistry with appropriate molecules for target recognition, the implementation of multi-detection schemes and the panoply of analytes determined, are also comprehensively examined. Ó 2020 Elsevier B.V. All rights reserved. Contents 1. Introduction .......................................................................................................... 00 2. Strategies for visual detection using quantum dots ........................................................................... 00 3. Visual sensing strategies exploring a single–emitter QDs ...................................................................... 00 3.1. Visual detection based on single-emitter QDs colour brightness modulation................................................. 00 3.2. Visual detection based on single-emitter QDs colour tonality modulation ................................................... 00 4. QDs-based ratiometric sensing platforms in visual detection approaches......................................................... 00 4.1. QDs-based ratiometric sensing platforms composed by a reference and an analyte-dependent fluorophore ....................... 00 4.1.1. QDs as both reference and analyte-dependent fluorophores ....................................................... 00 4.1.2. QDs as analyte dependent fluorophore ........................................................................ 00 4.1.3. QDs as reference fluorophore ............................................................................... 00 4.2. QDs-based ratiometric sensing platforms composed by dynamic fluorophores ............................................... 00 5. QDs-based immunochromatographic assays for visual detection ................................................................ 00 6. Conclusion and trends .................................................................................................. 00 CRediT authorship contribution statement ................................................................................. 00 Declaration of Competing Interest ........................................................................................ 00 Acknowledgments ..................................................................................................... 00 References ........................................................................................................... 00 https://doi.org/10.1016/j.ccr.2020.213637 0010-8545/Ó 2020 Elsevier B.V. All rights reserved. ⇑ Corresponding authors. E-mail addresses: dsmribeiro@gmail.com (D.S.M. Ribeiro), joaolms@ff.up.pt (J.L.M. Santos). Coordination Chemistry Reviews xxx (xxxx) xxx Contents lists available at ScienceDirect Coordination Chemistry Reviews journal homepage: www.elsevier.com/locate/ccr Please cite this article as: R.C. Castro, David S.M. Ribeiro and João L.M. Santos, Visual detection using quantum dots sensing platforms, Coordination Chem- istry Reviews, https://doi.org/10.1016/j.ccr.2020.213637