ORIGINAL PAPER Ratiometric arginine assay based on FRET between CdTe quantum dots and Cresyl violet Doris E. Ramírez-Herrera 1 & Antonio Tirado-Guízar 1,2 & Francisco Paraguay-Delgado 3 & Georgina Pina-Luis 1 Received: 9 December 2016 /Accepted: 19 March 2017 # Springer-Verlag Wien 2017 Abstract The authors report on the design of a new Förster resonance energy transfer (FRET) based ratiometric nanoprobe for the determination of arginine. The method is based on the inhibition of the efficiency of FRET in assemblies formed be- tween CdTe quantum dots capped with mercaptopropionic acid (QD-MPA) acting as energy donor, and the dye Cresyl Violet (CV) that acts as an energy acceptor at pH 8. Addition of arginine causes a displacement of the CV by arginine on the surface of the QD/MPA. Hence, the FRET between QD/MPA and CV is interrupted and fluorescence emission of the donor (QD/MPA) is restored. Arginine selectively binds to the QD/ MPA via electrostatic and hydrogen bonding interactions be- tween guanidinium and carboxylate. Under optimum condi- tions, the ratio of the fluorescence emissions peaking at 575 and 620 nm (under 400 nm excitation) is linear in the 1 to 30 μM arginine concentration range, and the detection limit is 0.51 μM. The nanoprobe displays good selectivity over 14 other amino acids, many metal ions, glucose, and ascorbic, tartaric and citric acids. The fluorescent nanoprobe was successfully applied to the determination of arginine in pure and spiked real samples and gave good recoveries. Its good selectivity, sensitivity, low-cost and rapidity make the QD-dye assembly a suitable nanoprobe for the quantitation of arginine. Keywords Arginine determination . Quantum dots-dye assemblies . Quantum yield . Salt bridge guanidinium-carboxylate . Energy transfer nanoprobe . Förster resonance energy transfer Introduction A main challenge in analytical chemistry is to develop fast, specific, and sensitive sensors for food, clinical and environ- mental applications. Förster resonance energy transfer (FRET) mechanism has been widely studied as a powerful and prom- ising sensory tool for detection and quantification of analytes of biological and chemical interest. FRET is a non-radiative process in which the electronic excitation energy of a donor (usually a fluorophore) is transferred to a ground state acceptor via dipole-dipole interactions [1]. Colloidal quantum dots (QD) are one of the most interesting new materials that have emerged over the last decades, their optical and spectroscopic properties allow their use as fluorescent labels for sensing and bioimaging applications [2–4]. QD properties also offer new opportunities and special ad- vantages in FRET assemblies as they can improve energy trans- fer efficiencies, facilitate the design of donor-acceptor configu- rations, and simplify quantitative measurements. Some of the advantageous properties of using QD as FRET energy donors are: broad absorption spectra, this allows selecting an excitation wavelength in which acceptor absorption is minimal, size- tunable fluorescence emission with high quantum yields Electronic supplementary material The online version of this article (doi:10.1007/s00604-017-2205-4) contains supplementary material, which is available to authorized users. * Georgina Pina-Luis gpinaluis@tectijuana.mx; gpinaluis@yahoo.com 1 Centro de Graduados e Investigación, Instituto Tecnológico de Tijuana, A.P. 1166, 22500 Tijuana, BC, Mexico 2 Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV-IPN), 97310 Mérida, Yucatán, Mexico 3 Centro de Investigación en Materiales Avanzados S. C. Departamento de Física de Materiales, Av. Miguel de Cervantes, 120 Chihuahua, Mexico Microchim Acta DOI 10.1007/s00604-017-2205-4