Nanocomposites and nanomaterials

Fluorescent nanostructured films with coumarin dyes and CdTe quantum dots with sensitivity to acetone and ammonia molecules in exhaled air
Lazorenko Ya.P., Mitsai V.P., Misyura A.G.
Institute of Applied Problems of Physics and Biophysics of the NAS of Ukraine,
Vasilya Stepanchenka 3, UA-03142 Kyiv, Ukraine
E-mail: lazorenko85@gmail.com

Nanosensors based on nanoparticles with molecules of organic fluorophores placed in organic or inorganic matrices are used to detect gases. Fluorescent chemosensors are promising to date [1]. One of the features of nanoparticles is the high chemical activity due to their increased ability to ion exchange, adsorption, the formation of surface bonds with the adsorbate. Thus, you can use the effects of enhancing the fluorescence of organic dyes located near such nanoparticles to increase the sensitivity of fluorescent sensors [2]. Sensors of this type can be used for non-invasive diagnosis of diseases by analysis of exhaled air.
A film with silica gel 60, and coumarin 7, and CdTe quantum dots (with luminescence at λ = 530-535 nm), a film with A-380 Aerosil and coumarin 4 were investigated. Fluorescence registration was performed on a FLx800T fluorimeter and on a Specord M40 UV-VIS device. The difference in the fluorescence intensity of the sample before pumping the gas mixture and at the end of pumping was considered the fluorescent response of the sample. The experiments showed an increase of the fluorescence intensity  of coumarin 7 in ethanol solution with the addition of quantum dots of CdTe in a ratio of 1:1 by 57%. Investigation of sensory properties of the films on ammonia and acetone, the fluorescent response of samples when interacting with analyte molecules in air, was performed. As shown by experimental measurements, the response to 10 ppm of ammonia was 13.2 ± 0.6%, and to 5000 ppm - 74.0 ± 1.1%. The response to 33 ppm of acetone was 0.56 ± 0.08%, and to 67 ppm - 1.2 ± 0.1%, and to 133 ppm - 2.2 ± 0.1%. It was found that after pumping clean air through the cell with the sample, the signal of its fluorescence intensity was almost completely restored for each of the samples.

1.	Mako T. L., Racicot J. M., Levine M. Supramolecular Luminescent Sensors // Chem. Rev.-2019.-119, N 1.-P. 322-477.
2.	Mitsai V. P., Misyura A. G., Kryvets S. V., Lazorenko Ya. P. Fluorescenсе Properties of Complexes of Coumarin Derivatives/CdTe Quantum Dots under Interaction with Ammonia Molecules in Microconcentrations // J. Nano- Electron. Phys.-2016.-8, N 4(1).-P. 04032-1.