Chemically heterogeneous carbon dots enhanced cholesterol detection by MALDI TOF mass spectrometry

Dominika Houdová; Juan Soto; Rita Castro; João Rodrigues; Mª Soledad Pino-González; Marijana Petković; Teresa J Bandosz; Manuel Algarra

doi:10.1016/j.jcis.2021.02.004

Chemically heterogeneous carbon dots enhanced cholesterol detection by MALDI TOF mass spectrometry

J Colloid Interface Sci. 2021 Jun:591:373-383. doi: 10.1016/j.jcis.2021.02.004. Epub 2021 Feb 7.

Authors

Dominika Houdová¹, Juan Soto², Rita Castro¹, João Rodrigues¹, Mª Soledad Pino-González³, Marijana Petković⁴, Teresa J Bandosz⁵, Manuel Algarra⁶

Affiliations

¹ CQM-Centro de Química da Madeira, Universidade da Madeira, Campus da Penteada, 9020-105 Funchal, Portugal.
² Department of Physical Chemistry. Faculty of Science, University of Málaga. Campus de Teatinos s/n, 29071 Malaga, Spain.
³ Department of Organic Chemistry. Faculty of Science, University of Málaga. Campus de Teatinos s/n, 29071 Málaga, Spain.
⁴ VINČA Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia. Electronic address: marijanapetkovic@vin.bg.ac.rs.
⁵ Department of Chemistry and Biochemistry, The City College of New York, 160 Convent Ave, New York, NY, 10031, USA. Electronic address: tbandosz@ccny.cuny.edu.
⁶ Department of Inorganic Chemistry. Faculty of Science, University of Málaga. Campus de Teatinos s/n, 29071 Málaga, Spain. Electronic address: malgarra@uma.es.

PMID: 33631525
DOI: 10.1016/j.jcis.2021.02.004

Abstract

A binary system composed of carbon dots (CDs) and N-doped CDs (N-CDs) embedded in an organic matrix was used for the analysis of cholesterol by MALDI (matrix-assisted laser desorption and ionization time-of-flight) mass spectrometry, as a model for detection of small, biologically relevant molecules. The results showed that both CDs are sensitive to the cholesterol and can be used either alone or in a binary system with 2,5-dihydroxybenzoic acid (DHB) to enhance the detection process. It was found that both COOH and NH₂ groups on CDs surface contributed to the enhancement in the cholesterol detection by MALDI mass spectrometry in the presence of inorganic cations. Nevertheless, in the presence of NaCl, N-CDs led to a better reproducibility of results. It was due to the coexistence of positive and negative charge on N-CDs surface that led to a homogeneous analyte/substrate distribution, which is an important detection parameter. The enhancing effect of carbon dots was linked to a negative Gibbs energy of the complex formation between CDs, Na⁺, cholesterol and DHB, and it was supported by theoretical calculations. Moreover, upon the addition of CDs/N-CDs, such features as a low ionization potential, vertical excitation, dipole moment and oscillator strength positively affected the cholesterol detection by MALDI in the presence of Na⁺.

Keywords: Carbon dots; Cholesterol; DFT calculations; MALDI TOF; N-doped Carbon dots.