Abstract
Quantum dots (QDs) are very attractive nanomaterials for analytical chemistry, due to high photostability, large surface area featuring numerous ways of bioconjugation with biomolecules, usually high quantum yield and long decay times. Their broad absorption spectra and narrow, sharp emission spectra of size-tunable fluorescence make them ideal tools for pattern-based sensing. However, almost always they are applied for specific sensing with zero-dimensional (0D) signal reporting (only peak heights or peak shifts are considered), without taking advantage of greater amount of information hidden in 1D signal (emission spectra), or huge amount of information hidden in 2D fluorescence maps (Excitation-Emission Matrixes, EEMs). Therefore, in this work we propose opposite strategy—non-specific interactions of QDs, which are usually avoided and regarded as their disadvantage, were exploited here for 2D fluorescence fingerprinting. Analyte-specific multivariate fluorescence response of QDs is decoded with the use of Partial Least Squares—Discriminant Analysis. Even though only one type of QDs is studied, the proposed pattern-based method enables to obtain satisfactory accuracy for all studied compounds—various neurotransmitters, amino-acids and oligopeptides. This is a proof of principle of the possibility of the identification of various bioanalytes by such fluorescence fingerprinting with the use of QDs.
Highlights
Colloidal semiconductor nanocrystals—quantum dots (QDs) are one of the most significant developments in nanotechnology
Non-specific interactions using multiple quantum dots in the form of softsensor array [12,13] could provide than characteristic, specific for a given analyte fingerprint, whose multidimensional structure could be deconvoluted with the use of numerical analysis using chemometric methods. We explore this possibility in this work, showing that using only one type of Quantum dots (QDs) it is possible to identify bioanalytes from various groups: selected neurotransmitters, amino acids and oligopeptides
High quantum yield can be quenched due to interaction with various biomolecules, which is facilitated by large biochemically-accessible surface area
Summary
Colloidal semiconductor nanocrystals—quantum dots (QDs) are one of the most significant developments in nanotechnology. With diameters in the range of 1–20 nanometers, they are constructed from elements of Group II (Zn, Cd, Hg)–VI (Se, S and Te), III–V and IV–VI of the periodic table, but until the last decade, most studies focused on II-VI QDs (CdSe or CdTe) [1]. With unique electro-optical properties, arising from the size-dependent and tunable photoluminescence and long-term photostability [1,3], these nanomaterials became advantageous alternatives to the commonly used molecular probes in biology and biomedical applications including bio-labelling, bio-imaging and bio-targeting [2]. Proposed as luminescent biological labels, they are finding new important fields of application in analytical chemistry, where their photoluminescent properties have been exploited in environmental monitoring, pharmaceutical and clinical analysis and food quality control for selective/specific detection of small molecules, ions, nucleic acids, proteins, enzymes, and other biologically important analytes [1,4,5].
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