Fluorescent nanodots have become increasingly prevalent in a wide variety of applications with special interest in analytical and biomedical fields. The present overview focuses on three main aspects: (i) a systematic description and reasonable classification of the most relevant types of fluorescent nanodots according to their nature, quantum confinement and crystalline structure is provided, starting with a clear distinction between semiconductor and carbon-based dots (graphene quantum dots, carbon quantum dots and carbon nanodots). A new set of abbreviations and definitions for them to avoid contradictions found in literature is also proposed; (ii) a rational classification allows the establishment of clear-cut differences and similarities among them. From a basic point of view, the origins of the photoluminescence of the different nanodots are also established, which is a relevant contribution of this overview. Additionally, the most outstanding similarities and differences in a great variety of criteria (i.e. year of discovery, synthesis, the physico-chemical characteristics like structure, nature, shape, size, quantum confinement, toxicity and solubility, the optical characteristics including the quantum yield and lifetime, limitations, applications as well as the evolution of publications) are thoroughly outlined; and (iii) finally, the promising future of fluorescent nanodots in both analytical and biomedical fields is discussed using selected examples of relevant applications.

Quantum dots (QDs) are a novel class of inorganic fluorophores, which are gaining widespread recognition as a result of their exceptional photophysical properties. They are rapidly being integrated into existing and emerging technologies, and could play an important role in many areas in the future. Significant phenomena, such as photoactivation, are still unknown and must be understood and more fully defined before they can be widely validated. This review provides an overview of the photoactivation process of quantum dots in a systematic way, covering QD characteristics, solubilisation strategies, and a description of different photoactivation mechanisms, depending on the type of QDs and their surrounding environment.

A set of three types of silver nanoparticles (Ag NPs) are prepared, which have the same Ag cores, but different surface chemistry. Ag cores are stabilized with mercaptoundecanoic acid (MUA) or with a polymer shell [poly(isobutylene-alt-maleic anhydride) (PMA)]. In order to reduce cellular uptake, the polymer-coated Ag NPs are additionally modifi ed with polyethylene glycol (PEG). Corrosion (oxidation) of the NPs is quantifi ed and their colloidal stability is investigated. MUA-coated NPs have a much lower colloidal stability than PMA-coated NPs and are largely agglomerated. All Ag NPs corrode faster in an acidic environment and thus more Ag(I) ions are released inside endosomal/lysosomal compartments. PMA coating does not reduce leaching of Ag(I) ions compared with MUA coating. PEGylation reduces NP cellular uptake and also the toxicity. PMA-coated NPs have reduced toxicity compared with MUA-coated NPs. All studied Ag NPs were less toxic than free Ag(I) ions. All in all, the cytotoxicity of Ag NPs is correlated on their uptake by cells and agglomeration behavior

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Water and methanol associations in ionic liquids (ILs) have been studied by means of FTIR spectroscopy. Spectra at different concentrations of water or methanol in ILs were obtained by means of on-line dilution using a flow injection analysis system. Spectral features in the OH stretching region revealed that most of the water and methanol molecules tended to be isolated from each other and to interact with the anion of the IL via H bonding. By means of two-dimensional correlation spectroscopy, the formation of methanol and water dimers was also detected. Multivariate curve resolution was used to recover pure spectra and concentration profiles of the different species. Methanol dimers form at concentrations higher than 0.8% (w/w) in the three studied ILs, 1-ethyl-3-methylimidazolium tetrafluoroborate (emimBF4), 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4), and 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6). Self-association of water molecules takes place in emimBF4 and bmimBF4 at a molar ratio similar to that of methanol molecules; however, water dimers cannot be detected in bmimPF6, the most hydrophobic IL studied. No evidence was found that bigger water clusters are formed in these ILs at the studied cosolvent concentrations.

Analytical science has gone through several turning points, one of the most decisive of which was signaled by the development and massive use of instruments for analytical purposes. One other pivotal turning point was the inception of computer science, which not only enabled the automatic control of analytical systems but also facilitated the acquisition of vast amounts of data and their processing with the aid of chemometrics. Following the growing significance of automation and miniaturization in recent times, the early 21st century is witnessing the rise of nanotechnology as a new, increasingly important, revolutionary trend in science in general and analytical science in particular. The ability to exploit molecular interactions between analytes and nanoparticles has opened up new, challenging prospects in this area. Good proof of the interest aroused by nanoparticles is the large number of papers on their use in quantum dots, fullerene, aurum nanoparticles, or carbon nanotubes published in recent years.

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