Carbon nanoparticles (CNPs) represent a recent class of nanomaterials, based on carbon sp² atoms in the inner core. These new nano-dots cover a wide range of application fields: analytical, sensing and biosensing, bioimaging, theranostic, and molecular communication. However, their use as nanocatalysts is relatively new. Although CNPs can be easily synthesized and obtained in good amounts, few reports on their catalytic applications have been reported. This minireview collects the use of these nanoparticles as catalysts highlighting the improvements with respect to the classic catalytic systems. In particular, due to their unique optical and electrical properties, and due to the possibility to cover the external shell with a wide variety of functional groups, CNPs have found catalytic applications in three main classes of reactions: (i) photocatalysis, (ii) acid–base catalysis and (iii) electro catalysis.

Supramolecular architectures developed after the initial studies of Cram, Lehn and Pedersen have become structurally complex but fascinating. In this context, supramolecular capsules based on resorcin[4]arenes, calix[n]arenes or metal–ligand structures are dynamic assemblies inspired by biological systems. The reversible formation of these assemblies, combined with the possibility to modify their dimensions and shapes in the presence of a guest (concepts of reversibility and adaptivity) make them similar to biological macromolecules, such as proteins and enzymes. The small space inside a supramolecular capsule is characterized by different properties compared to the bulk solution. This review describes concrete applications of capsular supramolecular self-assemblies in the biomedical field, in catalysis and in material science.

A new Cu(I) probe (OBEP-CS1), bearing an alkyl-pyridinium moiety to get complete water solubility, was synthesized. Fluorescence titrations support copper binding and high selectivity in a water solution whereas formation of aggregates was excluded by DOSY experiments. The detection capability for intracellular Cu(I), especially localized in mitochondria, was demonstrated in differentiated neuroblastoma cells by confocal microscopy.

Real-time sensing of Chemical Warfare Agents (CWAs) is today a crucial topic to prevent lethal effects of a chemical terroristic attack. For this reason, the development of efficient, selective, sensitive and reversible sensoristic devices, able to detect by optical response ppm levels of these compounds, both in water and in air, is strongly required. Here we report the design and synthesis of a fluorescent nanosensor, based on carbon nanoparticles covalently functionalized with ethanolamine arms, which exploits the multitopic supramolecular interaction with nerve agents, ensuring highly efficient (logK 6.46) and selective molecular recognition. Moreover, given the aqueous dispersibility of carbon nanoparticles, these nanosensors ensure even higher sensitivity, detecting sub-ppt concentration of nerve agents in water, and sub-ppm level in air by using a common digital camera or a smartphone. Our results pave the way to an innovative class of low-cost reusable CWA sensors prompting, for the first time, the simultaneous detection of nerve agents through gaseous and aqueous media, thus extending the protection range to public water supplies.

Fluorescent carbon quantum dots (CDs) are synthesized and employed as fluorescent nanochemosensors for selective detection of amino acids. A detailed investigation of excitation–emission maps revealed that the fluorescence properties of CDs are intensely and strongly influenced by the interaction at the surface with different amino acids. The discrimination capability was demonstrated by tensor rank decomposition of the differences induced by the surface reaction in the excitation–emission maps and by means of a common machine learning approach based on artificial neural networks.