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Luminescent carbon nanostructures (CNSs) have attracted great interest from the scientific community due to their photoluminescent properties, structural features, low toxicity, and a great variety of possible applications. Unfortunately, a few problems hinder their further development. These include the difficulties of separating a mixture of nanostructures after synthesis and the dependence of their properties on the environment and the aggregate state. The application of a silica matrix to obtain luminescent composite particles minimizes these problems and improves optical properties, reduces photoluminescence quenching, and leads to wider applications. We describe two methods for the formation of silica composites containing CNSs: inclusion of CNSs into silica particles and their grafting onto the silica surface. Moreover, we present approaches to the synthesis of multifunctional particles. They combine the unique properties of silica and fluorescent CNSs, as well as magnetic, photosensitizing, and luminescent properties via the combination of functional nanoparticles such as iron oxide nanoparticles, titanium dioxide nanoparticles, quantum dots (QDs), and gold nanoclusters (AuNCs). Lastly, we discuss the advantages and challenges of these structures and their applications. The novelty of this review involves the detailed description of the approaches for the silica application as a matrix for the CNSs. This will support researchers in solving fundamental and applied problems of this type of carbon-based nanoobjects.

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A new facile and fast approach to the synthesis of polyaniline (PANi) molecularly imprinted polymers (MIPs) based on aniline oxidative chemical polymerization was proposed for protein recognition. For the first time, a surface imprinting strategy was implemented for the synthesis of PANi MIPs on the inner surface of soft glass polycapillaries (PC) with a large (2237) number of individual microcapillaries. Two different PANi layers-(i) PANi film and (ii) protein imprinted PANi nanowires-were synthesized sequentially. Uniform and highly stable PANi film was synthesized by oxidative polymerization at pH< 1. The synthesis of PANi MIPs on the PANi film pre-coated surface improved the reproducibility of PANi MIP formation. PANi MIP nanowires were synthesized at "mild" conditions (pH > 4.5) to preserve the protein template activity. The binding of horseradish peroxidase (HRP) molecules on the PANi MIP selective sites was confirmed by photometry (TMB chromogenic reaction), SEM images, and FTIR spectroscopy. The developed PANi MIPs enable HRP determination with a limit of detection (LOD) as low as 1.00 and 0.07 ng mL −1 on the glass slips and PC, respectively. The PANi MIPs are characterized by high stability; they are reversible and selective to HRP. The proposed approach allows PANi MIPs to be obtained for proteins on different supports and to create new materials for separation and sensing.

Luminescent quantum dots (QDs) of I–III–VI2 semiconductors present a new class of luminescence materials that combine unique optical and electronic properties while exhibiting low toxicity compared to conventional cadmium-based QDs. Advances in the colloidal synthesis of ternary QDs have been used to develop fluorescence chemical and biological sensors for the detection of various analytes. The review covers the main approaches to synthesizing QDs of the I–III–VI2 structure, the features of their structure and properties, and current trends in their use as low-toxic luminescent labels in biomedicine and chemical analysis.