# Special Issue \"World of Biosensing\"
## 2 (Bio)Sensing
[18] described the fabrication of nanocomposites as potential medicines. The hybrid materials consisted of graphene oxide derivatives and nanoparticles of gold. The main task of the investigation was to characterize, in detail, the structure, composition, and properties of these nanocomposites owing to their possibility to become cytotoxic drugs. To evaluate the nanotoxicity of the nanocomposites on human neuroblastoma cells in vitro, a colorimetric sensor was developed. The paper submitted by [PERSON], [PERSON], [PERSON] et al. [19] reported on the dependence of the working characteristics of surface plasmon resonance (SPR) sensors on their configurations. Different SPR sensors, which contain multimode and tapered D-shaped plastic optical fibers, were fabricated and studied using water-glycerin mixtures. The optimized sensors, based on tapered optical fibers covered with gold film, were shown to possess increased sensitivity and may be prospective platforms for biosensor construction. Two papers are devoted to optic biosensors [20,21]. The article authored by [PERSON], [PERSON], [PERSON] et al. described a simple and quick method for colorimetric detection of _E. coli_ in seawater. Aptamer-coated magnetic beads were used for selective preconcentration of bacterial cells. The advantage of the PCR procedure, coming directly after magnetic pre-concentration, is the detection of target cells without the need for DNA isolation [20]. The paper of [PERSON], [PERSON], [PERSON] et al. discussed theoretical and experimental aspects of different approaches to the immune sensing of sulfonamides and fluoroquinolones [21]. It was shown that the cross-reactivity of enzymatic and fluorescent polarization immunoassays depends on the properties of antibodies and on the concentration ratio of immuno reagents/bioreceptors. The mathematical modeling and experimental comparison of both assays demonstrated the possibility of modulating immuno-detection selectivity without searching for new binding reactants. The last two papers in the SI presented a nanomechanical biosensor as a promising tool to study the biomolecular interactions, vibrations and aggregation states of macromolecules [22,23]. Such a biosensor belongs to a subfamily of micro-electrochemical systems and converts the energy of biological processes into measurable mechanical motion, which may be detected with optical or piezo-resistive devices. An atomic force microscopy (AFM) sensor was used to measure the changes in the conformational states of the enzyme horseradish peroxidase, which was placed in a cell over the coil. The influence of different liquids' motions in the flow-based system on the protein conformation was studied in both papers [22,23]. In the paper of [PERSON], [PERSON], [PERSON] et al., the flow of a nonaqueous liquid (glycerol) was shown to induce changes in the enzyme aggregation state and its adsorbability onto the mica surface [22]. Similar results were obtained during a study of water flow, as reported in another work by [PERSON], [PERSON], [PERSON] et al. [23]. The changes in protein conformational states may be explained by the influence of an electromagnetic field, which was induced due to triboelectric charge generation during the motion of liquids through the coiled communication pipes. An AFM sensor in the flow-based system, capable of monitoring the changes in the aggregation states of proteins of interest, may be promising for clinical diagnostics and veterinary medicine. All the papers published in this SI concerned chemical- [14,16,17,18,19] or macromolecular-based [13,15,20,21,22,23] sensors. It is worth mentioning that in the two years of the SI publication, the presented papers [13,15,20,21,22,23] have attracted a level of attention from the scientific community. Information concerning research interest in these papers was summarized up to January 2023 [24] and is presented in Figure 1.