The syntheses and biological applications of two novel fluorescent 9-phenylethynylpyronin analogues containing either carbon or silicon at the position 10 are reported. Both fluorescent probes exhibited a relatively strong fluorescence in methanol and phosphate buffer saline in the near-infrared region (705-738 nm) upon irradiation of either of their absorption maxima in the blue and red regions. The compounds showed high selectivity toward mitochondria in myeloma cells in vivo and allowed their visualization in a favored tissue-transparent window, which makes them promising NIR fluorescent tags for applications in bioimaging.

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Plasma polymers with NHx groups were deposited from cyclopropylamine in low pressure radio frequency (RF) discharges. The amount of NHx decreased with increasing average power Pav, whereas the layer dissolution in water decreased and high Pav led to a slight film swelling. The C2C12 cells demonstrated very high adhesion to the layers regardless of the deposition conditions. Although the surface chemistry of amine‐rich layers should enhance the cell proliferation, the WST‐1 assay, and immunocytochemistry revealed lower cell proliferation and viability on the layers exhibiting above 18% of relative thickness loss in water. Promising results were obtained on the layers with better water stability and bearing 7–10% of NHx.

Graphene quantum dots (GQDs) with tunable fluorescence emission promise excellent bioapplication potential, especially in bioimaging. We report the synthesis of nitrogen-doped GQDs (N-GQDs) from glucose and ethylenediamine, cheap and safe chemicals, using a one-step and fast microwave-assisted hydrothermal method. Our N-GQDs exhibit fluorescence in the entire visible spectral region, which extends to near-ultraviolet and slightly to near-infrared. Since the origin of fluorescence and its relation to the structure and synthesis conditions are not yet fully understood, we also concentrated on the fluorescence mechanism explanation. Structural characterization with steady-state and time-resolved photoluminescence measurements indicated that bandto-band transitions, size effect, and different nitrogen and oxygen functional groups play a role in this multicolor emission. Remarkably, we found for the first time the evidence that directly relates a change in the N-GQD work function to the change in oxygen groups under UV irradiation via ultraviolet photoelectron spectroscopy. Thus, we confirmed that for λ ex ≲ 380 nm, photooxidation processes occurred, which led to chemical modification, thereby lowering the work function in the N-GQDs. The N-GQDs were proved to be highly biocompatible by a cell viability assay using vascular smooth muscle cells. Together with the wide spectral range emission observed in confocal fluorescence imaging, it demonstrated the potential of the N-GQDs for in vitro bioimaging applications.

Our previously-obtained impressive results of highly increased C2C12 mouse myoblast adhesion to amine plasma polymers (PPs) motivated current detailed studies of cell resistance to trypsinization, cell proliferation, motility, and the rate of attachment carried out for fibroblasts (LF), keratinocytes (HaCaT), rat vascular smooth muscle cells (VSMC), and endothelial cells (HUVEC, HSVEC, and CPAE) on three different amine PPs. We demonstrated the striking difference in the resistance to trypsin treatment between endothelial and non-endothelial cells. The increased resistance observed for the non-endothelial cell types was accompanied by an increased rate of cellular attachment, even though spontaneous migration was comparable to the control, i.e., to the standard cultivation surface. As demonstrated on LF fibroblasts, the resistance to trypsin was similar in serum-supplemented and serum-free media, i.e., medium without cell adhesion-mediating proteins. The increased cell adhesion was also confirmed for LF cells by an independent technique, single-cell force spectroscopy. This method, as well as the cell attachment rate, proved the difference among the plasma polymers with different amounts of amine groups, but other investigated techniques could not reveal the differences in the cell behaviour on different amine PPs. Based on all the results, the increased resistance to trypsinization of C2C12, LF, HaCaT, and VSMC cells on amine PPs can be explained most probably by a non-specific cell adhesion such as electrostatic interaction between the cells and amine groups on the material surface, rather than by the receptor-mediated adhesion through serum-derived proteins adsorbed on the PPs.