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Small, carbon-based nanoparticles, carbon dots (CDs), are investigated as photosensitizers (PSs) for photodynamic therapy of cancers. The results presented here show biochemical changes in cancer cells treated with surface-modified CDs, which are augmented by illumination, indicating a high potential of CDs as selective drug carriers and potent PSs. In addition, we will show that CDs produced from black carrot extract (biomass) can be exploited for image-guided therapy and be cytotoxic for cancer cells, thanks to their fluorescence properties. Finally, since biomass-fabricated CDs interact strongly with nucleic acids, they can be further developed for cell cycle sensing purposes.

Metabolism of metals in microalgae and adaptation to metal excess are of significant environmental importance. We report a three-step mechanism that the green microalga Chlorella sorokiniana activates during the acquisition of and adaptation to manganese (Mn), which is both an essential trace metal and a pollutant of waters. In the early stage, Mn2+ was mainly bound to membrane phospholipids and phosphates in released mucilage. The outer cell wall was reorganized and lipids were accumulated, with a relative increase in lipid saturation. Intracellular redox settings were rapidly altered in the presence of Mn excess, with increased production of reactive oxygen species that resulted in lipid peroxidation and a decrease in the concentration of thiols. In the later stage, Mn2+ was chelated by polyphosphates and accumulated in the cells. The structure of the inner cell wall was modified and the redox milieu established a new balance. Polyphosphates serve as a transient Mn2+ storage ligand, as proposed previously. In the final stage, Mn was stored in multivalent Mn clusters that resemble the structure of the tetramanganese–calcium core of the oxygen-evolving complex. The present findings elucidate the bioinorganic chemistry and metabolism of Mn in microalgae, and may shed new light on water-splitting Mn clusters.

Nanocomposite system formulated from surface-modified S-doped carbon dot (S-CD) nanoparticle with a potential metallodrug, palladium(II) complex, dichloro(1,2-diaminocyclohexane)palladium(II), [Pd(dach)Cl2] (Pd@S-CD), was investigated as a model system for the treatment of cervical carcinoma (HeLa) cells. To examine the intracellular biochemical effects induced by the Pd@S-CD, we used Synchrotron Radiation-based Fourier-transform infrared spectroscopy (SR FTIR). SR FTIR spectroscopy was employed to investigate the alterations in cellular components’ biochemical composition and secondary structure upon exposure to Pd@S-CD. Spectral analysis, complemented by statistical techniques, revealed changes in biomolecules, lipids, proteins, nucleic acids, and carbohydrates caused by the treatment with Pd@CDs. These results and the increased cytotoxicity of the system demonstrate its high anti-cervical cancer therapeutic potential.

Carbon dots (CDs) and N-carbon dots (N-CDs) loaded with Ru-complex (CDs@RuCN, N-CDs@RuCN, respectively) were investigated as media imposing biochemical changes induced by UV illumination of ovarian cancer, A2780, and osteosarcoma, CAL72, cells. Synchrotron radiation-based Fourier Transform Infrared Spectroscopy was performed, and the spectra were subjected to a Principal Component Analysis. The CDs@RuCN and N-CDs@RuCN effects on cancer cells were analyzed by the theoretical modelling of the stability of the composite systems and a protein database search. Moreover, a detailed evaluation of surface and optical properties of CDs@RuCN and N-CDs@RuCN was carried out. Results demonstrated selective action of the CDs@RuCN and N-CDs@RuCN-based photodynamic therapy, with N-CDs@RuCN being the most active in inducing changes in A2780 and CDs@RuCN in CAL72 cells. We assume that different surface charges of nanoparticles led to direct interactions of N-CDs@RuCN with a Wnt signalling pathway in A2780 and those of CDs@RuCN with PI3–K/Akt in CAL72 cells and that further biochemical changes occurred upon light illumination.

Microalgae can be implemented in the remediation of mining and other metal-rich wastewaters as pioneer species. On the other hand, metals affect aquatic ecosystems through the negative impact on microalgae which are the primary producers of O2 and biomass. Redox processes represent an important component of the mechanisms of interaction of microalgae with transition metals. We analyzed the redox changes in Chlorella sorokiniana culture that are induced by high levels of Mn(II). Mn is the key metal pollutant, with five main oxidation forms that can bind to a variety of different ligands. Mn (1 mM) induced a significant increase in the intracellular production of reactive oxygen species. The boost appears to show two phases – the first is very fast (observed after 15 min), whereas the second starts after 1 h reaching a plateau at 24 h. The concentration of reduced thiols, which represent important targets of oxidation, appears to parallel this trend. Total glutathione concentration shows a drop at 1 h and recovery at 24 h. This implicates that either a glutathionylation of proteins or a synthesis of phytochelatins - sulfur-rich short-chain peptides that sequester metals, takes place early in the response to Mn. Further, FTIR analysis showed that Mn induced a decrease of C=C levels and CH2/CH3 ratio implicating increased lipid peroxidation. Finally, Mn ions that were accumulated in the cells were extracted with nitric oxide and analyzed by cyclic voltammetry. Two redox forms were detected - Mn(II) and Mn(IV). The latter appears to prevail at higher manganese concentrations and longer periods of incubation. These results demonstrate that redox response of C. sorokiniana to high Mn levels involves at least two phases. Initially, Mn(II) enters the cells and induces pro-oxidative changes that are mitigated by glutathione-based antioxidative defense. Later on, redox homeostasis is reestablished with concomitant inactivation of Mn in the more stable redox form.

Objects of the present study are improved fullerene C60 drug carrier properties trough encapsulation by microbial polysaccharides, levan (LEV), pullulan (PUL), and their hydrophobized cholesterol-derivatives (CHL and CHP), that show better interaction with cancer cells. The zeta potential, polydispersity index, and the diameter of particles were determined, and their cytotoxicity against three cancer cell lines were tested. Biochemical changes in HeLa cells are analyzed by synchrotron radiation (SR) FTIR spectro-microscopy combined with the principal component analysis (PCA). The most significant changes occur in HeLa cells treated with LEV-C60 and correspond to the changes in the protein region, i.e. Amide I band, and the changes in the structure of lipid bodies and membrane fluidity are evident. The highest cytotoxicity was also induced by LEV-C60. In HeLa cells, cytotoxicity could not be strictly associated with biochemical changes in lipids, proteins and nucleic acids, but these findings are significant contribution to the study of the mechanism of interaction of C60-based nanoparticles with cellular biomolecules. In conclusion, LEV, PUL, CHL, and CHP enhanced fullerene C60 potential to be used as target drug delivery system with the ability to induce specific intracellular changes in HeLa cancer cells.

Microalgae have evolved mechanisms to respond to changes in copper ion availability, which are very important for normal cellular function, to tolerate metal pollution of aquatic ecosystems, and for modulation of copper bioavailability and toxicity to other organisms. Knowledge and application of these mechanisms will benefit the use of microalgae in wastewater processing and biomass production, and the use of copper compounds in the suppression of harmful algal blooms. Here, using electron microscopy, synchrotron radiation-based Fourier transform infrared spectroscopy, electron paramagnetic resonance spectroscopy, and X-ray absorption fine structure spectroscopy, we show that the microalga Chlorella sorokiniana responds promptly to Cu2+ at high non-toxic concentration, by mucilage release, alterations in the architecture of the outer cell wall layer and lipid structures, and polyphosphate accumulation within mucilage matrix. The main route of copper detoxification is by Cu2+ coordination to polyphosphates in penta-coordinated geometry. The sequestrated Cu2+ was accessible and could be released by extracellular chelating agents. Finally, the reduction in Cu2+ to Cu1+ appears also to take place. These findings reveal the biochemical basis of the capacity of microalgae to adapt to high external copper concentrations and to serve as both, sinks and pools of environmental copper.