Piotr Piotrowski

The hybrid system BiVO₄/g-C₃N₄ is a prospective photocatalyst because of the favorable mutual alignment of the energy bands of both semiconductors. However, the path of the photocatalytic process is still unclear because of contradictory information in the literature on whether the mechanism of charge carrier separation at the BiVO₄/g-C₃N₄ interface is band-to-band or Z-scheme. In this work, we clarified this issue by comparative photocatalytic studies with the use of systems without a mediator and with different kinds of mediators including Au nanoparticles, fullerene derivatives, and the Fe³⁺/Fe²⁺ redox couple. Additionally, the charge transfer dynamics at the BiVO₄/g-C₃N₄ and BiVO₄/mediator/g-C₃N₄ interfaces were investigated by time-resolved photoluminescence (TRPL) measurements, while the influence of the mediator on the surface recombination of the charge carriers was verified by intensity-modulated photocurrent spectroscopy (IMPS). We proved that the charge carrier separation at the BiVO₄/g-C₃N₄ interface occurs according to the mechanism typical for a heterojunction of type II, while the incorporation of the mediator between BiVO₄ and g-C₃N₄ leads to the Z-scheme mechanism. Moreover, a very strong synergetic effect on caffeine (CAF) degradation rate was found for the system BiVO₄/Au/g-C₃N₄ in the presence of Fe³⁺ ions in the CAF solution.

The surface modification of magnetite nanoparticles (Fe₃O₄ NPs) is a promising approach to obtaining biocompatible and multifunctional nanoplatforms with numerous applications in biomedicine, for example, to fight cancer. However, little is known about the effects of Fe₃O₄ NP-associated reductive stress against cancer cells, especially against chemotherapy-induced drug-resistant senescent cancer cells. In the present study, Fe₃O₄ NPs in situ coated by dextran (Fe₃O₄@Dex) and glucosamine-based amorphous carbon coating (Fe₃O₄@aC) with potent reductive activity were characterized and tested against drug-induced senescent breast cancer cells (Hs 578T, BT-20, MDA-MB-468, and MDA-MB-175-VII cells). Fe₃O₄@aC caused a decrease in reactive oxygen species (ROS) production and an increase in the levels of antioxidant proteins FOXO3a, SOD1, and GPX4 that was accompanied by elevated levels of cell cycle inhibitors (p21, p27, and p57), proinflammatory (NFκB, IL-6, and IL-8) and autophagic (BECN1, LC3B) markers, nucleolar stress, and subsequent apoptotic cell death in etoposide-stimulated senescent breast cancer cells. Fe₃O₄@aC also promoted reductive stress-mediated cytotoxicity in nonsenescent breast cancer cells. We postulate that Fe₃O₄ NPs, in addition to their well-established hyperthermia and oxidative stress-mediated anticancer effects, can also be considered, if modified using amorphous carbon coating with reductive activity, as stimulators of reductive stress and cytotoxic effects in both senescent and nonsenescent breast cancer cells with different gene mutation statuses.

10 Indene C₆₀ and C₇₀ derivatives have been synthesized and characterized, and solar cells fabricated using them gave the best efficiency for hexyl derivatives.

Fullerene derivatives offer great scope for modification of the basic molecule, often called a buckyball. In recent years, they have been the subject of numerous studies, in particular in terms of their applications, including in solar cells. Here, the properties of four recently synthesized fullerene C60 derivatives were examined regarding their optical properties and the efficiency of the charge transfer process, both in fullerene derivatives themselves and in their heterojunctions with poly (3-hexylthiophene). Optical absorption, electron spin resonance (ESR), and time-resolved photoluminescence (TRPL) techniques were applied to study the synthesized molecules. It was shown that the absorption processes in fullerene derivatives are dominated by absorption of the fullerene cage and do not significantly depend on the type of the derivative. It was also found by ESR and TRPL studies that asymmetrical, dipole-like derivatives exhibit stronger light-induced charge transfer properties than their symmetrical counterparts. The observed inhomogeneous broadening of the ESR lines indicated a large disorder of all polymer–fullerene derivative blends. The density functional theory was applied to explain the results of the optical absorption experiments.

In this work, a series of C₆₀/C₇₀ fullerene derivatives bearing non-aromatic and mono-, bi-, tri- and tetracyclic aryl-substituents was synthesized according to the modified Bingel method and characterized using spectral methods: ESI-MS, ¹H NMR, ¹³C NMR, UV–Vis, FT-IR and cyclic voltammetry (CV). HOMO and LUMO energy levels and the band gaps for optimized structures of reported fullerene derivatives were determined according to the DFT functionals, B3LYP 6-31G(d) and PBE/6-311G(d,p). Results obtained from CV and UV–Vis measurements, which showed very good agreement, were compared to calculated theoretical values also revealing satisfactory level of compliance of the obtained results. We have studied the impact of presence and number of aromatic rings in malonate substituent of C₆₀/C₇₀ fullerene derivatives employed as acceptor materials on performance of BHJ solar cells prepared using PTB7-Th as donor material. We successfully prepared solar cells based on all the synthesized compounds, and the highest performance of the obtained photovoltaic devices was observed for fullerene derivatives bearing monocyclic and bicyclic aromatic moieties. The obtained voltage was about 0.8 V and current density was above 10 mA/cm². Optical studies showed absorption edges at 1.9 eV and 1.8 eV for C₆₀ and C₇₀ derivatives, respectively, with absorption coefficients comparable to C₆₀/C₇₀ PCBM samples. Photocurrent spectroscopy showed 20–40% quantum efficiency. Long-term ageing measurements showed T80 time between 105 days and 115 days for derivatives with phenyl and naphthalene substituents. Taking into account that synthesis of reported fullerene derivatives is very convenient, the reported compounds are very promising materials for construction of BHJ solar cells.

This study aimed to develop, characterize, and evaluate antibacterial and cytotoxic properties of novel fullerene derivative composed of C₆₀ fullerenol and standard aminoglycoside antibiotic–gentamicin (C₆₀ fullerenol-gentamicin conjugate). The successful introduction of gentamicin to fullerenol was confirmed by X-ray photoelectron spectroscopy which together with thermogravimetric and spectroscopic analysis revealing the formula of the composition as C₆₀(OH)₁₂(GLYMO)₁₁(Gentamicin)_0.8. The dynamic light scattering (DLS) revealed that conjugate possessed ability to form agglomerates in water (size around 115 nm), while Zeta potential measurements demonstrated that such agglomerates possessed neutral character. In vitro biological assays indicated that obtained C₆₀ fullerenol-gentamicin conjugate possessed the same antibacterial activity as standard gentamicin against Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli, which proves that combination of fullerenol with gentamicin does not cause the loss of antibacterial activity of antibiotic. Moreover, cytotoxicity assessment demonstrated that obtained fullerenol-gentamicin derivative did not decrease viability of normal human fibroblasts (model eukaryotic cells) compared to control fibroblasts. Thus, taking into account all of the results, it can be stated that this research presents effective method to fabricate C₆₀ fullerenol-gentamicin conjugate and proves that such derivative possesses desired antibacterial properties without unfavorable cytotoxic effects towards eukaryotic cells in vitro. These promising preliminary results indicate that obtained C₆₀ fullerenol-gentamicin conjugate could have biomedical potential. It may be presumed that obtained fullerenol may be used as an effective carrier for antibiotic, and developed fullerenol-gentamicin conjugate may be apply locally (i.e., at the wound site). Moreover, in future we will evaluate possibility of its applications in inter alia tissue engineering, namely as a component of wound dressings and implantable biomaterials.

Non-covalent modification of graphene is one of the strategies used for enhancing its energy storage properties. Herein, we report the design and synthesis of a series of fullerene derivatives that are capable of assembly on graphene sheets by π–π stacking interactions. Newly synthesized graphene-fullerene hybrid nanomaterials were characterized using spectroscopic and microscopic techniques. In order to determine the specific capacitance of obtained electrode materials galvanostatic charge-discharge measurements were performed. The obtained results allowed the determination of which fullerene core and type of substituent introduced on its surface can increase the capacitance of resulting electrode. Benefiting from introduced fullerene derivative molecules, graphene with naphthalene functionalized C₇₀ fullerene showed specific capacitance enhanced by as much as 15% compared to the starting material.

Graphene functionalized with dianthracene malonate was synthesized and used subsequently for construction of covalently bound graphene-fullerene hybrid nanomaterials. For this purpose, novel approach of Diels–Alder reaction of C₆₀/C₇₀ fullerene cores with anthracene moieties previously introduced onto graphene surface was successfully employed. Structure and composition of obtained graphene and its derivatives were characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopy. Obtained results revealed that both C₆₀ and C₇₀ fullerenes were found to be capable of formation desired Diels–Alder adducts, yielding products of different morphology. Capacitive properties of the synthesized energy storage nanomaterials were determined by means of cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) measurements, revealing that functionalization of graphene with C₆₀ moieties enhances its energy storage properties.

Background: Fullerenols (water-soluble derivatives of fullerenes), such as C₆₀(OH)₃₆, are biocompatible molecules with a high ability to scavenge reactive oxygen species (ROS), but the mechanism of their antioxidant action and cooperation with endogenous redox machinery remains unrecognized. Fullerenols rapidly distribute through blood cells; therefore, we investigated the effect of C₆₀(OH)₃₆ on the antioxidant defense system in erythrocytes during their prolonged incubation. Methods: Human erythrocytes were treated with fullerenol at concentrations of 50–150 µg/mL, incubated for 3 and 48 h at 37 °C, and then hemolyzed. The level of oxidative stress was determined by examining the level of thiol groups, the activity of antioxidant enzymes (catalase, glutathione peroxidase, glutathione reductase, and glutathione transferase), and by measuring erythrocyte microviscosity. Results: The level of thiol groups in stored erythrocytes decreased; however, in the presence of higher concentrations of C₆₀(OH)₃₆ (100 and 150 µg/mL), the level of -SH groups increased compared to the control. Extending the incubation to 48 h caused a decrease in antioxidant enzyme activity, but the addition of fullerenol, especially at higher concentrations (100–150 µg/mL), increased its activity. We observed that C₆₀(OH)₃₆ had no effect on the microviscosity of the interior of the erythrocytes. Conclusions: In conclusion, our results indicated that water-soluble C₆₀(OH)₃₆ has antioxidant potential and efficiently supports the enzymatic antioxidant system within the cell. These effects are probably related to the direct interaction of C₆₀(OH)₃₆ with the enzyme that causes its structural changes.