Molecular-Level Interactions of Nanodisc-Forming Copolymers Dissected by EPR Spectroscopy

In this study, we focus on analyzing the non-covalent interaction patterns between three lipid-nanodisc-forming polymers and nitroxide radicals which are used as small organic tracer molecules. Besides the negatively charged polymers DIBMA and SMA(2:1), we characterize the solvation behavior of a new zwitterionic styrene/maleic amide sulfobetaine copolymer named SMA-SB. The used nitroxide spin probes vary in their respective chemical structure, allowing the report of different local micropolarities and nanoscopic regions by recording temperature-dependent continuous-wave electron paramagnetic resonance (CW EPR) spectra. In combination with dynamic light scattering (DLS) and electrophoretic light scattering (ELS) experiments, we are able to provide a nanoscopic interpretation of the dominant interaction patterns between the polymer and the chosen guest molecule.

Molecular-Level Interactions of Nanodisc-Forming Copolymers Dissected by EPR Spectroscopy

In this study, we focus on analyzing the non-covalent interaction patterns between three lipid-nanodisc-forming polymers and nitroxide radicals which are used as small organic tracer molecules. Besides the negatively charged polymers DIBMA and SMA(2:1), we characterize the solvation behavior of a new zwitterionic styrene/maleic amide sulfobetaine copolymer named SMA-SB. The used nitroxide spin probes vary in their respective chemical structure, allowing the report of different local micropolarities and nanoscopic regions by recording temperature-dependent continuous-wave electron paramagnetic resonance (CW EPR) spectra. In combination with dynamic light scattering (DLS) and electrophoretic light scattering (ELS) experiments, we are able to provide a nanoscopic interpretation of the dominant interaction patterns between the polymer and the chosen guest molecule.

Doxyl Nitroxide Spin Probes Can Modify Toxicity of Doxorubicin towards Fibroblast Cells

The biological properties of doxyl stearate nitroxides (DSs): 5-DS, Met-12-DS, and 16-DS, commonly used as spin probes, have not been explored in much detail so far. Furthermore, the influence of DSs on the cellular changes induced by the anticancer drug doxorubicin (DOX) has not yet been investigated. Therefore, we examined the cytotoxicity of DSs and their ability to induce cell death and to influence on fluidity and lipid peroxidation (LPO) in the plasma membrane of immortalised B14 fibroblasts, used as a model neoplastic cells, susceptible to DOX-induced changes. The influence of DSs on DOX toxicity was also investigated and compared with that of a natural reference antioxidant α-Tocopherol. By employing the trypan blue exclusion test and double fluorescent staining, we found a significant level of cytotoxicity for DSs and showed that their ability to induce apoptosis and modify plasma membrane fluidity (measured fluorimetrically) is more potent than for α-Tocopherol. The most cytotoxic nitroxide was 5-DS. The electron paramagnetic resonance (EPR) measurements revealed that 5-DS was reduced in B14 cells at the fastest and Met-12-DS at the slowest rate. In the presence of DOX, DSs were reduced slower than alone. The investigated compounds, administered with DOX, enhanced DOX-induced cell death and demonstrated concentration-dependent biphasic influence on membrane fluidity. A-Tocopherol showed weaker effects than DSs, regardless the mode of its application—alone or with DOX. High concentrations of α-Tocopherol and DSs decreased DOX-induced LPO. Substantial cytotoxicity of the DSs suggests that they should be used more carefully in the investigations performed on sensitive cells. Enhancement of DOX toxicity by DSs showed their potential to act as chemosensitizers of cancer cells to anthracycline chemotherapy.

Effect of nitroxide spin probes on the transport properties of Nafion membranes

NMR, EPR, ODNP, conductivity, and hydration studies to examine Nafion water transport properties in the presence of TEMPO derived spin probes.