Rfs 100 s

The structural morphologies of the as-synthesized samples were analyzed by field emission scanning electron microscopy (FESEM, Hitachi, Tokyo, Japan). Furthermore, the internal morphology of the samples was evaluated by a high-resolution transmission electron microscope (HRTEM, JEOL Ltd., Tokyo, Japan) operated at 200 kV. The phase composition and crystal orientation of the samples were analyzed using high-resolution X-ray diffraction (HR-XRD, Rigaku Co., Tokyo, Japan). The degree of graphitization in carbon with CuS was studied with a high-resolution dispersive Raman microscope (RFS-100S, Bruker, Mannheim, Germany) with a laser source wavelength of 514 nm. The bonding configurations were determined by Fourier transform infrared spectroscopy (FTIR; Perkin Elmer, Waltham, MA, USA) and X-ray photoelectron spectroscopy (XPS; Thermo Fisher Scientific, Waltham, MA, USA).

Trypomastigotes (2 x 10⁶ cells per mL) were stimulated for 1h with 7.5 μM AA as above and centrifuged. Cells were then resuspended in 3.7% formaldehyde overnight, pelleted and analyzed by Raman spectroscopy without any labeling. Raman spectra of cells were recorded using a FT-Raman spectrometer model RFS 100S coupled to RamanScopeIII (Bruker Optik GmbH, Ettlingen, Germany), equipped with a ND:YAG laser with an excitation line at 1064 nm. For acquisition of the spectra, the laser power was adjusted to 500 mW (at source) and a good signal/noise ratio was obtained by performing 2048 scans in the region of 3500–50 cm^-1 with a spectral resolution of 4 cm^-1. The acquisition of Raman spectra was performed by OPUS 6.0 software (Bruker).
To investigate the presence of AA directly in LBs, purified LBs from untreated and 7.5 μM AA-treated groups were placed over 20 mm CaF₂ windows (cat. number 63207; Edmund Optics, Barrington, NJ, USA) and the data collected with a laser power of 20 mW, 50 s integration time and 5 co-additions, without any labeling. The Raman spectra were obtained in a Senterra Raman spectrometer (Bruker) based in a 180° backscattering configuration and using a 50x objective and the 632.8 nm wavelength of He-Ne laser output as excitation. A spectral resolution of 3–5 cm^-1 and slit width of 50x1000 μm were chosen.

Spectra were recorded at −140°C (Linkam cryostat, Resultec, Illerkirchberg, Germany) using a Fourier-Transform Raman spectrometer RFS-100/S (Bruker, Rosenheim, Germany) equipped with a 1,064 nm cw NdYAG laser (Compass 1064-1500N, Coherent LaserSystems, Santa Clara, CA, United States) as described (Moldenhauer et al., 2017 (link)). Although 1,064 nm excitation is not in resonance with chromophore absorption, the chromophore signals are ∼1:1,000 enhanced over the protein bands justifying use of the term “resonance Raman” (RR) spectroscopy for our pre-resonant conditions. For each RR spectrum, 1,000 single scans were averaged. The samples were prepared at a concentration of 230 µM (wild-type OCP) and 243 µM (OCP-W288_BTA) in 1xPBS, pH 7.4. For photoconversion, a 3-W LED (Avonec, Wesel, Germany) was used.

Electrochemical experiments were carried out on a 283 Potentiostat-Galvanostat electrochemical workstation (EG&G PARC with M270 software, Microsoft Windows XP) with a conventional three-electrode system, including the modified Pt electrode as the working electrode, a platinum wire (1 mm diameter) as the counter electrode, and an Ag/AgCl electrode (saturated with KCl) as the reference electrode. Transmission electron microscopy (TEM) image analysis was performed on a Tecnai G2 F20 instrument (Philips, Amsterdam, The Netherland). The EDX analysis was carried out on an energy-dispersive X-ray spectroscopy (EDX) analyzer that was equipped on the Tecnai G2 F20 instrument (Philips, Amsterdam, The Netherland). Fourier-transform infrared spectroscopy (FTIR) was conducted on a Bruker TENSOR37 (BRUKER, Karlsruhe, Germany) spectrometer with the KBr pressed-pellet transmission mode. Raman spectra were obtained with a Bruker RFS 100/S (BRUKER, Karlsruhe, Germany) spectrometer.