Tensor ftir spectrometer

Attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy analysis of peptide fibrils were performed using a Bruker Tensor FT-IR Spectrometer (Bruker Optics, Berlin, Germany) with a Golden Gate MKII ATR accessory. Each spectrum consisted of 16 independent scans, measured at spectral resolution of 1 cm^-1 within the 1800–1500 cm^-1 range. All spectral data were acquired and normalized using the OPUS MIR Tensor 27 software. Infrared spectra between 1725 and 1575 cm^-1 were fitted through overlapping Gaussian curves, and the amplitude and area for each Gaussian function were calculated employing the non-linear peak-fitting program (PeakFit package, Systat Software, San Jose, CA, United States). Aggregated peptides were prepared at 150 μM in PBS buffer and incubated for 48 h at 25°C. The PBS buffer without peptide was used as a control and subtracted from the absorbance signal before deconvolution.

Attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy analysis of peptide fibrils was performed using a Bruker Tensor FT-IR Spectrometer (Bruker Optics, Berlin, Germany) with a Golden Gate MKII ATR accessory. Aggregated peptide solution, previously sonicated for 10 min in an ultrasonic bath (VWR ultrasonic cleaner), was dried out under a N₂ (g) atmosphere and each spectrum consisted of 16 independent scans, measured at spectral resolution of 2 cm⁻¹ within the 1800–1500 cm⁻¹ range. Spectral data were acquired and normalized using the OPUS MIR Tensor 27 software. The individual components of the spectrum were determined through second derivative analysis of the spectra and deconvoluted afterwards into overlapping Gaussian curves. The amplitude, mass center, bandwidth at half of the maximum amplitude, and area for each Gaussian function were calculated employing the nonlinear peak-fitting program PeakFit v4.12 (Systat Software Inc., San Jose, CA, USA). The PBS pH 7.4 buffer without peptide was used as a control and subtracted from the absorbance signal before deconvolution.

The internal morphologies of the films were analyzed by SEM (SU8010, Hitachi, TYO, Japan). The samples were gold-coated in a sputtering unit and measured at a 10 kV working voltage. The FTIR spectra of the films were evaluated using a TENSOR FTIR spectrometer (Bruker, SB, German) by an attenuated total reflection method in a 4 cm⁻¹ step size from 4000 to 500 cm⁻¹, with an average of 70 scans.

The secondary structure of incubated peptides was analyzed by attenuated total reflectance Fourier transform infrared (ATR FT-IR) spectroscopy using a Bruker Tensor FT-IR Spectrometer (Bruker, Massachusetts, United States) with a Golden Gate MKII ATR accessory. The aggregated peptide solutions were dried out under N₂ (g) atmosphere. Each spectrum consisted of 32 scans and was measured at a spectral resolution of 4 cm⁻¹ within the 1800–1,500 cm⁻¹ range. All spectral data were acquired and normalized using the OPUS MIR Tensor 27 software and the Peak Fit 4.12 program (Systat Software Inc., San Jose, United States) was used for data deconvolution.

ATR FT-IR spectroscopy analysis of Rho peptide aggregates was performed using a Bruker Tensor FT-IR Spectrometer (Bruker Optics, Berlin, Germany) with a Golden Gate MKII ATR accessory. Each spectrum consists of 16 independent scans, measured at spectral resolution of 1 cm^-1. Infrared spectra between 1725 and 1575 cm^-1 were fitted through overlapping Gaussian curves, and the amplitude, and area for each Gaussian function were calculated employing the non-linear peak-fitting program (PeakFit package, Systat Software, San Jose, CA, USA).