Biochemical characterization of skin burn wound healing using ATR-FTIR

Abstract

Efficient biochemical characterization of skin burn healing stages can improve clinical routine to adjust patients treatment. The golden standard for diagnosing skin burning stages is the histological biopsy. This practice is often expensive and technically challenging. There have been advances in the treatment, and diagnostic of the critical skin burned patients due to the increase of multidisciplinary collaboration. The contributions from different fields of biomedical engineering motivate to develop a better procedure for clinical applications. Considering the difficulty of monitoring wound healing the Fourier Transform Infrared coupled with an Attenuated Total Reflectance (ATR-FTIR) accessory is an analytical technique that can provide information regarding spectral biomarkers in biological materials. This study aimed to evaluate the classification feasibility provided by ATR-FTIR technique in the burned skin to follow the regenerative process in vivo. 40 skin burned samples from the Wistar rats dorsum at 3,7, 14, 21 days after burn were compared with the corresponded healthy group samples, by registering their infrared absorption spectra in FTIR Thermo Nicolet 6700 coupled to a diamond crystal ATR. The spectra were separated in the region 900 to 1800 cm-1 for further chemometric calculations. The second derivative of spectra was applied for discrimination, which results demonstrated differences from control and burns wounded groups, as well as among, burn wounded groups, using Amide I (1628 cm-1) and Amide II (1514 cm-1) bands. Amide I and Amide II bands are two significant bands of the infrared protein spectrum. The Amide I band is mainly associated with the C=O stretching vibration (70-80%) and is directly related to the backbone conformation. The Amide II band results from the N-H bending vibration (40-60%) and from the C-N stretching vibration (18-40%). This band is conformationally sensitive. These bands suggest proteins activity changing associate to inflammatory and maturation stages when it is compared with the healthy group. The statistical difference with amide I occur in proliferation and maturation stages. These findings indicate that ATR-FTIR is suitable to detect the burn wound healing stages and in the future can be an auxiliary instrument for clinical routine.