Refractive Index Matching Efficiency in Colorectal Mucosa Treated With Glycerol

In this paper, we describe the study of the kinetics and efficiency of the refractive index matching mechanism created by highly concentrated glycerol solutions in human normal and pathological colorectal mucosa tissues. Considering the wavelength range between 200 and 1000 nm, higher efficiency was obtained for the pathological mucosa, which shows a decreasing efficiency with increasing wavelength. The normal mucosa presents similar values in the deep-ultraviolet and in the near-infrared. Minimal efficiency values of 1% and 1.5% were obtained in the normal and pathological mucosa at 266 nm (combined absorption of DNA/RNA and myoglobin/hemoglobin bands at 260 and 274 nm) and local maxima of 2.9% and 3.8% were obtained in the same tissues at 570 nm. The diffusion time of glycerol was estimated as 417.3±5.2 s in normal mucosa and 504.9±3.8 s in pathological mucosa, suggesting that less molecules are necessary in the pathological tissue to produce a higher magnitude RI matching.