Results
The second derivative spectra of the Healthy group showed a high intensity in the amide I band at 1648 cm-1, which was assigned to an-helix secondary structure of protein.
Albumin protein is rich in -helix, consistent with the changes in amide I band profile in diseased liver conditions compared to control.
The amide I is shifted to 1639 cm-1in cirrhosis and HCC spectra, which was assigned to greater predominance of -sheet secondary structure (Fig 3)The highest -sheet secondary structure (centered at 1639 cm-1)and the lowest lipid content (centered at 1745 cm-1) were detected in the HCC group compared with the Healthy and Cirrhosis groups.
(Fig 4) These results show that the decrease in absorbance in the lipid region of HCC could be related to patient condition with depressed triglycerides and cholesterol metabolism. In addition, we test the PLS-DA classification with individual unknown, the prediction of healthy, cirrhosis and HCC were found with 100%, 60%, 83.3%, respectively.(Fig 5).