A prospective study on peptide mapping of human fatigue saliva markers based on magnetic beads

In order to explore convenient and stable fatigue markers, we studied various high-molecular-weight peptide fragments under fatigue state and non-fatigue state in the saliva using time of flight mass spectrometry. The saliva samples were collected from 10 healthy volunteers that were in the condition of fatigue and non-fatigue, respectively. Moreover, the time of flight mass spectrometry was conducted using two kinds of sample treatment methods, the magnetic beads enrichment (MB) and direct detection of stock solution. This was followed by modeling via the mass spectra of MB and supernatant (stock solution) directly collected after centrifugation. Both MB and direct sampling produced good spectrograms between 1,000 and 15,000 Da, while some peaks were lost in the enrichment. The spectrograms in the early and late period were different in each individual. Due to the limited sample size, 20 early and 20 late spectrograms were used for modeling analysis. Three different peptides were identified in the stock solution samples that can be detected in both fatigue and non-fatigue groups. The cross validity of MB model was 92.06%, while that of the stock solution model was 95.49%. The results showed that there were different peaks within the molecular weight of 2,000-15,000 Da, which provided a scientific basis for further realization of the convenient fatigue detection method based on the biosensor technique, with important theoretical and practical significance.