A SERS-active swab for integrated sampling, response and detection of saliva of normal and sleep-deprived mice

The redox status is closely related to physiology and pathology of organisms. Saliva has received increasing attention in health monitoring and medical diagnosis and more importantly, saliva is an ideal sample of non-invasive detection. The technology of quickly, easily and accurately detecting the redox-related parameters of the body can promote clinical diagnosis, treatment monitoring, and scientific research.

The cotton fibers of a cotton swab were first fixed with PMMA, and then three micron-scaled SERS probes (redox potential, oxidative capacity, and pH) were dropped onto different surfaces of the cotton fiber to fabricate a SERS-active swab. The integration on the cotton swab did not affect the stability and responsiveness of the probes. During the three days of testing, mice with normal sleep patterns detected fluctuations of redox potential and pH in their saliva, but there was no significant circadian rhythm; the detected oxidative capacity is highest in the morning and lowest at night every day. In sleep-deprived mice, on the first day, the redox potential fluctuations were normal, but the oxidative capacity and pH were abnormal. From the second day to the fourth day, the redox potential underwent a partial oxidation to partial reduction, and finally continued to oxidation, the fluctuation of oxidative capacity became larger and irregular, and the pH value later became acidic.

Three steps including sampling, response and detection were carried out in a SERS-active swab, which is important for the detection of liable parameters such as redox-related parameters, The SERS-active swabs would be a versatile tool for integration of sampling and detection of varied liquid samples.