Battery-free, wireless, and flexible electrochemical patch for in situ analysis of sweat cortisol via near field communication.

Wearable and flexible biosensing devices have been widely developed for in situ detections. Cortisol is a vital biomarker which plays crucial regulatory role in numerous physiological processes of the human body. Here, a wireless, battery-free, and flexible integrated patch is developed for real-time on-body sweat cortisol detection. The patch integrated with all-printed flexible electrochemical immunosensor, which was used to detect cortisol through differential pulse voltammetry (DPV). The near field communication (NFC) module on the patch enables wireless power harvesting and data interaction with an NFC-enabled smartphone, which makes the patch get rid of rigid batteries and realize epidermal on-body testing. Multiple in situ detections on volunteers' sweat on the surface of skin showed that the flexible integrated patch could reflect the circadian rhythm of the body's sweat cortisol level changes in relaxed mood or under stress, which could be confirmed with the enzyme linked immunosorbent assay (ELISA) kit. In this way, the patch provides a rapid-detecting, convenient, and non-invasive sensing solution for in situ analysis of sweat cortisol, which can be applied for the personalized mental health management.

[Study on preparation of salidroside and polysaccharide in Rhodiola crenulata].

OBJECTIVE: To optimize the preparation process of salidroside and polysaccharide in Rhodiola crenulata. METHODS: Water-extraction and alcohol-precipitation was used. The effect of added water volume, decoction time and frequency on water-extracting process was investigated by L9 (3(4)) orthogonal design using extraction rate, content of salidroside and polysaccharide as the assessment indexes. The effect of liquor strength and ethanol concentration on alcohol-precipitating process was investigated as well, using content of salidroside and polysaccharide as the assessment indexes. RESULTS: The optimum conditions for water-extracting process were as follows: decocting 3 times, and each time adding 8 fold of water and extracting 2 h. For alcohol-precipitating process,it was that liquor strength was 0.4 g/mL, and ethanol concentration in liquor was 70%. CONCLUSION: The optimized process has guidance for the development and comprehensive utilization of this plant.