Biological information detection technology is mainly used for the detection of physiological and biochemical parameters closely related to human tissues and organ lesions, such as biomarkers. This technology has important value in the clinical diagnosis and treatment of chronic diseases in their early stages. Wearable biosensors can be integrated with the Internet of Things and Big Data to realize the detection, transmission, storage, and comprehensive analysis of human physiological and biochemical information. This technology has extremely wide applications and considerable market prospects in frontier fields including personal health monitoring, chronic disease diagnosis and management, and home medical care. In this review, we systematically summarized the sweat biomarkers, introduced the sweat extraction and collection methods, and discussed the application and development of epidermal wearable biosensors for monitoring biomarkers in sweat in preclinical research in recent years. In addition, the current challenges and development prospects in this field were discussed.

Healthcare technology has allowed individuals to monitor and track various physiological and biological parameters. With the growing trend of the use of the internet of things and big data, wearable biosensors have shown great potential in gaining access to the human body, and providing additional functionality to analyze physiological and biochemical information, which has led to a better personalized and more efficient healthcare. In this review, we summarize the biomarkers in interstitial fluid, introduce and explain the extraction methods for interstitial fluid, and discuss the application of epidermal wearable biosensors for the continuous monitoring of markers in clinical biology. In addition, the current needs, development prospects and challenges are briefly discussed.

Biogenic selenium nanoparticles (SeNPs) have emerged as novel promising modulators of biological reactions such as redox and immune responses due to their multiple bioactivities and unique physicochemical properties. The research objective of this investigation is to explore the mechanism of uptake and metabolism of SeNPs by intestinal epithelial cells and its protective effect on intestinal barrier function with gut-on-a-chip. We designed a gut-on-a-chip to replicate key structural and environmental features of the intestinal tract to investigate the effects of oxidative stress on the intestinal barrier function and immune homeostasis of the intestinal epithelial cells as well as the regulatory role of SeNPs, and verified it through mice and piglet models. Biogenic SeNPs can be effectively taken up by IPEC-J2 cells via clathrin- and caveolae-mediated endocytosis and further metabolized into selenocystine and trace amounts of selenite within cells, which are then incorporated into the synthesis of antioxidant selenoenzymes. A gut-on-a-chip model confirmed that Diquat-induced oxidative stress significantly impaired intestinal epithelial barrier integrity and damaged villi-like structures. In addition, the oxidative stress in IPEC-J2 cells induced activation of intestinal mucosal mast cells (MCs) to release IL-1β and TNF-α, further exacerbating oxidative stress in IPEC-J2 cells and leading to excessive ROS generation. However, SeNPs treatment increased cellular selenium content and antioxidant selenoenzyme activities, modulated AMPK/NLRP3/Nrf2 pathways, effectively alleviated oxidative stress, maintained mitochondrial homeostasis, inhibited pro-inflammatory factors expression. The mice and early-weaned piglet models further confirmed that SeNPs can increase the selenoproteins expression in the jejunum, reduce MCs activation, inhibited cell pyroptosis, and eventually exhibit an effective protective effect against intestinal barrier oxidative damage. These results indicated that biogenic SeNPs reinforced antioxidant enzyme defenses, maintained mitochondrial homeostasis, inhibited crosstalk between inflammatory cells and intestinal epithelial cells, thereby protecting the intestinal epithelial barrier against oxidative stress damage.

The normal physiological activities and functions of bone cells cannot be separated from the balance of the oxygenation level, and the physiological activities of bone cells are different under different oxygenation levels. At present, in vitro cell cultures are generally performed in a normoxic environment, and the partial pressure of oxygen of a conventional incubator is generally set at 141 mmHg (18.6%, close to the 20.1% oxygen in ambient air). This value is higher than the mean value of the oxygen partial pressure in human bone tissue. Additionally, the further away from the endosteal sinusoids, the lower the oxygen content. It follows that the construction of a hypoxic microenvironment is the key point of in vitro experimental investigation. However, current methods of cellular research cannot realize precise control of oxygenation levels at the microscale, and the development of microfluidic platforms can overcome the inherent limitations of these methods. In addition to discussing the characteristics of the hypoxic microenvironment in bone tissue, this review will discuss various methods of constructing oxygen gradients in vitro and measuring oxygen tension from the microscale based on microfluidic technology. This integration of advantages and disadvantages to perfect the experimental study will help us to study the physiological responses of cells under more physiological-relevant conditions and provide a new strategy for future research on various in vitro cell biomedicines.