Interstitial fluid-based optical biosensors

The high reproducibility and reliability of optical biosensors, alongside the extraordinarily features of interstitial fluid (ISF) as a promising biological fluid with blood-like composition and yet noninvasive or minimally invasive sampling, have led to the development of a variety of the ISF-based optical biosensors for diagnostic and health monitoring applications. In the present review, while introducing ISF, its characteristics, and the methods developed for its sampling, various types of optical biosensors developed so far for the colorimetric, fluorometric, and surface-enhanced Raman spectroscopy determination of (bio)chemical compounds in ISF are reviewed. Lastly, future prospects and views on the main challenges facing the further development of ISF-based optical biosensors are delineated. Building upon the extraordinary features of ISF-based optical biosensors as highly promising and potential biosensors, we anticipate that they will be greatly welcomed and many of the existing blood-based optical biosensors will be replaced by ISF-based ones in the near future. • Introducing interstitial fluid and its characteristics and sampling methods. • Reviewing the developed interstitial fluid-based optical biosensors. • Highlighting the bottlenecks, challenging issues ahead, and future outlook.