Hydroxyethyl cellulose-based wearable hydrogel SERS substrate for rapid and ultrasensitive detection of β-adrenergic stimulants in sweat

Hydroxyethyl cellulose (HEC), a biomolecule with good water solubility, pH stability and biocompatibility, is widely used in safety - critical fields like food and pharmaceuticals. Stimulants abuse is a major challenge in sports competitions, where urine is usually used as an analyte, so there is an urgent need to establish a non-invasive, hygienic and immediate detection method. Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive, non-destructive and rapid detection method, which is expected to be used for the rapid detection of stimulants, therefore, this study synthesized a hydrogel SERS substrate based on hydroxyethyl cellulose. The HEC - Ag NPs/PAAM hydrogel (HAP hydrogel) was prepared simply and efficiently, with a rich network structure that could sequester small molecules. Meanwhile, the hydrogel has hydrophilic groups that can adsorb β-adrenergic stimulants in sweat. The incorporation of cellulose and silver nanoparticles (Ag NPs) provides the sensor patch with excellent antimicrobial properties and good biocompatibility. SERS technology is capable of quantitatively analyzing agonists in sweat (detection limit of clenbuterol is 9.4 × 10 −9  g/L). HAP hydrogels sensor exhibit excellent sensitivity and stability during the detection process. This property is crucial for expanding SERS substrates' use in detecting sweat agonists.