Urea has environmental, agricultural and clinical importance being present in many bodily fluids including blood, urine, tears and sweat. Monitoring urea levels is crucial, serving as an early warning for many health issues such as dehydration, kidney and liver malfunctions. Herein, semi-interpenetrating network (semi-IPN) poly(ethylene glycol) (PEG) based hydrogels (PEG700-DA/PEG