Development of non‐enzymatic ZnO nanocomposite‐based optical sensor for l ‐lactate detection in tomato samples

Summary l ‐lactate is a conjugate base of α‐hydroxy acid, a key organic chemical in food processing, fermentation, biology and chemical industries. We are reporting for the first time a facile and rapid non‐enzymatic nanosensor for l ‐lactate detection in tomato‐based products using 3‐aminophenylboronic acid (3‐APBA)‐added zinc oxide nanoparticles (ZnO NPs). 3‐APBA‐functionalised ZnO NPs have a selective and stable SPR intensity change at pH 5.5 to 7.5 and forms a reversible ester with bound l ‐lactate revealing the wavelength shift from λ  = 300 nm to 288 nm in UV‐VIS absorption spectrometry. In the spiked (2.5–20 m m ) samples of tomato puree, absorption peak increased as per l ‐lactate addition with the lower detection limit of 3.98 m m . l ‐lactate binds with a trigonal form of 3‐boronate, thereby generating the tetrahedral complex. ZnO NPs stabilise the tetragonal complex. Nanosensor validated with standard HPLC. This method is useful for l ‐lactate detection and alternates to conventional techniques.