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 mm) samples of tomato puree, absorption peak increased as per l‐lactate addition with the lower detection limit of 3.98 mm. 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. [ABSTRACT FROM AUTHOR]