Methylene blue molecularly imprinted polymer for melatonin determination in urine and saliva samples

A highly sensitive and rapid electrochemical sensor was developed for detecting melatonin using a molecularly imprinted polymer (MIP) with methylene blue as the functional monomer and melatonin as the template. The MIP was synthesized via a simple electropolymerization process that did not require an initiating reagent. The sensor demonstrated good selectivity for melatonin against common interferences such as lactate, cytosine, cytidine, urea, ascorbic acid, creatine, creatinine, serotonin, and tryptophan. Melatonin detection was achieved at a potential of 0.60 V vs. Ag/AgCl with a sensitivity of 138.8 +/- 4.7 mu A mu M.1 in the linear range 0.097 - 200 mu M and a limit of detection of 29 nM (3SB/m). The sensor exhibited excellent reproducibility and repeatability for both within (intra) and between (inter) electrodes (%RSD < 3% for n = 3). The sensor was applied to authentic urine and saliva samples with recoveries of 103 +/- 1% and 102 +/- 1%, respectively.

Automated summary

A highly sensitive and rapid electrochemical sensor was developed using a molecularly imprinted polymer (MIP) for detecting melatonin. The MIP was synthesized through electropolymerization without the need for an initiating reagent. The sensor exhibited good selectivity for melatonin and showed excellent reproducibility and repeatability. It was successfully applied for detecting melatonin in urine and saliva samples with high recoveries.