Determination of 3-(4-Hydroxyphenyl)lactic Acid by an Amperometric Sensor with Molecularly Imprinted Polymers

Sepsis is a life-threatening organ dysfunction caused by a disorder in the regulation of a body’s response to infection. If sepsis is not recognized at an early stage and treatment is not started, it can lead to septic shock, multiple organ failure, and death. Sepsis diagnostics, traditionally based on the clinical picture and the detection of etiologically significant microorganisms in the blood and foci, has been improved in recent years through the search for and the implementation of various biomarkers. One of promising sepsis biomarkers is 3-(4-hydroxyphenyl)lactic acid (4-HPLA). In this work, an amperometric sensor modified with a molecularly imprinted polymer (MIP) of hydroxyphenyllactic acid is developed, and a fundamental possibility of determining 4-HPLA in model aqueous solutions using this sensor is demonstrated. Molecularly imprinted polymers are widely used in substance separation processes and in the fabrication of selective sensors. Among a variety of selective materials, polyimides are of particular interest. In this regard, MIP sensors with imprints of 4-hydroxyphenyllactic acid were developed based on a copolymer of 1,2,4,5-benzenetracarboxylic acid with 4,4'-diaminodiphenyl oxide. The sensors are obtained in two stages (stage I at 80°C, stage II at 180°C) using the non-covalent imprinting method. The high selectivity of the MIP sensors with respect to the target molecules was established. The analytical range of the acid is 0.0002−0.2 mg/L. The experimentally established limit of detection for 4-hydroxyphenyllactic acid is 4.5 × 10^–5 mg/L.