A molecularly imprinted sensor based on thermo-responsive calcium alginate nanohydrogels for lysozyme detection

Thermo-responsive lysozyme/calcium alginate- g -poly-N-isopropylacrylamide nanohydrogels (Lys/CA- g -PNIPAAm NHs) were prepared from the self-assembly of Lys and sodium alginate- g -poly-N-isopropylacrylamide (SA-g-PNIPAAm) and the ionic cross-linking of CaCl 2 in aqueous solution. The Lys/CA- g -PNIPAAm NHs were immobilized on the cleaned surface of a transducer to fabricate a Lys molecularly imprinted sensor (Lys@MIP NHs sensor), which can selectively rebind to Lys in a mixture of closely related compounds. The effects of temperature on the size and the morphology of the Lys/CA- g -PNIPAAm NHs, the removal of Lys templates, the rebinding of Lys targets, and the detection performance of the Lys@MIP NHs sensor were investigated by dynamic light scattering, transmission electron microscope, and differential pulse voltammetry measurements. Compared with other Lys sensors, the fabricated Lys@MIP NHs sensor exhibited the wide linear range from 1 × 10 −9 to 1 × 10 −3  mg·mL −1 at 30 °C and showed short analysis times, high accuracy, satisfactory selectivity, stability, repeatability, reproducibility, and practical application for Lys detection in urine sample. Graphical Abstract