Design of a Novel Electrochemical Aptasensor Based on Molybdenum Disulfide Nanosheets for Lysozyme Detection

The precise detection of lysozyme plays a crucial role in early diagnosis of kidney failure in leukemia patients. Herein, we designed an electrochemical aptasensor to detect lysozyme using a glassy carbon electrode (GCE) modified with molybdenum disulfide (MoS2) nanosheets decorated with chitosan (Ch) and gold nanoparticles (Au). In the next steps of aptasensor preparation, aptamer (Apt) strands were immobilized on MoS2–Au–Ch/GCE surface via electrostatic interactions, and bovine serum albumin (BSA) solution was applied to cover unbonded areas on Apt/MoS2–Au–Ch/GCE. The MoS2–Au–Ch nanocomposite can warrant enhanced immobilization of aptamers and strong signals because of wrinkle-like structure and base planes in MoS2 nanosheets, presence of abundant amino and carboxyl functional groups in chitosan and Au nanoparticles. Differential pulse voltammetry (DPV) was used to evaluate the electrochemical behavior of the aptasensor at each preparation step and its detection performance. The developed electrochemical aptasensor based on MoS2 nanosheets showed remarkable performance for lysozyme detection in the range from 1 pmol/L to 10 nmol/L with a limit of detection of 2.2 fmol/L. The proposed aptasensor provided excellent selectivity against BSA, uric acid, cytochrome C, lysozyme and their mixture. In addition, it displayed great stability of about 99.58% of the initial signal upon 21-day storage. Tests on human serum and urine samples yielded promising recoveries ranging from 98 to 105%. Hence, MoS2–Au–Ch nanocomposite-based aptasensor could be an outstanding candidate for medical device applications and protein quantification.