Ultrasensitive aptasensing of lysozyme by exploiting the synergistic effect of gold nanoparticle-modified reduced graphene oxide and MWCNTs in a chitosan matrix

The authors describe a lysozyme aptasensor based on the use of gold nanoparticles (AuNP) assembled on the carbon nanotubes, graphene oxide and chitosan. An electrochemical impedance spectroscopic study was performed to demonstrate the synergistic effect of the MWCNT-AuNP, Chit-AuNP and GO-AuNP composites and the order of the layers affect the performance of aptasensing. Different parameters were optimized in order to obtain successful and sensitive detection of lysozyme in urine and saliva samples. A plot of charge-transfer resistance versus the logarithm of the lysozyme concentration is linear in the 0.02 to 250 pM concentration range, with a 9 fM detection limit (at an S/N ratio of 3). The aptasensor is highly specific and selective. Clinical analyses were performed and data were found to be in good agreement with those obtained by HPLC. Graphical abstract Schematic of the procedure for aptamer-based detection of lysozyme using the electrochemical signal of the K 3 [Fe(CN) 6 ]/K 4 [Fe(CN) 6 ] amplified by AuNP, rGO and MWCNT. This assay has high sensitivity and good selectivity. It can presumably be transferred to other protein detection schemes.