Chemical modification of M13 bacteriophage as nanozyme container for dramatically enhanced sensitivity of colorimetric immunosensor

Abstract

Herein, a sulfydryl modification of M13 bacteriophage was introduced as bio-functional component including biological recognition, and nanozyme container for enhancing sensitivity of colorimetric immunsensor, where the seven peptide sequence fused on the p3 protein of M13 was used to mimic deoxynivalenol (DON) antigen for recognizing the anti-DON monoclonal antibody, while the sulfydryl groups modified on capsid proteins were used to load numerous Ag coated Au nanoparticles (AuNPs@Ag) for improving the peroxidase-like activity of AuNPs@Ag. Owing its great loading capacity, the M13 bacteriophage assembled AuNPs@Ag nanocomposites (M13DON@AuNPs@Ag) showed approximately 48- and 105-fold enhanced catalytic efficacy to hydrogen peroxide and tramethylbenzidine than those of natural horse radish peroxidase (HRP). Using the M13DON@AuNP@Ag as signal amplifier, the proposed immunosensor exhibits a very high sensitivity for DON detection with the 50 % competitive inhibition concentration (IC50) and detection limit (LOD) of 2.03 ng/mL and 13.67 pg/mL, respectively. These values are about 26- and 947-fold lower than those of conventional HRP based ELISA method (IC50 and LOD values =52.43 ng/mL and 12.95 ng/mL, respectively). In addition, the proposed method also showed good specificity and accepted accuracy for DON detection in real corn samples. Moreover, the reliability of this novel strategy was further confirmed through compared with the high performance liquid chromatography method (HPLC). All in all, the M13 bacteriophage exhibits a promising potential as nanozyme container for enhancing the sensitivity of immunosensor, and this novel signal amplification system can be easily extended for highly sensitive detection of other analytes by altering specific mimic peptide sequence.