Bimetallic Pt/Pd encapsulated mesoporous hollow CeO2 nanospheres for signal amplification toward electrochemical peptide based biosensing for matrix metalloproteinase 2
Abstract A facile electrochemical biosensor for matrix metalloproteinase 2 (MMP 2) was developed based on the target induced cleavage of a special designed peptide by using bimetallic Pt and Pd nanoparticles encapsulated mesoporous hollow ceria nanospheres (Pt/Pd/mhCeO 2 NS) as nanocarriers and electrocatalysts. Briefly, employing l lysine as bridge and linker, Pt/Pd/mhCeO 2 NS simply synthesized was used as a loading platform to immobilize electroactive thionine (Thi) and streptavidin (SA) resulting in the final formation of SA/Thi/Pt/Pd/mhCeO 2 NS nanoprobes. A specific biotin labeled peptide (biotin GPLGVRGKGGC, P1) acted as a molecular recognition element was firstly anchored on the Au nanoparticles modified electrode surface. In the presence of MMP 2, the P1 was specifically cleaved into two fragments at a certain site between G and V, while SA/Thi/Pt/Pd/mhCeO 2 NS nanoprobes were bonded onto the resulting electrode surface through the inherent interaction between streptavidin and biotin derived from uncleaved P1. In the proposed protocol, the electrochemical signal amplification was achieved by the effectively catalysis of Pt/Pd/mhCeO 2 NS to the decomposition of H 2 O 2 This could result in the significant enhancement of the electrochemical response for determining MMP 2 in the range of 0.1 pg mL 1 10 ng mL 1 with a detection limit of 0.078 pg mL 1 The present work demonstrated that the combination of the direct transduction of peptide cleavage events with the efficient Pt/Pd/mhCeO 2 NS catalysis method, providing a promising effective strategy for MMP 2 detection.