Specific intracellular binding peptide as sPD-L1 antibody mimic: Robust binding capacity and intracellular region specific modulation upon applied to sensing research

Publication year: 2021
Authors: Junjie Hu a, Zhao-huan Zhang b, Zhongzheng Zhu c, Jie Chen a,d, Xiaojun Hu a, Hongxia Chen a

a - Center for Molecular Recognition and Biosensing, School of Life Sciences, Shanghai University, Shanghai, 200444, PR China
b - Department of Laboratory Medicine, Changzheng Hospital, Naval Medical University, Shanghai, 200003, PR China
c - Department of Oncology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, 301 Middle Yanchang Road, Shanghai, 200072, PR China
d - School of Medicine, Shanghai University, Shanghai, 200444, PR China

Published in: Biosensors and Bioelectronics, 2021, Vol. 185, p. 113269
doi: 10.1016/j.bios.2021.113269

Programmed death ligand 1 (PD-L1) immune checkpoint has been regarded as a new target for predicting cancer immunotherapy. As a transmembrane protein, PD-L1 has very low blood concentration and is likely to deplete their native activity when separated from the membrane environment due to significant hydrophobic domains, which make it difficult to measure sensitively. The reported PD-L1 aptamers and antibodies are both extracellular region binding molecules with the overlapping binding sites, which seriously limit with the construction of biosensor. Specific intracellular binding peptide (SIBP) as a unique PD-L1 intracellular region homing probe molecule is utilized for specifically capture targets. A simple and sensitive surface plasmon resonance (SPR) sandwich assay was constructed to detect serum soluble PD-L1 (sPD-L1) based on the unique and strong binding ability of SIBP to the intracellular region of sPD-L1. The designed SPR sensor showed great selectivity and wide dynamic response range of sPD-L1 concentration from 10 ng/mL to 2000 ng/mL. The limit of detection was calculated to be 1.749 ng/mL (S/N = 3). Owing to the SIBP's strong and specific binding ability with sPD-L1, the sensitive sensor can successfully detect sPD-L1 in serum samples, paving the way for the development of efficient test tools for clinical diagnosis and analysis.

MP-SPR keywords: AuNP, biomarker detection, biosensor development