posted on 2024-02-26, 22:29authored byZheming Wang, Xiaoxia Xie, Zhenyun He, Zhichang Sun, Yongli Zhang, Fujing Mao, Hua Pei, Sihang Zhang, Bruce D. Hammock, Xing Liu
Sensitive detection of cancer biomarkers can contribute
to the
timely diagnosis and treatment of diseases. In this study, the whitespotted
bamboo sharks were immunized with human α-fetoprotein (AFP),
and a phage-displayed variable new antigen receptor (VNAR) single
domain antibody library was constructed. Then four unique VNARs (VNAR1,
VNAR11, VNAR21, and VNAR25) against AFP were isolated from the library
by biopanning for the first time. All of the sequences belong to type
II of VNAR, and the VNAR11 was much different from the rest of the
three sequences. Then VNAR1 and VNAR11 were selected to fuse with
the C4-binding protein α chain (C4bpα) sequence and efficiently
expressed in the Escherichia coli system. Furthermore,
a VNAR-C4bpα-mediated sandwich chemiluminescence immunoassay
(VSCLIA) was developed for the detection of AFP in human serum samples.
After optimization, the VSCLIA showed a limit of detection of 0.74
ng/mL with good selectivity and accuracy. Moreover, the results of
clinical serum samples detected by the VSCLIA were confirmed by an
automatic immunoanalyzer in the hospital, indicating its practical
application in actual samples. In conclusion, the novel antibody element
VNAR exhibits great potential for immunodiagnosis, and this study
also provides a new direction and experimental basis for AFP detection.