An enzyme-induced Au@Ag core-shell nanoStructure used for an ultrasensitive surface-enhanced Raman scattering immunoassay of cancer biomarkers.
Early detection of cancer is helpful for the control and prevention of diseases. Due to the low content of cancer biomarkers in the early disease phases, however, an ultrasensitive and selective method is critical. In this contribution, an ultrasensitive surface-enhanced Raman scattering (SERS) immunoassay is newly developed with the principle of introducing a common enzyme-induced deposition (EID) reaction to coat a silver layer on the surface of gold nanoparticles and to form a core-shell nanostructure of Au@Ag. By using alkaline phosphatase (ALP) to dephosphorylate its substrate, 2-phospho-l-ascorbic acid trisodium salt (AAP), to form vitamin C, silver ions could be reduced into silver atoms and coated on the surface of the AuNPs; a greatly enhanced SERS signal was then obtained. As a proof of concept, α-fetoprotein (AFP) was detected as a target, which is a biomarker of liver cancer. Excellent analytical performance of the SERS immunoassay could be achieved in the range from 0.5 to 100 pg mL-1with a limit of detection of 0.081 pg mL-1(3σ). Identical results could be obtained by using the newly proposed SERS immunoassay for the clinical detection of AFP in serum samples of patients to those clinically obtained by chemiluminescence immunoassays, demonstrating the potential applications of the developed method in clinical diagnosis.
Key Laboratory of Luminescence and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, P. R. China. chengzhi@swu.edu.cn.
Lin
L
Yang
Chongqing Key Laboratory of Biomedical Analysis (Southwest University), Chongqing Science & Technology Commission, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R.China. zsj@swu.edu.cn.
Ming Xuan
MX
Gao
Key Laboratory of Luminescence and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, P. R. China. chengzhi@swu.edu.cn.
Lei
L
Zhan
Department of Pathology, Institute of Surgery Research, Daping Hospital, Chongqing, 400042, P.R.China.
Min
M
Gong
Chongqing Key Laboratory of Biomedical Analysis (Southwest University), Chongqing Science & Technology Commission, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, P. R.China. zsj@swu.edu.cn.
Shu Jun
SJ
Zhen
Key Laboratory of Luminescence and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing 400715, P. R. China. chengzhi@swu.edu.cn.
Cheng Zhi
http://orcid.org/0000-0002-1260-5934
CZ
Huang
D014408:Biomarkers, Tumor / Q000032:analysis* / Q000097:blood; D006046:Gold; D006801:Humans; D007118:Immunoassay; D008113:Liver Neoplasms / Q000097:blood / Q000175:diagnosis; D053768:Metal Nanoparticles; D012834:Silver; D013059:Spectrum Analysis, Raman
D014408:Biomarkers, Tumor; D012834:Silver; D006046:Gold