Simultaneous Detection of Five Tumor Biomarkers of Lung Cancer by Electrochemical Immunoassay

Electronic Supplementary Material

Simultaneous detection of fivebiomarkers of lung cancer by electrochemical immunoassay

Jiao Shan, Zhanfang Ma*

Department of Chemistry, CapitalNormalUniversity, Beijing 100048, China

*Corresponding author, e-mail:

Fig. S1 XPS of PBG-Au (A), PPP-Au (B), PTBO-Au (C), PMCP-Au (D) and Cd NCs-Au (E)

Fig. S2 Optimization of pH value of detection solution (The error bars are standard deviations for n=3)

To achieve the optimal performance of the immunosensor, the pH of the detection solution was optimized by incubated with target antigen including 10 ng mL-1 CEA, 10 ng mL-1 NSE, 10 U mL-1 CA125, 10 ng mL-1Cyfra21-1 and 5 ng mL-1 SCCA. As shown in Fig. S2, the peak currents of immunosensor response to the pH value of detection solution were recorded in the pH ranging from 4.5 to 7.5. The peak current originallyincreased with the increasing pH of the detection solution and then tended to level off after pH 6.0. Hence, pH 6.0 was chosen the optimal pH of the detection solution.

Fig. S3 The specificity (A) and cross-reactivity (B) of the multiplexed immunoassay

Under the optimal condition, the specificity of the immunoassay was investigated. Glu, UA, AA, IgG and AFP were chosen as the possible interfering species (Fig. S3A). Comparative tests were conducted as follows: when the immunosensor was incubated with the mixture of five antigens (10 ng mL-1 for CEA, NSE, Cyfra21-1 and SCCA, 10 U mL-1 for CA125), the peak was much higher than that when the target was replaced by 10 ng mL-1 Glu, UA, AA, IgG or AFP, implying the good specificity of the immunosensor. The cross-reactivity of the multiplexed electrochemical immunosensor was investigated as shown in Fig. S3B. The prepared immunosensor was separately incubated with blank solution (curve a), CEA (curve b), NSE (curve c), CA125 (curve d), Cyfra21-1 (curve e), SCCA (curve f) or the blended solution containing all the five target antigens (curve g). Only one obvious current response was detected corresponding to the target antigen in the presence of only one antigen, and negligible current was detected for the absent other four antigens. When the immunosensor was incubated with the blended solution containing five target antigens, five detachable signals were detected in a single run, and the peak potential was in good accordance with the single detection of the corresponding antigen. The results indicated that the cross-reactivity of the multiplexed immunoassay was negligible.

Fig. S4 Thelong-term stability of the immunosensor was conducted by storing the immunosensor at 4C for one month and measuring every week (The error bars are standard deviations for n=3)

Under the optimal condition, the long-term stability experiment was conducted by storing the as-prepared immunosensor at 4C for about four weeks and measuring every other week. No obvious change of electrochemical response was revealed as shown in Fig. S4. The results demonstrated that the stability of the immunosensor was good.

Table S1 Performance parameters compared with other similar redox probe based immunosensors.

Probes / Biomarkers / Linear range / Detection limit / Reference
AuNPs-PB@rGO and AuNPs-Thi@rGO / AFP, CEA / CEA: 0.6-80 ng mL-1
AFP: 0.6-80 ng mL-1 / CEA: 0.12ng mL-1
AFP: 0.08ng mL-1 / [1]
Metal ions doped chitosan–poly(acrylic acid) nanospheres / CEA, CA199, CA125, CA242 / CEA: 0.1-100 ng mL-1
CA199: 1-150 U mL-1
CA125: 1-150 U mL-1
CA242: 1-150 U mL-1 / CEA: 0.02 ng mL-1
CA199: 0.4 U mL-1
CA125:0.3 U mL-1
CA242: 0.4 U mL-1 / [2]
polyaniline derivative-Au/Pd composites / CEA, AFP, CA199, CA724 / CEA: 0.01-100 ng mL-1
AFP: 0.01-100 ng mL-1
CA199: 0.01-100 U mL-1
CA724: 0.01-100 U mL-1 / CEA: 8.1 pg mL-1
AFP: 6.3 pg mL-1
CA199: 0.0076 U mL-1
CA724: 0.0069 U mL-1 / [3]
CNTs-AuNPs@Aq
CNTs-AuNPs@Thi
CNTs-AuNPs@Fc
CNTs-AuNPs@Co(bpy)33+ / CEA, CA199, CA125, CA242 / CEA : 0.016-15 ng mL−1
CA199: 0.008-10 ng mL−1
CA125: 0.012-12 ng mL−1
CA242: 0.010-10 ng mL−1 / CEA : 4.2 pg mL-1
CA199: 2.8 pg mL-1
CA125: 3.3 pg mL-1
CA242: 3.8 pg mL−1, / [4]
PBG-Au composite
PPP-Au composite
PTBO-Au composite
PMCP-Au composite
Cd NCs-Au / CEA, NSE, CA125, Cyfra21-1, SCCA / CEA: 1-150 ng mL-1
NSE: 1-150 ng mL-1
Cyfra21-1: 1-150 ng mL-1
CA125: 1-150 U mL-1
SCCA: 0.1-100 ng mL-1 / CEA: 0.2 ng mL-1
NSE: 0.9 ng mL-1
Cyfra21-1: 0.4 ng mL-1
CA125: 0.9 U mL-1
SCCA: 0.03 ng mL-1 / This work

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