Supporting Information Spatial-Resolved Photoelectrochemical Biosensing Array Based on CdS@g-C 3 N 4 Heterojunction: A Universal Immunosensing Platform for Accurate Detection Yu-Xiang Dong,, Jun-Tao Cao, *,, Bing Wang,, Shu-Hui Ma, and Yan-Ming Liu *,, College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000, China Institute for Conservation and Utilization of Agro-bioresources in Dabie Mountains, Xinyang Normal University, Xinyang 464000, China Xinyang Central Hospital, Xinyang 464000, China * To whom correspondence should be addressed. * Tel/Fax: +86-376-6392889. Email: liuym9518@sina.com (Y.-M. Liu) * Tel/Fax: +86-376-6391172. Email: jtcao11@163.com (J.-T. Cao) S-1
Materials and reagents. Prostate specific antigen (PSA) standards, capture PSA antibody (Ab 1 ), and signal PSA antibody (Ab 2 ) were purchased from Shanghai Linc-Bio Science Co., Ltd. (Shanghai, China). Cadmium acetate [Cd(CH 3 COO) 2 ], thiourea, copper nitrate [Cu(NO 3 ) 2 ], and melamine were obtained from Aladdin Reagent Co., Ltd. (Shanghai, China). Sylgard 184 [including poly(dimethylsiloxane) (PDMS) monomer and curing agent] were from Dow Corning (Midland, MI, USA). Chloroauric acid (HAuCl 4 3H 2 O), sodium sulfide (Na 2 S 9H 2 O), chitosan, and ascorbic acid (AA) were bought from Shanghai Reagent Co., Ltd. (Shanghai, China). Human serum albumin (HSA), bovine serum albumin (BSA), and human immunoglobulin (higg) were from Shanghai Solarbio Bioscience & Technology Co., Ltd. (Seebio Biotechnology). Thioglycolic acid (TGA), N-(3-Dimethylaminopropyl)-N-ethyl-carbodiimide hydrochloride (EDC), and N-hydroxysuccinimide (NHS) were from Sigma-Aldrich. Gold nanoparticles (AuNPs, 15 ± 2 nm in diameter) were prepared and characterized in our previous work. 1 All reagents were of analytical grade and used as received. All aqueous solutions were prepared using pure water (18.2 MΩ cm, ultrapure water system from Aike Water Treatment Solution Provider, China). Apparatus. PEC signal was performed on a homemade PEC system equipped with a 500 W Xe lamp (Beijing 7-s Optical Instruments Co., Itd.). Photocurrent and electrochemical impedance spectroscopy (EIS) were detected by a RST5000 electrochemical workstation (Zhengzhou Shiruisi Technology Co., Ltd., China) with a three-electrode system: the modified ITO electrode with a geometrical area of 0.25 cm 2 was as working electrode, a Pt wire and a saturated Ag/AgCl electrode were used as the auxiliary electrode and the reference electrode, respectively. The UV vis absorption spectrum was recorded on an UVmini-1240 UV vis spectrophotometer (Shimadzu, Japan). Scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) images were obtained by S-4800 (Hitachi, Tokyo, Japan). X-ray photoelectron spectra (XPS) were measured on a K-Alpha X-ray photoelectron spectrometer (Thermo Fisher Scientific Co., USA). Transmission electron microscope (TEM), high resolution transmission electron microscope images (HRTEM) and S-2
element mapping images were recorded by Tecnai G2 F20 TEM (FEI Co., Hillsboro, Oregan, USA). Figure S1. (A) HRTEM image of CdS@g-C3N4; (B) the scanning transmission electron microscopy (STEM) image of CdS@g-C3N4; (C-F) element mapping images of CdS@g-C3N4 heterojunction: (C) C, (D) N, (E) S and (F) Cd. Figure S2. (A) TEM and (B) UV vis absorption spectra of AuNPs. S-3
Figure S3. Photocurrent response of g-c 3 N 4, CdS, and CdS@g-C 3 N 4 with different g-c 3 N 4 contents: (a) pure g-c 3 N 4, (b) pure CdS, (c) CN2, (d) CN4, (e) CN6, (f) CN8. The PEC measurements were carried out in 0.01 M PBS (ph 7.4) containing 0.1 M AA. Figure S4. (A) Selectivity of the PEC immunesensor for PSA detection; (B) time-based photocurrent response of the immunesensor incubation with 0.01 ng ml -1 PSA on WE1 and 1.0 ng ml -1 PSA on WE2, and then incubation with Ab 2 -CuS. S-4
Table S1. Comparison of the assay results from the ROCHE ECL method and the proposed method Serum ROCHE ECL This work Relative errors RSDs samples (ng ml -1 ) (ng ml -1 ) (%) (%, n = 3) 1 1.48 1.59 7.4 5.5 2 1.06 0.98-7.5 6.3 3 2.23 2.12-4.9 5.7 4 13.54 12.83-5.2 5.6 5 8.35 8.10-3.0 7.1 6 8.65 8.98 3.8 6.4 7 3.16 3.31 4.7 8.2 References (1) Cao, J. T.; Zhang, J. J.; Gong, Y.; Ruan, X. J.; Liu, Y. M.; Chen, Y. H.; Ren, S. W. A Competitive Photoelectrochemical Aptasensor for Thrombin Detection Based on The Use of TiO 2 Electrode and Glucose Oxidase Label. J. Electroanal. Chem. 2015, 759, 46-50. S-5