Colorimetric Immunosensor Based on Au@g-C₃N₄-Doped Spongelike 3D Network Cellulose Hydrogels for Detecting α-Fetoprotein

Abstract

A colorimetric immunoassay is a powerful tool for detecting tumor markers, with outstanding advantages of visualization and convenience. This study designed a colorimetric immunoassay using the antibody/antigen to control the catalytic activity to be "switched on/off". This system, where Au NPs (18.5 ± 3.9 nm) were loaded on the g-C 3 N 4 nanosheets that were fixed in a three-dimensional porous cellulose hydrogel, was used as a binding site for the antibody/antigen. After being incubated with an antibody of a cancer marker, the turned-off catalytic sites on Au NPs in Au@g-C 3 N 4 /microcrystalline cellulose hydrogels would not be "turned on" until the corresponding antigen was added. The number of the recovered Au active sites was related to the amount of the antigen added. The Fourier transform infrared and X-ray photoelectron spectroscopy measurements did not detect the existence of Au−S bonds. Catalyzed by the turned-on Au NPs, 4-nitrophenol was reduced to 4aminophenol accompanied by a color fading. The color and the absorption spectrum changes in the process were used as the colorimetric quantitative basis for immunoassays. The colorimetric immunoassay showed a linear relationship with the liver cancer marker (α-fetoprotein, AFP) in the range of 0.1−10 000 ng/mL with the detection limit of 0.46 ng/mL. In addition, 4nitrophenol had a significant color fading when the AFP concentration exceeded the healthy human threshold. The clinical patient's serum test results obtained from the developed colorimetric immunosensor were consistent with those obtained from the commercial enzyme-linked immunosorbent assay. Furthermore, the immunosensor exhibited a good selectivity, repeatability, and stability, which demonstrated its potential for practical diagnostic application.

Dual cocatalysts decorated three dimensionally ordered mesoporous g‐C3N4 with homogeneous wall thickness for enhanced photocatalytic performance

“…The peak at 531.52 eV indicates the existence of surface adsorbed water and the peak at 532.59 eV belongs to the N‐C‐O groups. Besides, as shown in Figure e‐h, the peaks at 84.02 and 88.23 eV are attributed to Au 4f 7/2 and 4f 5/2 of Au . The peaks at 1021.45 and 1044.76 eV are attributed to Zn 2p 3/2 and 2p 1/2 .…”

The importance of precision medicine in modern molecular oncology

“…For example, α‐fetoprotein (AFP) is a target marker for some tumor‐related albuminoid proteins. If the concentration of AFP increases, some severe diseases, such as abnormal dendritic cells metabolism, even liver, stomach, pancreas cancer, and AFP‐producing gastric cancer, will follow 17‐20 . Carcinoembryonic antigen (CEA), an acidic glycoprotein, is related to cervical carcinoma, cystadenocarcinoma, BC, and colorectal cancer (CRC) 21–23 .…”

“…If the concentration of AFP increases, some severe diseases, such as abnormal dendritic cells metabolism, even liver, stomach, pancreas cancer, and AFP-producing gastric cancer, will follow. [17][18][19][20] Carcinoembryonic antigen (CEA), an acidic glycoprotein, is related to cervical carcinoma, cystadenocarcinoma, BC, and colorectal cancer (CRC). [21][22][23] There are other markers, such as human epidermal growth factor receptor 2 (HER2), fibrinogen C domain containing 1 (FIBCD1), and poly ADP-ribose polymerases (PARPs), which are closely connected to BC, gastric cancer, and nonsmall-cell lung cancer.…”

Facile Fabrication of Photocatalyst-Immobilized Gel Beads with Interconnected Macropores for the Efficient Removal of Pollutants in Water

“…Until now, several typical kinds of methods have been reported for fabricating photocatalyst-immobilized gels with interconnected macropores, including lyophilization, ,,− 3D printing, formation of pores with the help of microcrystals at high temperature, etc. Lyophilization is a common method to introduce interconnected macropores into photocatalyst-immobilized gel matrixes.…”