ABSTRACT
A photochemical assay was reported based on CdS nanocrystal (NC)\hexagonal carbon-nitrogen tube (HCNT) nanocomposite for the detection of Ag+. When CdS NCs were combined with HCNT, the photocurrent intensity was increased extensively. After incubation of Ag+ with CdS NC\HCNT nanocomposite-modified electrode, Ag2S was formed on the electrode by the ion-change reaction. As the band gap of Ag2S cannot match well with HCNT, the photogenerated electron-hole pairs cannot separate efficiently, so the photocurrent intensity decreases. A good linear relationship between the concentration of Ag+ in the range from 0.01 to 3 µM and the corresponding photocurrent intensity was obtained with a detection limit of 3.3 nM (S/N = 3). The assay was employed to detect Ag+ in lake water and human serum with satisfactory results, which indicated that it might have a broad application in different areas. Photoelectrochemical assay was reported based on CdS nanocrystal\hexagonal carbon-nitrogen tube nanocomposite for detection of Ag.
ABSTRACT
In this work, we developed a photoelectrochemical assay for circulating tumor cells (CTCs) detection based on hexagonal carbon-nitrogen tubes (HCNT) as visible light-sensitive materials. The MCF-7 cell was selected as the model CTC and was captured through specific recognition between epithelial cell adhesion molecules (EpCAM) on the cell surface and anti-EpCAM antibodies. Anti-EpCAM antibody-modified magnetic nanoparticles were used to enrich and separate MCF-7 cells from samples. The detection signal was amplified by Ag2S nanocrystals, which can compete with HCNTs for absorbing visible light, leading to a decrease of photocurrent intensity. The linear range of the assay for MCF-7 cells is from 10 to 5000 cells mL-1, with a detection limit of 3 cells mL-1 (S/D = 3). The assay has good selectivity for MCF-7 detection over HeLa cells. The assay was successfully applied for the detection of MCF-7 in human whole blood, which indicates the potential for clinical application.
Subject(s)
Aptamers, Nucleotide/chemistry , Biosensing Techniques/methods , Nanoparticles/chemistry , Neoplastic Cells, Circulating/pathology , Silver/chemistry , Electrochemical Techniques/methods , Epithelial Cell Adhesion Molecule/analysis , HeLa Cells , Humans , Immunomagnetic Separation/methods , MCF-7 Cells , Neoplasms/blood , Neoplasms/pathologyABSTRACT
A sensitive photoelectrochemical (PEC) sensor based on hexagonal carbon nitride tubes (HCNT) as photoactive material was prepared for the detection of human epidermal growth factor receptor 2 (HER2). Magnetic Fe3O4 nanospheres (MNs) modified with anti-HER2 antibodies were employed for highly efficient capture of HER2 from serum sample, and Co3O4 nanoparticles (Co3O4 NPs) modified with ascorbic acid oxidase (AAO) as well as HER2 aptamer were used for signal amplification. When the aptamer-Co3O4-AAO probe was captured onto the electrode surface through the specific binding of the aptamer with HER2, the photocurrent intensity decreased. This was because Co3O4 NPs competed with HCNT for consumption of the excitation energy. As a consequence AAO catalyzed the oxidation of the electron donor (AA), and the aptamer-Co3O4-AAO probe increased the steric hindrance at the electrode surface, leading to significant photocurrent intensity decrease, thus realizing multiple signal amplification. Based on this signal amplification strategy, at 0 V (vs Ag/AgCl), the PEC sensor shows a wide linear response ranging from 1 pg mL-1 to 1 ng mL-1 with a low detection limit of 0.026 pg mL-1 for HER2. Importantly, the prepared PEC sensor was applied for detection of HER2 in human serum samples with recoveries between 98.8 and 101%. Sensitive photoelectrochemical sensor based on Co3O4 nanoparticles modified with ascorbic acid oxidase for signal amplification is reported.
Subject(s)
Ascorbate Oxidase/chemistry , Cobalt/chemistry , Electrochemical Techniques/methods , Oxides/chemistry , Receptor, ErbB-2/blood , Antibodies, Immobilized/immunology , Aptamers, Nucleotide/chemistry , Ascorbic Acid/chemistry , Biosensing Techniques/methods , Enzymes, Immobilized/chemistry , Humans , Immunomagnetic Separation , Limit of Detection , Magnetite Nanoparticles/chemistry , Nanocomposites/chemistry , Photochemical Processes , Receptor, ErbB-2/chemistry , Receptor, ErbB-2/immunology , Reproducibility of ResultsABSTRACT
In this work, an aptamer-based photoelectrochemical (PEC) assay is reported for the determination of MCF-7 breast cancer cells using hexagonal carbon nitride tubes (HCNTs) as photoactive material. The aptamer immobilized on the HCNT surface can specifically bind with mucin 1 protein (MUC1) that is overexpressed on the surface of MCF-7 cell. Thus, the PEC assay has high specificity for the determination of MCF-7. The determination of MCF-7 is due to the binding of MCF-7 onto HCNT that suppressed the photocurrent intensity. The PEC assay displays good performances for MCF-7 determination with a linear range from 1 × 102 to 1 × 105 cell mL-1 and limit of detection down to 17 cells mL-1. Meanwhile, the PEC assay can distinguish MCF-7 from normal cells in blood samples, which may have potential applications in cancer diagnostics and therapeutics.
