In this work, we first reported the electrochemiluminescence (ECL) properties of 2-hydroxynicotinic acid (2-HNA) with 0.09 M K 2 S 2 O 8 in 0.5 M H 3 BO 3 – Na 2 B 4 O 7 buffer solution. The effects of the type of co-reactant, the concentration of K 2 S 2 O 8 and the pH of the buffer solution on the ECL intensity of this system were investigated. And the possible mechanism of 2-HNA/ K 2 S 2 O 8 system has been speculated by fluorescence spectrum and ECL spectrum. Besides, we found that phloxine B (PB) can significantly enhance the ECL intensity of the 2-HNA/ K 2 S 2 O 8 system. It is speculated that an electrochemiluminescence resonance energy transfer (ECL-RET) process may occur between 2-HNA and PB, so that PB enhanced the ECL of the 2-HNA system. Combining the ultraviolet spectrum and density functional theory (DFT) calculations further proved the rationality of this speculation. Based on this, a new method of ECL detection of PB with high sensitivity and high selectivity was established.
Xinfeng Zhang,Li Deng,Chengpeng Huang,Jinyi Zhang,Xiandeng Hou,Peng Wu,Juewen Liu
Graphical Green ELISA : The photosensitizer phloxine B (PB) is explored for the activation of molecular oxygen to allow direct oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB), eliminating the need for the unstable enzymes and H 2 O 2 required for traditional immunoassays. Visual detection of carcinoembryonic antigen (CEA) is possible for concentrations as low as 50 pg mL −1 (see figure). H 2 O 2 and horseradish peroxidase (HRP) are commonly used together in bioassays. HRP is required to accelerate the reaction between a chromogenic substrate (e.g., 3,3′,5,5′-tetramethylbenzidine, TMB) and H 2 O 2 , and thus amplifies the signal. Herein, molecular oxygen for enzyme-free and H 2 O 2 -free oxidation is explored, still using the same colorimetric reaction. Restricted by spin selection rules, the ground-state triplet oxygen needs to be converted to the singlet state to oxidize TMB. Phloxine B (PB) is used as the photosensitizer because of its excellent performance and safety. Under green light irradiation, each PB has a turnover of approximately 51 TMB molecules in 20 min, making PB a “molecular enzyme mimic” for signal amplification. With its small size, multiple PB molecules are loaded on a graphene oxide nanosheet to design a modified enzyme-linked immunosorbance (ELISA) assay (termed photosensitization immunosorbent assay, PISA), improving the 1:1 enzyme/target ratio to n :1. PISA is more sensitive for carcinoembryonic antigen than a commercial ELISA kit, and successfully measures the antigen in the serum of multiple cancer patients. This simple and green method of oxidation coupled with the small size of the photosensitizer and graphene oxide may enable many other applications in biosensor development, smart materials, and energy harvesting.
An ultrasensitive 1 O 2 -based electrochemical aptasensor by on-line assembly of photosensitizers using graphene oxide (GO) as a cartridge is reported. In the presence of target protein lysozyme, the interaction of lysozyme with aptamer led to the dissociation of dsDNA and release of the aptamer-lysozyme complex to solution, with DNA-c retaining on the electrode; then, the photosensitizer phloxine B (PB) was assembled on the electrode since GO can simultaneously adsorb DNA-c and PB molecules. Upon irradiation by a green LED, 1 O 2 was generated by photocatalysis of PB molecules and then cleaved the DNA-c, leading to remarkably decreased impedance signals that linearly respond with the logarithm of lysozyme concentration. Benefitting from the efficient photosensitization ability of PB and the high PB-loading capacity of GO, the developed sensor allowed determination of 0.001 to 100 nM lysozyme with a limit of detection of about 0.14 pM. The relative standard deviation (RSD) for five independent electrodes with 1 nM lysozyme was 3.1%, indicating satisfactory reproducibility. The sensor also showed excellent selectivity toward lysozyme in the presence of interfering substances and was applied to the determination of lysozyme in urine samples with recoveries ranging from 91 to 101%. The on-line assembly of photosensitizer technique opens a new way for amplified electrosensing of biomolecules.
An on-line assembly of photosensitizers and DNA on electrode was developed using graphene oxide a cartridge and the photocatalytic electrosensor can be used for label-free detection of lysozyme as low as 1 pM.
危险品化学品经营许可证（带存储）