Na Bin,Weili Li,Xuehua Yin,Xiaohua Huang,Qingyun Cai
A novel electrochemiluminescence (ECL) aptasensor was proposed for ultrasensitive detection of cytochrome c (cyt c) using CdS:Mn quantum dot-modified TiO 2 nanowires (NWs) as electrode. The Mn-doped CdS was deposited on the TiO 2 NWs by successive ion layer adsorption and reaction (SILAR) as ECL emitter, on which thiol-modified aptamer of cyt c was attached via Cd–S bond. Due to the high photo-electrical transfer efficiency, the as-prepared aptasensor shows high selectivity and sensitivity towards cyt c with a detection limit of 9.5 fM and a linear range from 50 fM to 125 pM.
Deng Xunxun,Yang Xinlan,Guan Xingxing,Song Jie,Wu Shuo
A photoelectrochemical (PEC) immunosensing strategy based on the multiple quenching of polydopamine nanoparticles (PDA NPs) to Mn 2+ -doped CdS-modified TiO 2 nanoparticles (TiO 2 /CdS:Mn) was designed for the highly sensitive detection of carcinoembryonic antigen (CEA). The uniform PDA NPs possessed good dispersibility, good biocompatibility, and abundant functional groups for biomolecule assembly. They also had unique photophysical properties, with light absorption spanning the visible to infrared light range. When the immune-recognition brought the PDA NPs close to the TiO 2 /CdS:Mn interface, the PDA NPs competed with TiO 2 /CdS:Mn to absorb light, consumed photoelectrons generated in the TiO 2 /CdS:Mn, and hindered the access of electron donors to photoactive materials. The contribution from these aspects thus led to a significant decrease in photocurrent. Benefiting from the multiple quenching mechanism, the PEC immunosensor showed high sensitivity for CEA detection. Under optimal conditions, a low detection limit of 0.02 pg/mL and a wide linear relationship from 0.1 pg/mL to 100 ng/mL were obtained. The immunoassay showed good reproducibility and stability, and good selectivity and high accuracy in serum sample analysis. In this regard, PEC immunosensors may have great application potential for screening tumor markers and the prevention and monitoring of serious diseases.
Bing Wang,Yu-Xiang Dong,Yu-Ling Wang,Jun-Tao Cao,Shu-Hui Ma,Yan-Ming Liu
A novel and simple photoelectrochemical (PEC) biosensing method for microRNA-21 (miRNA-21) detection is reported based on energy transfer (ET) between CdS:Mn doped structure (CdS:Mn) and Au nanoparticles (AuNPs). In this protocol, TiO 2 -CdS:Mn hybrid structure was used as a sensing platform for hairpin DNA immobilization. In the absence of miRNA-21, the immobilized DNA was in the hairpin form. In this state, the photocurrent of the electrode was greatly depressed, due to the effective ET effect produced by short interparticle distance between CdS:Mn and AuNPs. In the presence of miRNA-21, the hairpin DNA hybridized with miRNA-21 and changed into a more rigid, rodlike double helix, which forced the AuNPs away from the electrode surface, leading to obvious recover of photocurrent because of the vanished damping effect. Integrating the fine PEC performance of TiO 2 -CdS:Mn hybrid structure with the significant ET effect between CdS:Mn and AuNPs, the sensitive detection of miRNA-21 was realized in a linear range of 1.0 fM to 10.0 pM with a low detection limit of 0.5 fM. This method might be aussichtsreich for the detection of miRNAs and other biomarkers.
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