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Herein, this paper describes a novel label-free and extensibility electrochemical sensing platform based on porphyrin-ionic liquid (Por-IL) aggregate for the detection of antibody. The Por-IL was synthesized with water-soluble porphyrins Zn(II) meso -tetrakis (4-sulfonatophenyl)porphyrin (ZnTPPS)) and the ionic liquid 1-decyl-alkyl-3-methylimidazolium bromide (C 10 mimBr) under room temperature, which exhibited high singlet oxygen (1O 2) quantum yields and electrocatalytic activity toward hydrogen peroxide (H 2 O 2). In the presence of antibody, the antibody could be introduced on the surface of the electrode on the basis of antigen-antibody biorecognition. Under light illumination, the 1O 2 formed, then water and the formed 1O 2 could be catalyzed by antibody via the antibody catalyzed water oxidation pathway to produce H 2 O 2 which could be detected by the electrode, leading to the electrochemical signal for readout. Using anti -carcinoembryonic antigen (anti -CEA) as a model target, this method displayed a wide linear detection range and a lower detection limit. In particular, Por-IL demonstrated lower detection limit of 1.67 fg/mL. Furthermore, the Por-IL sensors were able to detect antibody in complex samples. The immunosensor platform has the features of label-free, sensitivity, only with air and on/off light switching and could be used to detect of a variety of antibody by using corresponding antigen, showing potential application in medical diagnosis. [Display omitted] • An electrochemical immunosensor platform based on porphyrin (Por)-ionic liquid (IL) aggregate was designed. • The Por-IL aggregate has high catalytic activity toward H 2 O 2 and singlet oxygen quantum yields. • The sensor has the extensibility. [ABSTRACT FROM AUTHOR]

S-nitrosothiols (RSNO) as the potential nitric oxide (NO) storage, transfer and delivery vehicles under physiological condition have been identified as important in a number of disease states. However, a detection and quantification of RSNO method with simple and sensitive in biological media is currently lacking. A novel electrochemical sensing platform based on ionic liquid (IL) and copper porphyrin (PorCu) decorated cuprous oxide (Cu 2 O) nanocomposites was developed to detect RSNO under physiological condition. In this system, RSNO were decomposed by Cu(I) in IL/PorCu/Cu 2 O to release NO, following the generated NO could be oxidized on the electrode to generate current signal. By taking advantage of the synergetic effect of IL, PorCu and Cu 2 O, the sensor exhibited excellent sensitivity and linearity toward various RSNO species in phosphate buffer solution (PBS), pH 7.4. A low detection limit for N-Acetyl-3-(nitrososulfanyl)valine (SNAP), S-nitrosocysteine (CysNO) and S-nitrosoglutathione (GSNO) was 110 nM, 20 nM and 67 nM (S/N = 3), respectively. Furthermore, this method displayed good selectivity, which could be used in complex application. The detection scheme with the features of high sensitivity and ease of operation, implies the potential of IL/PorCu/Cu 2 O for further various complex physiological studies. A novel electrochemical sensing platform based on porphyrin decorated Cu 2 O as nano-catalyst and electrode material was developed for sensitive S-Nitrosothiols detection under physiological pH. [Display omitted] • A electrochemical biosensor based on ionic liquid and porphyrin modified Cu 2 O (IL/PorCu/Cu 2 O) as nanocrystals was designed. • The IL/PorCu/Cu 2 O composite has high catalytic activity toward RSNO. • By taking advantage of the synergy of IL, PorCu and Cu 2 O, the sensor exhibited excellent sensitivity and selectivity. • The method could be used in complex matrix. • The sensor showed good performance. [ABSTRACT FROM AUTHOR]

Herein, a cost-effective, simple and sensitive electrochemical sensing platform was established based on aptamer - target recognition and target-triggering signal amplification strategy for protein detection. Due to the high affinity between the aptamer and target, the assistant DNA1 (a1) could release from a1-aptamer duplex and trigger the following DNA circuits. The strand displacement and branch migration reaction brought assistant DNA3 (a3) released. Eventually, a large number of duplex structures of a3−Hairpin DNA3 were formed on the surface of electrode. Consequently, the capture DNA on the surface of platinum nanoparticles could hybridize with the unfolded DNA fragment of Hairpin DNA3 on the sensor surface, resulting in the electrochemical signal readout of H 2 O 2 reduction. Using thrombin as a model target, under the optimal conditions, this method exhibited a linear detection range from 0.5 pM to 300 nM with a detection limit of 0.17 pM. The proposed detection strategy was enzyme-free and exhibited good selectivity and sensitivity for a variety of protein targets detection by using corresponding DNA-based affinity probes, which makes it possible to apply the sensor for sensitivity detection of analytes in bioassays. A novel electrochemical sensing platform based on target-triggering cascade enzyme-free signal amplification strategy was developed for sensitive protein detection. [Display omitted] • Electrochemical detection of thrombin using target-triggering cascade enzyme-free signal amplification strategy was proposed. • The method was PCR-free, enzyme-free, low cost, and without the need for any additional separation steps. • The sensor for thrombin showed good performance. [ABSTRACT FROM AUTHOR]