Metal Porphyrin Complex Combined with Polymerization and Isomerization Cyclic Amplification for a Sensitive Photoelectrochemical Assay

Abstract

5,10,15,-21H,23H-porphine (TPAPP) possesses good light-harvesting ability and photoelectrochemical (PEC) cathode response signal; however, the disadvantages of easy stacking and weak hydrophilicity limit its application as a signal probe in PEC biosensors. Based on these, we prepared a Fe 3+ and Cu 2+ co-coordinating photoactive material (TPAPP-Fe/Cu) with horseradish peroxidase (HRP)-like activity. The metal ions in the porphyrin center not only enabled the directional flow of photogenerated electrons between electron-rich porphyrin and positive metal ions within inner-/intermolecular layers but also accelerated electron transfer through a synergistic redox reaction of Fe(III)/Fe(II) and Cu(II)/Cu(I) as well as rapid generation of superoxide anion radicals (O 2 −• ) by mimicking catalytically produced and dissolved oxygen, thereby providing the desired cathode photoactive material with extremely high photoelectric conversion efficiency. Accordingly, by combining with toehold-mediated strand displacement (TSD)-induced single cycle and polymerization and isomerization cyclic amplification (PICA), an ultrasensitive PEC biosensor was constructed for the detection of colon cancer-related miRNA-182-5p. The ultratrace target could be converted to abundant output DNA by TSD possessing the desirable amplifying ability to trigger PICA for forming long ssDNA with repetitive sequences, thus decorating substantial TPAPP-Fe/Cu-labeled DNA signal probes for producing high PEC photocurrent. Meanwhile, the Mn(III) mesotetraphenylporphine chloride (MnPP) was embedded in dsDNA to further exhibit a sensitization effect toward TPAPP-Fe/Cu and an acceleration effect analogous to that of metal ions in the porphyrin center above. As a result, the proposed biosensor displayed a detection limit as low as 0.2 fM, facilitating the development of high-performance biosensors and showing great potential in early clinical diagnosis.

Novel Porphyrinic Covalent Organic Polymer with Polarity-Switchable Dual Wavelength for Accurate and Sensitive Photoelectrochemical Sensing

“…First, the S1–S2 duplex was acquired by mixing 5 μL of 2 μM S1 and S2 and then annealing at 95 °C for 5 min. Following that, S1–S2 and 10 μL of 1 μM aptamer strand (A) were injected into 40 μL of prepared AuNPs 1 @Fe 3 O 4 (Supporting Information) with overnight reaction at 4 °C . Subsequently, the precipitate obtained by magnetic separation was redispersed in 6 μL of tris-HCl buffer to prepare S1–S2/A/Au nanoparticles 1 (AuNPs 1 ) @Fe 3 O 4 .…”

“…Following that, S1−S2 and 10 μL of 1 μM aptamer strand (A) were injected into 40 μL of prepared AuNPs 1 @Fe 3 O 4 (Supporting Information) with overnight reaction at 4 °C. 33 Subsequently, the precipitate obtained by magnetic separation was redispersed in 6 μL of tris-HCl buffer to prepare S1−S2/A/Au nanoparticles 1 (AuNPs 1 ) @Fe 3 O 4 . Next, 1 μL of T7 Exo (1 U/μL), 1 μL of 10 × NE buffer, and 2 μL of target AFM1 with different concentrations were added to the mixture above and cleaved at 25 °C for 18 min.…”

Split-type photoelectrochemical immunoassay for sensitive quantification of carcinoembryonic antigen based on target-induced in situ formation of Z-type heterojunction

“…[11][12][13] Yuan's group designed a polarity-switchable dual-wavelength PEC biosensing strategy using a porphyrinic covalent organic polymer for the detection of aatoxin M 1 . 14 Zhou et al proposed a near-infrared lightdriven photoelectrochemical/uorescence dual-mode biosensor based on a bipedal DNA walker with cascade amplication. 15 Generally speaking, PEC sensors achieve the goal of quantitative analysis based on the photoelectrode signals before and aer the biological reaction.…”