Single-molecule porphyrin-metal ion interaction and sensing application

• Published in: Biosensors & bioelectronics Vol. 109; pp. 272 - 278
• Main Authors: Wei, Keke, Yao, Fujun, Kang, Xiao-Feng
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 30.06.2018
• Subjects: Biosensing Techniques; Biosensor; Copper - chemistry; Copper - isolation & purification; Copper ion; Hemolysin Proteins - chemistry; Ions - chemistry; Ions - isolation & purification; Metals - chemistry; Metals - isolation & purification; Nanopores; Porphyrins - chemistry; Porphyrins - isolation & purification; Single Molecule Imaging; Single-molecule detection; TPPS; Water - chemistry; α-hemolysin nanopore; TPPS; α-hemolysin nanopore; Copper ion; Biosensor; Single-molecule detection
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2018.03.002

It remains a significant challenge to study the interactions between metal ions and porphyrin molecules at single ion level. Here, we constructed a nanopore-based sensing for label-free and real-time analysis of the interaction between Cu2+ and 5,10,15,20-tetrakis(4-sulfonatophenyl)-porphyrin (TPPS). The results demonstrate that emerging electronic signatures of the Cu2+-TPPS complex that is completely different form the original free TPPS were observed in the α-hemolysin (α-HL) nanopore. Based on the distinctive electronic signal patterns between TPPS and Cu2+-TPPS complex, the unique nanopore sensor can achieve a highly sensitive detection of Cu2+ in aqueous media. The frequency of signature events showed a linear response toward the concentration of Cu2+ in the range of 0.03 µM – 1.0 μM, with a detection limit of 16 nM (S/N = 3). The sensing system also exhibited high selectivity against other metal ions, and the feasibility of this approach for practical applications was demonstrated with the determination of Cu2+ in running water. •Metal ion-porphyrin interactions were investigated at single ion level.•A highly sensitive and selective assay for Cu2+ was proposed using α-HL nanopore.•TPPS was employed as a recognition probe.•The detection limit for Cu2+ is as low as 16 nM in aqueous solution.•The nanopore sensor is potential for Cu2+ detection in real sample.