| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 867773 | Biosensors and Bioelectronics | 2011 | 6 Pages |
Porphyrin is able to specifically combine with phosphorus, thus a novel bifunctional sensing platform for determination of porphyrin by visual colorimetry and electrochemistry was demonstrated. A pretreated gold sheet (or electrode) with 2-mercatpoethanol (2-ME) was chemically modified by POCl3 to obtain the surface phosphate active sites. The different stages of modified electrode were characterized by electrochemical impedance spectroscopy (EIS). The 1:1 cationic sitting-atop (SAT) complex P(V)–porphyrin was formed due to the high affinity of the modified gold sheet (or electrode) towards the porphyrin, resulting in electron transfer resistance increase of the electrode surface. Meanwhile, a dramatic color changing from burgundy to dark green of porphyrin solution was observed with the naked-eye within 3 s. What's more, this was reflected by the notable change of the Soret band of porphyrin when using UV–vis. Two sensing systems provide different sensitivity for porphyrin analysis. With visual colorimetry, porphyrin can be detected at a level of 1.0 × 10−6 M, whereas the detection limit of porphyrin is 3.0 × 10−8 M using the EIS method. The practical application of the sensor to determination of pheophytin which was obtained from fresh spinach leaves has been accomplished. The results demonstrate the facility and effectivity of our introduced bifunctional biosensor for quantitative analysis of porphyrin.
► A feasible method of fabricating porphyrin bifunctional biosensor was developed byphosphate-based self-assembled monolayerfor the first time. ► Our research focuses on detecting porphyrin with two detection methods: visual colorimetry and electrochemistry. Visual colorimetry is one of the simplest microanalysis methods; it was employed to detect porphyrin via observed color change of porphyirn solution, which has advantages of rapidity, simpleness, high sensitiveness and easy miniaturization. Furthermore, the electrochemical impedance spectroscopy (EIS) has a good response for studying porphyrin and the resistance value is linearly dependent on the logarithm of porphyrin concentration within the range. ► Detailed mechanism of sensing porphyrin utilizing phosphate-based self-assembled monolayer was proposed in the methodology. ► In this work, the practical application of using the designed sensor to determine pheophytin obtained from fresh spinach leaves received satisfactory results. The results demonstrate the facility and effectivity of our introduced phosphate modified gold sheet (or electrode) for quantitative analysis of porphyrin.
