Carbon dots (C-dots) display strong cathodic electrogenerated chemiluminescence (ECL) in neutral aqueous solution in the presence of potassium persulfate. ECL intensities strongly depend on the method of synthesis of C-dots. The reactions between the electrochemically reduced intermediates of C-dots and potassium persulfate generate a strong ECL signal. Spectral and electrochemical studies revealed that cytochrome c reacts with potassium persulfate before its electrochemical reduction to generate the strong oxidant radical SO 4
•- which reacts with C-dots to give an enhanced ECL signal. This finding was exploited to design a sensitive ECL assay for cytochrome c. The effects of the amount of C-dots, the pH value, and the persulfate concentration were optimized. Under the optimal conditions, the ECL signals (generated at −1.4 V) increase linearly with the concentration of cytochrome c in the range from 1.0 nM to 10 μM, with a detection limit of 0.2 nM. The modified electrode exhibits high sensitivity and good selectivity.
Carbon dots display strong cathodic electrogenerated chemiluminescence (ECL) in neutral condition with potassium persulfate as coreactant. Cytochrome c strongly enhances the ECL signal, and can be sensitively detected by exploiting this effect.
A multifunctional catalytic nanomaterial (Co-MOF@AuNP@ABEI) composed of cobalt-doped metal–organic frameworks (Co-MOF), gold nanoparticles (AuNP), and N -(4-aminobutyl)- N -(ethylisoluminol) (ABEI) is reported. Co-MOF@AuNP@ABEI exhibits high synergistic and zero-distance catalytic properties, which are beneficial to the improvement of the detection sensitivity of an electrochemiluminescent (ECL) biosensor. After coupling with the ECL system and 3D magnetic walking nanomachine amplification strategy, the Co-MOF@AuNP@ABEI can achieve an ultrasensitive ECL assay of Burkholderia pseudomallei with the limit of detection (LOD) of 60.3 aM, which is 2 and 4 orders of magnitude lower than individual ECL system without the nanomachine (4.97 fM) and individual walking nanomachine (340 fM), and superior to the pathogenic bacteria analyses in the previous report. Moreover, the LOD of the proposed ECL detection system for the determination of B. pseudomallei in serum sample was as low as 9.0 CFU mL −1 . The relative standard deviations (RSD) of ECL intensity for the detection of five B. pseudomallei -spiked serum samples were 4.02%, 0.84%, 0.84%, 1.55%, and 0.21%, respectively. The recoveries of the ECL biosensor for the detection of B. pseudomallei DNA-spiked serum samples were 93.63 ~ 107.83%. Therefore, this work demonstrated that the developed multifunctional catalytic nanomaterial with synergistic and zero-distance catalytic properties can be used as excellent ECL signal reporter to improve the detection sensitivity of ECL biosensor. Graphical abstract
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