Enzymatic biofuel cell (EBFC)-based self-powered biosensors could offer significant advantages: no requirement for an external power source, simple instruments, and easy miniaturization. However, they also suffered from the limitations of lower sensitivity or specific targets. In this study, a self-powered biosensor for the ultrasensitive and selective detection of single nucleotide polymorphisms (SNPs) produced by combining the toehold-mediated strand displacement reaction (SDR) and DNA hybridization chain reaction (HCR) was proposed. Herein, the capture probe (CP) with an external toehold was designed to switch on the sensing system. In the presence of target sequence, both SDR and DNA HCR reaction would happen to produce a long double-helix chain. Because of the electrostatic interaction between [Ru(NH3)6]3+ and the double-helix chain described above, the open circuit voltage (E OCV) of the as-proposed biosensor was significantly elevated, thus realizing the detection of SNPs. Overall, in this work, an ingeniously constructed self-powered biosensor for the detection of SNPs was created by integrating EBFCs with a DNA amplification strategy. Furthermore, the as-proposed self-powered biosensor not only showed prominent specificity to distinguish the p53 gene fragment from random sequences (e.g., single-base mutant sequences) but exhibited excellent sensitivity with the detection limit of 20 aM. More importantly, the results obtained from the real cell lysate sample have laid a strong foundation for disease diagnostics and, potentially, as a powerful tool for even more fields.
Black phosphorus (BP) has attracted tremendous attention as a new two-dimensional semiconductor material with excellent optical and electrical properties. Unfortunately, the mimicking enzyme characteristics of BP have never been investigated. Herein, BP is discovered to exhibit glucose dehydrogenase-like behavior, which can enable catalytic glucose oxidation without any byproducts (e.g., H 2 O 2 ). More importantly, the BP nanosheets also exhibited excellent catalytic performance in broad pH and temperature scope, as well as high stability. This discovery breaks the situation where only glucose oxidase (GOx)-like nanozyme for glucose oxidation is reported. When BP nanosheets were utilized as anodic enzymes for enzymatic biofuel cells (EBFCs), the EBFCs exhibited superior power output and high stability compared with that of bioenzyme-based EBFCs. This work not only develops the application of BP in the nanozyme field but also provides a new viewpoint to construct EBFCs with excellent performance and stability.
Flexible enzymatic biofuel cells (EBFCs) have been considered as alternative power sources for wearable devices, in which, the design of the substrate electrode is of significance for its mechanical robustness and performance output. Herein, we developed an integrated flexible EBFC based on N-doped graphene directly obtained with a polyimide film precursor via a simple laser-scribed method. Encouragingly, the laser-scribed N-doped graphene (LSNG) possessed excellent mechanical robustness and conductibility. More importantly, the LSNG electrode exhibited excellent electrocatalysis performance, which can remarkably reduce the overpotential of the cofactor enzyme. With glucose and O2 as fuels, the integrated flexible EBFC could produce a maximum power density (P max) to 27 ± 1.7 μW cm–2 at open-circuit voltages (E OCV) of 0.45 ± 0.03 V, being superior or comparable to those of the reported flexible EBFC. In addition, the E OCV of the device retained 78% of its initial value even after storage for 20 days and it showed almost no change after bending 100 times. Overall, the LSNG was an appealing alternative candidate to construct integrated biofuel cells and other flexible devices.
The classic luminol-based electrochemiluminescence (ECL) platform generally suffers from self-decomposition of the coreactant (i.e., H 2 O 2 ) during the reaction process, seriously hampering the luminous signal stability, as well as its practical application. To address this issue, apart from the introduction of complex exogenous species, preoxidation of the luminophore, and electrocatalysis for ECL signal amplification, we proposed a novel ECL model to realize the signal enhancement via in situ selfphotocatalytic generation of the coreactant H 2 O 2 . Interestingly, the luminescence of luminol was simultaneously utilized as the light source to promote the conversation of O 2 to H 2 O 2 with the assistance of the photocatalyst resorcinol-formaldehyde resin, which could further improve the luminescence of luminol in turn. In comparison with the traditional case, this new ECL model not only exhibited obvious signal amplification but also efficiently boosted its stability of signal output. To sum up, an exogenous coreactant-free, highly stable ECL platform was obtained via simply integrating the photocatalyst RF and the luminol-based system. This work will not only inspire the design of a new integrated ECL system with a coreactant translator but also provide an ingenious insight for the construction of a new generation of ECL models.
Aberrant DNA methylation catalyzed by DNA methyltransferases (MTase) has proved to be associated with human diseases such as cancers. Thus, the development of an efficient strategy to accurately detect DNA MTase is highly desirable in medical diagnostics. Herein, we proposed a robust “signal-on” enzymatic biofuel cell (EBFC)-based self-powered biosensing platform with excellent anti-interference ability for DNA MTase activity analysis and inhibitor screening. In the presence of target MTase, the MTase-catalyzed DNA methylation occurred and hindered the HpaII endonuclease-catalyzed dsDNA dissociation, which enabled more bilirubin oxidase (BOD) to immobilize at the cathode surface via amidation. Then, BOD-catalyzed oxygen reduction took place by accepting electrons generated at the anode via glucose oxidation, thus leading to an elevated open-circuit voltage value, the amplitude of which was directly related to MTase concentration. The direct detection limit of the M.SssI assay was down to 0.005 U/mL, which was lower than that of those reported results. Notably, the as-proposed protocol was competent to detect DNA MTase activity directly in human serum samples without enrichment and separation, and applicable to the screening of M.SssI inhibitors. Considering the virtues of the excellent anti-interference ability, no requirement of external power, simplicity, and high accuracy, the biosensing platform would hold great potential in DNA MTase bioassay and clinical diagnosis of cancers.
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