A glucose/O2 biofuel cell integrated with an exonuclease-powered DNA walker for self-powered sensing of microRNA

Advanced Self-Powered Biofuel Cells with Capacitor and Nanogenerator for Biomarker Sensing

Self-powered biofuel cells (BFCs) have evolved for highly sensitive detection of biomarkers such as noncodon micro ribonucleic acids (miRNAs) in the presence of interfering substrates. Self-charging supercapacitive BFCs for in vivo and in vitro cellular microenvironments represent the most prevalent sensing mechanism for diagnosis. Therefore, self-powered biosensing (SPB) with a capacitor and contact separation with a triboelectric nanogenerator (TENG) offers electrochemical and colorimetric dual-mode detection via improved electrical signal intensity. In this review, we discuss three major components: stretchable self-powered BFC design, miRNA sensing, and impedance spectroscopy. A specific focus is given to 1) assembling of sensors for biomarkers, 2) electrical output signal intensification, and 3) role of supercapacitors and nanogenerators in SPBs. We outline the key features of stretchable SPBs and the sequence of miRNA sensing by SPBs. We have emphasized the need of a supercapacitor and nanogenerator for SPBs in the context of advanced assembly of the sensing unit. Finally, we outline the role of impedance spectroscopy in the detection and estimation of biomarkers. We highlight key challenges in SPBs for biomarker sensing, which needs improved sensing accuracy, integration strategies of electrochemical biosensing for in vitro and in vivo microenvironments, and the impact of miRNA sensing on cancer diagnostics. This article attempts a specific focus on the accuracy and limitations of sensing unit for miRNA biomarkers and associated tool for boosting electrical signal intensity for a potential big step further.

An ingenious designed dual mode self-powered biosensing platform based on graphdiyne heterostructure substrate for instant hepatocarcinoma marker detection

We report here for the first time a self-powered biosensing platform based on graphene/graphdiyne/graphene (GDY-Gr) heterostructure substrate material for ultrasensitive hepatocarcinoma marker (microRNA-21) detection in both electrochemical and colorimetric test modes. The dual-mode signal intuitively displayed on a smartphone fundamentally improves the detection accuracy. In electrochemical mode, the calibration curve is established in the linear range of 0.1-10000 fM, and the detection limit is as low as 0.333 fM (S/N = 3). Simultaneously, colorimetric analysis of the miRNA-21 is realized by using ABTS as an indicator. The detection limit is confirmed as 32 fM (S/N = 3), and miRNA-21 of concentration from 0.1 pM to 1 nM exhibit a linear relationship with R2 = 0.9968. Overall, the combination of GDY-Gr and multiple signal amplification strategy significantly improved the sensitivity by 310 times compared with traditional enzymatic biofuel cells (EBFCs) based detection platform, showing broad application prospects for on-site analysis and future mobile medical services.

Assembly of DNA triangular pyramid frustum for ultrasensitive quantification of exosomal miRNA

Early screening of biomarkers benefits therapy and prognosis of cancers. MiRNAs encapsulated in tumor-derived exosomes are emerging biomarkers for early diagnosis of cancers. Nevertheless, traditional methods suffer certain drawbacks, which hamper their wide applications. In this contribution, we have developed a convenient electrochemical approach for quantification of exosomal miRNA based on the assembly of DNA triangular pyramid frustum (TPF) and strand displacement amplification. Four single-stranded DNA helps the formation of primary DNA triangle with three thiols for gold electrode immobilization at the bottom and three amino groups on overhangs for the capture of silver nanoparticles. On the other hand, target miRNA induced strand displacement reaction produces abundant specific DNA strands, which help the DNA structural transition from triangle to TPF. Amino groups are thus hidden and the declined silver stripping current can be used for the evaluation of target miRNA concentration. This biosensor exhibits excellent analytical performances and successfully achieves analysis of exosomal miRNAs from cells and clinical serum samples.

Tailoring enzymatic loading capacity on 3D macroporous gold by catalytic hairpin assembly and hybridization chain reaction: Application for ultrasensitive self-powered microRNA detection

It is important to develop effective strategies to construct enzymatic biofuel cell based self-powered biosensors. We report here the facile regulation of enzymatic loading capacity on the bioanode by utilizing a concatenated catalytic hairpin assembly (CHA)/hybridization chain reaction (HCR) and its application for self-powered microRNA-141 (miRNA-141) detection. To construct the bioanode, a concatenated CHA/HCR process triggered by miRNA-141 was conducted on the three-dimensional macroporous gold (3DMG) electrode to generate long double-stranded DNA nanowires for glucose oxidase immobilization. Quartz crystal microbalance study reveals that the enzymatic loading capacity on the bioanode increases at an increasing miRNA-141 concentration, leading to enhanced catalytic performance for glucose oxidation. The short-circuit currents of the assembled glucose/O2 biofuel cells increase at increasing miRNA-141 concentrations, enabling ultrasensitive detection of miRNA-141. The self-powered biosensor features a wide dynamic range for detecting miRNA-141 from 10-17 to 10-11 M, with an ultralow detection limit of 1.3 aM. This work provides a highly sensitive self-powered biosensing platform for miRNA detection.

Fluorescence DNA Switch for Highly Sensitive Detection of miRNA Amplified by Duplex-Specific Nuclease

DNA is a type of promising material for the construction of sensors owing to its sequence programmability to control the formation of certain structures. MicroRNA (miRNA) can be applied as promising biomarkers for the diagnosis of a range of diseases. Herein, a novel fluorescent sensing strategy for miRNA is proposed combining duplex-specific nuclease (DSN)-mediated amplification and dumbbell DNA structural switch. Gold nanoparticles (AuNPs) are employed, which provide a 3D reaction interface. They also act as effective fluorescence quenchers. The proposed sensor exhibits high sensitivity (sub-femtomolar level) with a wide dynamic range. In addition, excellent selectivity to distinguish homology sequences is achieved. It also performs satisfactorily in biological samples. Overall, this fluorescent sensor provides a powerful tool for the analysis of miRNA levels and can be applied for related biological studies and clinical diagnosis.