Integration of Biofuel Cell-Based Self-Powered Biosensing and Homogeneous Electrochemical Strategy for Ultrasensitive and Easy-To-Use Bioassays of MicroRNA

Biofuel cell (BFC)-based self-powered biosensors have attracted substantial attentions because of their unique merits such as having no need for power sources (only two electrodes are needed). More importantly, in case it can also work in a homogeneous system, more efficient and easy-to-use bioassays could come true. Thus, herein, we proposed a novel homogeneous self-powered biosensing strategy via the integration of BFCs and a homogeneous electrochemical method, which was further utilized for ultrasensitive microRNA (miRNA) detection. To construct such an assay protocol, the cathodic electron acceptor [Fe­(CN)₆]^3– was entrapped in the pores of positively charged mesoporous silica nanoparticles and capped by the biogate DNAs. Once the target miRNA existed, it would trigger the controlled release of [Fe­(CN)₆]^3–, leading to the dramatic increase of the open circuit voltage. Consequently, the “signal-on” homogeneous self-powered biosensor for the ultrasensitive miRNA assay was realized. Encouragingly, the limit of detection for the miRNA-21 assay was down to 2.7 aM (S/N = 3), obviously superior to those of other analogous reported approaches. This work not only provides an ingenious idea to construct the ultrasensitive and easy-to-use bioassays of miRNA but also exhibits a successful prototype of a portable and on-site biomedical sensor

Ultrasensitive Self-Powered Aptasensor Based on Enzyme Biofuel Cell and DNA Bioconjugate: A Facile and Powerful Tool for Antibiotic Residue Detection

Herein, we reported a novel ultrasensitive one-compartment enzyme biofuel cells (EBFCs)-based self-powered aptasensing platform for antibiotic residue detection. By taking full advantage of the unique features of both EBFCs-based self-powered sensors and aptamers, the as-proposed aptasensing platform has the merits of simple instrumentation, anti-interference ability, high selectivity, and low cost. In this study, DNA bioconjugate, i.e., SiO₂@gold nanoparticles–complementary strand of aptamer (SiO₂@AuNPs–csDNA), was elaborately designed and played a key role in blocking the mass transport of glucose to the bioanode. While in the presence of the target antibiotic, SiO₂@AuNPs–csDNA bioconjugate broke away from the bioanode due to the aptamer recognition of the target. Without the blocking of glucose by the DNA bioconjugate, a significantly elevated open circuit voltage of the EBFCs-based aptasensor was obtained, whose amplitude was dependent on the antibiotic concentration. In addition, this proposed aptasensor was the first reported self-powered aptasensing platform for antibiotic determination and featured high sensitivity owing to the elaborate design of the DNA bioconjugate modified bioanode of EBFC, which was superior to those previously reported in the literature. Furthermore, due to the anti-interference ability and the excellent selectivity of the aptasensor, no special sample pretreatment was needed for the detection of antibiotics in milk samples. Therefore, the proposed EBFCs-based self-powered aptasensor has a great promise to be applied as a powerful tool for on-site assay in the field of food safety

Ultrasensitive Ratiometric Homogeneous Electrochemical MicroRNA Biosensing via Target-Triggered Ru(III) Release and Redox Recycling

A new label-free and enzyme-free ratiometric homogeneous electrochemical microRNA biosensing platform was constructed via target-triggered Ru­(III) release and redox recycling. To design the effective ratiometric dual-signal strategy, [Ru­(NH₃)₆]³⁺ (Ru­(III)), as one of the electroactive probes, was ingeniously entrapped in the pores of the positively charged mesoporous silica nanoparticle (PMSN), and another electroactive probe, [Fe­(CN)₆]^3– (Fe­(III)), was selected to facilitate Ru­(III) redox recycling due to its distinctly separated reduction potential and different redox properties. Owing to the liberation of the formed RNA–ssDNA complex from PMSN, the target miRNA triggered the Ru­(III) release and was quickly electroreduced to Ru­(II), and then, the in-site-generated Ru­(II) could be chemically oxidized back to Ru­(III) by Fe­(III). Thus, with the release of Ru­(III) and the consumption of Fe­(III), a significant enhancement for the ratio of electroreduction current [Ru­(NH₃)₆]³⁺ over [Fe­(CN)₆]^3– (<i>I</i>_Ru(III)/<i>I</i>_Fe(III)) value was observed, which was dependent on the concentration of the target miRNA. Consequently, a simple, accurate, and ultrasensitive method for the miRNA assay was readily realized. Furthermore, the limit of detection (LOD) of our method was down to 33 aM (S/N = 3), comparable or even superior to other approaches reported in literature. More importantly, it also exhibited excellent analytical performance in the complex biological matrix cell lysates. Therefore, this homogeneous biosensing strategy not only provides an ingenious idea for realizing simple, rapid, reliable, and ultrasensitive bioassays but also has a great potential to be adopted as a powerful tool for precision medicine

Enzymatic Fuel Cell-Based Self-Powered Homogeneous Immunosensing Platform via Target-Induced Glucose Release: An Appealing Alternative Strategy for Turn-On Melamine Assay

Enzymatic fuel cell (EFC)-based self-powered biosensors have attracted considerable attention because of their unique feature of no need for extra power sources during the entire detection process, which endows them with the merits of simplicity, rapidness, low cost, anti-interference, and ease of use. Herein, we proposed, for the first time, an EFC-based self-powered homogeneous immunosensing platform by integrating the target-induced biofuel release and bioconjugate immunoassay for ultrasensitive melamine (ME) detection. In this design, the biofuel, i.e., glucose molecules, was entrapped in the pores of positively charged mesoporous silica nanoparticles and capped by the biogate AuNPs-labeled anti-ME antibody (AuNPs-Ab). The presence of the target ME triggered the entrapped glucose release due to the removal of the biogate via immunoreaction, which resulted in the transfer of electrons produced by glucose oxidation at the bioanode to the biocathode, and thus, the open-circuit voltage of the EFC-based self-powered immunosensor dramatically increased, realizing the ultrasensitive turn-on assay for ME. The limit of detection for ME assay was down to 2.1 pM (S/N = 3), superior to those previously reported in the literature. Notably, real milk samples need no special sample pretreatment for the detection of ME because of the good anti-interference ability of EFC-based self-powered biosensors and the excellent selectivity of the homogeneous immunoassay. Therefore, this appealing self-powered homogeneous immunosensing platform holds great promise as a successful prototype of portable and on-site bioassay in the field of food safety