Ultrasensitive Photocathodic Biosensor Based on the Cu₂O/PTB7-Th/PDA⁺ Composite with Enhanced Photoelectrochemical Performance for the Detection of MicroRNA-375-3p

Abstract

Herein, an ultrasensitive photocathodic biosensor was fabricated based on Cu 2 O/PTB7-Th/PDA + photoactive materials with high photocarrier separation efficiency for the detection of microRNA-375-3p. Impressively, the photocathodic signal of the Cu 2 O material was significantly enhanced by using PTB7-Th as an energy level-matching photoactive material to enhance the bulk charge separation and N,N-bis (2-(trimethylammoniumiodide) propylene) perylene-3,4,9,10-tetracarboxydiimide (PDA + ) as an interfacial charge transfer mediator to efficiently suppress charge recombination at the photoelectrode/electrolyte interface. Compared with the pristine Cu 2 O as a photocathode, the obtained Cu 2 O/PTB7-Th/PDA + exhibited a 17 times higher photocathodic signal. As a proof of concept, a PEC biosensor was fabricated by using Cu 2 O/PTB7-Th/PDA + as a photoactive material and a target-triggered 3D DNA walker integrated with the dumbbell hybridization chain reaction (DHCR) as a signal amplifier to achieve the sensitive detection of microRNA-375-3p with a detection limit of 0.3 fM. This work provided a method to increase the photocurrent signal and the sensitivity of PEC-sensing platforms for the detection of biomarkers and disease diagnosis.

A concise overview of advancements in ultrasensitive biosensor development

“…Nanowires, on the other hand, have a high aspect ratio that enables direct electron transmission from the analyte to the electrode surface ( Zhou et al, 2023 ). Their one-dimensional structure makes it easier to immobilize bio-recognition components and increases the efficiency of charge transfer, increasing the sensitivity of the biosensors ( Gao et al, 2013 ).…”

“…Under optimal conditions, this approach enables good detection of target miRNA with a LOD of 5.0 fM ( Fan et al, 2007 ). Recent developments have been made on NW sensors by incorporating several nanoparticles with specific binding ability ( Tran et al, 2023 ; Zhou et al, 2023 ).…”

“…Although these investigations yield remarkable detection limits, showcasing the potential of QDs and NW-based sensors, there remains a significant need for further investigation to tackle their constraints. These limitations encompass potential toxicity concerns and challenges associated with precise control over size, shape, and composition during the synthesis process ( Zhou et al, 2023 ).…”

“…The photoactive material not only offers active sites to enhance reaction kinetics but also minimizes charge recombination events ( Gao et al, 2020 ). Zhou et al (2023) , utilizing a Cu 2 O(PTB7-Th/PDA+) designed a PEC biosensor for miRNA detection. In this setup, (Poly ([2,6′-4,8-di (5-ethylhexylthienyl)benzo [1,2- b; 3,3- b] dithiophene] {3-fluoro-2 [ (2-ethylhexyl)carbonyl]thieno [3,4-b]thiophenediyl}) (PTB7-Th) boosts Cu 2 O signals, facilitating charge separation in the bulk material, while N , N -bis(2-(trimethyl ammonium iodide)propylene)perylene-3,4,9,10 tetra -carboxydiimide (PDA + ) acts as a mediator for charge transfer.…”

“…To amplify signals, a 3D DNA walker connected to a dumbbell HCR was employed. The photoanode electrode, when exposed to light, exhibited substantially increased peak current compared to the pristine material, attributable to enhanced electron and hole movement and separation ( Zhou et al, 2023 ). Another research group ( Cui et al, 2023 ) employed a similar PEC sensing method for methylated RNA protein detection, utilizing a molybdenum diselenide/bismuth oxide (MoSe 2 /BiO) heterojunction as the photocathode.…”