Enhancing the Photoelectrochemical Response of DNA Biosensors Using Wrinkled Interfaces

Abstract

Photoelectrochemical (PEC) biosensors, with optical biasing and electrochemical readout, are expected to enhance the limit-of-detection of electrochemical biosensors by lowering their background signals. However, when PEC transducers are functionalized with biorecognition layers, their current significantly decreases, which reduces their signal-to-noise ratio and dynamic range. Here, we develop and investigate a wrinkled conductive scaffold for loading photoactive quantum dots into an electrode. The wrinkled photoelectrodes demonstrate an order of magnitude enhancement in the magnitude of the transduced PEC current compared to their planar counterparts. We engineer PEC biosensors by functionalizing the wrinkled photoelectrodes with nucleic acid capture probes. We challenge the sensitivity of the wrinkled and planar biosensors with various concentrations of DNA target and observe a 200 times enhancement in the limit-of-detection for wrinkled versus planar electrodes. In addition to enhanced sensitivity, the wrinkled PEC biosensors are capable of distinguishing between fully complementary and targets with a single base-pair mismatch, demonstrating the suitability of these biosensors for use in clinical diagnostics.

Surface modification of TiO2 for photoelectrochemical DNA biosensors

“…The photocurrent decreases after probe deposition and decreases further after target capture. Probe immobilization causes photocurrent decrease by limiting the access of AA from the solution to the photoelectrode surface (Saha et al, 2018). Complementary target causes further photocurrent decrease by causing increased steric hindrance when it hybridizes with the probe to form dsDNA (Yan, Liu, Yang, & Zhang, 2015).…”

“…Photoelectrochemical (PEC) signal transduction combines optical excitation with electrochemical readout to increase the sensitivity and reduce the background signal of biosensors (Zhao, Xu, & Chen, 2014). Particularly in PEC DNA biosensors, DNA hybridization is translated to a change in photocurrent (Saha, Chan, & Soleymani, 2018) with a signal change that is proportional to the concentration of the target DNA sequence.…”

Affinity-Based Detection of Biomolecules Using Photo-Electrochemical Readout

“…In signal-off PEC biosensing, it is crucial to have a high photocurrent before target introduction because high concentrations of the target can completely diminish the PEC signal (Saha et al, 2018). Different approaches have been used to obtain high baseline PEC currents.…”

“…Different approaches have been used to obtain high baseline PEC currents. Depositing photoactive materials into three-dimensional scaffolds such as wrinkled electrodes has been used to increase the photocurrent of PEC biosensors (Saha et al, 2018). The wrinkle electrodes showed 10 times higher photocurrent than a planar electrode composed of CdTe QDs.…”

Nanostructured Architectures for Biomolecular Detection inside and outside the Cell

“…[140] The random orientation of wrinkles can aid immensely with mitigating tensile stress on the electrode, and complete recovery of conductivity after repeated straining has been reported. [141] Wrinkling of gold electrodes has been widely adopted into biosensing strategies from nucleic acid detection [140,142] to wearable sensors for detection of biomarkers in biological fluids. [143,144] These nanostructured materials have also been applied to microbial fuel cells.…”