Differential photoelectrochemical biosensing using DNA nanospacers to modulate electron transfer between metal and semiconductor nanoparticles

Sudip Saha, Amanda Victorious, Richa Pandey, Amanda Clifford, Igor Zhitomirsky, Leyla Soleymani*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


As dynamic biorecognition agents such as functional nucleic acids become widely used in biosensing, there is a need for ultrasensitive signal transduction strategies, beyond fluorescence, that are robust and stable for operation in heterogeneous biological samples. Photoelectrochemical readout offers a pathway toward this goal as it offers the simplicity and scalability of electrochemical readout, in addition to compatibility with a broad range of nanomaterials used as labels for signal transduction. Here, a differential photoelectrochemical biosensing approach is reported, in which DNA nanospacers are used to program the response of two sensing channels. The differences in the motional dynamics of DNA probes immobilized on different channels are used to control the interaction between Au and TiO2 nanoparticles positioned at the two ends of the DNA nanospacer to achieve differential signal generation. Depending on the composition of the DNA constructs (fraction of the DNA sequence i.e., double-stranded), the channels can be programmed to produce a signal-on or a signal-off response. Incident photon-to-current conversion efficiency, UV-vis spectroscopy, and flat-band potential measurement indicate that direct transfer of electrons between metallic and semiconductive nanoparticles is responsible for the signal-on response, and incident light absorption and steric hindrance are responsible for the signal-off response. The differential photoelectrochemical signal readout developed here increases the device sensitivity by up to three times compared to a single channel design and demonstrates a limit of detection of 800 aM.

Original languageEnglish
Pages (from-to)36895-36905
Number of pages11
JournalACS Applied Materials and Interfaces
Issue number33
StatePublished - 19 Aug 2020
Externally publishedYes


  • DNA sensing
  • Gold nanoparticles
  • Photoelectrochemical biosensing
  • Photoelectrochemistry
  • Plasmonic biosensing
  • TiO


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