Label-free detection of DNA using a light-addressable potentiometric sensor modified with a positively charged polyelectrolyte layer

Abstract

A multi-spot (16 spots) light-addressable potentiometric sensor (MLAPS) consisting of an Al-p-Si-SiO2 structure modified with a weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was applied for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge for the first time. To achieve a preferentially flat orientation of DNA strands and thus, to reduce the distance between the DNA charge and MLAPS surface, the negatively charged probe single-stranded DNAs (ssDNA) were electrostatically adsorbed onto the positively charged PAH layer using a simple layer-by-layer (LbL) technique. In this way, more DNA charge can be positioned within the Debye length, yielding a higher sensor signal. The surface potential changes in each spot induced due to the surface modification steps (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), non-specific adsorption of mismatched ssDNA) were determined from the shifts of photocurrent-voltage curves along the voltage axis. A high sensor signal of 83 mV was registered after immobilization of probe ssDNA onto the PAH layer. The hybridization signal increases from 5 mV to 32 mV with increasing the concentration of cDNA from 0.1 nM to 5 μM. In contrast, a small signal of 5 mV was recorded in the case of non-specific adsorption of fully mismatched ssDNA (5 μM). The obtained results demonstrate the potential of the MLAPS in combination with the simple and rapid LbL immobilization technique as a promising platform for the future development of multi-spot light-addressable label-free DNA chips with direct electrical readout.

The effect of gold nanoparticles on the impedance of microcapsules visualized by scanning photo-induced impedance microscopy

“…High-quality impedance images of polymer films were obtained using SPIM, and a good agreement with the spectra measured with classical ac-impedance spectroscopy was confirmed [18]. By measuring local photocurrents while biasing the EIS structure towards depletion, local surface potentials could also be recorded -a technique termed light-addressable potentiometric sensors (LAPS) [20][21][22].…”

In situ electrical monitoring of cancer cells invading vascular endothelial cells with semiconductor‐based biosensor

“…Biomolecular charges at the gate electrode/electrolyte solution interface were detected using the FET biosensor, depending on the Debye length at the interface (Sakata & Miyahara ; Wu et al . ). The Debye length is estimated from the charge distribution at a solid/liquid interface, which corresponds to the distance from a substrate on the basis of Stern and diffusion layers indicating EDL and varies according to the ionic strength in a measurement solution (Debye & Hückel ; Israelachvili ; Maekawa et al .…”

“…During this time, the total change in V out was approximately 10 mV, which was smaller than DV T determined from the decomposition of Matrigel, as shown in Fig 2. This can be explained by detection limit based on the Debye length, as follows. Biomolecular charges at the gate electrode/electrolyte solution interface were detected using the FET biosensor, depending on the Debye length at the interface (Sakata & Miyahara 2007;Wu et al 2015). The Debye length is estimated from the charge distribution at a solid/liquid interface, which corresponds to the distance from a substrate on the basis of Stern and diffusion layers indicating EDL and varies according to the ionic strength in a measurement solution (Debye & H€ uckel 1923;Israelachvili 1991;Maekawa et al 2013).…”

Label-Free Detection of E. coli O157:H7 DNA Using Light-Addressable Potentiometric Sensors with Highly Oriented ZnO Nanorod Arrays

“…For instance, the label-free detection of E. coli O157:H7 DNA has been reported using piezoelectric sensors and electrochemical biosensors [5,[15][16][17]. More recently, field-effect devices (FEDs) have offered a promising direct electrical readout for label-free DNA detection [18][19][20][21]. DNA-FEDs detect the intrinsic molecular charges of DNA molecules.…”

“…The light-addressable potentiometric sensor (LAPS) is a type of FEDs. It has a light-addressable gate surface and is suitable for use as a transducer for the label-free electrical detection of DNA molecules based on their intrinsic molecular charges [21,24]. ZnO nanorods have shown promising potential in many applications, including sensors, due to their properties of having a direct wide bandgap, large exciton binding energy, and a high aspect ratio [25].…”