Label‐free electrical detection of DNA with a multi‐spot LAPS: First step towards light‐addressable DNA chips

Abstract

6009 53235A multi-spot (4 Â 4 spots) light-addressable potentiometric sensor (MLAPS) consisting of an Al-p-Si-SiO 2 structure has been applied for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization by the intrinsic molecular charge for the first time. Single-stranded probe ssDNA molecules (20 bases) were covalently immobilized onto the silanized SiO 2 gate surface. The unspecific adsorption of mismatch ssDNA on the MLAPS gate surface was blocked by bovine serum albumin molecules. To reduce the screening effect and to achieve a high sensor signal, the measurements were performed in a low ionic-strength solution. The photocurrent-voltage (I-V) curves were simultaneously recorded on all 16 spots after each surface functionalization step. Large shifts of I-V curves of 25 mV were registered after the DNA immobilization and hybridization event. In contrast, a small potential shift ($5 mV) was observed in case of mismatch ssDNA, revealing good specificity of the sensor. The obtained results demonstrate the potential of the MLAPS as promising transducer platform for the multi-spot label-free electrical detection of DNA molecules by their intrinsic molecular charge.

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].…”

Recent Developments of High-Resolution Chemical Imaging Systems Based on Light-Addressable Potentiometric Sensors (LAPSs)

“…The detection of inorganic salt ions (e.g., K + , Ca 2+ , Na + , Mg 2+ , Zn 2+ , Li + , NO 3 − , CO 3 2− , and SO 4 2− ) can be achieved by depositing polymer membranes carrying ionophores such as PVC membranes [53,70,71,72,73,74,75,76], silicone rubber membranes [77,78,79,80,81] and photocurable membranes [82]. Immobilization of enzymes [83,84,85,86,87,88,89,90], antibodies [23,91,92] or DNA [93,94,95,96] on the sensing layer enables the detection of biomolecules such as glucose, urea, penicillin G, antigens, immunoglobulins G (IgG) and target DNA, etc. The sensing materials and target species have been systematically summarized [20,21,22].…”

Biological imaging using light-addressable potentiometric sensors and scanning photo-induced impedance microscopy

“…Non-labelled DNA biosensors based on LAPS were developed to detect the hybridization of probe DNA and target DNA [3,[110][111][112][113][114]. Potential shifts were caused by the intrinsic negative charge of DNA.…”