Influences of Probe’s Morphology for Metal Ion Detection Based on Light-Addressable Potentiometric Sensors

Abstract

The sensing mechanism of binding Hg2+ into thymine-thymine (T-T) mismatched base pairs was introduced into a light-addressable potentiometric sensor (LAPS) with anti-Hg2+ aptamer as the sensing units. Three kinds of T-rich single-strand DNA (ssDNA) chains with different spacer lengths, from 0 to 12 –CH2 groups, were designed to investigate surface charge and morphological effects on the LAPS’ output. First, by comparing the responding of LAPS modified with three kinds of ssDNA, it was found that the best performance for Hg2+ sensing was exhibited by the probe without –CH2 groups. The detection limit of Hg2+ ion was 1 ppt under the optimal condition. Second, the cooperative effects of surface charge and morphology on the output were observed by the controlled experiments. The two effects were the negative charge balanced by metal cations and the morphological changing caused by the formation of T-Hg2+-T structure. In conclusion, not only the influences of the aptamer probe’s morphology and surface charge was investigated on the platform of LAPS, but also sensing Hg2+ ions was achieved for the first time by the presented aptamer LAPS.

Studies of Functional Nucleic Acids Modified Light Addressable Potentiometric Sensors: X-ray Photoelectron Spectroscopy, Biochemical Assay, and Simulation

“…It is indicated that V out is enhanced by the increased V RE . Though qualitative explanation has been provided for this observation, − , we still want to have an intrinsic view in LAPS, so that a clear computable LAPS principle could be formed, it will promote LAPS developing in a broader discipline. This work has not been reported up-to-now and will be accomplished here, for the first time.…”

“…However, to the best of our knowledge, only three reports are found, they belong to two of three FNA sensors 18 and named as (1) genoLAPS, which is modified by single strand DNA (ssDNA) to monitor DNA hybridization; 28−30 (2) aptaLAPS, which is modified by aptamer to realize Hg + detection. 31 The work for DNAzyme type LAPS (DNAzyme-LAPS) is missing. Moreover, in-depth understanding for the intrinsic mechanisms of FNA-LAPS experimental results are still in necessary, since the current surface charge (SC) sensing mechanisms 28−31 cannot explain why LAPS output signals (V out or I out ) can respond to the erecting FNAs reaction, 31 and our measured changing of V out (ΔV out) caused by long FNAs is smaller than short ones.…”

“…31 The work for DNAzyme type LAPS (DNAzyme-LAPS) is missing. Moreover, in-depth understanding for the intrinsic mechanisms of FNA-LAPS experimental results are still in necessary, since the current surface charge (SC) sensing mechanisms 28−31 cannot explain why LAPS output signals (V out or I out ) can respond to the erecting FNAs reaction, 31 and our measured changing of V out (ΔV out) caused by long FNAs is smaller than short ones. Though the researches about charge transfer (CT) studies of FNAs may provide an answer, which indicate longer FNAs chains tend to have bigger resistances (R CT ).…”

“…Meanwhile, a light addressable potentiometric sensor (LAPS) as a typical field-effect transducer with electrolyte-insulator-semiconductor (EIS) structure, its smooth and insulating surface is favorable for the microfluidic device, chemical imaging, accommodating versatile biochemical assays for biomarkers, and cancer cells, etc. However, to the best of our knowledge, only three reports are found, they belong to two of three FNA sensors and named as (1) genoLAPS, which is modified by single strand DNA (ssDNA) to monitor DNA hybridization; − (2) aptaLAPS, which is modified by aptamer to realize Hg + detection . The work for DNAzyme type LAPS (DNAzyme-LAPS) is missing.…”

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

“…Hg 2+ was detected with an aptamer-modified LAPS. The surface potential was influenced by the aptamer's morphology and charge [116]. A carboxylated graphene oxide (GO-COOH)-modified LAPS substrate was developed for the label-free detection of circulating tumour cells by measuring potential shifts [117].…”