Development of an electrochemical surface-enhanced Raman spectroscopy (EC-SERS) aptasensor for direct detection of DNA hybridization

Abstract

Rapid detection of disease biomarkers at the patient point-of-care is essential to timely and effective treatment. The research described herein focuses on the development of an electrochemical surface-enhanced Raman spectroscopy (EC-SERS) DNA aptasensor capable of direct detection of tuberculosis (TB) DNA. Specifically, a plausible DNA biomarker present in TB patient urine was chosen as the model target for detection. Cost-effective screen printed electrodes (SPEs) modified with silver nanoparticles (AgNP) were used as the aptasensor platform, onto which the aptamer specific for the target DNA was immobilized. Direct detection of the target DNA was demonstrated through the appearance of SERS peaks characteristic for adenine, present only in the target strand. Modulation of the applied potential allowed for a sizeable increase in the observed SERS response and the use of thiol back-filling prevented non-specific adsorption of non-target DNA. To our knowledge, this work represents the first EC-SERS study of an aptasensor for the direct, label-free detection of DNA hybridization. Such a technology paves the way for rapid detection of disease biomarkers at the patient point-of-care.

Advances in surface-enhanced vibrational spectroscopy at electrochemical interfaces

“…The nanoparticle ensemble approach to EC-SERS has been applied to various systems in recent years including ionic liquid adsorption [40,41], pyridine adsorption [42], uric acid detection [43] and DNA hybridisation [44]. The dye compound Nile Blue (NB) has found significant attention as a probe molecule in this arena due to its strong resonance Raman signal which is lost upon its two-electron reduction [45][46][47][48][49][50].…”

Quality assessment of cryopreserved biospecimens reveals presence of intact biomolecules

“…Acquisition of spectra of randomly chosen 19 samples each of short-term (OS 2T, OS 4N, OS 6T, OS 8T, OS 10N, OS 10T, OS 12T, OS 13T, BS 1N, BS 2N, BS 3N, BS 7N, BS 7T, BS 9N, CS 1T, CS 3N, CS 6N, CS 6T, CS 10T) and long-term (OL 3N, OL 8N, OL 10N, OL 10T, BL 1N, BL 1T, BL 2N, BL 2T, BL 3T, BL 5T, BL 6N, BL 6T, BL 8N, CL 2N, CL 2T, CL 6N, CL 6T, CL 9N, CL 9T) cryopreserved genomic DNA showed prominent peaks previously reported in human genomic DNA; 780 cm −1 -cytosine, thymine, 915 cm −1 -deoxyribose ring, 1061 cm −1 -d(vCO), 1251 cm −1 -cytosine, adenine, 1345 cm −1 -adenine, guanine, 1468 cm −1 -d(CH2δ), 1576 cm −1 -ring mode guanine, adenine vibration ( Figure 5A,B). The absence of characteristic RNA, amide I and amide III bands at around 815 cm −1 , 1300 cm −1 , 1655 cm −1 , respectively, confirms the samples are devoid of RNA and protein [17,32], [35][36][37][38]. Notably, we observed a distinct sharp band at 1012 cm −1 in all the extracted genomic DNA samples irrespective of the cryopreservation period which instigated the need to analyze other components of the PAXgene Tissue DNA Kit (PreAnalytiX).…”

Spectroelectrochemistry, the future of visualizing electrode processes by hyphenating electrochemistry with spectroscopic techniques

“…There is a large variety of different materials for Raman electrodes. Reports range from standard metallic electrodes such as Au electrodes, to cells made by 3D printing, 130 screen-printed electrodes [131][132][133][134][135][136][137][138] and even electrodes on fabric. 139 In the literature, several different cell configurations are described.…”

“…Research aimed towards real world applications is also present in Raman-SEC, although underrepresented and almost solely performed by the group of Brosseau. Some interesting applications include a portable SERS-SEC device for the detection of melanine in milk, 136 the detection of DNA biomarkers in synthetic urine, 137 the detection of 6-thiouric acid in synthetic urine, 213 the quantitative detection of uric acid in synthetic urine 138 and a point of care device based on SERS-SEC on a fabric substrate. 139…”

“…At the moment Raman-SEC is mostly used for a large number of applications in material sciences, but as of yet does not have a large number of real world applications, some notable exceptions are for instance the work by the group of Brosseau. [136][137][138][139] When the advancements of SERS-SEC as highlighted above take place, the technique will likely become more attractive for real world applications.…”