“…[27][28][29] In this work, a small fragment of the IS6110 sequence was used as the target biomarker and detected directly via hybridization to a specific probe sequence. There are many techniques that are used to detect DNA hybridization with the aid of a label molecule, [30][31][32][33] however, these methods typically have low sensitivity, require significant method development, and most importantly the target affinity of the DNA probes may be reduced due to labelling with fluorescent or electroactive species. 34 As a result, label-free DNA detection methods are highly sought after.…”
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.
“…[27][28][29] In this work, a small fragment of the IS6110 sequence was used as the target biomarker and detected directly via hybridization to a specific probe sequence. There are many techniques that are used to detect DNA hybridization with the aid of a label molecule, [30][31][32][33] however, these methods typically have low sensitivity, require significant method development, and most importantly the target affinity of the DNA probes may be reduced due to labelling with fluorescent or electroactive species. 34 As a result, label-free DNA detection methods are highly sought after.…”
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.
“…Although metal ions have been used as signal tags, the modification processes were generally time-consuming. For example, Gao et al utilized the encapsulated Cu 2+ ions into the dendrimer as the signal tags for sensitive electrochemical detection of DNA hybridization . Given the unique properties of this signal probe, it is highly beneficial to construct novel electrochemical systems for the early diagnosis of serious diseases.…”
A novel and simple electrochemical immunoassay for C-reactive protein was developed using metal-organic frameworks (Au-MOFs) as signal unit. In this study, we found MOFs could be used as signal probe. And this new class of signal probe differs from traditional probe. The signal of the copper ions (Cu) from MOFs could be directly detected without acid dissolution and preconcentration, which would greatly simplify the detection steps and reduce the detection time. Moreover, MOFs contain large amounts of Cu ions, providing high electrochemical signals. Our report represents the first example of using MOFs themselves as electrochemical signal probe for biosensors. Platinum nanoparticle modified covalent organic frameworks (Pt-COFs) with high electronic conductivity was employed as the substrate, which is the first time demonstrating the use of Pt-COFs for electrochemical immunoassay. Under the optimized experimental conditions, the proposed sensing strategy provides a linear dynamic ranging from 1 to 400 ng/mL. A detection limit of 0.2 ng/mL was obtained, indicating an improved analytical performance. With these merits, this stable, simple, low-cost, sensitive and selective electrochemical immunoassay shows promise for applications in the point-of-care diagnostics of dieses and environmental monitoring.
“…Routine approaches usually consist of ligand-conjugated enzymes or electroactive materials. − Inspiringly, metal ions (e.g., cadmium, copper, zinc, and lead) could exhibit specific voltammetric characteristics at different applied potentials. , Dai et al employed Cu 2+ ion as the electroactive indicator to successfully construct an electrochemical Cu 2+ sensor . Gao et al utilized the encapsulated Cu 2+ ions into the dendrimer as the signal tags for sensitive electrochemical stripping detection of DNA hybridization . Significantly, Cu 2+ ion could be coordinated in the presence of pyrophosphate (PPi) on the basis of the strong interaction between PPi and Cu 2+ .…”
A novel flow-through microfluidic device based on a magneto-controlled graphene sensing platform was designed for homogeneous electronic monitoring of pyrophosphatase (PPase) activity; enzymatic hydrolysate-induced release of inorganic copper ion (Cu(2+)) from the Cu(2+)-coordinated pyrophosphate ions (Cu(2+)-PPi) complex was assessed to determine enzyme activity. Magnetic graphene nanosheets (MGNS) functionalized with negatively charged Nafion were synthesized by using the wet-chemistry method. The Cu(2+)-PPi complexes were prepared on the basis of the coordination reaction between copper ion and inorganic pyrophosphate ions. Upon target PPase introduction into the detection system, the analyte initially hydrolyzed pyrophosphate ions into phosphate ions and released the electroactive copper ions from Cu(2+)-PPi complexes. The released copper ions could be readily captured through the negatively charged Nafion on the magnetic graphene nanosheets, which could be quantitatively monitored by using the stripping voltammetry on the flow-through detection cell with an external magnet. Under optimal conditions, the obtained electrochemical signal exhibited a high dependence on PPase activity within a dynamic range from 0.1 to 20 mU mL(-1) and allowed the detection at a concentration as low as 0.05 mU mL(-1). Coefficients of variation for reproducibility of the intra-assay and interassay were below 7.6 and 9.8%, respectively. The inhibition efficiency of sodium fluoride (NaF) also received good results in pyrophosphatase inhibitor screening research. In addition, the methodology afforded good specificity and selectivity, simplification, and low cost without the need of sample separations and multiple washing steps, thus representing a user-friendly protocol for practical utilization in a quantitative PPase activity.
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