Aptasensing Platform Research Articles

Self-coordinated nanozyme on Cu3BiS3 nanorods for high-performance aptasensing.

Anovel strategy is reportedto access high-performance nanozymes via the self-coordination of ferrocyanides ([Fe(CN)6]4-) onto the surface of the Cu3BiS3 (CBS) nanorods. Notably, the in situ formed nanozymes had high catalytic activity, good stability, low cost, and easy mass production. The formed nanozyme catalyzed the oxidation of the typical chromogenic substrate of 3,3',5,5'-tetramethylbenzidine (TMB) with a distinctive absorption peak at 652nm, accompanied by a blue color development. Moreover, the attachment of deoxyribonucleoside 5'-monophosphates (dNMP) beforehand onto the surface of CBS prevented coordination of ferrocyanides and resulted in the tunable formation of the nanozyme, thereby enabling the construction of an exquisite biosensing platform. Taking the aptasensing of chloramphenicol (CAP) as an example, the engineered nanozyme allowed the construction of a homogenous, label-free, and high-performance bioassay in terms of its convenience and high sensitivity. Under the optimal conditions, changes in the absorption intensity at 652nm for the oxidized TMB provides a good linear correlation with the logarithm of CAP concentrations in the range 0.1pM to 100nM, and the limit of detection was 0.033pM (calculated from 3σ/s). Considering a vast number of bioreactions can be connected to dNMP production, we expect the engineerable nanozyme as a universal signal transduction scaffold for versatile applications in bioassays. Through the attachment of deoxyribonucleoside 5'-monophosphate (dNMP) on the surface of CBS to regulate the generation of self-coordinated nanozyme CBS/BiHCF, a homogeneous, label-free, and high-performance universal aptasensing platform was constructed.

Nanomaterial-based sandwich-type electrochemical aptasensor platform for sensitive voltammetric determination of leptin.

A sandwich-type electrochemical aptasensor was designed for sensitive detection of leptin in biological samples, including human serum and human plasma. The developed aptasensor was produced by electrodeposition of gold nanoparticles on a screen-printed electrode modified with zinc oxide nanoparticles. The synergy effect of zinc oxide and gold nanoparticles improved the electrocatalytic activity of the aptasensor. The obtained high surface area allowed more aptamer molecules to be loaded on the electrode surface. Signal amplification significantly increases the detection sensitivity of a developed biosensor. Although the use of nanomaterials is the most preferred detection tool for this purpose, as an alternative, enzyme-catalyzed signal amplification is widely used in the construction of a biosensor due to its specificity and high catalytic efficiency. Therefore, both nanomaterial-supported and an alkaline phosphatase-based aptasensor design were developed, which can produce in situ electroactive product by enzymatic hydrolysis of the inactive substrate to achieve a higher signal-to-background ratio. Under optimal conditions, the developed aptasensor exhibited a wide linear concentration range from 0.01 pg mL-1 to 100.0 pg mL-1 with a detection limit of 0.0035 pg mL-1. While the developed aptasensor provided excellent selectivity in the presence of some interfering compounds, it possessed outstanding reproducibility and stability. In addition, the developed aptasensor has been applied with good recoveries in the range 96.31 to 108.79% in human serum and plasma samples. In conclusion, all the obtained results showed the feasibility of the developed aptasensor for practical applications.

A new double signal on electrochemical aptasensor based on gold nanoparticles/graphene nanoribbons/MOF-808 as enhancing nanocomposite for ultrasensitive and selective detection of carbendazim

The fungicide carbendazim (CBZ) is a carcinogen, which is widely found in the environment. It is a broad-spectrum benzimidazole fungicide that acts by disrupting fungal cell division. To detect CBZ in water samples, an ultrasensitive and selective dual-signal electrochemical aptasensing platform based on the interaction of SH-complementary carbendazim aptamer (SH-cCBZ) and carbendazim aptamer (CBZA) was developed. Gold nanoparticles (AuNP) modified with graphene nanoribbons (GNR), which were produced from multiwalled carbon nanotubes, and Zr-based metal-organic framework (MOF-808) (AuNP@GNR/MOF-808) were used for enhancing the signals for the first time. The SH-cCBZ produced a double-stranded structure along with CBZA. CBZ dispersed the double strands, thereby amplifying the electrochemical response. The electrochemical aptasensor showed a linear response to CBZ in the concentration range from 1.0 fmol L−1 to 100.0 pmol L−1 and 0.8 fmol L−1 to 100.0 pmol L−1 under ideal conditions. The detection limits obtained via electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) were 0.4 and 0.2 fmol L−1, respectively. Moreover, the proposed aptasensor was used to determine the CBZ levels in Bangkok tap water and Chao Phraya river water samples, the results were in good agreement with UPLC-MS/MS. The recoveries ranged from 97.5% to 102.8%, suggesting various potential applications.

A label-free PEC aptasensor platform based on g-C3N4/BiVO4 heterojunction for tetracycline detection in food analysis

A simple low-cost label-free photoelectrochemical (PEC) biosensing platform based on red blood cell shaped BiVO4 modified g-C3N4 was designed for tetracycline detection under room temperature. The prepared g-C3N4/BiVO4 heterojunction not only demonstrated a high surface area, excellent physicochemical stability and favorable PEC activity, but also can be employed as nanostructure support for aptamers to construct a visible-light-driven PEC aptasensor due to rich π-π accumulation sites. More importantly, the proposed PEC aptasensor showed a favorable linear toward tetracycline in the range from 5 × 10-9 to 2 × 10-7 M with a detection limit of 1.6 nM, which well covered the Food Standards Testing requirements. Practical food sample analysis further revealed the accuracy and feasibility of the g-C3N4/BiVO4 heterostructure based PEC platform. It is expected that such a label-free and cost-effective PEC strategy should act as a promising candidate for tetracycline determination in food quality control and supervision.

Naked-eye detection of Staphylococcus aureus in powdered milk and infant formula using gold nanoparticles

Nonspecific binding of proteins from complex food matrices is a significant challenge associated with a biosensor using gold nanoparticles (AuNPs). To overcome this, we developed an efficient EDTA chelating treatment to denature milk proteins and prevent their adsorption on AuNPs. The use of EDTA to solubilize proteins enabled a sensitive label-free apta-sensor platform for colorimetric detection of Staphylococcus aureus in milk and infant formula. In the assay, S. aureus depleted aptamers from the test solution, and the reduction of aptamers enabled aggregation of AuNPs upon salt addition, a process characterized by a color change from red to purple. Under optimized conditions, S. aureus could be visually detected within 30 min with the detection limit of 7.5 × 104 CFU/mL and 8.4 × 104 CFU/mL in milk and infant formula, respectively. The EDTA treatment provides new opportunities for monitoring milk contamination and may prove valuable for biosensor point-of-need applications.

Synthetic antibodies for methamphetamine analysis: Design of high affinity aptamers and their use in electrochemical biosensors

An aptamer-based electrochemical biosensor was designed and fabricated for methamphetamine (METH) analysis. Several aptamer sequences developed by the GO-SELEX method were immobilized onto gold electrodes (GE) via gold-thiol affinity. Surface characterizations were performed by electrochemical methods including cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectrometry (EIS). GE/Apta-4/METH aptasensor was selected for further studies since the best results were obtained with the Apta-4 sequence in terms of analytical parameters. Accordingly, it exhibited good selectivity for METH analysis with a wide linear range of 0.1–50 ng/mL and a low limit of detection (LOD) which was found to be 0.467 ng/mL. The proposed aptasensor platform displayed good selectivity for the detection of METH in synthetic urine samples spiked with METH.

Spectroscopic ellipsometry-based aptasensor platform for bisphenol a detection

Endocrine-disrupting chemicals (EDC) are pollutants that alter the function of the endocrine system by interfering with hormone biosynthesis, metabolism, or action. In this study, a spectroscopic ellipsometry platform is proposed using aptamers for the sensitive and selective detection of an EDC, 2,2-Bis(4-hydroxyphenyl)propane (Bisphenol A, BPA). Two different BPA-specific aptamers (Anti-BPA1 and Anti-BPA2) were immobilized to silicon wafer chips by the layer-by-layer self-assembly, a detection limit of 215 pM and 36 pM was obtained using the ellipsometric method for Anti-BPA1 and Anti-BPA2, respectively. Sensor specificity was tested with 2,2-Bis(4-hydroxyphenyl)butane and a maximum RSD of 3.8% was obtained. It has been reported that both aptasensors based on spectroscopic ellipsometry exhibit adequate analytical performance.

Gold-Ceria nanocomposite based highly sensitive and selective aptasensing platform for the detection of the Chlorpyrifos in Solanum tuberosum

Contamination of food products due to the pesticide is a common problem. Pesticides, being one of the most harmful chemicals to human beings necessitates early and rapid on-site diagnostics to avoid chronic diseases due to their exposure. Their early and quick detection of edible products is crucial from the food safety point of view. We have fabricated an electrochemical aptasensing platform for the detection of Chlorpyrifos (CPF) using gold-ceria nanocomposite (Au@CeO2 nc). The electrochemical aptasensing platform has shown excellent linear response against CPF with good linearity of R2 = 0.96 in the range of 10 pM to 500 nM. The sensitivity of the aptasensor was evaluated from the slope of the calibration plot given by 12.68 mA nM−1 cm−2 and the limit of detection was estimated to be 0.12 pM. The applicability in vegetable samples was estimated by utilizing spiked cucumber (Cucumis sativus) and potato (Solanum tuberosum) samples of which Solanum tuberosum showed very good detection. Then extract from potato was used directly with increasing volume and studied against the electrochemical aptasensing platform where very good linearity and sensitivity were obtained. These studies demonstrate that the electrochemical aptasensing platform can be utilized for quick, label-free, and highly sensitive detection of pesticide, Chlorpyrifos in real samples.

Portable Vertical Graphene@Au-Based Electrochemical Aptasensing Platform for Point-of-Care Testing of Tau Protein in the Blood.

Alzheimer’s disease (AD) is a long-term neurodegenerative disease that poses a serious threat to human life and health. It is very important to develop a portable quantitative device for AD diagnosis and personal healthcare. Herein, we develop a portable electrochemical sensing platform for the point-of-care detection of AD biomarkers in the blood. Such a portable platform integrates nanoAu-modified vertical graphene (VG@Au) into a working electrode, which can significantly improve sensitivity and reduce detection limit due to the large specific surface, excellent electrical conductivity, high stability, and good biocompatibility. The tau protein, as an important factor in the course of AD, is selected as a key AD biomarker. The results show that the linear range of this sensing platform is 0.1 pg/mL to 1 ng/mL, with a detection limit of 0.034 pg/mL (S/N = 3), indicating that this portable sensing platform meets the demand for the detection of the tau protein in the blood. This work offers great potential for AD diagnosis and personal healthcare.

Self-powered Aptasensors Made with the In2O3-In2S3-Ti3C2 Composite for Dual-mode Detection of Microcystin-LR.

A dual-mode self-powered aptasensing platform of photoelectrochemical (PEC) and photofuel cell (PFC) was constructed for Microcystin-LR (MC-LR) detection. Specifically, the In2O3-In2S3-Ti3C2 (IO-IS-TC) composite was facilely assembled on the base of MOF-derived In2O3 hollow tubulars, and the integrated mechanism and photoconversion efficiency are proposed and discussed in detail. Herein, a promising dual-mode sensing platform was constructed using the IO-IS-TC composite as a photoanode matrix with higher output power and obvious photocurrent response. Moreover, the dual-mode sensing platform did not require external bias and the addition of sacrificial agents under visible light irradiation. The enhanced PEC properties can be attributed to the matched energy level of ternary components and the improved separation of photogenerated carriers. Moreover, aptamer-based recognition was adopted to catch MC-LR molecules, which realized the highly sensitive and selective detection. The PFC aptasensor was exhibited at 50-5 × 105 pmol/L with a detection limit of 17.4 pmol/L, and the PEC aptasensor was realized from 0.5 to 4 × 105 pmol/L with a detection limit of 0.169 pmol/L. The proposed aptasensing platform showed good specificity, reproducibility, and stability, which paved the way for the construction of a fast and ultrasensitive PEC sensing methodology for environmental analysis.

Target-activated dual-amplified photothermal aptasensing platform for highly sensitive monitoring antibiotic residue in foods

Antibiotic residues have attracted increasing public attention in food safety because extensive use or misuse of antibiotics seriously threatens public health and safety. Thus, it is important to develop accurate and sensitive analytical methods for the detection of residual antibiotics in foods. Herein, we developed a novel, reliable and highly sensitive photothermal aptasensing platform for analysis of antibiotic residue in food samples. By virtue of CuS/cyanine dye nanocomposite as an excellent photothermal conversion reagent, and dual amplification strategy consisting of exonuclease I-aided target recycling and hybridization chain reaction, highly sensitive detection of antibiotic, i.e. chloramphenicol (CAP), was successfully realized with a detection limit as low as 2.8 pM, which was superior to most of the reported methods for CAP determination. In addition, the as-proposed dual-amplified photothermal aptasensing platform was highly applicable for monitoring antibiotic residue in various food samples with good accuracy and repeatability. More importantly, this work was the first constructed photothermal aptasensing platform for antibiotic detection. Therefore, with the excellent features of simplicity, portability, wide availability, and easy manipulation, this sensing platform has great potential to be applied in antibiotic-related food safety monitoring.

Spontaneously formation of peroxidase mimetics on CuWO4 for homogeneous and universal aptasensing platform

This study addresses the demand for high–performance aptasensing by reporting a spontaneously formed nanozyme on the surface of CuWO4 nanomaterials. The self–coordination of [Fe(CN)6]3- with CuWO4 nanomaterials led to the in situ formation of CuHCF on its surface, which demonstrated efficient peroxidase–like activity for the catalytic oxidation of the chromogenic substrate of 3,3′,5,5′-tetramethylbenzidine (TMB). This spontaneously formed nanozyme enabled its coupling with the stimuli–responsive mesoporous silica nanoparticles (MSN) molecule gates and the nuclease (DNase I) cleavage reaction assisted target recycling for achieving colorimetric aptasensing in label–free, immobilization–free, and highly amplified modes. The developed approach allowed the detection of 0.1–100 nM kanamycin (KANA) with the low detection limit of 3.5 pM, which could also satisfactorily identify the content of KANA in treated milk and lake water samples. The formed nanozyme may in principle be universally applicable for the detection of a range of targets of interest. We hope this spontaneously formed nanozyme would arouse the exploration of more ingenious nanozyme with exquisite biosensing applications.

Handheld pH‐Meter‐based Electrochemical Aptasensing of Carcinoembryonic Antigen on Multifuctional Magnetic Beads

AbstractMethods derived from immunoassays and aptasensors have been established for monitoring of carcinoembryonic antigen (CEA) in biological fluids, but most involved complex procedure and various reactions. We designed an uncomplicated and convenient electrochemical aptasensing platform for the quantitative monitoring of CEA on multifunctionalized magnetic beads with a handheld pH meter as the read‐out. Initially, CEA‐specific aptamers were covalently conjugated to magnetic beads, and then hybridized with glucose oxidase‐labeled complementary strands to construct multifunctional nanoprobes. After addition of target CEA, the analyte interacts with the corresponding aptamer and then release the complementary strand. After magnetic separation, the released glucose oxidase‐labeled complementary strands hydrolysed glucose, thereby leading to a change in pH of the detection solution, which was quantitatively monitored on a hand‐held pH meter. Under the optimum conditions, the aptasensor based on pH meter exhibited well responses relative to CEA concentrations inside the dynamic range between 0.01 and 100 ng mL−1 and detection limit at least 9.3 pg mL−1. Good duplicability, high specificity and ability for long‐term stable storage are obtained for the as‐prepared aptasensors. Additionally, human serum specimens were determined through pH‐meter‐based aptasensors, and the results closely matched the commercial enzyme‐linked immunosorbent assay (ELISA) of human CEA.

An aptasensing platform for detection of heat shock protein 70 kDa (HSP70) using a modified gold electrode with lady fern-like gold (LFG) nanostructure

Early diagnosis of diseases depends on accessibility and the ability to detect associated biomarkers. Using aptamers and equipping signal transducers with nanomaterials have facilitated, accelerated, and provided sensitive and selective nanoaptasensors. In this study, the first aptasensor to detect heat shock protein 70 kDa (HSP70) has been developed by applying a modified gold electrode (GE) with the lady fern-like gold (LFG) nanostructure. The nanostructure solution contained HAuCl4, H2SO4, and histamine and was electrochemically synthesized on the surface of the GE with an average size of ∼20 nm. The analysis to find the optimized time for immobilization of aptamer (a single-stranded RNA) as the biorecognition element on the surface of the working electrode was performed using the open-circuit potential (OCP) technique. This aptasensor could detect HSP70 in a linear range from 0.05 to 75 ng mL−1 with the limit of detection (LOD) ∼ 0.02 ng mL−1. In order to find out about the performance of the designed aptasensor, other analytical analyses for knowing about the figure of metrics were shadowed through reproducibility, stability, regeneration, selectivity, accuracy, and precision experiments.

CRISPR-Cas12a-Based Aptasensor for On-Site and Highly Sensitive Detection of Microcystin-LR in Freshwater

On-site monitoring of trace organic pollutants with facile methods is critical to environmental pollutant prevention and control. Herein, we proposed a CRISPR-Cas12a-based aptasensor platform (named as MC-LR-Casor) for on-site and sensitive detection of microcystin-LR (MC-LR). After hybridization with blocker DNA, the MC-LR aptamers were conjugated to magnetic beads (MBs) to get the MB aptasensor. In the presence of MC-LR, their interactions with aptamers were triggered and the specific binding caused the release of blocker DNA. Using the programmability of the CRISPR-Cas system, the released blocker DNA was designed to activate a Cas12a-crRNA complex. Single strand DNA reporters were rapidly cleaved by the complex. Signal readout could be achieved by fluorometer or lateral flow strips, which were positively correlated to MC-LR concentration. Benefiting from the CRISPR-Cas12a amplification system, the proposed sensing platform exhibited high sensitivity and reached the limit of detection of ∼3 × 10-6 μg/L (fluorescence method) or 1 × 10-3 μg/L (lateral flow assay). In addition, the MC-LR-Casor showed excellent selectivity and good recovery rates, demonstrating their good applicability for real water sample analysis. During the whole assay, only two steps of incubation at a constant temperature were required and the results could be visualized when employing flow strips. Therefore, the proposed assay offered a simple and convenient alternative for in situ MC-LR monitoring, which may hold great promise for future environmental surveillance.

Fully printed and flexible multi-material electrochemical aptasensor platform enabled by selective graphene biofunctionalization

The demand for flexible biochemical sensors has increased with advances in computational functionality and wireless communication. Advances in materials science and biochemistry have enabled the development and fabrication of biosensors for selective detection of biological analytes leveraging ink-printed technologies, including in flexible form-factors. However, despite these advances, minimal effort has been devoted to translating the multi-material, three-electrode electrochemical cell, which is widely regarded as the standard for laboratory-scale studies, into a flexible form-factor for use in immunosensors, especially in a manner that is compatible with rapid and scalable additive manufacturing. Here, we report a fully printed and flexible electrochemical non-enzymatic immunosensor platform that integrates four chemically compatible inks and a non-covalent, two-step biofunctionalization scheme. The robustness of the platform is demonstrated using a model aptasensor that enables lysozyme detection using both electrochemical impedance spectroscopy and square wave voltammetry. The flexible, fully ink-printed aptasensor shows competitive performance to commercially available rod/disc electrodes in a bath cell. Overall, this work establishes a methodology for high-throughput fabrication of robust, flexible, multi-material, three-electrode immunosensors that can be generalized to a range of biosensor applications.

Synergistic effect of silver plasmon resonance and p-n heterojunction enhanced photoelectrochemical aptasensing platform for detecting chloramphenicol

Synergistic effect of silver plasmon resonance and p-n heterojunction enhanced photoelectrochemical aptasensing platform for detecting chloramphenicol

A Simple Fluorescent Aptasensing Platform Based on Graphene Oxide for Dopamine Determination.

Dopamine (DA) is a catecholamine neurotransmitter playing an important role in different biological functions including central nervous, renal, cardiovascular, and hormonal systems. The sensitive and selective detection of this neurotransmitter plays a key role in the early diagnosis of various diseases related to abnormal levels of dopamine. Therefore, it is of great importance to explore rapid, simple, and accurate methods for detection of dopamine with high sensitivity and specificity. We propose in this work a fluorescent aptasensor based on graphene oxide (GO) as a quencher, for the rapid determination of dopamine. The principle of this aptasensor is based on fluorescence resonance energy transfer (FRET), where GO was used as energy donor, and a carboxy fluorescein (FAM)-labeled aptamer as acceptor. In the absence of DA, FAM-aptamer was adsorbed on the surface of GO through π-π stacking interactions between nucleotide bases and the carbon network, leading to a weak FRET and a quenching of the FAM fluorescence. However, by adding the target, the aptamer undergoes a conformational change to bind to DA with high affinity, resulting in a fluorescence recovery. Under the optimal experimental conditions, the fluorescence recovery was linearly proportional to the concentration of DA in the range of 3-1680 nM, with a limit of detection of 0.031 nM and a limit of quantification of 0.1 nM. Moreover, the developed assay exhibited minor response in the presence of various interferents and it revealed a satisfactory applicability in human serum samples.

Gold nanostructures integrated on hollow carbon N-doped nanocapsules as a novel high-performance aptasensing platform for Helicobacter pylori detection

Gold nanostructures integrated on hollow carbon N-doped nanocapsules as a novel high-performance aptasensing platform for Helicobacter pylori detection

An “Off-On” Mode Electrochemiluminescence Aptasensing Platform for Lincomycin Residues Detection Based on CDS Qds/Carboxylated G-C3n4 Nanocomposite

An “Off-On” Mode Electrochemiluminescence Aptasensing Platform for Lincomycin Residues Detection Based on CDS Qds/Carboxylated G-C3n4 Nanocomposite