Aptasensor System Research Articles

Fluorescent aptasensor based on target-induced hairpin conformation switch coupled with nicking enzyme-assisted signal amplification for detection of beta-amyloid oligomers in cerebrospinal fluid.

Afluorescent aptasensor was developedbased on target-induced hairpin conformation switch coupled with nicking enzyme-assisted signal amplification (NESA) to detect the oligomeric form of ß-amyolidpeptide (AβO) in cerebrospinal fluid. The hairpin DNA probe (HP) was specifically designed to recognize AβO. When AβO is present in the sensing system, it induces an HP conformational switch and triggers the NESA reaction. After evaluating the parameters of the aptasensor system, we selected Hairpin10, which has a 10-nucleotide extended sequence, as the hairpin sequence that interacts with AβO. The quantitative linear range of the proposed aptasensor is from11.3 to 113 ng mL-1 in artificial cerebrospinal fluid (aCSF), and the detection limit was 7.29 ng mL-1. The present work realized the assay of AβO in aCSF with satisfactory quantitative results.

Potentiometric enzymatic aptasensing of paralytic shellfish toxins using graphene-wrapped magnetic nanospheres and an all-solid-state cadmium-selective microelectrode

A highly sensitive potentiometric enzymatic aptasensing system for the detection of paralytic shellfish toxins (PSTs) is developed by integrating graphene-wrapped magnetic nanospheres (Fe3O4@SiO2@rGO) with an all-solid-state ion-selective microelectrode. The multilayered core-shell structure of Fe3O4@SiO2@rGO enhances the efficient adsorption of aptamer molecules tagged with cadmium sulfide (CdS) nanoparticles. These CdS-aptamer conjugates, when bound with PST molecules, can be desorbed from the Fe3O4@SiO2@rGO surface into the sample solution and subsequently digested by deoxyribonuclease I (DNase I). This digestion process releases the PST molecules for recirculation, significantly reducing the retention of CdS on the surface of Fe3O4@SiO2@rGO. After magnetic separation and acid dissolution, the released Cd2+ from the magnetic nanospheres are measured using an all-solid-state Cd2+-selective microelectrode, enabling sensitive potentiometric detection of PSTs. Using gonyautoxin 1/4 (GTX 1/4) as a model, the sensing system exhibits a linear concentration range from 5 to 150 pM and a low detection limit of 1.7 pM for GTX 1/4, and has been successfully applied in the analysis of seawater samples.

Development of novel DNA aptamers and colorimetric nanozyme aptasensor for targeting multi-drug-resistant, invasive Salmonella typhimurium strain SMC25

Invasive, biofilm-forming Non-typhoidal Salmonella (iNTS), propagating through the global food and water supply chain, presents a significant risk to food safety and public health. Developing a robust detection system is crucial for enabling point-of-care, affordable, and equipment-free identification of this pathogen throughout the supply chain. In this study, we screened a novel pool of ssDNA aptamers specific to a multidrug resistant iNTS strain SMC25, previously isolated from Indian poultry products in our earlier research. Through 13 rounds of whole-cell SELEX, we identified, characterized, and selected seven full-length aptamers (ST18, ST19, ST25, ST28, ST29, ST31, and ST32). Flow cytometric analysis reveals superior binding of ST25, ST28, ST29, and ST31. These aptamers were translated onto Nanozyme-based aptasensing system for efficient, cost-effective detection of SMC25. This system harnesses the aptamer-mediated, reversible peroxidase-like activity of gold nanoparticles (GNPs) to oxidize the TMB substrate into a one-electron oxidation state, resulting in a blue-colored Diamine charge transfer complex (DCTC). The catalytic process, coupled with GNP aggregation, induces a visible color change in the test mixture from ruby-red to blue. Post-SELEX truncations identified the optimal aptamer sequence (T_ST31), which selectively detected SMC25 in water with a limit of detection (LOD) of ∼10⁴ CFU/mL. Lower concentrations (10 CFU/mL) of SMC25 could be detected after non-selective enrichment within 120 min. This research introduces a novel pool of iNTS-specific aptamers along with a cost-effective (0.25 USD per sample) solution for colorimetric detection by the naked eye.

Disposable electrochemical aptasensor with mesoporous carbon spheres modified screen-printed dual-working electrodes for Pb2+ and Hg2+ detection

Electrochemical biosensing combined with screen-printed paper technology provides an effective strategy for the quantitative analysis of metal ions, particularly suitable for in-situ determination. In this study, a disposable, economical and user-friendly screen-printed dual-working electrodes (SPDEs) aptasensor system for the determination of lead ions (Pb2+) and mercury ions (Hg2+) was described. The sensor system consists of dual-working electrodes, a counter electrode and a reference electrode fabricated using screen printing technology. The aptasensor demonstrates high sensitivity and selectivity towards Pb2+ and Hg2+, owing to the larger specific surface area (1334.7 m2/g) and excellent conductivity of mesoporous carbon nanoparticles (MCNs). Additionally, the specific recognition ability and high affinity of G-quadruplex and T-Hg2+-T structures for Pb2+ and Hg2+, respectively, further enhance the performance. Under optimized experimental conditions, the aptasensor achieves a low limit of detection (LOD) of 0.088 ng/mL for Pb2+ and 0.0007 ng/mL for Hg2+ (S/N = 3), a wide linear range (0.1–1000.0 ng/mL for Pb2+ and 0.001–100.0 ng/mL for Hg2+), and high accuracy (relative standard deviation, RSD≤10.0 %) and selectivity. Importantly, the SPDEs aptasensor can detect Pb2+ and Hg2+ in a sample without competition and interference, achieving accuracy comparable to that of commercial inductively coupled plasma mass spectrometry (ICP-MS). These advantages make the SPDEs aptasensor highly suitable for practical applications in environmental monitoring, food safety, and clinical diagnosis.

Near-infrared light-driven lab-on-paper cathodic photoelectrochemical aptasensing for di(2-ethylhexyl)phthalate based on AgInS2/Cu2O/FeOOH photocathode

Di(2-ethylhexyl)phthalate (DEHP) is commonly released from plastics in aqueous environment, which can disrupt endocrine system and cause adverse effects on public health. There is a pressing need to highly sensitive detect DEHP. Herein, a near-infrared (NIR) light-driven lab-on-paper cathodic photoelectrochemical aptasensing platform integrated with AgInS2/Cu2O/FeOOH photocathode and “Y”-like ternary conjugated DNA nanostructure-mediated “ON-OFF” catalytic switching of hemin monomer-to-dimer was established for ultrasensitive DEHP detection. Profiting from the collaborative roles of the effective photosensitization of NIR-response AgInS2 and the fast hole extraction of FeOOH, the NIR light-activated AgInS2/Cu2O/FeOOH photocathode generated a markedly enhanced photocathodic signal. The dual hemin-labelled “Y”-like ternary conjugated DNA nanostructures made the hemin monomers separated in space and they maintained highly active to catalyze in situ generation of electron acceptors (O2). The hemin monomers were relocated in close proximity with the help of target-induced allosteric change of DNA nanostructures, which could spontaneously dimerize into catalytically inactive hemin dimers and fail to mediate electron acceptors generation, resulting in a decreased photocathodic signal. Therefore, the ultrasensitive DEHP detection was realized with a linear response range of 1 pM–500 nM and a detection limit of 0.39 pM. This work rendered a promising prototype to construct powerful paper-based photocathodic aptasensing system for sensitive and accurate screening of DEHP in aqueous environment.

Improving the detection accuracy of the dual SERS aptasensor system with uncontrollable SERS “hot spot” using machine learning tools

BackgroundSimultaneous detection of food contaminants is crucial in addressing the collective health hazards arising from the presence of multiple contaminants. However, traditional multi-competitive surface-enhanced Raman scattering (SERS) aptasensors face difficulties in achieving simultaneous accurate detection of multiple target substances due to the uncontrollable SERS “hot spots”. In this study, using chloramphenicol (CAP) and estradiol (E2) as two target substances, we introduced a novel approach that combines machine learning methods with a dual SERS aptasensor, enabling simultaneous high-sensitivity and accurate detection of both target substances. ResultsThe strategy effectively minimizes the interference from characteristic Raman peaks commonly encountered in traditional multi-competitive SERS aptasensors. For this sensing system, the Au@4-MBA@Ag nanoparticles modified with sulfhydryl (SH)-CAP aptamer and Au@DTNB@Ag NPs modified with sulfhydryl (SH)-E2 aptamer were used as signal probes. Additionally, Fe3O4@Au nanoflowers integrated with SH-CAP aptamer complementary DNA and SH-E2 aptamer complementary DNA were used as capture probes, respectively. When compared to linear regression random forest, and support vector regression (SVR) models, the proposed artificial neural network (ANN) model exhibited superior precision, demonstrating R2 values of 0.963, 0.976, 0.991, and 0.970 for the training set, test set, validation set, and entire dataset, respectively. Validation with ten spectral groups reported an average error of 244 μg L−1. SignificanceThe essence of our study lies in its capacity to address a persistent challenge encountered by traditional multiple competitive SERS aptasensors – the interference generated by uncontrollable SERS “hot spots” that hinders simultaneous quantification. The accuracy of the predictive model for simultaneous detection of two target substances was significantly improved using machine learning tools. This innovative technique offers promising avenues for the accurate and high-sensitive simultaneous detection of multiple food and environmental contaminants.

Green Synthesis of Ceria Nanoparticles from Cassava Tubers for Electrochemical Aptasensor Detection of SARS-CoV-2 on a Screen-Printed Carbon Electrode.

Green synthesis approaches for making nanosized ceria using starch from cassava as template molecules to control the particle size are reported. The results of the green synthesis of ceria with an optimum calcination temperature of 800 °C shows a size distribution of each particle of less than 30 nm with an average size of 9.68 nm, while the ratio of Ce3+ to Ce4+ was 25.6%. The green-synthesized nanoceria are applied to increase the sensitivity and attach biomolecules to the electrode surface of the electrochemical aptasensor system for coronavirus disease (COVID-19). The response of the aptasensor to the receptor binding domain of the virus was determined with the potassium ferricyanide redox system. The screen-printed carbon electrode that has been modified with green-synthesized nanoceria shows 1.43 times higher conductivity than the bare electrode, while those modified with commercial ceria increase only 1.18 times. Using an optimized parameter for preparing the aptasensors, the detection and quantification limits were 1.94 and 5.87 ng·mL-1, and the accuracy and precision values were 98.5 and 89.1%. These results show that green-synthesized ceria could be a promising approach for fabricating an electrochemical aptasensor.

In-situ construction of 1D β-FeOOH nanobelts/2D porous g-C3N4 heterojunction for enhanced “signal-on” photoelectrochemical aptasensing

Bisphenol A (BPA), a prevalent organic pollutant found in wastewater environment, is notorious for its resistance to natural degradation, raising significant ecological and human health concerns. In this study, a “signal-on” photoelectrochemical aptasensing system was designed for detecting BPA in real water samples with high specificity and sensitivity. One-dimensional (1D) β-FeOOH nanobelts were synthesized on a two-dimensional (2D) porous carbon nitride (g-C3N4) through an in-situ growth procedure. The β-FeOOH/g-C3N4 nanocomposites demonstrated superior photoelectric conversion efficiency due to several factors: (i) The 1D nanobelt-like structure of β-FeOOH shortens the charge transfer path within the nanocomposite, enabling directional and rapid migration of photoinduced charges from the interior to the surface. (ii) β-FeOOH possesses strong visible absorption capabilities, enhancing the utilization of g-C3N4 under photoexcitation, resulting in the generation of numerous photo-induced carriers. (iii) The in-situ formation of the β-FeOOH/g-C3N4 heterojunction establishes an intimate interfacial contact, facilitating the rapid separation and transfer of charges between β-FeOOH and g-C3N4. A photoelectrochemical aptasensing platform based on the photoactive material of β-FeOOH/g-C3N4 detects BPA with reduced photocurrent owing to the presence of BPA-aptamer macromolecules on the electrode surface. This BPA detection system exhibits excellent linearity over a wide concentration range from 10 pM to 10 nM, with high sensitivity (a detection limit of 3.5 pM), stability, specificity, and repeatability. Furthermore, this research offers a straightforward and rapid sensing platform for monitoring BPA enriched water environments.

Dual-signal fluorescence aptasensing system for adenosine triphosphate assisting by MoS2 nanosheets

Adenosine triphosphate (ATP) has an irreplaceable role in the maintenance of many physiological processes and biological functions, and can be employed as an indicator of many diseases. In this work, we constructed a simple and sensitive dual-signal fluorescence aptasensing system for ATP detection with berberine as the signal reporter, ATP-aptamer as the recognition unit and MoS2 nanosheets as the signal amplification. In the absence of ATP, berberine can bind to the single-stranded DNA (ssDNA) of ATP-aptamer and selectively assemble on the surface of MoS2 nanosheets, leading to the fluorescence quenching of bererbine based on the fluorescence resonance energy transfer, denoted by “OFF”. Accordingly, the fluorescence anisotropy signal is enhanced due to restriction on rotate of the fluorescent probe and denoted as “ON”. Conversely, in the presence of ATP, it specifically interacts with ATP-aptamer and switches the free-curled single-stranded of ATP-aptamer to the G-quadruplex structure of ATP-aptamer/ATP/berberine, causing the detachment from the surface of the MoS2 nanosheet. Accordingly, the fluorescence signal was reversed from “OFF” to “ON”, and the fluorescence anisotropy signal was turned “ON” to “OFF”. The developed aptasensing system achieved a desirable sensitivity of 40.0 nM with fluorescent mode, and of 20.8 nM with fluorescent anisotropic mode. The sensing system has demonstrated high quality detection performance in human serum sample, and obtained the satisfactory recovery results for fluorescent of 93.0–108.5%, fluorescent anisotropic of 96.4–106.7%.

Rational Design of Trident Aptamer Scaffold for Rapid and Accurate Monitoring of 25-Hydroxyvitamin D3 Metabolism in Living Cells.

The level of 25-hydroxyvitamin D3 [25(OH)VD3] in human blood is considered as the best indicator of vitamin D status, and its deficiency or excess can lead to various health problems. Current methods for monitoring 25(OH)VD3 metabolism in living cells have limitations in terms of sensitivity and specificity and are often expensive and time-consuming. To address these issues, an innovative trident scaffold-assisted aptasensor (TSA) system has been developed for the online quantitative monitoring of 25(OH)VD3 in complex biological environments. Through the computer-aided design, the TSA system includes an aptamer molecule recognition layer that is uniformly oriented, maximizing binding site availability, and enhancing sensitivity. The TSA system achieved the direct, highly sensitive, and selective detection of 25(OH)VD3 over a wide concentration range (17.4-12,800 nM), with a limit of detection of 17.4 nM. Moreover, we evaluated the efficacy of the system in monitoring the biotransformation of 25(OH)VD3 in human liver cancer cells (HepG2) and normal liver cells (L-02), demonstrating its potential as a platform for drug-drug interaction studies and candidate drug screening.

A near-infrared photoelectrochemical aptasensing system based on Bi2O2S nanoflowers and gold nanoparticles for high-performance determination of MCF-7 cells

Circulating tumor cells (CTCs) are commonly considered as the major cause of tumor metastasis and can eventually lead to death. Therefore, developing a high-performance method for the determination of CTCs is very significant for promoting the cancer survival rate. Photoelectrochemical biosensing systems have been extensively investigated and applied for bioassays. Herein, Bi2O2S nanoflowers were successfully prepared through a simple one-step hydrothermal method. After being integrated with gold nanoparticles with a diameter of ∼45 nm, AuNPs/Bi2O2S nanocomposites were coated onto an ITO electrode surface to build a photoelectrochemical sensing platform which can be excited with near-infrared light to produce photocurrent response. Subsequently, mercapto-group functionalized aptamer (SH-Apt) was fixed onto the AuNPs/Bi2O2S/ITO surface. Due to the overexpress of MUC1 protein in the cell membrane, MCF-7 cells were specifically trapped on the SH-Apt/AuNPs/Bi2O2S/ITO surface. The introduce of MCF-7 cells lead to an obvious decrease on the photocurrent response. The photocurrent variation shows a satisfied linear relationship to the logarithm of MCF-7 cells concentration ranged from 50 to 6 × 105 cell mL−1. The detection limit obtained is 17 cell mL−1. The PEC biosensor shows excellent sensitivity, selectivity and stability for sensing MCF-7 cells, even for determining MCF-7 cells in clinical serum samples.

Upconversion nanoparticle-based aptasensor for rapid and ultrasensitive detection of Staphylococcus aureus by low-speed centrifugation.

Opportunistic foodborne pathogens such as Staphylococcus aureus (S. aureus) can cause a wide variety of threats to public health. There is an urgent clinical need for a fast, simple, low-cost, and sensitive method. Here, we designed a fluorescence-based aptamer biosensor (aptasensor) for S. aureus detection using core-shell structured upconversion nanoparticles (CS-UCNPs) as a beacon. A S. aureus-specific aptamer was modified on the surface of CS-UCNPs for binding pathogens. The S. aureus bound to CS-UCNPs can then be isolated from the detection system by simple low-speed centrifugation. Thus, an aptasensor was successfully established for the detection of S. aureus. The fluorescence intensity of CS-UCNPs correlated with the concentration of S. aureus within the range of 6.36 × 102 to 6.36 × 108 CFU mL-1, resulting in the detected limit of S. aureus being 60 CFU mL-1. The aptasensor performed well in real food samples (milk) with a detection limit of 146 CFU mL-1 for S. aureus. Furthermore, we applied our aptasensor in chicken muscles for S. aureus detection, and compared it with the plate count gold standard method. There was no significant difference between our aptasensor and the plate count method within the detected limit, while the time for the aptasensor (0.58 h) was shorter than that of the plate count method (3-4 d). Therefore, we succeeded in the design of a simple, sensitive and fast CS-UCNPs aptasensor for S. aureus detection. This aptasensor system would have the potential for the detection of a wide range of bacterial species by switching the corresponding aptamer.

Portable chemiluminescence optical fiber aptamer-based biosensors for analysis of multiple mycotoxins

Multiple mycotoxin contamination in foodstuffs causes significant threat to human health especially considering their synergistic effects. Herein, we present a novel chemiluminescence optical fiber aptamer-based biosensors for ultrasensitive on-site assay of multiplex mycotoxins in food samples. The optical fiber aptasensor is developed based on the specific recognition of single-stranded binding protein (SSB) and mycotoxin aptamers for the selective analysis. Optical fibers are utilized not only as the carrier to immobilize SSB to prepare the sensing region, but also as the transducer of the chemiluminescent emission to detect the sensor response. Multiple-channel fiber sensors are coupled together toward the detector and a compact and portable design of the chemiluminescence optical fiber aptasensor system is proposed, allowing four mycotoxins (AFB1, FB1, OTA or ZEN) to be simultaneously determined from one run without any tedious operation procedure. The optical fiber aptasensor system can perform sensitive analysis with a wide detection range from pg/mL to 105 pg/mL and low limit-of-detection in the range of 0.015 pg/mL-0.423 pg/mL for different target mycotoxins. The method is successfully applied for simultaneous and sensitive detection of multiple mycotoxins in infant cereals, showing its practical application in on-site analysis of real food samples.

Competitive smartphone-based portable electrochemical aptasensor system based on an MXene/cDNA-MB probe for the determination of Microcystin-LR

A competitive smartphone-based portable electrochemical aptamer sensing system was developed for MC-LR detection. The platform was composed with a smartphone-controlled portable electrochemical system, a smartphone with custom application and a screen-printed carbon electrode (SPCE). The portable electrochemical system consisted a homemade ARM STM32 with chronoamperometry (CA), cyclic voltammetry (CV) and square wave voltammetry (SWV) modules that had a similar performance to commercial electrochemical workstations. The control of the portable electrochemical system, reception and visualization of the assay results were implemented by a smartphone. SPCE was modified by in situ electrodeposition with gold nanoparticles (AuNPs) and reduced graphene oxide (rGO). Subsequently, the aptamer was incubated onto the SPCE through Au-S bonds. The complementary DNA labeled with methylene blue (cDNA-MB) was conjugated onto the surface of MXene to form the probe for signal amplification. The competitive aptasensor was accomplished when the probe was complemented with the aptamer. The fabricated system exhibited the outstanding capability for the determination of MC-LR over a range of 0.0001–5 nM with a limit of detection of 4 × 10−5 nM. Furthermore, the system demonstrated acceptable stability, reproducibility, specificity and high recovery rate. The smartphone-based competitive aptasensor system exhibited the merits of portability, low-cost and fast-response to satisfy the demand for on-site detection of MC-LR.

Modular Assembly of a Concatenated DNA Circuit for In Vivo Amplified Aptasensing.

Probing endogenous molecular profiles in living entities is of fundamental significance to decipher biological functions and exploit novel theranostics. Despite programmable nucleic acid-based aptasensing systems across the breadth of molecular imaging, an aptasensing system enabling in vivo imaging with high sensitivity, accuracy, and adaptability is highly required yet is still in its infancy. Artificial catalytic DNA circuits that can modularly integrate to generate multiple outputs from a single input in an isothermal autonomous manner, have supplemented powerful toolkits for intracellular biosensing research. Herein, a multilayer nonenzymatic catalytic DNA circuits-based aptasensing system is devised for in situ imaging of a bioactive molecule in living mice by assembling branched DNA copolymers with high-molecular-weight and high-signal-gain based on avalanche-mimicking hybridization chain reactions (HCRs). The HCRs aptasensing circuit performs as a general and powerful sensing platform for precise analysis of a series of bioactive molecules due to its inherent rich recognition repertoire and hierarchical reaction accelerations. With tumor-targeting capsule encapsulation, the HCRs aptasensing circuit is specifically delivered into tumor cells and allowed the high-contrast imaging of intracellular adenosine triphosphate in living mice, highlighting its potential for visualizing these clinically important biomolecules and for studying the associated physiological processes.

Phosphorescence aptasensing system for sulfadimethoxine with petal-like MoS2 nanosheets for signal amplification

The fast and accurate detection of residual veterinary antibiotics in food has great significance for the ecological balance and human health. This study presents a room temperature phosphorescence aptasensing system for sulfadimethoxine (SDM) detection with sulfadimethoxine-aptamer (SDM-APT) modified manganese doped ZnS quantum dots (Mn-ZnS QDs) as the signaling and recognition unit. The signal amplification was achieved by petal-like molybdenum disulfide nano sheets (MoS2 NS). As the selective adsorption of single-stranded DNA (ssDNA) on MoS2 NS, SDM-APT-Mn-ZnS QDs are assembled on the surface of MoS2 NS, and lead to the efficient phosphorescence quenching of Mn-ZnS QDs. Once SDM is brought in the sensing system, the specific interaction between SDM-APT and SDM will switch the conformation of SDM-APT from random coil to hairpin structure, resulting in the exfoliation of SDM-APT-Mn-ZnS QDs from MoS2 NS, along with the phosphorescence recovery. This SDM detection system has a linear range from 2.0 ng/mL to 400 ng/mL with LOD as 0.91 ng/mL (S/N = 3) at the optimal experimental condition. The feasibility, specificity and recovery have been verified from the detection of real samples, interfering experiments and standard recovery experiments. The SDM detection system may also be applied to other residual veterinary drugs with different aptamers.

AuNP Aptasensor for Hodgkin Lymphoma Monitoring.

A liquid biopsy based on circulating small extracellular vesicles (SEVs) has not yet been used in routine clinical practice due to the lack of reliable analytic technologies. Recent studies have demonstrated the great diagnostic potential of nanozyme-based systems for the detection of SEV markers. Here, we hypothesize that CD30-positive Hodgkin and Reed–Sternberg (HRS) cells secrete CD30 + SEVs; therefore, the relative amount of circulating CD30 + SEVs might reflect classical forms of Hodgkin lymphoma (cHL) activity and can be measured by using a nanozyme-based technique. A AuNP aptasensor analytics system was created using aurum nanoparticles (AuNPs) with peroxidase activity. Sensing was mediated by competing properties of DNA aptamers to attach onto surface of AuNPs inhibiting their enzymatic activity and to bind specific markers on SEVs surface. An enzymatic activity of AuNPs was evaluated through the color reaction. The study included characterization of the components of the analytic system and its functionality using transmission and scanning electron microscopy, nanoparticle tracking analysis (NTA), dynamic light scattering (DLS), and spectrophotometry. AuNP aptasensor analytics were optimized to quantify plasma CD30 + SEVs. The developed method allowed us to differentiate healthy donors and cHL patients. The results of the CD30 + SEV quantification in the plasma of cHL patients were compared with the results of disease activity assessment by positron emission tomography/computed tomography (PET-CT) scanning, revealing a strong positive correlation. Moreover, two cycles of chemotherapy resulted in a statistically significant decrease in CD30 + SEVs in the plasma of cHL patients. The proposed AuNP aptasensor system presents a promising new approach for monitoring cHL patients and can be modified for the diagnostic testing of other diseases.

Competitive Smartphone-Based Portable Electrochemical Aptasensor System Based on an Mxene/Cdna-Mb Probe for the Determination of Microcystin-Lr

Competitive Smartphone-Based Portable Electrochemical Aptasensor System Based on an Mxene/Cdna-Mb Probe for the Determination of Microcystin-Lr

An electrochemical microfluidic biochip for the detection of gliadin using MoS2/graphene/gold nanocomposite.

Testing gluten content in food, before it reaches the consumer, becomes a major challenge where cross-contamination during processing and transportation is a very common occurrence. In this study, a microfluidic electrochemical aptasensing system for the detection of gliadin has been proposed. The fabrication of the sensor involves its modification by using a combination of 2D nanomaterial molybdenum disulfide (MoS2)/graphene with the addition of gold (Au) nanoparticles. Aptamers, a short string of nucleotide bases that are very specific to gliadin, were used in this sensor as the biomarker. The electrochemical standard reduction potential of the ferro-ferricyanide indicator was found to be ~ 530mV. This setup was integrated with a unique polydimethylsiloxane (PDMS)-based flexible microfluidic device for sample enrichment and portability. The results of this sensor show that the limit of detection was 7 pM. The total sample assay time was 20min and a good linear range was observed from 4 to 250nM with an R2 value of 0.982. Different flour samples sourced from the local market were tested and interfering molecules were added to ensure selectivity. The study shows promise in its applicability in real-time gliadin detection.Graphical abstract.

Development of a Novel ssDNA Sequence for a Glycated Human Serum Albumin and Construction of a Simple Aptasensor System Based on Reduced Graphene Oxide (rGO).

Diabetes is one of the top 10 global causes of death. About one in 11 global adults have diabetes. As the disease progresses, the mortality rate increases, and complications can develop. Thus, early detection and effective management of diabetes are especially important. Herein, we present a novel glycated human serum albumin (GHSA) aptamer, i.e., GABAS-01, which has high affinity and specificity. The aptamer was selected by reduced graphene oxide-based systematic evolution of ligands by exponential enrichement (rGO-based SELEX) against GHSA. After five rounds of selection through gradually harsher conditions, GABAS-01 with high affinity and specificity for the target was obtained. GABAS-01 was labeled by FAM at the 5′-end and characterized by measuring the recovery of a fluorescence signal that is the result of fluorescence quenching effect of rGO. As a result, GABAS-01 had low-nanomolar Kd values of 1.748 ± 0.227 nM and showed a low limit of detection of 16.40 μg/mL against GHSA. This result shows the potential application of GABAS-01 as an effective on-site detection probe of GHSA. In addition, these properties of GABAS-01 are expected to contribute to detection of GHSA in diagnostic fields.