The innovation of nanoparticles assumes a critical part of encouraging and giving open doors and conceivable outcomes to the headway of new era devices utilized as a part of biosensing. The focused ...on the quick and legitimate detecting of specific biomolecules using functionalized gold nanoparticles (Au NPs), and carbon nanotubes (CNTs) has turned into a noteworthy research enthusiasm for the most recent decade. Sensors created with gold nanoparticles or carbon nanotubes or in some cases by utilizing both are relied upon to change the very establishments of detecting and distinguishing various analytes. In this review, we will examine the current utilization of functionalized AuNPs and CNTs with other synthetic mixes for the creation of biosensor prompting to the location of particular analytes with low discovery cutoff and quick reaction.
•Wide range of and application of carbon nanotube and gold nanoparticles based on electrochemistry has been overviewed.•We have summarized and future outlooks the application of CNT and AuNP in different biosensing applications.•Wide range of readers will be benefited.
The progesterone (P4) level in body fluids can act as an indicator for early pregnancy diagnosis and offers insight into mammalian somatic function. In this work, we designed an antibody-aptamer ...based sandwich assay as a cathodic photoelectrochemical (PEC) biosensor for P4 detection. The composites of carbon dots and graphene oxide (CDs-GO) with favorable cathodic photocurrent response were used as photoactive materials on which the antibody (Ab) of P4 was immobilized. Meanwhile, high affinity truncated P4 aptamer was immobilized on Au–CuO–Cu2O to act as a bioconjugate. When P4 was present, the aptamer-Au-CuO-Cu2O bioconjugate could amplify the cathodic photocurrent of CDs-GO modified electrode through Ab-P4-aptamer interactions. Under optimum conditions, the cathodic photocurrent of the constructed PEC biosensor was found to increase linearly with P4 in a wide concentration range from 0.5 nM to 180 nM, with a low detection limit (3S/N) of 0.17 nΜ. The proposed cathodic PEC sensing platform demonstrated high selectivity, satisfying reproducibility, good stability. The sensor was successfully applied in the determination of P4 in human serum samples.
•An antibody-aptamer based sandwich assay for progesterone is proposed.•A cathodic photoelectrochemical biosensor with sandwich structure is designed.•Carbon dots-graphene oxide composites are used as photocathodic materials.•Aptamer-conjugated photoactive nanoparticles provide a signal-on sensing strategy.
Multiplexed point-of-care testing (xPOCT), which is simultaneous on-site detection of different analytes from a single specimen, has recently gained increasing importance for clinical diagnostics, ...with emerging applications in resource-limited settings (such as in the developing world, in doctors’ offices, or directly at home). Nevertheless, only single-analyte approaches are typically considered as the major paradigm in many reviews of point-of-care testing. Here, we comprehensively review the present diagnostic systems and techniques for xPOCT applications. Different multiplexing technologies (e.g., bead- or array-based systems) are considered along with their detection methods (e.g., electrochemical or optical). We also address the unmet needs and challenges of xPOCT. Finally, we critically summarize the in-field applicability and the future perspectives of the presented approaches.
Benefiting from emerging miniaturized and equipment-free nucleic acid testing (NAT) technologies, fully integrated NAT devices at point of care (POC) with the capability of “sample-in-answer-out” are ...proceeding at a break-neck speed to eliminate complex operations and reduce the risk of contamination. Like the development of polymerase chain reaction (PCR) technology (the standard technique for NAT), the detection signal of fully integrated NAT devices has evolved from qualitative to quantitative and recently to digital readout, aiming at expanding their extensive applications through gradually improving detection sensitivity and accuracy. This review firstly introduces the existing commercial products, and then illustrates recent fully integrated microfluidic devices for NAT at POC from the aspect of detection signals (i.e., qualitative, quantitative and digital). Importantly, the key issues of existing commercial products and the main challenges between scientific research and product development are discussed. On this basis, we envision that the MARCHED (miniaturized, automatic, reagent-preloaded, commercializable, high-throughput, environment-independent and disposable) NAT devices are expected to be realized in the near future.
•The key issues of existing commercial products and the main challenges for product development were discussed.•Advances in fully integrated NAT devices from qualitative to quantitative to digital readout were introduced.•The MARCHED NAT devices were proposed as prospective development tendency.
Cyanazine is a beneficial herbicide in the triazines group that inhibits photosynthesis in plants and monitoring of this herbicide is so important for study agriculture products. The present ...researches have been focused on monitoring of cyanazine by a straightforward and fast electrochemical strategy. Herein, to monitor the cyanazine level, Pt and Pd doped CdO nanoparticle decorated SWCNTs composite (Pt-Pd-CdO/SWCNTs) has been synthesized as a conductive mediator and characterized by EDS, SEM and TEM techniques. The Pt-Pd-CdO/SWCNTs and ds-DNA have been used for modification of the gold electrode (GE). Moreover, the oxidation signal of guanine relative to ds-DNA at the surface of Pt-Pd-CdO/SWCNTs/ds-DNA/GE has been considered as an bioelectroanalytical issue to monitoring cyanazine for the first time. Electrochemical impedance spectroscopic (EIS) signals have confirmed that the inclusion of Pt-Pd-CdO/SWCNTs at the surface of the GE has lowered charge-transfer resistance by ca.1.54 times and created a highly conductive state for monitoring of cyanazine in nanomolar concentration. On the other hand, differential pulse voltammograms (DPV) of Pt-Pd-CdO/SWCNTs/ds-DNA/GE have indicated a linear dynamic range of 4.0 nM–70 µM with a detection limit of 0.8 nM to the monitoring of cyanazine. In addition, the molecular docking study has emphasized that cyanazine herbicide is capable of binding to ds-DNA preferably at the guanine-cytosine rich sequences, and confirmed experimental results. In the final step, Pt-Pd-CdO/SWCNTs/ds-DNA/GE has been successfully utilized for the monitoring of cyanazine herbicide in food and water samples.
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•First electrochemical biosensor for monitoring of cyanazine herbicide.•cyanazine herbicide was detected by highly sensitive electrochemical biosensor.•Docking investigation confirm intercalation of guanine base in ds-DNA and cyanazine.
Continuous glucose monitoring from sweat and tears can improve the quality of life of diabetic patients and provide data for more accurate diagnosis and treatment. Current continuous glucose sensors ...use enzymes with a one-to-two week lifespan, which forces periodic replacement. Metal oxide sensors are an alternative to enzymatic sensors with a longer lifetime. However, metal oxide sensors do not operate in sweat and tears because they function at high pH (pH > 10), and sweat and tears are neutral (pH = 7). Here, we introduce a non-enzymatic metal oxide glucose sensor that functions in neutral fluids by electronically inducing a reversible and localized pH change. We demonstrate glucose monitoring at physiologically relevant levels in neutral fluids mimicking sweat, and wireless communication with a personal computer via an integrated circuit board.
Abstract
As part of our massive spectroscopic survey of 25 Galactic globular clusters with MUSE, we performed multiple epoch observations of NGC 3201 with the aim of constraining the binary fraction. ...In this cluster, we found one curious star at the main-sequence turn-off with radial velocity variations of the order of 100 km s− 1, indicating the membership to a binary system with an unseen component since no other variations appear in the spectra. Using an adapted variant of the generalized Lomb–Scargle periodogram, we could calculate the orbital parameters and found the companion to be a detached stellar-mass black hole with a minimum mass of 4.36 ± 0.41 M⊙. The result is an important constraint for binary and black hole evolution models in globular clusters as well as in the context of gravitational wave sources.
The opportunistic human pathogen Pseudomonas aeruginosa (Pa) causes several infections acquired in a healthcare setting. During initial stages of infection, Pa produces redox-active phenazine ...metabolites, including pyocyanin (PYO), 5-methylphenazine-1-carboxylic acid (5-MCA), and 1-hydroxyphenazine (OHPHZ), which have toxic effects on surrounding host cells and/or other microbes. Rapid and sensitive detection of these metabolites provides important evidence about the onset of Pa infections. Herein, we investigate differences in Pa phenazine production and dynamics in polymicrobial communities. Specifically, Pa was co-cultured with two pathogens of clinical relevance, Staphylococcus aureus (Sa) and Escherichia coli (Ec), which typically populate infection sites with Pa. Phenazine production rates and biosynthesis dynamics were electrochemically monitored during a 48-h period using recently developed transparent carbon ultramicroelectrode arrays (T-CUAs). Moreover, the effect on phenazine production rates and dynamics was explored in two growth media, lysogeny broth (LB) and tryptic soy broth (TSB). The concentrations of PYO and highly reactive 5-MCA were determined in different polymicrobial culture samples in both media. The results demonstrate that other bacterial pathogens noticeably influence Pa phenazine production and dynamics. In particular, Sa caused a decrease in phenazine production in TSB. However, the presence of Ec in polymicrobial samples drastically inhibited phenazine production rates in both LB and TSB. Conclusively, the media type significantly influences phenazine product distribution, especially in polymicrobial co-cultures, signifying the need for analytical standardization of simulation media in the study of polymicrobial communities.
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•Carbon ultramicroelectrode arrays were prepared to detect P. aeruginosa phenazine metabolites in polymicrobial environments.•P. aeruginosa cells were co-cultured with other clinically relevant pathogens in two different simulated growth media.•P. aeruginosa phenazine production and dynamics were electrochemically monitored and quantified over 48 hr.•Ultramicroelectrode arrays differentiate between phenazine products and intermediates produced in polymicrobial samples.
Multiple and sensitive detection of oncomiRs for accurate cancer diagnostics is still a challenge. Here, a synergetic amplification strategy was introduced by combining a MXene-based electrochemical ...signal amplification and a duplex-specific nuclease (DSN)-based amplification system for rapid, attomolar and concurrent quantification of multiple microRNAs on a single platform in total plasma. Synthesized MXene-Ti3C2Tx modified with 5 nm gold nanoparticles (AuNPs) was casted on a dual screen-printed gold electrode to host vast numbers of DNA probes identically co-immobilized on dedicated electrodes. Interestingly, presence of MXene provided biofouling resistance and enhanced the electrochemical signals by almost 4 folds of magnitude, attributed to its specious surface area and remarkable charge mobility. The 5 nm AuNPs were perfectly distributed within the whole flaky architect of the MXene to give rise to the electrochemical performance of MXene and provide the thiol-Au bonding feature. This synergetic strategy reduced the DSN-based biosensors' assay time to 80 min, provided multiplexability, antifouling activity, substantial sensitivity and specificity (single mutation recognition). The limit of detection of the proposed biosensor for microRNA-21 and microRNA-141 was respectively 204 aM and 138 aM with a wide linear range from 500 aM to 50 nM. As a proof of concept, this newly-developed strategy was coupled with a 96-well adaptive sensing device to successfully profile three cancer plasma samples based on their altered oncomiR abundances.
•A newly-developed synergetic MXene-based and duplex-specific nuclease (DSN)-based signal amplification system is reported.•Electrochemical detection of multiple miRNAs in a rapid (80 min) and attomolar fashion on a single electrode is reported.•MXene-Ti3C2Tx is synthesized and modified with 5 nm gold nanoparticles to boost the electrochemical signals by ~ 4 times.•DSN-based amplification system enhanced the assay sensitivity and provided single-mutation recognition ability.•The fabricated 96-well adaptive sensing device could profile three cancer plasma samples with a sound antifouling activity.
A competitive electrochemical aptasensor based on a cDNA-ferrocene/MXene probe is used to detect the breast cancer marker Mucin1 (MUC1). MXene (Ti3C2) nanosheets with excellent electrical ...conductivity and large specific surface area are selected as carriers for aptamer probes. The ferrocene-labeled complementary DNA (cDNA-Fc) is first bound on the surface of MXene to form a cDNA-Fc/MXene probe. Then, the MUC1 aptamer is fixed to the electrode by Au–S bonds. The sensing electrode is named Apt/Au/GCE. After the probe is complementary to the aptamer, a cDNA-Fc/MXene/Apt/Au/GCE aptasensor is fabricated. When the aptasensor is used for detection of MUC1, a competitive process happens between the cDNA-ferrocene/MXene probe and MUC1, which makes cDNA-Fc/MXene probe detach from the sensing electrode, resulting in a decrease in electrical signal. The difference in the corresponding peak current before and after the competition can be used to indicate the quantitative change in bound MUC1. The proposed competitive electrochemical aptasensor gives a wide linear range of 1.0 pM–10 μM and a low detection limit of 0.33 pM (S/N = 3), which is promising for clinical diagnosis.
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•An electrochemical aptasensor for detection of Mucin1 was developed.•MXene was severed as nanocarrier for cDNA-ferrocene probe.•The competitive recognition was utilized for the Mucin1 detection.
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