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The quest for solar-blind photodetectors with outstanding optoelectronic properties and weak signals detection capability is essential for their applications in the field of imaging, communication, warning, etc. To date, Ga2O3 has demonstrated potential for high-performance solar-blind photodetectors. However, the performance usually decays superlinearly at low light intensities due to carrier-trapping effect, which limits the weak signal detection capability of Ga2O3 photodetectors. Herein, a Ga2O3 solar-blind photodetector with ultra-thin absorbing medium has been designed to restrain trapping of photo-generated carriers during the transporting process by shortening the carrier transport distance. Meanwhile, multiple-beam interference is employed to enhance the absorption efficiency of the Ga2O3 layer using an Al/Al2O3/Ga2O3 structure. Based on the ultra-thin absorbing medium with enhanced absorption efficiency, a 7 × 7 flexible photodetector array is developed, and the detectivity can reach 1.7 × 1015 Jones, which is among the best values ever reported for Ga2O3 photodetectors. Notably, the performance of the photodetector decays little as the illumination intensity is as weak as 5 nW/cm2, revealing the capacity to detect ultra-weak signals. In addition, the flexible photodetector array can execute the functions of imaging, spatial distribution of light source intensity, real-time light trajectory detection, etc. Our results may provide a route to high-performance solar-blind photodetectors for ultra-weak light detection.

A series of probes KJ-x (x = 1−3) with carbon chains of different lengths based on the matrix of rhodamine B were engineered to detect Ag+ in aqueous solution in this work. Among them, KJ-1 is selected as the best option after in vitro investigation in view of its most sensitive and rapid response to Ag+, whose possible sensing mechanism is studied by experimental investigation and theoretical calculation. To identify the practical application of the probe, the detection of Ag+ in nonantibiotic fungicide Silver&Health and differentiation between normal hepatocytes and hepatoma cells using confocal imaging was conducted.

INTRODUCTION Evidence strongly suggests that soluble oligomers of amyloid beta protein (oAβ) help initiate the pathogenic cascade of Alzheimer's disease (AD). To date, there have been no validated assays specific for detecting and quantifying oAβ in human blood. METHODS We developed an ultrasensitive oAβ immunoassay using a novel capture antibody (71A1) with N-terminal antibody 3D6 for detection that specifically quantifies soluble oAβ in the human brain, cerebrospinal fluid (CSF), and plasma. RESULTS Two new antibodies (71A1; 1G5) are oAβ-selective, label Aβ plaques in non-fixed AD brain sections, and potently neutralize the synaptotoxicity of AD brain-derived oAβ. The 71A1/3D6 assay showed excellent dilution linearity in CSF and plasma without matrix effects, good spike recovery, and specific immunodepletion. DISCUSSION We have created a sensitive, high throughput, and inexpensive method to quantify synaptotoxic oAβ in human plasma for analyzing large cohorts of aged and AD subjects to assess the dynamics of this key pathogenic species and response to therapy.

Sensing devices own a vital role in supporting medical needs for the early recognition and diagnosis of diseases. In the past half-century, researchers have developed many biosensors for suitable applications, but only a limited number of biosensors are commercially available. The biosensors are biological recognition devices with high target specificity and high sensitivity leading to commercialization and wider acceptability in the existing market of health care industries. The nanosized materials are indispensable in the biomedical field because of their captivating characteristics like increased surface area and novel quantum effects. Nanoscale materials are very closer to biological molecules in size and own good specificity when used in biosensors. An overview of the working principles of various commonly used biosensors will be presented and a special emphasis is given to graphene-based biosensors to monitor the interaction of biological molecules. Graphene is one of the most superior nanocomposite that provides an opportunity for the best sensing platform in the field of bioanalysis. The supremacy of Graphene and GFET devices in biosensors for analyzing the biological samples and to provide consistent data is investigated using a simulation tool. Meanwhile, the performance behavior of nano-biosensors based on their dimensional influence is also explored. This review may provide constructive guidance for examining the interfacial interaction between nano composites and tiny biological components to impart knowledge or regulate things based on the application chosen.

Field-effect transistors (FET) using low-dimensional materials has attracted attention for detection of DNA hybridization. Here, we proposed a photocurrent-modulated FET sensor, where the I p h o t o c u r r e n t ( g a t e ) + I p h o t o c u r r e n t ( D N A ) dramatically enhance the response signal, I c u r r e n t , compared to a traditional FET sensor. The proposed sensor successfully detects DNA signals with a limit of detection (LOD) down to attomolar concentrations that is nearly 100x lower than a traditional FET sensor. The sensing mechanism is postulated and discussed. The results suggest that photo-coupled modulation opens new avenues for further development of the FET in biosensing applications.

In recent years, aging of the population has become a major social problem. Various types of sensor networks have been applied to elderly monitoring for addressing the care problems of the elderly living alone. We have also proposed elderly monitoring systems based on wireless sensor network devices. However, vision-based sensors can also cause a mental burden on the elderly’s privacy. Furthermore, the number of sensors must be reduced, if possible. Therefore, this study proposes an elderly monitoring system composed of two vibration sensors placed on the floor and a pneumatic sensor placed on the bed. Because both sensors include considerable measurement noise, we propose a human behavior estimation method that includes anomaly detection from time-series measurement data using an autocorrelation coefficient. Finally, we discuss the effectiveness and usability of the proposed system through several experimental results. The accuracy of walking detection reaches 94.4%, while the error of heartbeat detection is 3.01 bpm.

This article demonstrates the use of a p-MoS2/n-WO3 heterojunctions based ultra sensitive and selective chemiresistive ammonia sensor that operates at 200◦ C. Surprisingly, the composite based sens...

Antibiotics are a kind of chief contaminants in water, which have severe effects on the environment and mortal health. The achievement of easy and promising methods for antibiotic sensing is vastly desirable but still challenging. Fast, facile, and dependable recognition of these hazardous antibiotic contaminants by luminescent probes have importance in environmental safety. Herein, we synthesized a highly luminescent cadmium-based MOF [Cd(BPDC)(BP4VA)·2DMF]n (1) using 9,10-bis((E)-2-(pyridin-4-yl)vinyl)anthracene (BP4VA) and biphenyl-4,4′-dicarboxylic acid (H2BPDC) as ligands. The as-prepared compound is highly stable in water within a wide range of pH (2–12). The attained LOD values up to μM level shows higher selectivity towards antibiotics. 1 exhibits attractive detection sensitivity (Ksv = 106 M−1) towards selected antibiotics among earlier reported MOF-based luminescent probes.

A highly emissive and chemically stable multiple resonance (MR) effect-based organoboron derivative is designed and used as a fluoride ion probe for the first time, exhibiting a record low detection limit together with good selectivity and reversibility.

Skin-like ionogels have attracted much attention in artificial electronic skins and wearable sensors. However, it is challenging to develop ionogel-based multifunctional sensors that exhibit favorable durability, high sensitivity, and multisignal detection capability in diverse application environments. Herein, a mechanically durable, highly stretchable, and ultra-sensitive micronanostructured ionogel-based i-skin (MIS) with biomimetic hierarchical structures is fabricated. Moreover, with the highly conductive MIS as an ionic conductive layer, a MIS-based sensor with excellent superhydrophobicity has been developed by sandwiching the MIS film between two layers of acrylic elastomer film. By virtue of the well-designed surface structure and ingenious combination of various fascinating functions, the resultant MIS sensor features prominent sensing performance, including a wide sensing range of strain (0.1–400%), pressure (0.001–15 kPa), and temperature (25–95 °C), an ultralow detection limit (0.1% strain and 0.001 kPa pressure), a rapid response (67 ms), and ultra-durable stability (over 10 000 uninterrupted strain or compression cycles), showing competitive and even superior comprehensive performance to those of the existing ionogel sensors. Significantly, the versatile MIS sensor can not only be applied in wearable movement monitoring, multi-signal detection, and high-precision written stroke recognition, but is also capable of detecting subtle underwater vibrations caused by liquid drops or waves, a robotic fish, or human action, demonstrating its greater potential for diverse applications such as human health monitoring, human–machine interaction, marine environmental protection and biological research.

Even though there are reports on Transition Metal Dichalcogenide (TMD) based humidity sensors, one crucial thing that remains unnoticed is the electropositivity of the transition metal as it plays a vital role in humidity sensing. It is found that Re has an elevated value of electropositivity in comparison to widely explored transition metals, which signifies that rhenium disulfide has higher surface energy to attain water molecules and attach to the substrate. Surprisingly, there are fewer reports on ReS2 based humidity sensors and hence there is an urgent need to explore them. This work demonstrates the utilization of ReS2 on cellulose paper as a flexible, cost-effective, and environmentally friendly humidity sensor and its real time multifunctional applications. The ReS2 based humidity sensor exhibited an enhanced sensitivity (∼18.26), a quicker response time (∼142.94 s), and improved long-term stability (∼1300 s) in comparison to other TMDs as well as a commercially available humidity sensor. Furthermore, to validate different real time applications, the 2D ReS2 based flexible humidity sensor was utilized as a respiration sensor to detect slow, fast, and normal breath patterns, to estimate human skin conditions (dry, moist), and also to monitor baby diaper wetting. To distinguish various breath patterns, the frequency and amplitude of breath patterns are used which hold promising applications in non-invasive healthcare. Furthermore, a detailed sensing mechanism in terms of tunneling, proton hopping, and electron transfer is explained in the context of electropositivity of Re. The successful demonstration of an economical humidity sensor based on 2D ReS2 deposited on bio-degradable and flexible cellulose paper provides promising applications in flexible and wearable electronics.

Fabrication of high-performance sensory materials for the ultra-sensitive detection of antibiotics in water is of significant importance for community health and environmental quality. Herein, two Zn(II)-based metal–organic frameworks, {[Zn3(cbbi)2(bpe)(H2O)6]·2H2O}n (FCS-4) and {[Zn4(OH)2(cbbi)2(bpee)(H2O)4]·2H2O}n (FCS-5), were prepared hydrothermally and employed as chemosensors for the ultra-sensitive detection of nitrofuran antibiotics. Interestingly, different spacers and flexibility in the nitrogen-donor ancillary ligands resulted in different topological structures and fluorescence properties. FCS-5 exhibited much better sensitivity for nitrofurazone and nitrofurantoin detection, with limits of detection (LOD) of 0.22 and 0.15 ppm, respectively. Furthermore, mechanism exploration indicated that photon-induced electron transfer plays a key role in the ultra-sensitive detection of nitrofuran antibiotics.

Flexible devices for capturing anatomical and physiological movements are essential for improving the quality of life in, e.g., disease monitoring, physical rehabilitation, and assistance for people with cognitive disorders. They require high sensitivity, wide detection range, multi-functional applicability, etc. Nevertheless, the current devices and technologies face the challenge of simultaneous achievement of these features, mainly sensitivity and detection range, and thus their utility and applications are limited. Herein we report on the design and production of dual-microstructures of surface micro-bumps and internal hollow pores in a conductive material, an MXene, for obtaining a multifunctional high-performance pressure sensor. The designed sensor has ultra-high sensitivity (401.01 kPa−1, 0–12 kPa), a wide detection range (1.96 Pa to 100 kPa), and stability in a wide range of human physiological and anatomical movement types, including wide range movement (joint movement and gesture), slight movement (muscle movement and wrist pulse), and synchronous movement (respiration, carotid artery, and head movement). With data-mining methods, we show an ultra-sensitive ability to extract gesture behavioral information and physiological information from the sensor signals, and its implications for human health. These performances could be used as a shuttling pad for motor function assessment and dexterous human–robot interaction for rehabilitation robots and intelligent prosthetics.

An ultra-sensitive modified catalytic spectrophotometric method for vanadium determination in lubricating oils was developed. The method was based on catalytic effect of vanadium(V) on N,N-diethyl-p-phenylenediamine (DPD) oxidation by bromate. The oxidized product was spectrophotometrically measured at 550 nm after 30 min from starting the reaction. Thirty activators at different concentrations were examined to obtain the maximum sensitivity. 5-sulfosalicylic acid in the presence of citric acid recorded ultra-sensitivity with limits of detection and quantification of 5 and 17 pg/mL, respectively. These levels allow for direct determination of vanadium with no need of preconcentration approaches. The optimum concentrations (mmol/L) were as follows: 1.50 DPD, 40 bromate, 4.0 5-sulfosalicylic acid, and 60 citric acid. Excellent linearity, with a correlation coefficient of 0.9998, was obtained in the range of 0.02–0.50 ng/mL. The method was also precise with relative standard deviations of intra- and inter-day precision of 1.6 and 2.6%, respectively. The method was applied to different lubricating oil samples. The mean concentrations (ng/mL) and standard deviation (n = 3) values for virgin engine, hydraulic, and gear oils were 19.7 ± 0.27, 4.175 ± 0.175, and 10.085 ± 0.16, respectively, while those for used engine and gear oils were 599.77 ± 5.39 and 60.34 ± 2.18, respectively. The range of recovery values of vanadium in oil samples, which were obtained from spiking in all samples, were 100.1–103.8% indicating good accuracy.

Fluorescent probes have been widely employed in biological imaging and sensing. However, it is always a challenge to design probes with high sensitivity. In this work, based on rhodamine skeleton, we developed a general strategy to construct sensitivity-enhanced fluorescent probe with the help of theoretical calculation for the first time. As a proof of concept, we synthesized a series of HOCl probes. Experiment results showed that with the C-9 of pyronin moiety of rhodamine stabilized by an electron donor group, probe DQF-S exhibited an importantly enhanced sensitivity (LOD: 0.2 nmol/L) towards HOCl together with fast response time ( 650 nm) and large Stokes shift. Bioimaging studies indicated that DQF-S can not only effectively detect basal HOCl in various types of cells, but also be successfully applied to image tumor tissue in vivo. These results demonstrate the potential of our design as a useful strategy to develop excellent fluorescent probes for bioimaging.

This paper focuses on four structural parameters of reflective microfiber coupler (MFC), including taper length, taper width, coupling length, and coupling diameter. The influences of those paramet...

Tin oxide (SnO2) and 2 mol% Ce-doped SnO2 nanoparticles synthesized by the hydrothermal method to detect ammonia vapors at room temperature. X-ray diffraction investigations have been confirmed that the synthesized nanoparticles are polycrystalline in nature with tetragonal rutile phase. The particle size is determined using Scherrer’s formula and it is found to increase with the “Ce” dopant. Scanning electron microscopy observations reveal that these samples have spherical morphology composed of fine crystallites. The EDX spectra reveal the dominant presence of Sn and O in the case of pure SnO2 nanoparticles. Whereas in the case of doped sample, the EDX reveals the existence of Ce in lesser percentage in comparison with the Sn and O. Atomic force microscopy studies reveals that the root mean square roughness of the nanoparticles is increased from 4.4 nm to 15.3 nm due to the Ce dopant in the SnO2 matrix. Optical bandgap is calculated with the Tauc plot and it is increased with the doping of cerium atoms and it is due to the Burstein–Moss effect. Gas-sensing characterization has been performed using static liquid distribution technique against various volatile organic compounds (VOCs) such as ammonia, ethanol, methanol and toluene in the range of 1 to 25ppm at room temperature.

The human UDP-glucuronosyltransferase 1A1 (UGT1A1), one of the most essential conjugative enzymes, is responsible for the metabolism and detoxification of bilirubin and other endogenous substances, as well as many different xenobiotic compounds. Deciphering UGT1A1 relevance to human diseases and characterizing the effects of small molecules on the activities of UGT1A1 requires reliable tools for probing the function of this key enzyme in complex biological matrices. Herein, an easy-to-use assay for highly-selective and sensitive monitoring of UGT1A1 activities in various biological matrices, using liquid chromatography with fluorescence detection (LC-FD), has been developed and validated. The newly developed LC-FD based assay has been confirmed in terms of sensitivity, specificity, precision, quantitative linear range and stability. One of its main advantages is lowering the limits of detection and quantification by about 100-fold in comparison to the previous assay that used the same probe substrate, enabling reliable quantification of lower amounts of active enzyme than any other method. The precision test demonstrated that both intra- and inter-day variations for this assay were less than 5.5%. Furthermore, the newly developed assay has also been successfully used to screen and characterize the regulatory effects of small molecules on the expression level of UGT1A1 in living cells. Overall, an easy-to-use LC-FD based assay has been developed for ultra-sensitive UGT1A1 activities measurements in various biological systems, providing an inexpensive and practical approach for exploring the role of UGT1A1 in human diseases, interactions with xenobiotics, and characterization modulatory effects of small molecules on this conjugative enzyme., Graphical abstract Image 1, Highlights • An easy-to-use assay for sensing UGT1A1 activities has been developed, using LC-FD. • The newly developed assay is fully validated. • The LC-FD based assay is currently the most sensitive UGT1A1 activity assay.

Motivation T-cell receptors (TCRs) function to recognize antigens and play vital roles in T-cell immunology. Surveying TCR repertoires by characterizing complementarity-determining region 3 (CDR3) is a key issue. Due to the high diversity of CDR3 and technological limitation, accurate characterization of CDR3 repertoires remains a great challenge. Results We propose a computational method named CATT for ultra-sensitive and precise TCR CDR3 sequences detection. CATT can be applied on TCR sequencing, RNA-Seq and single-cell TCR(RNA)-Seq data to characterize CDR3 repertoires. CATT integrated de Bruijn graph-based micro-assembly algorithm, data-driven error correction model and Bayesian inference algorithm, to self-adaptively and ultra-sensitively characterize CDR3 repertoires with high performance. Benchmark results of datasets from in silico and experimental data demonstrated that CATT showed superior recall and precision compared with existing tools, especially for data with short read length and small size and single-cell sequencing data. Thus, CATT will be a useful tool for TCR analysis in researches of cancer and immunology. Availability and implementation http://bioinfo.life.hust.edu.cn/CATT or https://github.com/GuoBioinfoLab/CATT. Supplementary information Supplementary data are available at Bioinformatics online.

Background: The continual need for the development and validation of ultra-sensitive (low pg/ml) LC–MS/MS assays in the pharmaceutical industry is largely driven by the ultra-low analyte exposure or very low sample volume. Methodology: Strategies and systematic approaches for sensitivity enhancement are provided which cover all aspects of a LC–MS/MS bioanalysis. A case study where such strategies were applied for the validation of a 5.0 pg/ml assay for a STING agonist is discussed. Conclusion: Analytical protocols were developed to extract analytes from large volume of plasma samples (600 and 400 μl) with high throughput. The guidance provided in this publication can serve as a resource to influence LC–MS/MS method development activities.

Embolization therapy is an attractive strategy for antitumor therapy, especially for solid tumors. In vivo self-coagulation behavior holds great potential in a new type of tumor embolization therapy. However, spatiotemporal controllable in situ formation of thrombus in tumor is a challenge. Herein, an ultrasound (US)-responsive ultra-sensitive "thrombus constructor" (UUNC), which was prepared by loading thrombin into a nanobubble, and modified with NGR peptide on its surface, is rational designed for tumor embolization therapy. Benefiting from the targeting ability of NGR peptides to tumor neovascularization, UUNC efficiently enriched in tumor vessels, and then released thrombin rapidly to form thrombi in situ of tumor blood vessels in the presence of US. In vivo antitumor experiments demonstrated that UUNC could significantly lead to tumor cell apoptosis and necrosis, and the tumor growth inhibition rate (TGI) was 85.3% with a transient US in tumor, while maintain high stability, and no obvious thrombus was observed in normal tissues. UUNC holds an attractive potential for tumor embolization therapy via spatiotemporal controllable thrombus construct strategy.

Background: In this work, a novel and extra sensitive blood sample determination method for on-line monitoring of Daptomycin is represented. Materials and Methods: This technique is in accordance with the electro-membrane extraction (EME) and stripping fast Fourier transform continuous cyclic voltammetry (SFFTCCV) coupling. Briefly, the potential waveform had become constantly utilized over a Gold Electrode and the electrode impulse was acquired by taking away the base current and developing the current in the particular potential area of oxidation of sample. Results: This method was performed by utilizing a DC potential and migration of Daptomycin from the analyte fluid to the layer of 4-methyl-2-pentanol as well as following migration to the acceptor fluid. Conclusion: A low and valuable detection limit of 3.5 ng ml-1 and quantification limit of 10.2 ng ml-1 are considered as a part of the sensible results of this experiment. Furthermore, efficient linearity in the range of 10.0-600 ng ml-1 was observed.

Nanotechnology has a remarkable impact on the preclinical development of future medicines. However, the complicated preparation and systemic toxicity to living systems prevent them from translation to clinical applications. In the present report, we developed a polyepicatechin-based on/off switchable ultra-sensitive magnetic resonance imaging (MRI) visible theranostic nanoparticle (PEMN) for image-guided photothermal therapy (PTT) using our strategy of integrating polymerization and biomineralization into the protein template. We have exploited natural polyphenols as the near infra-red (NIR) switchable photothermal source and MnO2 for the MRI-guided theranostics. PEMN demonstrates excellent MRI contrast ability with a longitudinal relaxivity value up to 30.01 mM-1 s-1. PEMN has shown great tumor inhibition on orthotopic breast tumors and the treatment could be made switchable with an on/off interchangeable mode as needed. PEMN was found to be excretable mainly through the kidneys, avoiding potential systemic toxicity. Thus, PEMN could be extremely useful for developing on-demand therapeutics via'see it and treat it' means with distinguished MRI capability and on/off switchable photothermal properties.

Nanotheranostics (combined diagnosis and therapy) is emerging as an integral part of future therapeutic strategies. However, the development and fabrication of a nanotheranostic module involves multistep processes and always faces formulation challenges. The complexity involved in its multi-step formulations hinders its reproducible industrial production and clinical translation. Therefore, a facile synthesis of multifunctional nanotheranostics is critical to its translational success. In this report, we have developed a one-pot facile strategy to prepare a MRI-visible photothermal theranostic switchable module (T-SWITCH). These nanoparticles are synthesized through polymerization of levodopa together with the reduction of KMnO4 in the presence of silk sericin for the formation of manganese dioxide particles within the T-SWITCH. The synthesized T-SWITCH showed a uniform size distribution of around 95.77 nm and high longitudinal relaxivity coefficient (r1) of up to 61.94 mM-1 s-1. The reported r1 of the T-SWITCH is exceedingly higher than that of any other previously reported manganese-based contrast agents with first-rate in vitro and in vivo contrast enhancement capability. The T-SWITCH can be activated to switch its therapeutic mode using near-infrared (NIR) light. It exhibited strong excitable absorption in the safer and biological NIR window between 650 and 900 nm. We have validated the significant anti-cancer therapeutic efficacy of T-SWITCH both in vitro and in vivo through switchable photothermal therapy.

Zeranol (α-zearalanol) has been used as a growth promoter in livestock since 1969 in some non-EU countries; the residues of zeranol and its five analogues in animal origin foods may endanger human health due to their strong estrogenic and anabolic activities. Therefore, it is urgent to establish simple, rapid, real-time, broad-spectrum and high-sensitivity detection methods for the residues of zeranol and its analogues. In this study, an ultrasensitive indirect-competition enzyme-linked immunosorbent assay (ic-ELISA) was established for the rapid multi-residue detection of zeranol and its five analogues in cattle origin samples, which was based on a broad-spectrum monoclonal antibody (mAb) that specifically bound to zeranol and its analogues with high sensitivity. The half maximal inhibitory concentration (IC50) values for zeranol, β-zearalanol, zearalanone, α-zearalenol, β-zearalenol, and zearalenone were 0.103, 0.080, 0.161, 0.177, 0.254, and 0.194 ng mL−1, respectively, the recovery rates of cattle origin samples spiked with zeranol ranged from 79.2–104.2%, and the coefficient of variation (CV) values were less than 11.4%. Excellent correlation (R2 = 0.9845) was obtained between the results of HPLC-MS/MS and ic-ELISA. In conclusion, the developed ic-ELISA could be employed as an ultrasensitive and broad-spectrum detection method for monitoring trace ZEN residues in cattle origin foods.

In this research work, an anisotropic photonic crystal fiber (PCF) biosensor working on a refractive index (RI) variation and based on surface plasmon resonance (SPR) is presented. Liquid analytes (LA) having a RI within the range of 1.340 to 1.380 RIU are investigated from the proposed biosensor. Spectroscopy analysis of LA having RI values of 1.340 RIU, 1.360 RIU, and 1.380 RIU is performed from the developed sensing setup for modeling an ultrasensitive biosensor. The numerical analysis of the sensing parameters for the proposed sensor presents a maximum wavelength sensitivity (WS) of 20000 nm/RIU for x- polarization (x − pol.) and 18000 nm/RIU for y- polarization (y − pol.), respectively, using the wavelength interrogation technique. Maximum amplitude sensitivity (AS) of 2158 RIU−1 and 3167 RIU−1 is obtained for x − pol. and y − pol., respectively, using the amplitude interrogation technique. Maximum sensor resolution (SR) of 5.00 × 10−6 RIU and 5.55 × 10−6 RIU is obtained for x − pol. and y − pol., respectively. The linear relationship of the resonant wavelength (RW) with the RI produces R2 = 0.9972 and R2 = 0.9978, corresponding to a degree (2) for x − pol. and y − pol., respectively. The figure of merit (FOM) for x − pol. and y − pol. are 93.45 RIU−1 and 105.88 RIU−1, respectively. The sensing parameters have obtained the maximum value for the LA having a RI value of 1.375 RIU.

In this study, we investigated the axial coordination reaction between pyridine and zinc meso-tetra(4-sulfonatophenyl)porphyrin (ZnTPPS) incorporated in a transparent layered double hydroxide (LDH) film modified with 1-decanesulfonate (C10S) in an aqueous solution. The apparent equilibrium constant ($${K}_{11}$$ K 11 ) of the axial coordination reaction between pyridine and ZnTPPS incorporated in the transparent ZnTPPS/C10S/LDH film was approximately 260 times that of the corresponding reaction in an aqueous solution. The hydrophobisation of the LDH interlayer space by C10S, which led to the elimination of water molecules surrounding ZnTPPS and enabled the accumulation of pyridine molecules, was responsible for such a significant increase in the apparent $${K}_{11}$$ K 11 value. The developed film can detect pyridine in aqueous solutions with ultra-high sensitivity in the order of 10−5 mol/L through changes in the colour tone, which is comparable to the molecular detection ability of insect antennae. The sensing response was also observed at pyridine concentrations as low as 10−9 mol/L.

Background: Early recurrence of Plasmodium vivax is a challenge for malaria control in the field, particularly because this species is associated with lower parasitemia, which hinders diagnosis and monitoring through blood smear testing. Early recurrences, defined as the persistence of parasites in the peripheral blood despite adequate drug dosages, may arise from resistance to chloroquine. The objective of the study was to estimate early recurrence of P. vivax in the Brazilian Amazon by using a highly-sensitive detection method, in this case, PCR. Methods: An ultra-sensitive qPCR that targeted mitochondrial DNA was used to compare a standard qPCR that targeted 18S rDNA to detect early recurrence of P. vivax in very low densities in samples from patients treated with chloroquine. Results: Out of a total of 312 cases, 29 samples (9.3%) were characterized as recurrences, from which 3.2% (10/312) were only detected through ultra-sensitive qPCR testing. Conclusions: Studies that report the detection of P. vivax early recurrences using light microscopy may severely underestimate their true incidence.

Digital proximity ligation assay (PLA) detects single protein molecules with a pair of oligonucleotide-conjugated antibodies and digital PCR (dPCR) readout, which allows absolute quantitation of proteins in single cells with high sensitivity. The pipeline also allows simultaneous measurement of protein and mRNA from the same single cell. The sensitivity of the assay has been further improved with implementation of the assay on a microfluidic system, which enables quantitation of rare protein species, with expression level as low as ~3000 protein molecules per cell.

Identifying reliable biomarkers and ultra-sensitive techniques are crucial for the early detection of neurodegenerative disorders (NDDs) to improve the clinical diagnosis and development of effective disease-modifying treatments. Here, we discussed recent technological advancements that enabled scientists to monitor brain health by detecting biological molecules even at lower levels. These technologies enabled the detection of neurological biomarkers in blood, revolutionizing the diagnosis and prognosis of NDDs. Moreover, it provided a better understanding of disease pathology's long-term effects, resulting in fewer invasive tests, early diagnosis, faster drug development, and possibly more effective therapies as possible outcomes.

A key science priority for planetary exploration is to search for signs of life in our Solar System. Life-detection mission concepts aim to assess whether or not biomolecular signatures of life are present, which requires highly sensitive instrumentation. This introduces greater risk of false positives, and perhaps false negatives. Stringent science-derived contamination requirements for achieving science measurements on life-detection missions necessitate mitigation approaches that minimize, protect from, and prevent science-relevant contamination of critical surfaces of the science payload and provide high confidence to life-detection determinations. To this end, we report on technology advances that focus on understanding contamination transfer from pre-launch processing to end of mission using high-fidelity physics in the form of computational fluid dynamics and sorption physics for monolayer adsorption/desorption, and on developing a new full-spacecraft bio-molecular barrier design that restricts contamination of the spacecraft and instruments by the launch vehicle hardware. The bio-molecular barrier isolates the spacecraft from biological, molecular, and particulate contamination from the external environment. Models were used to evaluate contamination transport for a designs reference mission that utilizes the barrier. Results of the modeling verify the efficacy of the barrier and an in-cruise decontamination activity. Overall mission contamination tracking from launch to science operations demonstrated exceptionally low probability on contamination impacting science measurements, meeting the stringent contamination requirements of femtomolar levels of compounds. These advances will enable planetary missions that aim to detect and identify signatures of life in our Solar System.

Highly sensitive methods of optical and magnetic measurements have been developed and tested for analytical applications, medical diagnostics, food safety control, etc. The achieved detection limits are unique for express assays: DNA - 6 × 10-19 mol (without amplification), haptens - 16 fg/ml, protein biomarkers - 4 pg/ml.

We report the rapid detection of SARS-CoV-2 in infected patients (mid-turbinate swabs and exhaled breath aerosol samples) in concentrations as low as 60 copies/mL of the virus in seconds by electrical transduction of the SARS-CoV-2 S1 spike protein antigen via SARS-CoV-2 S1 spike protein antibodies immobilized on bilayer quasi-freestanding epitaxial graphene without gate or signal amplification. The sensor demonstrates the spike protein antigen detection in a concentration as low as 1 ag/mL. The heterostructure of the SARS-CoV-2 antibody/graphene-based sensor is developed through a simple and low-cost fabrication technique. Furthermore, sensors integrated into a portable testing unit distinguished B.1.1.7 variant positive samples from infected patients (mid-turbinate swabs and saliva samples, 4000-8000 copies/mL) with a response time of as fast as 0.6 s. The sensor is reusable, allowing for reimmobilization of the crosslinker and antibodies on the biosensor after desorption of biomarkers by NaCl solution or heat treatment above 40 °C.

The past few decades have witnessed the tremendous progress of human–machine interface (HMI) in communication, education, and manufacturing fields. However, due to signal acquisition devices’ limitations, the research on HMI related to communication aid applications for the disabled is progressing slowly. Here, inspired by frogs’ croaking behavior, a bionic triboelectric nanogenerator (TENG)‐based ultra‐sensitive self‐powered electromechanical sensor for muscle‐triggered communication HMI application is developed. The sensor possesses a high sensitivity (54.6 mV mm−1), a high‐intensity signal (± 700 mV), and a wide sensing range (0–5 mm). The signal intensity is 206 times higher than that of traditional biopotential electromyography methods. By leveraging machine learning algorithms and Morse code, the safe, accurate (96.3%), and stable communication aid HMI applications are achieved. The authors' bionic TENG‐based electromechanical sensor provides a valuable toolkit for HMI applications of the disabled, and it brings new insights into the interdisciplinary cross‐integration between TENG technology and bionics., Inspired by frogs’ croaking behavior, a bionic triboelectric nanogenerator‐based ultra‐sensitive self‐powered electromechanical sensor is developed for muscle‐triggered communication human–machine interface (HMI) application. The sensor possesses a high sensitivity, a high‐intensity signal, and a wide sensing range. By leveraging machine learning algorithms and Morse code, the safe, accurate, and stable communication aid HMI applications are achieved.

Clostridium difficile (C. diff) infection is one of the most contagious diseases associated with high morbidity and mortality rates in hospitalised patients. Accurate diagnosis can slow its spread by determining the most effective treatment. Herein, we report a novel testing platform as a proof-of-concept for the selective, sensitive, rapid and cost-effective diagnosis of C. diff infection (CDI) based on a duplex measurement. This was achieved by detecting two specific biomarkers, surface layer protein A (SlpA) and toxin B (ToxB), using a surface enhanced Raman scattering-based lateral flow assay (SERS-based LFA). The simultaneous duplex detection of SlpA with ToxB has not been described for the clinical diagnosis of CDI previously. The SlpA biomarker “AKDGSTKEDQLVDALA” was first reported by our group in 2018 as a species-specific identification tool. The second biomarker, ToxB, is the essential virulence biomarker of C. diff pathogenic strains and is required to confirm true infection pathogenicity. The proposed SERS-based LFA platform enabled rapid duplex detection of SlpA and ToxB on separate test lines using a duplex LF test strip within 20 minutes. The use of a handheld Raman spectrometer to scan test lines allowed for the highly sensitive quantitative detection of both biomarkers with a lowest observable concentration of 0.01 pg μL−1. The use of a handheld device in this SERS-based LFA instead of benchtop machine paves the way for rapid, selective, sensitive and cheap clinical evaluation of CDI at the point of care (POC) with minimal sample backlog.

Many methods for early diagnosis of the disease use biomarker tests, which measure indicators of biological state in body fluids or blood. However, a limitation of these methods is their low sensitivity to biomarkers. In this study, human serum albumin (HSA) based nanoparticles capable of encapsulating excess horseradish peroxidase (HRP) are synthesized and applied to the development of enzyme-linked immunosorbent assay (ELISA) kit with ultra-high sensitivity. The size of the nanoparticles and the amount of encapsulated enzyme are controlled by varying the synthesis conditions of pH and protein concentration, and the surface of the nanoparticles is modified with protein A (proA) to immobilize antibodies to the nanoparticles by self-assembly. Using the synthesized nanoparticles, the biomarker of breast cancer, thioredoxin-1, can be measured in the range of 10 fM to 100 pM by direct sandwich ELISA, which is 105 times more sensitive than conventional methods.

Objective and significance: The systemic bioavailability of tiotropium following administration via inhalation is known to be very low. A validated ultra-sensitive bioanalytical method with the low...

The most sensitive technologies for ultra-low-level analyses of long-lived radionuclides have been accelerator mass spectrometry and inductively coupled plasma mass spectrometry, reaching detection limits about 1 nBq/g. Together with underground operation of large volume HPGe detectors they have had great impact on underground physics experiments, approaching new frontiers in radioanalytics—a single atom counting.