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Abstract Background Application of numerous malaria control interventions has led to reduction in clinical malaria cases and deaths but also the realisation that asymptomatic parasite carriers play a key role in sustaining transmission. This study assessed the effectiveness of using the Ultra-sensitive NxTek eliminate RDT (uRDT) and conventional SD Bioline HRP2 RDT (cRDT) in diagnosing asymptomatic parasitaemia while measuring the impact of mass testing, treatment and tracking (MTTT) on the prevalence of asymptomatic malaria over a 1-year period in Ghana. Methods A total of 4000 targeted participants from two towns, Obom and Kofi Kwei, with their surrounding villages, were tested for asymptomatic malaria four times over the study period using uRDT (intervention) and the cRDT (control) respectively. Participants carrying malaria parasites were followed by home visit and phone calls for compliance to treatment, and filter paper blood blots collected from participants were used to determine true parasite carriage by PET-PCR. A mathematical model of the study site was developed and used to test the impact of test sensitivity and mass migration on the effect of MTTT. Results The start and end point sensitivities of the cRDT were 48.8% and 41.7% and those for the uRDT were 52.9% and 59.9% respectively. After a year of MTTTs, asymptomatic parasite prevalence, as determined by PCR, did not differ statistically in the control site (40.6% to 40.1%, P = 0.730) but decreased at the intervention site (55.9% to 46.4%, P

Highly performance flexible strain sensor is a crucial component for wearable devices, human‐machine interfaces, and e‐skins. However, the sensitivity of the strain sensor is highly limited by the strain range for large destruction of the conductive network. Here the quasi‐1D conductive network (QCN) is proposed for the design of an ultra‐sensitive strain sensor. The orientation of the conductive particles can effectively reduce the number of redundant percolative pathways in the conductive composites. The maximum sensitivity will reach the upper limit when the whole composite remains only "one" percolation pathway. Besides, the QCN structure can also confine the tunnel electron spread through the rigid inclusions which significantly enlarges the strain‐resistance effect along the tensile direction. The strain sensor exhibits state‐of‐art performance including large gauge factor (862227), fast response time (24 ms), good durability (cycled 1000 times), and multi‐mechanical sensing ability (compression, bending, shearing, air flow vibration, etc.). Finally, the QCN sensor can be exploited to realize the human‐machine interface (HMI) application of acoustic signal recognition (instrument calibration) and spectrum restoration (voice parsing). [ABSTRACT FROM AUTHOR]

Background: Application of numerous malaria control interventions has led to reduction in clinical malaria cases and deaths but also the realisation that asymptomatic parasite carriers play a key role in sustaining transmission. This study assessed the effectiveness of using the Ultra-sensitive NxTek eliminate RDT (uRDT) and conventional SD Bioline HRP2 RDT (cRDT) in diagnosing asymptomatic parasitaemia while measuring the impact of mass testing, treatment and tracking (MTTT) on the prevalence of asymptomatic malaria over a 1-year period in Ghana. Methods: A total of 4000 targeted participants from two towns, Obom and Kofi Kwei, with their surrounding villages, were tested for asymptomatic malaria four times over the study period using uRDT (intervention) and the cRDT (control) respectively. Participants carrying malaria parasites were followed by home visit and phone calls for compliance to treatment, and filter paper blood blots collected from participants were used to determine true parasite carriage by PET-PCR. A mathematical model of the study site was developed and used to test the impact of test sensitivity and mass migration on the effect of MTTT. Results: The start and end point sensitivities of the cRDT were 48.8% and 41.7% and those for the uRDT were 52.9% and 59.9% respectively. After a year of MTTTs, asymptomatic parasite prevalence, as determined by PCR, did not differ statistically in the control site (40.6% to 40.1%, P = 0.730) but decreased at the intervention site (55.9% to 46.4%, P < 0.0001). Parasite prevalence by RDT, however, indicated statistical reduction in the control site (25.3% to 22.3%, P = 0.017) and no change in the intervention site (35.1% to 36.0%, P = 0.614). The model predicted a mild effect of both diagnostic sensitivity and human movement in diminishing the impact of MTTT in the study sites. Conclusions: Asymptomatic parasite prevalence at the molecular level reduced significantly in the site where the uRDT was used but not where the cRDT was used. Overall, the uRDT exhibited higher sensitivity relative to the cRDT. Highly sensitive molecular techniques such as PET-PCR should be included in parasite prevalence estimation during MTTT exercises. [ABSTRACT FROM AUTHOR]

Abstract Highly performance flexible strain sensor is a crucial component for wearable devices, human‐machine interfaces, and e‐skins. However, the sensitivity of the strain sensor is highly limited by the strain range for large destruction of the conductive network. Here the quasi‐1D conductive network (QCN) is proposed for the design of an ultra‐sensitive strain sensor. The orientation of the conductive particles can effectively reduce the number of redundant percolative pathways in the conductive composites. The maximum sensitivity will reach the upper limit when the whole composite remains only “one” percolation pathway. Besides, the QCN structure can also confine the tunnel electron spread through the rigid inclusions which significantly enlarges the strain‐resistance effect along the tensile direction. The strain sensor exhibits state‐of‐art performance including large gauge factor (862227), fast response time (24 ms), good durability (cycled 1000 times), and multi‐mechanical sensing ability (compression, bending, shearing, air flow vibration, etc.). Finally, the QCN sensor can be exploited to realize the human‐machine interface (HMI) application of acoustic signal recognition (instrument calibration) and spectrum restoration (voice parsing).

Key biomarkers such as Brain Derived Neurotrophic Factor (BDNF) and Neurofilament light chain (NfL) play important roles in the development and progression of many neurological diseases, including multiple sclerosis, Alzheimer's disease, and Parkinson's disease. In these clinical conditions, the underlying biomarker processes are markedly heterogeneous. In this context, robust biomarker discovery is of critical importance for screening, early detection, and monitoring of neurological diseases. The difficulty of directly identifying biochemical processes in the central nervous system (CNS) is challenging. In recent years, biomarkers of CNS inflammatory response have been identified in various body fluids such as blood, cerebrospinal fluid, and tears. Furthermore, biotechnology and nanotechnology have facilitated the development of biosensor platforms capable of real-time detection of multiple biomarkers in clinically relevant samples. Biosensing technology is approaching maturity and will be deployed in communities, at which point screening programs and personalized medicine will become a reality. In this multidisciplinary review, our goal is to highlight clinical and current technological advances in the development of multiplex-based solutions for effective diagnosis and monitoring of neuroinflammatory and neurodegenerative diseases. The trend in the detection if BDNF and NfL. [ABSTRACT FROM AUTHOR]

Adenosine triphosphate (ATP) is closely related to the pathogenesis of certain diseases, so the detection of trace ATP is of great significance to disease diagnosis and drug development. Graphene field-effect transistors (GFETs) have been proven to be a promising platform for the rapid and accurate detection of small molecules, while the Debye shielding limits the sensitive detection in real samples. Here, a three-dimensional wrinkled graphene field-effect transistor (3D WG-FET) biosensor for ultra-sensitive detection of ATP is demonstrated. The lowest detection limit of 3D WG-FET for analyzing ATP is down to 3.01 aM, which is much lower than the reported results. In addition, the 3D WG-FET biosensor shows a good linear electrical response to ATP concentrations in a broad range of detection from 10 aM to 10 pM. Meanwhile, we achieved ultra-sensitive (LOD: 10 aM) and quantitative (range from 10 aM to 100 fM) measurements of ATP in human serum. The 3D WG-FET also exhibits high specificity. This work may provide a novel approach to improve the sensitivity for the detection of ATP in complex biological matrix, showing a broad application value for early clinical diagnosis and food health monitoring. [ABSTRACT FROM AUTHOR]

Wearable sensors are one of the key components in applications such as motion monitoring, smart medical care, and human-computer interaction systems. In the present work, we focus on the simultaneous improvements of flexible sensors in both performance and functionality. Here, with a porous fiber network of multi-walled carbon nanotubes (MWCNTs)–polydimethylsiloxane (PDMS) as an active layer, a flexible pressure sensor with ultra-high sensitivity and superior capability of identifying transverse shear force and temperature signals is designed and constructed. The fibral MWCNTs–PDMS piezoresistive layer was formed with a scouring pad (SP) fiber network as skeleton, and the PDMS thin layer formed by self-assembly can effectively increase the initial resistance. Attributing to the unique compressibility of the fibral porous network and the adjustable nanoscale contacts, the MWCNT-PDMS/SP sensor exhibits a wide detection range (0–360 kPa), and in particular, an ultra-high sensitivity (84,818.2 kPa–1 when <100 pa). Beyond the highly sensitive characteristics, the sensor also has a high shear-force sensitivity (GF = 6.15 under 0.05 N). The sensor can still maintain a relatively stable performance even after operating for more than 10,000 pressure cycles, showing as a potential candidate for the applications of electronic skin, intelligent robots, etc. [ABSTRACT FROM AUTHOR]

In photoacoustic and ultrasound imaging, optical transducers offer a unique potential to provide higher responsivity, wider bandwidths, and greatly reduced electrical and acoustic impedance mismatch when compared with piezoelectric transducers. In this paper, we propose a total-internal-reflection-based Fabry–Pérot resonator composed of a 12-nm-thick gold layer and a dielectric resonant cavity. The resonator uses the same Kretschmann configuration as surface plasmon resonators (SPR). The resonators were analyzed both theoretically and experimentally. The experimental results were compared with those for an SPR for benchmarking. The 1.9-μm-thick-PMMA- and 3.4-μm-thick-PDMS-based resonators demonstrated responsivities of 3.6- and 30-fold improvements compared with the SPR, respectively. The measured bandwidths for the PMMA, PDMS devices are 110 MHz and 75 MHz, respectively. Single-shot sensitivity of 160 Pa is obtained for the PDMS device. The results indicate that, with the proposed resonator in imaging applications, sensitivity and the signal-to-noise ratio can be improved significantly without compromising the bandwidth.

The arrival of surgical robots in high-end medical equipment is a landmark, and the realization of tactile sensation a major challenge in this important cutting-edge research field. Aiming to address this issue, we present ultra-sensitive ionic electronic skin in the form of flexible capacitive pressure sensors, which incorporate multistage bionic microstructures in ion gels for the purpose of monitoring the delicate operations of surgical robots. Significantly, the ionic skin exhibits an ultra-high sensitivity of 9484.3 kPa−1 (<15 kPa), and the sensitivity remains higher than 235 kPa−1 in the wide range of 15–155 kPa. The device has also achieved a detection limit as low as 0.12 Pa or, equivalently, 0.31 mg, fast response within 24 ms, and high robustness (loading/unloading for 5000 cycles without fatigue). The sensor facilitates the challenging task of tele-operated robotic threading, which exceeds the human tactile perception limit when threading a needle. We have also confirmed that ionic skin can be used in robot-assisted invasive surgery, such as incision/resection of tissues and suturing of wounds, providing tactile information to surgeons to improve operation success rates. The flexible ionic skin is capable of conforming to the various shapes of robotic manipulators, thus has great promise for applications in robotic dexterous manipulation, prosthetics and human–machine interfaces. [ABSTRACT FROM AUTHOR]

Recent advances in supercapacitive pressure sensors based on iontronic film have a significant capacitive response and a low detection limit due to their large capacitance change resulting from electrical double layer (EDL) and these pressure sensors are used to detect a wide range of pressure with high resolution for various applications such as prosthesis, wearable devices, and robotics. Thus, the enhancements to the EDL capacitive response are significantly important challenges for advanced applications with outstanding performances. Herein, an ultra‐sensitive and quick‐responsive hybrid‐supercapacitive iontronic pressure sensor using a novel sensing mechanism and facile fabrication technique is reported to overcome the limitations of the existing iontronic pressure sensors. As a sensing material, conductive polymer and carbon nanotube are incorporated into the iontronic film, as pseudo‐ and EDL‐capacitive material, respectively. Moreover, vinyl silica nanoparticle (VSNP) is used to decrease the recovery time by making the iontronic film quick‐response. The developed hybrid‐supercapacitive pressure sensor exhibited an ultra‐high sensitivity of 301.5 kPa−1 over a wide pressure range of up to 63.3 kPa along with a fast recovery time of ≈32 ms. It is believed that the proposed hybrid‐supercapacitive mechanism in iontronic film will significantly enhance the performance of conventional iontronic pressure sensors. [ABSTRACT FROM AUTHOR]

Transition metal oxide (TMO)-based nanomaterials are effectively utilized to fabricate clinically useful ultra-sensitive sensors. Different nanostructured nanomaterials of TMO have attracted a lot of interest from researchers for diverse applications. Herein, we utilized a hydrothermal method to develop porous nanosheets of cobalt oxide. This synthesis method is simple and low temperature-based. The morphology of the porous nanosheets like cobalt oxide was investigated in detail using FESEM and TEM. The morphological investigation confirmed the successful formation of the porous nanosheet-like nanostructure. The crystal characteristic of porous cobalt oxide nanosheets was evaluated by XRD analysis, which confirmed the crystallinity of as-synthesized cobalt oxide nanosheets. The uric acid sensor fabrication involves the fixing of porous cobalt oxide nanosheets onto the GCE (glassy carbon electrode). The non-enzymatic electrochemical sensing was measured using CV and DPV analysis. The application of DPV technique during electrochemical testing for uric acid resulted in ultra-high sensitivity (3566.5 µAmM−1cm−2), which is ~7.58 times better than CV-based sensitivity (470.4 µAmM−1cm−2). Additionally, uric acid sensors were tested for their selectivity and storage ability. The applicability of the uric acid sensors was tested in the serum sample through standard addition and recovery of known uric acid concentration. This ultrasensitive nature of porous cobalt oxide nanosheets could be utilized to realize the sensing of other biomolecules. [ABSTRACT FROM AUTHOR]

Thermotropic nematic liquid crystals (LC) have been utilized to sense/detect various analytes such as polymers, surfactants, lipids, etc. However, their use for protein detection depends on pre-adsorbed molecules, co-nematogens, or biomolecular agents for specificity. This approach impedes the platform's sensitivity with a detection limit for the folded proteins generally reported in the micromolar concentration range. Here, this work provides fundamental insights into the type of molecular interactions and their modulation that can drive ultrasensitive protein detection at an LC microdroplet/aqueous interface formed without adding an auxiliary co-nematogen. Using ultraviolet (UV) light treated 4-cyano-4'-pentylbiphenyl (5CB) LC and a flow-focused microfluidic device, we prepared different populations of monodisperse and highly negatively charged microdroplets in water. Adding an aqueous solution of various model proteins (α-synuclein, α-chymotrypsin, myoglobin, or bovine serum albumin, BSA) with different secondary structures and surface charges triggers a rapid radial- to bipolar-defect transition in these microdroplets. Isothermal titration calorimetry measurement and molecular dynamic simulation studies attribute this to the dominant electrostatic force-mediated adsorption of proteins at the LC/aqueous interface. Further, bioconjugation-based variation of protein surface charge allows tuning their detection limit. These findings can provide crucial physical cues for designing responsive LC systems and establishing a foundation for developing versatile, molecularly tailored, and highly specific biomolecular detection platforms., (© 2024 Wiley‐VCH GmbH.)

Hydrogen sulfide (H 2 S) as a common gas plays an important role in both industrial production and clinical pathology. Therefore, the realization of dynamic detection of trace H 2 S gas is of great significance. In this paper, an ultra-sensitive optical H 2 S sensor based on thermal conversion and ultraviolet differential optical absorption spectroscopy (UV-DOAS) is developed for dynamic measurement of H 2 S concentration. The H 2 S concentration can be derived from the measurement of the change in sulfur dioxide (SO 2) concentration before and after conversion. First, the evaluation method of SO 2 concentration based on UV-DOAS is presented, and the performance indicators of SO 2 concentration measurement are given. Second, the conversion characteristics of H 2 S under different temperatures and flow rates are investigated, and H 2 S can be efficiently converted to SO 2 in the flowing gas state by controlling the conversion conditions. Finally, the performance indicators of H 2 S sensor are evaluated. The sensor realizes H 2 S measurements with a detection limit of 14 ppb * m, while its sensitivity and reliability of measuring H 2 S concentration increase tenfold, making it suitable for dynamic measurements of trace H 2 S. In addition, the feasibility of the sensor for applications in atmospheric monitoring and human exhaled breath detection is demonstrated by practical tests. • An ppb-level H 2 S senor based on thermal conversion and UV-DOAS is reported. • Dynamic detection of H 2 S was achieved by introducing thermal conversion. • Over 98 % H 2 S converted to SO 2 by regulating thermal conversion conditions. • The minimum detection limit of H 2 S in air is 14 ppb per meter. • Practical tests proved the feasibility of the sensor to detect H 2 S in various fields. [ABSTRACT FROM AUTHOR]

Ribonuclease A (RNase A) plays significant roles in several physiological and pathological conditions and can be used as a valuable diagnostic biomarker for human diseases such as myocardial infarction and cancer. Hence, it is of great importance to develop a rapid and cost-effective method for the highly sensitive detection of RNase A. The significance of RNase A assay is further enhanced by the growing attention from the biotechnology and pharmaceutical industries to develop RNA-based vaccines and drugs in large part as a result of the successful development of mRNA vaccines in the COVID-19 pandemic. Herein, we report a label-free method for the detection of RNase A by monitoring its proteolytic cleavage of an RNA substrate in a nanopore. The method is ultra-sensitive with the limit of detection reaching as low as 30 fg per milliliter. Furthermore, sensor selectivity and the effects of temperature, incubation time, metal ion, salt concentration on sensor sensitivity were also investigated. [Display omitted] • A label-free nanopore single-molecule sensing system for detection of RNase A activity was developed. • The sensor was selective and highly sensitive with LOD reaching 30 fg per milliliter. • Temperature, incubation time, metal ion, salt concentration and especially salt gradient affected sensor sensitivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microfluidic fluorescence sensor can detect multiple heavy metals simultaneously. • The sensor can visual detection by "light up" different color emission. • The sensor arrays consist of organic molecular fluorescent probes. The majority of the environmental heavy metal ions exist in the form of multi-components, and the current single-to-single rapid detection methods are unable to meet the needs of simultaneous multi-component detection. Here, we have designed a microfluidic fluorescence sensor array by combining microfluidic sensing and organic fluorescent switches for the real-time and simultaneous visual detection of multi-component heavy metal ions. A series of "light-up" organic molecular probes was designed and synthesized, exhibiting a strong ability to bind heavy metal ions and resulting in the opening of probe fluorescence. Meanwhile, we design microfluidic sensor plate, the patterned path of the microfluidic plate has drainage channel wall and 2.70° downward slope, which can enable the samples to quickly reach the detection area. By loading organic molecular probes into the detection area, the microfluidic sensor array achieves simultaneous detection of four heavy metal ions. Combined with intelligent terminal, read and analyze the RGB color mode (RGB) results of detection, obtain quantitative information. The microfluidic fluorescence sensor array developed here can meet the requirements for in situ and semi-quantitative detection of a range of heavy metal ions with a low detection limit, fast reaction speed, and without the need for pretreatment. It represents a novel engineering technology approach for real-time detection of multi-components in the environment. [ABSTRACT FROM AUTHOR]

Over 3 in 4 adults with diabetes live in low- and middle-income counties and health expenditure also increased 316% over the last 15 years. In this regard, we fabricate low cost, reusable and rapid detection of diabetes sensor based on zinc oxide rod inserted ruthenium-doped carbon nitride (ZnO–g–Ru–C3N4) modified sensor device. Developed sensor device physically and electrochemically characterized using X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), chronoamperometry (CA) and differential pulse voltammetry (DPV). Sensing device as an effective enzyme-free glucose detection with high sensitivity (346 μA/mM/cm2) over the applied lower potential of +0.26 V (vs. Ag/AgCl), fast response (3 s) and broad linear range of (2–28) mM, coupled with a lower limit of detection (3.5 nM). The biosensing device gives better anti-interference ability with justifiable reproducibility, reusability (single electrode re-use 26 times in physiological buffer and 3 times in serum) and stability. Moreover, the real-time applicability of the sensor device was evaluated in human blood, serum and urine samples. [ABSTRACT FROM AUTHOR]

Conductive hydrogels have drawn increasing attention, but their applications are severely hindered due to insufficient sensitivities at tiny strains and poor recovery ratio upon external loads. Herein, a poly(vinyl alcohol)/aluminum sulfate composite hydrogel (T‐PVA‐Al) was designed to address this issue by introducing aluminum sulfate into poly(vinyl alcohol) aqueous solution, followed with three freezing–thawing cycles. The triply dynamic knots (hydrogen bonds, crystalline regions, and coordination interactions) worked in tandem to achieve high resilience (94% recovery ratio after 100 cycles) and fatigue resistance. Remarkably, the introduction of the immobile Al3+ cation and free sulfate (SO42−) anion endowed the T‐PVA‐Al hydrogel with outstanding sensitivity (a gauge factor=13.9, at 0.2% strain). It could precisely and quickly monitor external stress as low as 0.5 kPa, superior to most conductive hydrogels. Notably, the hydrogel sensor possessed the capacity to precisely and reliably detect subtle variations, for example, gentle finger touching, making it an ideal candidate for human‐motion detections, artificial skins, and wearable devices. [ABSTRACT FROM AUTHOR]

Abstract Background The use of molecular diagnostics has revealed an unexpectedly large number of asymptomatic low-density malaria infections in many malaria endemic areas. This study compared the gains in parasite prevalence obtained by the use of ultra-sensitive (us)-qPCR as compared to standard qPCR in cross-sectional surveys conducted in Thailand, Brazil and Papua New Guinea (PNG). The compared assays differed in the copy number of qPCR targets in the parasite genome. Methods Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) parasites were quantified by qPCR amplifying the low-copy Pf_ and Pv_18S rRNA genes or the multi-copy targets Pf_varATS and Pv_mtCOX1. Cross-sectional surveys at the three study sites included 2252 participants of all ages and represented different transmission intensities. Results In the two low-transmission areas, P. falciparum positivity was 1.3% (10/773) (Thailand) and 0.8% (5/651) (Brazil) using standard Pf_18S rRNA qPCR. In these two countries, P. falciparum positivity by Pf_varATS us-qPCR increased to 1.9% (15/773) and 1.7% (11/651). In PNG, an area with moderate transmission intensity, P. falciparum positivity significantly increased from 8.6% (71/828) by standard qPCR to 12.2% (101/828) by us-qPCR. The proportions of P. falciparum infections not detected by standard qPCR were 33%, 55% and 30% in Thailand, Brazil and PNG. Plasmodium vivax was the predominating species in Thailand and Brazil, with 3.9% (30/773) and 4.9% (32/651) positivity by Pv_18S rRNA qPCR. In PNG, P. vivax positivity was similar to P. falciparum, at 8.0% (66/828). Use of Pv_mtCOX1 us-qPCR led to a significant increase in positivity to 5.1% (39/773), 6.4% (42/651) and 11.5% (95/828) in Thailand, Brazil, and PNG. The proportions of P. vivax infections missed by standard qPCR were similar at all three sites, with 23%, 24% and 31% in Thailand, Brazil and PNG. Conclusion The proportional gains in the detection of P. falciparum and P. vivax infections by ultra-sensitive diagnostic assays were substantial at all three study sites. Thus, us-qPCR yields more precise prevalence estimates for both P. falciparum and P. vivax at all studied levels of endemicity and represents a significant diagnostic improvement. Improving sensitivity in P. vivax surveillance by us-qPCR is of particular benefit, because the additionally detected P. vivax infections signal the potential presence of hypnozoites and subsequent risk of relapse and further transmission.

This work reports a vertically extended drain double gate Si0.5Ge0.5 source tunnel FET for the biomolecules detection using its electrical properties modulation in presence of biomolecules like cell, DNA, protein, etc. The reported biosensor has a dual source of Si0.5Ge0.5 and two cavities above each source-channel interface for the immobilization of biomolecules. This immobilization modulates the screening/tunneling length and energy range available for tunneling due to the dielectric constant and charge density variations of the biomolecules. The dual cavity structure increases the control of biomolecules on the source to channel tunneling probability and thus realizes an increased control on electrical performance parameters of the biosensor enabling it to have a higher sensitivity towards the biomolecules. Further, the cavity length of the reported biosensor is kept as 45 nm making it suitable for large sized biomolecules and polymers detection also. Our study demonstrates that the reported biosensor structure is resilient towards the process variations and temperature effects. Moreover, the effect of dielectric modulation and charge density modulation has also been analyzed in terms of the variation in the drive current, ON state current, threshold voltage, transconductance, and sub-threshold slope (SS). The sensitivity of the reported biosensor is also compared with the existing biosensors and it is found to be highly sensitive. [ABSTRACT FROM AUTHOR]

Dielectric elastomer is a very popular composite material used for different applications. Calcium copper titanate (CCTO) particles have a high dielectric constant, while polydimethylsiloxane (PDMS) is a commonly used flexible elastomer with good elastic property and durable chemical resistance, and their composite has shown an important and unique character for the fabrication of the pressure/force sensor. To improve the sensitivity of the capacitive sensor, various elastomers’ microstructures have been introduced; but the methods used to manufacture microstructures in PDMS have so far been more difficult, requiring special equipment or hazardous chemicals such as strong acids and alkalis, otherwise, the sponge-like structures produced are slightly larger and cannot be applied to very small scenes. In this report, the extraction method was used to manufacture porous microstructures of the PDMS with multiple porosities; the influence of different porosities and pore sizes on the sensitivity of capacitive pressure sensors, which can increase the sensitivity of capacitive pressure sensors, the measuring force range, and also applied to tiny scenes, were explored. Additionally, the current methodology for manufacturing porous PDMS composite membranes is also suitable for the manufacture of other thinner PDMS composite porous membranes.

Inorganic pyrophosphatase (PPase) is key enzyme playing a key role in biochemical transformations such as biosynthesis of DNA and RNA, bone formation, metabolic pathways associated with lipid, carbohydrate and phosphorous. It has been reported that lung adenocarcinomas, colorectal cancer, and hyperthyroidism disorders can result from abnormal level of PPase. Therefore, it is of notable significance to develop simple and effective real time assay for PPase enzyme activity monitoring for screening of many metabolic pathways as well as for early disease diagnosis. The fluorometric detection of PPase enzyme in near infrared region-1 (NIR-1) has been carried out using bimetallic nanoclusters (LA@AuAg NCs). The developed sensing strategy was based on quenching of fluorescence intensity of LA@AuAg NCs upon interaction with copper (Cu2+) ions. The off state of LA@AuAg_Cu2+ ensemble was turned on upon addition of pyrophosphate anion (PPi) due to strong binding interaction between PPi and Cu2+. The catalytic conversion of PPi into phosphate anion (Pi) in the presence of PPase led to liberation of Cu2+ ions, and again quenched off state was retrieved due to interaction of free Cu2+ with LA@AuAg NCs. The ultrasensitive detection of PPase was observed in the linear range of 0.06–250 mU/mL with LOD as 0.0025 mU/mL. The designed scheme showed good selectivity towards PPase enzyme in comparison to other bio-substrates, along with good percentage recovery for PPase detection in real human serum samples. The developed NIR based assay is ultrasensitive, highly selective and robust for PPase enzyme and can be safely employed for other enzymes detection. This highly sensitive nature of biosensor was result of involvement of fluorescence-based technique and synergistic effect of dual metal in NIR based bimetallic NCs. Moreover, owing to the emission in NIR domain, in future, these nanoclusters can be safely employed for many biomedical applications for In vivo studies. [Display omitted] • Sensing strategy for multicomponent detection; Cu2+, PPi anion and PPase enzyme. • Bimetallic LA@AuAg NCs as NIR based fluorometric nanoprobe. • Developed sensor depicted lowest LOD of 0.0025 mU/mL for PPase enzyme. • Selective and specific approach for PPase in presence of other biosubstrates. • Highly robust and good percentage recovery in real human serum. [ABSTRACT FROM AUTHOR]

In the contemporary era of scientific and medical advancements, the accurate and ultra-sensitive detection of proteins, nucleic acids and metabolites plays a pivotal role in disease diagnosis and treatment monitoring. Single-molecule detection technologies play a great role in achieving this goal. In recent years, digital detection methods based on single molecule arrays (SIMOA) have brought groundbreaking contributions to the field of single-molecule detection. By confining the target molecules to femtoliter-sized containers, the SIMOA technology achieves detection sensitivity of attomolar. This review delves into the historical evolution and fundamentals of SIMOA technology, summarizes various approaches to optimize its performance, and describes the applications of SIMOA for the ultrasensitive detection of biomarkers for diseases such as cancer, COVID-19, and neurological disorders, as well as in DNA detection. Currently, some SIMOA technologies have been realized for high-throughput and multiplexed detection. It is believed that SIMOA technology will play a significant role in medical monitoring and disease prevention in the future. [Display omitted] • Introduction of SIMOA principle in the enhancement of the sensitivity down to single molecule. • Exploration of diverse applications of SIMOA in the ultra-sensitive detection of disease biomarkers. • Prospection of the challenges and the possible development of SIMOA. [ABSTRACT FROM AUTHOR]

Sensitivity and multi‐directional motivation are major two factors for developing optimized humidity‐response materials, which are promising for sensing, energy production, etc. Organic functional groups are commonly used as the water sensitive units through hydrogen bond interactions with water molecules in actuators. The multi‐coordination ability of inorganic ions implies that the inorganic ionic compounds are potentially superior water sensitive units. However, the particle forms of inorganic ionic compounds produced by classical nucleation limit the number of exposed ions to interact with water. Recent progress on the inorganic ionic oligomers has broken through the limitation of classical nucleation, and realized the molecular‐scaled incorporation of inorganic ionic compounds into an organic matrix. Here, the incorporation of hydrophilic calcium carbonate ionic oligomers into hydrophobic poly(vinylidene fluoride) (PVDF) is demonstrated. The ultra‐small calcium carbonate oligomers within a PVDF film endow it with an ultra‐sensitive, reversible, and bidirectional response. The motivation ability is superior to other bidirectional humidity‐actuators at present, which realizes self‐motivation on an ice surface, converting the chemical potential energy of the humidity gradient from ice to kinetic energy. [ABSTRACT FROM AUTHOR]

Over 3 in 4 adults with diabetes live in low- and middle-income counties and health expenditure also increased 316% over the last 15 years. In this regard, we fabricate low cost, reusable and rapid detection of diabetes sensor based on zinc oxide rod inserted ruthenium-doped carbon nitride (ZnO–g–Ru–C3N4) modified sensor device. Developed sensor device physically and electrochemically characterized using X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), chronoamperometry (CA) and differential pulse voltammetry (DPV). Sensing device as an effective enzyme-free glucose detection with high sensitivity (346 μA/mM/cm2) over the applied lower potential of +0.26 V (vs. Ag/AgCl), fast response (3 s) and broad linear range of (2–28) mM, coupled with a lower limit of detection (3.5 nM). The biosensing device gives better anti-interference ability with justifiable reproducibility, reusability (single electrode re-use 26 times in physiological buffer and 3 times in serum) and stability. Moreover, the real-time applicability of the sensor device was evaluated in human blood, serum and urine samples.

In this work, an ultra-sensitive and highly-specific electrochemical immunosensor was developed based on three-dimensional graphene/nickel foam (GF) decorated with gold nanoparticles (AuNPs) for the detection of Neutrophil Gelatinase-Associated Lipocalin (NGAL), a biomarker of Acute Kidney Injury (AKI). A low NGAL limit of detection (LOD) of 42 pg/ml and a linear range (LR) of 0.05–210 ng/ml were achieved. Though several electrode platforms have been proposed, either LOD or LR are limited for each method. Our platform can achieve low LOD while keeping broad LR of sensing. Self-Assembled-Monolayer (SAM) and 11-mercaptoundecanoic acid (11-MUA) were used to assist antibody binding on AuNPs. Electrochemical determination of NGAL were conducted using cyclic voltammetry and chronoamperometry on ferri/ferrocyanide redox measurement. Specificity was tested for NGAL detection against uric acid and creatinine interference. The attained performances might be ascribed to large specific surface area of GF and AuNPs, improved electron transfer from analyte via graphene‑nickel‑gold electric dipole enhancement. The results demonstrated the proposed platform was potential for ultra-sensitive, highly specific, non-invasive and real-time electrochemical detection of NGAL.

Septicemia and bacteremia are serious infections in the bloodstream. Thus, time-saving and ultra-sensitive pathogenic bacteria detection is highly required. Herein, we constructed gold nanoparticle-modified polystyrene microspheres (Au/PS) as plasmon-coupled microcavities to realize simultaneous detection of Staphylococcus aureus and Escherichia coli based on a fluorescence and surface-enhanced Raman spectroscopy (SERS) dual-mode method. Fluorescence imaging, serving as a means for assistant validation and rapid screening, was carried out to achieve qualitative and semi-quantitative determination, which gave us visual information of the existence and distribution of the target bacteria. Meanwhile, SERS test was conducted to realize ultra-sensitive quantitative detection. The evanescent wave aroused from total internal reflection in PS microcavities coupled with the localized electromagnetic field from surface plasmons of gold nanoparticles to improve light-matter interaction synergistically, leading to an enhancement factor of 2.25 × 1011 for SERS sensing. The whole measurement was carried out in a typical sandwich assay of "capture probe-target bacteria-signal probe." As a result, calibrated concentration response curves demonstrated the sensitive quantitative detection with the limit of detection (LOD) of 3 cfu/mL for S. aureus and 2 cfu/mL for E. coli. This rapid, ultra-sensitive, and visual sensing method was further developed for dual-bacteria detection in the whole blood samples. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract A novel pH-responsive Ag@polyacryloyl hydrazide (Ag@PAH) nanoparticle for the first time as a surface-enhanced Raman scattering (SERS) substrate was prepared without reducing agent and end-capping reagent. Ag@PAH nanoparticles exhibited an excellent tunable detecting performance in the range from pH = 4 to pH = 9. This is explained that the swelling-shrinking behavior of responsive PAH can control the distance between Ag NPs and the target molecules under external pH stimuli, resulting in the tunable LSPR and further controlled SERS. Furthermore, Ag@PAH nanoparticles possessed an ultra-sensitive detecting ability and the detection limit of Rhodamine 6G reduced to 10−12 M. These advantages qualified Ag@PAH NP as a promising smart SERS substrate in the field of trace analysis and sensors.

Quantification of ultra-trace analytes in complex biological samples using micro-solid-phase extraction followed by direct detection with internal extractive electrospray ionization mass spectrometry (μSPE–iEESI–MS) was demonstrated. 1-Hydroxypyrene (1-OHP) and papaverine at attomole levels in human raw urine samples were analyzed under negative and positive ion detection mode, respectively. The μSPE was simply prepared by packing a disposable syringe filter with octadecyl carbon chain (C18)-bonded micro silica particles, which were then treated as the "bulk sample" after the analytes were efficiently enriched by the C18 particles. Under the optimized experimental conditions, the analytes were readily eluted by isopropanol/water (80/20, V/V) at a high voltage of ± 4.0 kV, producing analyte ions under ambient conditions. The limit of detection (LOD) was 0.02 pg/L (9.2 amol) for 1-hydroxypyrene and 0.02 pg/L (5.9 amol) for papaverine. The acceptable linearity (R2 > 0.99), signal stability (RSD ≤ 10.7%), spike recoveries (91–95%), and comparable results for real urine samples were also achieved, opening up possibilities for quantitative analysis of trace compounds (at attomole levels) in complex bio-samples. [ABSTRACT FROM AUTHOR]

Highlights • The detection system was driven by Zn2+-dependent Cleavage DNAzyme (17E). • A "turn-off"fluorescent quantitative biosensor based on the cleaved substrate chains unsuitable for RT-qPCR. • This detection system is ultra-sensitive with the minimum limit of 58.61 pM. • In this study, the most active cDNAzyme was selected. • No largE–Scale instruments were needed during the entire detection process. Abstract Although it is normal for trace elements of zinc (Zn2+) to be present in the human body, the lack or excess thereof will affect general human health. Due to the low content of Zn2+ found in the environment, detection technology possessing enhanced sensitivity capabilities is necessary for its identification. For the purpose of this study, a "turn-off" ultra-sensitive fluorescent quantitative biosensor was established, based on Zn2+-dependent Cleavage DNAzyme for the sensitive and specific recognition of Zn2+. Furthermore, the original sequence of the substrate chain, as well as the added primer-binding sequences on either side of the substrate chain were examined without destroying the catalytic and cleavage sites of the enzyme. In the presence of Zn2+, the biosensor circulates continuously to promote catalyzation of the substrate chains cleavage by 17E at the proper temperature. The cleaved substrate chains cannot be used as templates for amplification reactions, while the uncleaved substrate chains can be expanded by PCR amplification and synthesized into large amounts of double-stranded DNA to produce a strong fluorescent signal. Consequently, the cutting effect is demonstrated by the change in the Cq value (ΔCq) both before and after the separation process. The larger the ΔCq value, the smaller the remaining substrate chain, and the better the cutting effect. Sensitivity, detection limit, and specificity analysis, indicates that the Zn2+ quantitative detection system established in this paper displays high sensitivity and specificity. The minimum limit of detection (LOD) can reach at 58.61 pM, which dramatically improves the sensitivity of Zn2+ detection. In conclusion, a simple, rapid, accurate quantitative detection system for Zn2+ was established with both high sensitivity and specificity. [ABSTRACT FROM AUTHOR]

Since the quantum concept of parity-time (PT) symmetry has been introduced into the conventional inductor–capacitor resonance, strategies based on exceptional points (EP) based strategies redefine our understanding of sensitivity limitation. This considerable enhancement of sensitivity originated in exploration of the non-Hermitian physics in photonics, acoustics and electronics, which exhibits a substantial application to the miniaturization of implanted electronic sensors in medicine field. By continuously accessing the EP, the spectral response of reader ∆ ω follows a dependency of Δ ω ∼ κ ^2/3 to a weakly coupling rate (| κ | ≈ 0), which may approach the theoretical limit of sensitivity in a second-order EP system. In this paper, we experimentally demonstrate a high-order (higher than second-order) PT symmetric system for weak coupling detection, in which a third-order EP can be employed to fulfill the sensitivity of Δ ω ∼ κ ^1/2 . Particularly, we introduce the incoming wave as an effective gain to balance the loss and obtain a pair of purely real eigenfrequencies. There are absence of imaginary parts despite corresponding real parts shifts dramatically by using a neutral resonator, without a broadening of the reflection spectrum so that maintaining a high resolution on the sensitivity. This work may reveal the physical mechanics of a small perturbation at a high-order EP and promote applications in implanted medicine devices.

As a common heavy metal pollutants, lead ion (Pb2+) content monitoring has always been the focus of environmental protection. The rapid development of self-powered electrochemical biosensors open up the broad application prospects for Pb2+ detection. In this work, we innovatively design three-dimensional (3D) hollow cube bimetallic sulfide heterojunction microparticles combine with DNAzyme functional nucleic acid mediated by hybridization chain reaction (HCR) strategy to construct the ultra-sensitive self-powered sensor. The multiple amplification technology synergically enhanced the sensitivity. The electrochemical data show that the sensor has a wide linear response in the range of 0.0010–25 ng·mL−1 with the low detection limit is 3.10 pg·mL−1 (S / N = 3). The most special feature is that the introduction of commercial smart phone APP can effectively reduce cost, simplify process, and realize rapid on-site detection. In conclusion, the work can provide a feasible strategy for monitoring other hazardous substances, and advance the determination of environmental pollutants in the field. • High-performance electrochemical sensor achieves sensitive detection of heavy metal ions. • Hollow cube structure increases the specific surface area and enhances catalytic activity. • Commercial app contribute to on-site detection and has strong practical significance. [ABSTRACT FROM AUTHOR]

Split DNAzymes have been designed as multifunctional biosensors. However, their limited sensitivity and low resistance to nuclease hinder their applications in biological samples. Herein, we developed a sodium-dependent and butanol accelerated split DNAzyme fluorescent sensor named Na+-BAS DNAzyme which has an ultra-sensitivity for quantifying PIWI-interacting RNAs/microRNAs and can be directly applied in blood biopsy to detect nucleic acids within the extracellular vesicles (EVs). The Na+-BAS DNAzyme consists of two split DNA strands based on NaA43 DNAzyme, a starting hairpin DNA for binding target to initiate the combining of the split enzymes, and a hairpin RNA-embedded DNA substrate labeled a quencher and a fluorophore for signal readout after its cleavage by the assembled DNAzyme complex. To achieve ultra-sensitivity, we employed a simple but key approach of butanol dehydration to highly accelerate the measuring reaction. The sensor has achieved an ultra-low detection limit of 12 × 10−18 M miR-21 after 30 min reaction, and 3.98 or 2.69 particles μL−1 MCF-7 EVs through miR-21 or piR-20365 detection. With these high performances, the sensor can detect extremely trace abundance of miR-21 in a single MCF-10a or MCF-7 EV, quantifying it as 5.93 × 10−3 or 0.12 copies per EV. Without any chemical structure modification, the sensor can be directly used in the plasma sample for breast cancer diagnosis which has obtained both 100% sensitivity and specificity using the biomarker of piR-20365. The Na+-BAS DNAzyme sensor's ultra-sensitivity, high efficiency, universality, and simplicity make it a great potential in the clinical diagnostic application. [Display omitted] • A split DNAzyme sensor based on NaA43 was designed to use in plasma biopsy. • The sensor achieved detection limit of aM grade in nucleic acid measurement. • The ultra-sensitivity ascribed to the key procedure of butanol dehydration. [ABSTRACT FROM AUTHOR]

Ranibizumab (Lucentis®), a humanized antigen-binding fragment (Fab) monoclonal antibody that blocks VEGF-A activity, is currently approved for the treatment of several retinal degenerative diseases. The assessment of drug pharmacokinetics (PK) is essential for evaluating exposure as it relates to drug safety and efficacy. For drugs administered intravitreally, systemic drug levels during the course of clinical studies are typically 100 to 1000-fold lower than those of similar therapeutics dosed intravenously, posing a significant bioanalytical challenge for PK measurements. Thus, the development of a highly-sensitive assay for measuring pg/mL levels of ranibizumab in patients' sera after intravitreal administration was needed to support clinical studies. In this report, we describe the development of a novel method that utilizes a high-affinity murine monoclonal anti-ranibizumab-VEGF-complexes antibody (MARA) reagent to measure ranibizumab in human serum. The assay format utilizes a semi-homogeneous solution phase step using a monoclonal antibody (the MARA) that binds specifically to the ranibizumab-VEGF complex, but not to either alone. This unique reagent exhibited low non-specific binding and high selectivity, increasing signal-to-noise readouts and maximizing assay sensitivity. The resulting MARA enzyme-linked immunosorbent assay (ELISA) has a lower limit of quantification of 15 pg/mL in human serum. In the assay, serum samples are incubated overnight with a mixture containing biotinylated-VEGF and MARA, which form a three-molecule complex with ranibizumab in the sample. These complexes are then captured onto streptavidin-coated wells, followed by enzymatic detection using a horseradish peroxidase-labeled-anti-murine antibody reagent and a colorimetric reaction. The assay conditions were optimized to allow for quantitative detection of “total” ranibizumab levels in serum. The assay was fully validated, establishing its high tolerance to sample matrix, as well as its suitable specificity, accuracy, dilution linearity, as well as intra- and inter-assay precision. The MARA ELISA's novel and unique approach has resulted in a considerably more sensitive ranibizumab PK assay compared to earlier versions of this assay. The MARA ELISA has been used for PK measurements in multiple ranibizumab studies, supporting this drug's life-cycle management and related preclinical and clinical-development studies. [ABSTRACT FROM AUTHOR]

Precise triboelectric nanogenerators (TENGs) with large-scale pressure sensing ability can be realized by effectively harvesting physical pressure. Extensive research on efficient pressure sensors is ongoing, yet the pressure detection limit and sensitivity of most of the reported pressure sensors are not satisfactory for practical and wearable device applications. Herein, we demonstrate a highly efficient approach toward detecting a wide range of pressures, from 5 kPa to 450 kPa, with a record high sensitivity of 0.51 V/kPa. We aim at maximizing the energy conversion efficiency of 48.17% by optimally tuning the internal impedance of the triboelectric nanogenerator at 2.5 MΩ, because low internal impedance results in high output power. This paper reports the structural design, fabrication, and experimental validation of a self-powered and highly durable TENG pressure sensor for large-scale pressure detection based on double-side tribological layers of micro-patterned polydimethylsiloxane (PDMS) and PDMS-multiwall carbon nanotube (CNT) nanocomposites. An in-sole application of the proposed TENG is demonstrated for varying foot pressures corresponding to different walking patterns, which is likely to be applicable in sports sciences, high-risk diabetic foot ulceration, and rehabilitation. Our present contribution not only facilitates large-scale pressure sensing but also paves the way toward the realization of next-generation self-powered and maintenance-free sensing devices. [ABSTRACT FROM AUTHOR]

Herein, we propose an in-situ fabrication method to prepare S-doped graphene sensor integrated with micro-hotplatform (MHP). During the fabrication process, the graphene is transfeauthorrred only one time and sulfur is in-situ doped in graphene at 500 °C. The as-prepared sulfur doped graphene (SG) sensors are sensitive to NO 2 with large range from 500 ppt to 100 ppm at room temperature (RT). With the help of heater integrated in MHP, the SG sensors could quickly recover to the baseline within 5 min. Furthermore, the SG sensors exhibit excellent selectivity for NO 2 which is essential for practical applications. [ABSTRACT FROM AUTHOR]

The porous structured zinc oxide (ZnO) microspheres decorated with silver nanoparticles (Ag NPs) have been fabricated as surface-enhanced Raman scattering (SERS) substrate for ultra-sensitive, highly reproducible and stable biological/chemical sensing of various organic molecules. The ZnO microspheres were hydrothermally synthesized without any template, and the Ag NPs decorated on microspheres via photochemical reaction in situ, which provided stable Ag/ZnO contact to achieve a sensitive SERS response. It demonstrates a higher enhancement factor (EF) of 2.44 × 10 11 and a lower detection limit of 10 −11 M–10 −12 M. This porous SERS substrate could also be self-cleaned through a photocatalytic process and then further recycled for the detection of same or different molecules, such as phenol red (PhR), dopamine (DA) and glucose (GLU) with ultra-low concentration and it possessed a sensitive response. The excellent performances are attributed to morphology of porous microspheres, hybrid structure of semiconductor/metal and corresponding localized field enhancement of surface plasmons. Therefore, it is expected to design the recyclable ultra-sensitive SERS sensors for the detection of biological molecules and organic pollutant monitoring. [ABSTRACT FROM AUTHOR]

In this work, an ultrasensitive and highly stable non-enzymatic glucose sensor is developed with CuO nanostructures through a facile, low price, wet-chemistry route. Three kinds of CuO nanostructures are obtained by kinetic control. The best as-prepared CuO electrode with rough petal-like structure exhibits a quantitative sensitivity as high as 7546.37 μA cm −2 mM −1 and an ultra low limit detection 0.259 μM, which are much better than some previously reported. The rough petals might augment the contact area for kinetic mass transfer between CuO nanostructures and the electrode in an alkaline environment, which significantly improves the performances of electro-oxidation of glucose. Furthermore, the as-fabricated non-enzymatic glucose sensors have also shown excellent anti-interference property, fast response time, good reproducibility and long duration stability. Thus, as-fabricated CuO electrode can be a promising material in the application of non-enzymatic glucose sensors. [ABSTRACT FROM AUTHOR]

Flexible tactile sensor can be integrated into artificial skin and applied in industrial robot and biomedical engineering. However, the presented tactile sensors still have challenge in increasing sensitivity to expand the sensor’s application. Aiming at this problem, this paper presents an ultra-sensitive flexible tactile sensor. The sensor is based on piezoresistive effect of graphene film and is composed of upper substrate (PDMS bump with a size of 5 mm × 7 mm and a thickness of 1 mm), medial Graphene/PET film (Graphene/PET film with a size of 5 mm × 7 mm, PET with a hardness of 2H) and lower substrate (PI with fabricated electrodes). We presented the structure and reduced the principle of the sensor. We also fabricated several sample devices of the sensor and carried out experiment to test the performance. The results show that the sensor performed an ultra high sensitivity of 10.80/kPa at the range of 0−4 kPa and have a large measurement range up to 600 kPa. The sensor has 4 orders of magnitude between minimum resolution and maximum measurement range which have great advantage compared with state of the art. The sensor is expected to have great application prospect in robot and biomedical.

A novel pH-responsive Ag@polyacryloyl hydrazide (Ag@PAH) nanoparticle for the first time as a surface-enhanced Raman scattering (SERS) substrate was prepared without reducing agent and end-capping reagent. Ag@PAH nanoparticles exhibited an excellent tunable detecting performance in the range from pH = 4 to pH = 9. This is explained that the swelling-shrinking behavior of responsive PAH can control the distance between Ag NPs and the target molecules under external pH stimuli, resulting in the tunable LSPR and further controlled SERS. Furthermore, Ag@PAH nanoparticles possessed an ultra-sensitive detecting ability and the detection limit of Rhodamine 6G reduced to 10 M. These advantages qualified Ag@PAH NP as a promising smart SERS substrate in the field of trace analysis and sensors. [ABSTRACT FROM AUTHOR]

Immuno-PCR (IPCR) combines the versatile ELISA antigen detection with ultrasensitive PCR signal amplification, thereby enabling the highly sensitive detection of a broad range of targets with a typically very large dynamic detection range. The quantification of the antigen is usually achieved by real-time PCR, which provides a correlation between the target concentration and amplified DNA marker. We here report on the implementation of digital droplet PCR as a means for direct quantification of DNA copies to enable the highly sensitive detection of protein biomarkers. To this end, two alternative approaches, based on either magnetic microbead-based IPCR or a microplate-release IPCR were tested. The latter format worked well and revealed an extraordinary high robustness and sensitivity. While rtIPCR already fulfills typical immunoassay acceptance criteria, ddIPCR enables improved accuracy and precision of the assay because signal response and analyte concentrations are directly correlated. The utility of the novel ddIPCR technology is demonstrated at the example of two cytokines, interleukin 2 and interleukin 6 (IL2, IL6, respectively), with an overall average CV% of 5.0 (IL2) and 7.4 (IL6). [ABSTRACT FROM AUTHOR]

The existing immunoassay format that combines the electrophoretic collection of charged analytes on an antibody microarray with the detection of the bound analytes by magnetic beads coated with secondary antibodies displays extreme sensitivity and speed, but suffers from low precision because of high signal scatter and low signal-to-concentration ratio. Here we report three innovations that substantially improve the precision of this method and enable quantitative measurements of analyte concentrations as low as 10 fg/ml. The improvements were achieved by (i) employing parallel titration of analytes by measuring signal response to a series of sample dilutions with increasing analyte concentration, (ii) internally normalizing the signal (by relating signal intensity to that of positive controls on the same microarray) and (iii) taking measurements in the linear range of the calibration curve at concentrations close to the limit of detection. This improved method was used to quantitatively measure in human serum the titer of immunoglobulins specific to antigens secreted by Mycobacterium tuberculosis. [ABSTRACT FROM AUTHOR]

Here, we developed an ultra-sensitive and absolute quantitative detection method of Cu 2+ based on DNAzyme and digital PCR. The binding model between DNAzyme and Cu 2+ and the influence caused by the additional primer sequence were revealed to ensure quantitation independent of standard curves. The binding model of DNAzyme and Cu 2+ showed that one molecular DNAzyme could bind one Cu 2+ in the biosensor step. Thus, the final quantitative results, evaluated by three parallels, showed that the limit of quantitation (LOQ) was as low as 0.5 pmol, while the sensitivity was evaluated as 50 fmol. The specificity evaluation of our methodologies shows that extremely low crossing signal is existed within the non-specific ions. Moreover, the results of practical detection have shown that the quantitative results were stable and accurate among different food substrates. In conclusion, a flexible quantitative detection method with ultra-sensitivity was developed to detect trace amounts Cu 2+ within different substrates. [ABSTRACT FROM AUTHOR]

Rapid and ultra-sensitive detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is critical for early screening and management of COVID-19. Currently, the real-time reverse transcription polymerase chain reaction (rRT-PCR) is the primary laboratory method for diagnosing SARS-CoV-2. It is not suitable for at-home COVID-19 diagnostic test due to the long operating time, specific equipment, and professional procedures. Here an all-printed photonic crystal (PC) microarray with portable device for at-home COVID-19 rapid antigen test is reported. The fluorescence-enhanced effect of PC amplifies the fluorescence intensity of the labeled probe, achieving detection of nucleocapsid (N-) protein down to 0.03 pg mL -1 . A portable fluorescence intensity measurement instrument gives the result (negative or positive) by the color of the indicator within 5 s after inserting the reacted PC microarray test card. The N protein in inactivated virus samples (with cycle threshold values of 26.6-40.0) can be detected. The PC microarray provides a general and easy-to-use method for the timely monitoring and eventual control of the global coronavirus pandemic., (© 2023 Wiley-VCH GmbH.)