Dynamic Response Range Research Articles

Autism spectrum disorder variation as a computational trade-off via dynamic range of neuronal population responses

Individuals diagnosed with autism spectrum disorder (ASD) show neural and behavioral characteristics differing from the neurotypical population. This may stem from a computational principle that relates inference and computational dynamics to the dynamic range of neuronal population responses, reflecting the signal levels for which the system is responsive. In the present study, we showed that an increased dynamic range (IDR), indicating a gradual response of a neuronal population to changes in input, accounts for neural and behavioral variations in individuals diagnosed with ASD across diverse tasks. We validated the model with data from finger-tapping synchronization, orientation reproduction and global motion coherence tasks. We suggested that increased heterogeneity in the half-activation point of individual neurons may be the biological mechanism underlying the IDR in ASD. Taken together, this model provides a proof of concept for a new computational principle that may account for ASD and generates new testable and distinct predictions regarding its behavioral, neural and biological foundations.

Detection of Short-Chain Chlorinated Aliphatic Hydrocarbons through an Engineered Biosensor with Tailored Ligand Specificity.

Short-chain chlorinated aliphatic hydrocarbons (SCAHs), commonly used as industrial reagents and solvents, pose a significant threat to ecosystems and human health as they infiltrate aquatic environments due to extensive usage and accidental spills. Whole-cell biosensors have emerged as cost-effective, rapid, and real-time analytical tools for environmental monitoring and remediation. While the broad ligand specificity of transcriptional factors (TFs) often prohibits the application of such biosensors. Herein, we exploited a semirational transition ligand approach in conjunction with a positive/negative fluorescence-activated cell sorting (FACS) strategy to develop a biosensor based on the TF AlkS, which is highly specific for SCAHs. Furthermore, through promoter-directed evolution, the performance of the biosensor was further enhanced. Mutation in the -10 region of constitutive promoter PalkS resulted in reduced AlkS leakage expression, while mutation in the -10 region of inducible promoter PalkB increased its accessibility to the AlkS-SCAHs complex. This led to an 89% reduction in background fluorescence leakage of the optimized biosensor, M2-463, further enhancing its response to SCAHs. The optimized biosensor was highly sensitive and exhibited a broader dynamic response range with a 150-fold increase in fluorescence output after 1 h of induction. The detection limit (LOD) reached 0.03 ppm, and the average recovery rate of SCAHs in actual water samples ranged from 95.87 to 101.20%. The accuracy and precision of the proposed biosensor were validated using gas chromatography-mass spectrometry (GC-MS), demonstrating the promising application for SCAH detection in an actual environment sample.

Impact of time intervals on drug efficacy and phenotypic outcomes in acute respiratory distress syndrome in mice

Acute respiratory distress syndrome is a severe lung condition resulting from various causes, with life-threatening consequences that necessitate intensive care. The phenomenon can be modeled in preclinical models, notably through the use of lipopolysaccharide (LPS) instillation in mice. The phenotype induced closely recapitulates the human syndrome, including pulmonary edema, leukocyte infiltration, acute inflammation, impaired pulmonary function, and histological damage. However, the experimental designs using LPS instillations are extremely diverse in the literature. This highly complicates the interpretation of the induced phenotype chronology for future study design and hinders the proper identification of the optimal time frame to assess different readouts. Therefore, the definition of the treatment window in relation to the beginning of the disease onset also presents a significant challenge to address questions or test compound efficacy. In this context, the temporality of the different readouts usually measured in the model was evaluated in both normal and neutrophil-depleted male C57bl/6 mice using LPS-induction to assess the best window for proper readout evaluation with an optimal dynamic response range. Ventilation parameters were evaluated by whole-body plethysmography and neutrophil recruitment were evaluated in bronchoalveolar lavage fluids and in lung tissues directly. Imaging evaluation of myeloperoxidase along with activity in lung lysates and fluids were compared, along with inflammatory cytokines and lung extravasation by enzyme-linked immunoassays. Moreover, dexamethasone, the gold standard positive control in this model, was also administered at different times before and after phenotype induction to assess how kinetics affected each parameter. Overall, our data demonstrate that each readout evaluated in this study has a singular kinetic and highlights the key importance of the timing between ARDS phenotype and treatment administration and/or analysis. These findings also strongly suggest that analyzes, both in-life and post-mortem should be conducted at multiple time points to properly capture the dynamic phenotype of the LPS-ARDS model and response to treatment.

Development of an Ion Mobility Spectrometer Based on a Pulsed Photoelectric Effect Ionization Source.

Ion mobility spectrometry (IMS) is a compact and sensitive trace gas analysis instrument that ionizes the sample into ions for detection. Typically, an ion gate is used to cut the continuous ion beam into ion packets for separation and detection. However, commonly used ion gates suffer from complex structures or low ion transmission rates, making the gateless IMS a viable alternative. In this study, an IMS based on a pulsed photoelectric effect ionization source was designed. The photoelectrons were generated by irradiating a photoelectric material with a back-illuminated pulsed xenon lamp. This allows for low-energy photoelectron generation and the production of simple reactant ions (O2-(H2O)n) and thus negative product ions. The photoelectron current generated by this ionization source was analyzed, which can reach an intensity of a few microamperes and can be converted into an ion signal exceeding 10 nA. The introduction of the pulsed photoelectric effect ionization source makes it possible to generate separate ion packets and complete ion injection when a constant electric field is maintained in the ionization region. And with an assisted pulsed electric field in the ionization region, the resolving power of the system can be effectively improved to 1.85 times that of the constant electric field. The IMS developed in this study was used for the detection of common volatile hazardous chemicals, yielding effective results. The detection limit for phenol was below 1 ppb, and the dynamic response range exceeded 1 order of magnitude, which implies the potential applications of this IMS to detect substances with high electron affinity, such as explosives detection in public safety.

Novel pore confinement enhanced europium functionalized porphyrin covalent organic framework electrochemiluminescence microreactor and its application to microRNA-21 detection

Here, an electrochemiluminescence (ECL) microreactor lanthanide europium functionalized porphyrin covalent organic framework (Eu@TAPP-COF) was developed through Schiff base condensation between 1,3,5-benzenetricarboxaldehyde (BTCA) and 5,10,15,20-tetrakis(4-aminophenyl)-porphyrin (TAPP) with the coordination reaction between the COF skeleton and Eu3+. Compared with O2/S2O82− and TAPP-COF/S2O82− systems, the ECL intensity of Eu@TAPP-COF/S2O82− is significantly enhanced by 5.1 and 1.3 times, respectively. It can be attributed to the positively charged micropore structure of the Eu@TAPP-COF, providing a relatively independent reaction environment for the electrochemical oxidation of S2O82− and the intermediate SO4•−, moreover shortening the distance among the ECL luminophore TAPP, the co-reaction accelerator Eu3+, and the co-reaction reagent S2O82−. Based on this novel emitter, an ECL biosensor was developed for microRNA-21 detection via the signal amplification strategy of catalytic hairpin assembly (CHA). The as-prepared biosensor displayed high sensitivity for target with a dynamic linear response range from 100 aM to 100 pM, and a lower detection limit of 21 aM (S/N = 3). This work provides an idea for the sensing application of weak luminophore and a simple, effective and accurate detection platform for tumor markers.

Hydroxyurea maintains working memory function in pediatric sickle cell disease.

Sickle cell disease (SCD) decreases the oxygen-carrying capacity of red blood cells. Children with SCD have reduced/restricted cerebral blood flow, resulting in neurocognitive deficits. Hydroxyurea is the standard treatment for SCD; however, whether hydroxyurea influences such effects is unclear. A key area of SCD-associated neurocognitive impairment is working memory, which is implicated in other cognitive and academic skills. The neural correlates of working memory can be tested using n-back tasks. We analyzed functional magnetic resonance imaging (fMRI) data of patients with SCD (20 hydroxyurea-treated patients and 11 controls, aged 7-18 years) while they performed n-back tasks. Blood-oxygenation level-dependent (BOLD) signals were assessed during working memory processing at 2 time points: before hydroxyurea treatment and ~1 year after treatment was initiated. Neurocognitive measures were also assessed at both time points. Our results suggested that working memory was stable in the treated group. We observed a treatment-by-time interaction in the right cuneus and angular gyrus for the 2- >0-back contrast. Searchlight-pattern classification of the 2 time points of the 2-back tasks identified greater changes in the pattern and magnitude of BOLD signals, especially in the posterior regions of the brain, in the control group than in the treated group. In the control group at 1-year follow-up, 2-back BOLD signals increased across time points in several clusters (e.g., right inferior temporal lobe, right angular gyrus). We hypothesize that these changes resulted from increased cognitive effort during working memory processing in the absence of hydroxyurea. In the treated group, 0- to 2-back BOLD signals in the right angular gyrus and left cuneus increased continuously with increasing working memory load, potentially related to a broader dynamic range in response to task difficulty and cognitive effort. These findings suggest that hydroxyurea treatment helps maintain working memory function in SCD.

Ultrasensitive electrochemical sensor based on synergistic effect of Ag@MXene and antifouling cyclic multifunctional peptide for PD-L1 detection in serum.

Asensing interface co-constructed from the two-dimensional conductive material (Ag@MXene) and an antifouling cyclic multifunctional peptide (CP)is described. While the large surface area of Ag@MXene loads more CP probes, CP binds to Ag@MXene to form a fouling barrier and ensure the structural rigidity of the targeting sequence. This strategy synergistically enhances the biosensor's sensitivity and resistance to contamination. The SPR results showed that the binding affinity of the CP to the target was 6.23 times higher than that of the antifouling straight-chain multifunctional peptide (SP) to the target. In the 10mg/mL BSA electrochemical fouling test, the fouling resistance of Ag@MXene + CP (composite sensing interface of CP combined with Ag@MXene) was 30 times higher than that of the bare electrode. The designed electrochemical sensor exhibited good selectivity and wide dynamic response range at PD-L1 concentrations from 0.1 to 50 ng/mL. The lowest detection limit was 24.54 pg/mL (S/N = 3). Antifouling 2D materials with a substantial specific surface area, coupled with non-straight chain antifouling multifunctional peptides, offer a wide scope for investigating the sensitivity and antifouling properties of electrochemical sensors.

Paper-based enzyme-linked biosensor combined with smartphone for simultaneous colorimetric sensing of xanthines and sarcosine

A portable paper-based enzyme-linked biosensor that integrates a multi-enzyme cascade reaction, natural enzyme, and nanozyme with filter paper, combined with smartphones, is proposed for the detection of xanthine (XA) and sarcosine (SA) in urine. The primary biological component of the sensor is horseradish peroxidase (HRP). By chemically modifying cellulose filter paper (CFP) the HRP in horseradish crude extract is specifically immobilized through boron affinity and metal chelation techniques. Furthermore, the incorporation of UiO-66 on CFP had a good synergistic effect on the electron transfer of HRP and the detection of H2O2, significantly increasing the sensor's sensitivity. Under optimized experimental conditions, the sensor demonstrated a dynamic response range of 8–400 μmol L−1 for SA with a minimum detection limit (LOD) of 5 μmol L−1, and a dynamic response range of 10–400 μmol L−1 with an LOD of 8 μmol L−1 for XA. Additionally, the well-designed detection area of the portable test strip simplifies the detection operation, reduces the detection time, and enables rapid on-site analysis. UV-Vis analysis further confirmed the sensor's accuracy in detecting disease markers in urine. The sensing platform has good reproducibility, specificity and stability, suitable for the detection of SA and XA in real human urine samples, and the sensor has the advantages of simple manufacturing, easy operation, strong portability, low reagent consumption, and low cost benefit. Therefore, the development of this paper-based enzyme-linked biosensor offers a novel approach to the detection of disease markers in urine and has potential applications in medical testing.

Development of a novel fluorescent protein-based probe for efficient detection of Pb2+ in serum inspired by the metalloregulatory protein PbrR691

BackgroundThe accurate and rapid detection of blood lead concentration is of paramount importance for assessing human lead exposure levels. Fluorescent protein-based probes, known for their high detection capabilities and low toxicity, are extensively used in analytical sciences. However, there is currently a shortage of such probes designed for ultrasensitive detection of Pb2+, and no reported probes exist for the quantitative detection of Pb2+ in blood samples. This study aims to fill this critical void by developing and evaluating a novel fluorescent protein-based probe that promises accurate and rapid lead quantification in blood. ResultsA simple and small-molecule fluorescent protein-based probe was successfully constructed herein using a peptide PbrBD designed for Pb2+ recognition coupled to a single fluorescent protein, sfGFP. The probe retains a three-coordinate configuration to identify Pb2+ and has a high affinity for it with a Kd’ of 1.48 ± 0.05 × 10−17 M. It effectively transfers the conformational changes of the peptide to the chromophore upon Pb2+ binding, leading to fast fluorescence quenching and a sensitive response to Pb2+. The probe offers a broad dynamic response range of approximately 37-fold and a linear detection range from 0.25 nM to 3500 nM. More importantly, the probe can resist interference of metal ions in living organisms, enabling quantitative analysis of Pb2+ in the picomolar to millimolar range in serum samples with a recovery percentage of 96.64%–108.74 %. SignificanceThis innovative probe, the first to employ a single fluorescent protein-based probe for ultrasensitive and precise analysis of Pb2+ in animal and human serum, heralds a significant advancement in environmental monitoring and public health surveillance. Furthermore, as a genetically encoded fluorescent probe, this probe also holds potential for the in vivo localization and concentration monitoring of Pb2+.

Nanostructures of Prussian blue supported on activated biochar for the development of a glucose biosensor

This work emphasizes the utilization of biochar, a renewable material, as an interesting platform for anchoring redox mediators and bioreceptors in the development of economic, environmentally friendly biosensors. In this context, Fe(III) ions were preconcentrated on highly functionalized activated biochar, allowing the stable synthesis of Prussian blue nanostructures with an average size of 58.3 nm. The determination of glucose was carried out by indirectly monitoring the hydrogen peroxide generated through the enzymatic reaction, followed by its subsequent redox reaction with reduced Prussian blue (also known as Prussian white) in a typical electrochemical-chemical mechanism. The EDC/NHS (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and N-Hydroxysuccinimide) pair was employed for the stable covalent immobilization of the enzyme on biochar. The biosensor demonstrated good enzyme-substrate affinity, as evidenced by the Michaelis-Menten apparent kinetic constant (4.16 mmol L−1), and analytical performance with a wide linear dynamic response range (0.05–5.0 mmol L−1), low limits of detection (0.94 μmol L−1) and quantification (3.13 μmol L−1). Additionally, reliable repeatability, reproducibility, stability, and selectivity were obtained for the detection of glucose in both real and spiked human saliva and blood serum samples.

In primary visual cortex fMRI responses to chromatic and achromatic stimuli are interdependent and predict contrast detection thresholds

Chromatic and achromatic signals in primary visual cortex have historically been considered independent of each other but have since shown evidence of interdependence. Here, we investigated the combination of two components of a stimulus; an achromatic dynamically changing check background and a chromatic (L-M or S cone) target grating. We found that combinations of chromatic and achromatic signals in primary visual cortex were interdependent, with the dynamic range of responses to chromatic contrast decreasing as achromatic contrast increased. A contrast detection threshold study also revealed interdependence of background and target, with increasing chromatic contrast detection thresholds as achromatic background contrast increased. A model that incorporated a normalising effect of achromatic contrast on chromatic responses, but not vice versa, best predicted our V1 data as well as behavioural thresholds. Further along the visual hierarchy, the dynamic range of chromatic responses was maintained when compared to achromatic responses, which became increasingly compressive.

Highly efficient self-powered CH3NH3Pbl3 perovskite photodiode with double-sided poly(methyl methacrylate) passivation layers

Hybrid organohalide perovskites have recently attracted significant attention due to their outstanding photovoltaic (PV) conversion capabilities in optoelectronic devices. Herein, to develop a highly sensitive and self-powered perovskite-based PV photodiode (PVPD), we implement the selective use of poly(methyl methacrylate) (PMMA) as noise-current-reducing passivation layers on both the front and rear sides of a CH3NH3PbI3 (MAPbI3) perovskite light-absorbing layer. It is found that the PMMA layers effectively suppress carrier recombinations at the interfaces, resulting in fairly high power conversion efficiency of 17.6%. Additionally, the double-sided PMMA-passivated MAPbI3 PVPD shows exceptional specific detectivity values (1.0 × 1014 Jones from the dark current and 1.3 × 1012 Jones from the noise current), significantly outperforming conventional MAPbI3 PVPDs without passivation layers. The device also exhibits a very wide linear dynamic response range of ∼139 dB, with rapid rise and decay response times of 57 and 18 μs, respectively. The double-sided PMMA-passivated MAPbI3 PVPD also is shown to be highly durable in terms of its dynamic responses even after a prolonged storage period of 1500 h. These results suggest that advanced interface engineering using double PMMA passivation layers holds great potential for developing high-performance self-powered perovskite photodetectors for a range of optoelectronic applications.

Visible proton Bragg curve imaging by colour centre photoluminescence in radiation detectors based on lithium fluoride films on silica

Passive solid-state radiation detectors, based on the visible photoluminescence (PL) of radiation-induced colour centres in optically transparent lithium fluoride (LiF), polycrystalline thin films are under investigation for proton beam advanced diagnostics. After proton exposure, the latent images stored in LiF as local formations of stable F2 and F3 + aggregate defects, are directly read with a fluorescence microscope under illumination in the blue spectral range. Adopting a suitable irradiation geometry, the energy density that protons deposit in the material can be recorded as a spatial distribution of these light-emitting defects, from which a luminous replica of the proton Bragg curve can be thereafter extracted and analysed to reconstruct the proton beam energy spectrum. Their peculiar properties, such as wide dynamic range and linearity of the spectrally-integrated PL response vs. dose, make the investigation of two-dimensional LiF film radiation detectors grown on several types of substrate highly attractive. Here, the case of a LiF thin film thermally evaporated on a silica substrate, irradiated at grazing incidence with a 35 MeV proton beam, is investigated and reported for the first time. A comparison of the measured photoluminescent Bragg curve with Monte Carlo simulations demonstrates that the Bragg peak in the film is located at the very same position that would be expected in the underlying silica substrate rather than in LiF. The film packing density is shown not to have a significant effect on the peak depth, while even small nonzero grazing angle of the impinging proton beam is able to significantly modify the shape of the Bragg curve. These findings are ascribed to the effects of multiple Coulomb scattering in both the film and the substrate and are interesting for proton beam diagnostics and dosimetry.

The preparation of a fluorescent dual-modality nanosensor for the discrimination and determination of biothiols in real samples and its practical detection kit.

Biothiols widely exist in living organisms and have a crucial function of maintaining redox balance in the human body. It is vital yet difficult to develop probes that can simultaneously detect and distinguish biothiols. In this study, a highly sensitive dual-modality nanosensor, NBD-Nap@NCC, was developed for the discrimination and determination of biothiols in real samples, and its practical application was elucidated based on RGB analysis using a smartphone. The sensitive nanosensor was successfully prepared through the surface modification of nanocrystalline cellulose (NCC), combining NBD and naphthalene fluorophores. Owing to the high electron-withdrawing behavior of the NBD group, which led to a PET mechanism between the fluorophores, the prepared NBD-Nap@NCC nanosensor had a very weak fluorescence response. However, after treatment with Hcy or Cys, NBD-Nap@NCC quickly provided remarkable and different rates of fluorescence "turn-on" responses in both blue and green channels, which was attributed to naphthalene and NBD fluorophores as a result of the inhibition of the PET mechanism. However, after treatment with GSH, only a significant blue-channel emission, which was attributed to the naphthalene fluorophore was obtained, indicating the inhibition of the PET mechanism. Furthermore, the NCC platform demonstrated improved sensitivity and selectivity because of the increased surface area and higher number of binding sites due to modification of the NBD group on the surface. The detection limit ranged from 0.910 to 1.150 μmol L-1 for biothiols with a large dynamic response range. The accuracy of the sensor in determining the concentrations of Hcy, Cys, and GSH in real samples was evaluated via HPLC and spike/recovery analysis. Additionally, paper-based analysis kits were fabricated for the practical detection of biothiols based on RGB changes using a smartphone application.

Schiff base fluorescent sensor with aggregation induced emission characteristics for the sensitive and specific Fe3+ detection

An aggregation induced emission based compound ((E)-4-((2-hydroxy-5-methoxybenzylidene)amino)benzoic acid) was synthesized through facile Schiff base condensation and characterized by various spectral techniques. The as-prepared compound represented a typical aggregation induced emission behavior in aqueous solution and exploited as a turn-off fluorescent sensor for Fe3+ detection in THF-H2O system (3:7, v/v) with high sensitivity and selectivity. The mechanism of the fluorescence quenching was intensively studied, which was attributed to both dynamic quenching and inner filter effect. The fluorescence probe displayed a highly broad dynamic response range (0.5–500 μM) for selective detection of Fe3+ with a limit of detection of 0.079 μM. The proposed method was successfully employed for detection and quantification of Fe3+ in human urine samples and proved to have potential for practical applications in biological field.

Enhancing 4-aminophenol detection using bismuth ferrite nanoparticles in functional nanochannels

This work presents a simple and rapid electrochemical method employing a conical nanochannel modified with bismuth ferrite (BFO) nanoparticles for the direct determination of 4-aminophenol (4-AP), a commonly used drug intermediate in pharmaceutical preparations. The phase pure BFO nanoparticles were synthesized by the coprecipitation technique. Subsequently, we created the single conical nanochannels within polyethylene terephthalate (PET) membranes using the asymmetric track-etching method. To facilitate the immobilization of BFO nanoparticles onto the nanochannel's surface, we initially functionalized it with poly (allylamine hydrochloride) (PAH). The BFO-modified single conical nanochannel obtained was utilized for sensing 4-AP, demonstrating significantly improved sensitivity within a linear dynamic response range from 400 μM to 1 mM, as compared to both unmodified and PAH-modified channels. To gain further insights into the interaction between BFO and 4-AP, we employed cyclic voltammetry and differential pulse voltammetry techniques. Our in-depth analysis, based on scan rate voltammograms, revealed that the interaction mechanism primarily involved the adsorption phenomenon between BFO nanoparticles and 4-AP. This enhancement in sensitivity, as corroborated by the electrochemical techniques, underscores the efficacy of the BFO-modified nanochannel for 4-AP detection. Robust conical nanochannels functionalized with nanoparticles, show promise in developing highly selective, cost-effective, and portable biosensors.

Interface Engineering to Drive High-Performance MXene/PbS Quantum Dot NIR Photodiode.

The realization of a controllable transparent conducting system with selective light transparency is crucial for exploring many of the most intriguing effects in top-illuminated optoelectronic devices. However, the performance is limited by insufficient electrical conductivity, low work function, and vulnerable interface of traditional transparent conducting materials, such as tin-doped indium oxide. Here, it is reported that two-dimensional (2D)titanium carbide (Ti3 C2 Tx ) MXene film acts as an efficient transparent conducting electrode for the lead sulfide (PbS) colloidal quantum dots (CQDs) photodiode with controllable near infrared transmittance. The solution-processed interface engineering of MXene and PbS layers remarkably reduces the interface defects of MXene/PbS CQDs and the carrier concentration in the PbS layer. The stable Ti3 C2 Tx /PbS CQDs photodiodes give rise to a high specific detectivity of 5.51×1012 cmW-1 Hz1/2 , a large dynamic response range of 140dB, and a large bandwidth of 0.76MHz at 940nm in the self-powered state, ranking among the most exceptional in terms of comprehensive performance among reported PbS CQDs photodiodes. In contrast with the traditional photodiode technologies, this efficient and stable approach opens a new horizon to construct widely used infrared photodiodes with CQDs and MXenes.

Sensitivity measurements for a 250 MHz quartz shear-horizontal surface acoustic wave biosensor under liquid viscous loading

Surface acoustic wave (SAW) devices have been used in biochemical assays due to their high sensitivity. The device sensitivity is a function of changes in the density and viscosity of the liquid. Here, we studied the effect of fluid viscosity using a 250 MHz quartz shear-horizontal (SH)-SAW biosensor by monitoring different concentrations of binary aqueous/glycerol solutions. In this study, the sensitivity of the biosensor was determined by fitting the data to models derived from perturbation theory. Measurements in water were used as the reference. For a 0% to 50% glycerol solution, an 87°–204° separation in the phase shift was observed. The slope of the plot of the phase shift vs (ηρ)0.5 was used to indicate the sensor’s sensitivity. The sensitivity for our 250 MHz quartz SH-SAW sensors was calculated to be 3.7×10−3m2sKg. The corresponding mass sensitivity was determined to be 9.25 × 105m2Kg. The limit of detection was calculated to be 36 picograms (pg), while the limit of quantification or LOQ was calculated to be 109 pg. Traditionally, liquid phase measurements have been challenging for SAW devices because liquids dampen the vibrating sensors severely. This problem has been largely solved using a transverse (shear) wave instead of the more popular longitudinal or Rayleigh waves. Liquid measurements are now possible using transverse waves, also known as shear waves, because transverse waves are only minimally attenuated by liquids. Shear-horizontal SAW sensors (SH-SAW) show great promise as label-free biosensors because of their ability to handle liquid samples. However, the viscosity of the liquid still induces loading effects and can be measured when the liquid is loaded onto the SH-SAW propagating surface (delay line). When the liquid above the delay line is perturbed by physical or chemical changes, such as binding to a receptor, it alters the propagating acoustic wave. The SH-SAW device can measure these changes in liquid properties as a change in the wave’s phase compared to the original wave. The device’s phase shift was recorded as a function of the changes in the density and viscosity of the binary glycerol solution and used to determine the sensitivity in the linear dynamic range of responses.

SPRi/SERS dual-mode biosensor based on ployA-DNA/ miRNA/AuNPs-enhanced probe sandwich structure for the detection of multiple miRNA biomarkers

MicroRNA (miRNA) has broad application prospects in the early detection of various cancers. In this work, a SPRi/SERS dual-mode biosensor was developed on the same gold chip by AuNPs as the reinforcing medium. High throughput and sensitivity detection of three typical cervical cancer markers miRNA21, miRNA124 and miRNA143 were achieved based on the sandwich structure of polyA blocks-DNA capture probe/target miRNA/AuNPs-assistant probe or SERS nanoprobes. AuNPs greatly improved the SPR response due to mass increase and more sensitive refractive index changes. Meanwhile, due to the LSPR effect of AuNPs, the signal of SERS nanoprobe can be amplified. The miRNAs were detected in serum to verify its practicality. SPRi achieved detection of three miRNAs simultaneously. LODs were 6.3 fM, 5.3 fM and 4.6 fM, respectively, and wide dynamic response range of 500 pM-10 nM. While SERS assay ensured high sensitivity with LODs as low as 1 fM, 0.8 fM and 1.2 fM, respectively, and with the recoveries in the range of 90.0 %-100.2 %. The redundant detection signals of the two modes can provide more reliable data to prevent false positive or false negative detection, and have great application prospects in detection of cancer-related nucleic acids in early stage of disease.

NLISA versus enzyme-linked immunosorbent assay: Nanozyme-linked immunosorbent array based on platinum sub-nanocluster nanozyme for α-fetoprotein detection.

Rapid and accurate identification of tumor metabolic markers is important for early tumor diagnosis and individualized treatment. Here, a stable monodisperse sub-nanometer platinum (Pt) material was developed as a highly efficient nanozyme with a specific activity of peroxidase as high as 20.86 U mg-1 through the growth of in situ domain-limited Pt quantum dots via the polymer polyvinylpyrrolidone. Further, the synthesis of large quantities of Pt-loaded SiO2 (Pt-SiO2 ) was determined by silylation reaction and used for naked eye colorimetric testing of human alpha-fetoprotein (AFP). In particular, the immunization incubation process occurred in preprepared microplates. A nanozyme-based immunomodel was constructed in the presence of the target AFP, and a chromogenic reaction occurred with exogenous hydrogen peroxide and the chromogenic substrate tetramethylbenzidine. On optimization of experimental conditions, the dynamic working response range for AFP was found to be 0.05-20 ng mL-1 , with a limit of detection of 38.7pg mL-1 . This work provides a new strategy to design efficient nanozyme-based enzyme-linked immunochromatographic platforms to meet the practical use of replacing natural enzymes.