Landscape and Dynamics of Single Immune Cells in Hepatocellular Carcinoma.

The immune microenvironment of hepatocellular carcinoma (HCC) is poorly characterized. Combining two single-cell RNA sequencing technologies, we produced transcriptomes of CD45+ immune cells for HCC patients from five immune-relevant sites: tumor, adjacent liver, hepatic lymph node (LN), blood, and ascites. A cluster of LAMP3+ dendritic cells (DCs) appeared to be the mature form of conventional DCs and possessed the potential to migrate from tumors to LNs. LAMP3+ DCs also expressed diverse immune-relevant ligands and exhibited potential to regulate multiple subtypes of lymphocytes. Of the macrophages in tumors that exhibited distinct transcriptional states, tumor-associated macrophages (TAMs) were associated with poor prognosis, and we established the inflammatory role of SLC40A1 and GPNMB in these cells. Further, myeloid and lymphoid cells in ascites were predominantly linked to tumor and blood origins, respectively. The dynamic properties of diverse CD45+ cell types revealed by this study add new dimensions to the immune landscape of HCC.

Mass Production of Carbon Nanotube Transistor Biosensors for Point-of-Care Tests.

Low-dimensional semiconductor-based field-effect transistor (FET) biosensors are promising for label-free detection of biotargets while facing challenges in mass fabrication of devices and reliable reading of small signals. Here, we construct a reliable technology for mass production of semiconducting carbon nanotube (CNT) film and FET biosensors. High-uniformity randomly oriented CNT films were prepared through an improved immersion coating technique, and then, CNT FETs were fabricated with coefficient of performance variations within 6% on 4-in. wafers (within 9% interwafer) based on an industrial standard-level process. The CNT FET-based ion sensors demonstrated threshold voltage standard deviations within 5.1 mV at each ion concentration, enabling direct reading of the concentration information based on the drain current. By integrating bioprobes, we achieved detection of biosignals as low as 100 aM through a plug-and-play portable detection system. The reliable technology will contribute to commercial applications of CNT FET biosensors, especially in point-of-care tests.

Nanosensor-Driven Detection of Neuron-Derived Exosomal Aß42 with Graphene Electrolyte-Gated Transistor for Alzheimer's Disease Diagnosis.

Blood-based tests have sparked tremendous attention in non-invasive early diagnosis of Alzheimer's disease (AD), a most prevalent neurodegenerative malady worldwide. Despite significant progress in the methodologies for detecting AD core biomarkers such as Aß42 from serum/plasma, there remains cautious optimism going forward due to its controversial diagnostic value and disease relevance. Here, a graphene electrolyte-gated transistor biosensor is reported for the detection of serum neuron-derived exosomal Aß42 (NDE-Aß42), which is an emerging, compelling trove of blood biomarker for AD. Assisted by the antifouling strategy with the dual-blocking process, the noise against complex biological background was considerably reduced, forging an impressive sensitivity gain with a limit of detection of 447 ag/mL. An accurate detection of SH-SY5Y-derived exosomal Aß42 was also achieved with highly conformable enzyme-linked immunosorbent assay results. Importantly, the clinical analysis for 27 subjects revealed the immense diagnostic value of NDE-Aß42, which can outclass that of serum Aß42. The developed electronic assay demonstrates, for the first time, nanosensor-driven NDE-Aß42 detection, which enables a reliable discrimination of AD patients from non-AD individuals and even the differential diagnosis between AD and vascular dementia patients, with an accuracy of 100% and a Youden index of 1. This NDE-Aß42 biosensor defines a robust approach for blood-based confident AD ascertain.

Amplification-Free Detection of SARS-CoV-2 Down to Single Virus Level by Portable Carbon Nanotube Biosensors.

The rapid and sensitive detection of trace-level viruses in a simple and reliable way is of great importance for epidemic prevention and control. Here, a multi-functionalized floating gate carbon nanotube field effect transistor (FG-CNT FET) based biosensor is reported for the single virus level detection of SARS-CoV-2 virus antigen and RNA rapidly with a portable sensing platform. The aptamers functionalized sensors can detect SARS-CoV-2 antigens from unprocessed nasopharyngeal swab samples within 1 min. Meanwhile, enhanced by a multi-probe strategy, the FG-CNT FET-based biosensor can detect the long chain RNA directly without amplification down to single virus level within 1 min. The device, constructed with packaged sensor chips and a portable sensing terminal, can distinguish 10 COVID-19 patients from 10 healthy individuals in clinical tests both by the RNAs and antigens by a combination detection strategy with an combined overall percent agreement (OPA) close to 100%. The results provide a general and simple method to enhance the sensitivity of FET-based biochemical sensors for the detection of nucleic acid molecules and demonstrate that the CNT FG FET biosensor is a versatile and reliable integrated platform for ultrasensitive multibiomarker detection without amplification and has great potential for point-of-care (POC) clinical tests.

Recent advances in the detection of pathogenic microorganisms and toxins based on field-effect transistor biosensors.

In food safety analysis, the detection and control of foodborne pathogens and their toxins are of great importance. Monitoring of virus transmission is equally important, especially in light of recent findings that coronaviruses have been detected in frozen foods and packages during the current global epidemic of coronavirus disease 2019. In recent years, field-effect transistor (FET) biosensors have attracted considerable scholarly attention for pathogenic microorganisms and toxins detection and sensing due to their rapid response time, high sensitivity, wide dynamic range, high specificity, label-free detection, portability, and cost-effectiveness. FET-based biosensors can be modified with specific recognition elements, thus providing real-time qualitative and semiquantitative analysis. Furthermore, with advances in nanotechnology and device design, various high-performance nanomaterials are gradually applied in the detection of FET-based biosensors. In this article, we review specific detection in different biological recognition elements are immobilized on FET biosensors for the detection of pathogenic microorganisms and toxins, and we also discuss nonspecific detection by FET biosensors. In addition, there are still unresolved challenges in the development and application of FET biosensors for achieving efficient, multiplexed, in situ detection of pathogenic microorganisms and toxins. Therefore, directions for future FET biosensor research and applications are discussed.

The Janus-faced role of TRPM2-S in retroperitoneal liposarcoma via increasing ROS levels.

BACKGROUND: Retroperitoneal liposarcoma (RPLS) is a specific soft tissue sarcoma with a high recurrence rate. The short isoform of transient receptor potential cation channel subfamily M member 2 (TRPM2-S) plays an important role in the regulation of reactive oxygen species (ROS). However, the association between TRPM2-S and RPLS and its underlying mechanisms remains unclear. METHODS: The expression of both TRPM2-S and TRPM2-L in RPLS tissues was verified by kimmunohistochemistry (IHC). The regulation on Ca2+ influx by TRPM2-S was evaluated by Fluo-4 AM staining. The effect of TRPM2-S on cell proliferation and apoptosis was tested by 5-Ethynyl-2'-deoxyuridine (EdU) staining and Flow cytometry respectively. The level of cellular ROS was assessed by the DCFH-DA probe. Different concentrations of H2O2 were used to provide oxidative stress on RPLS cells. The underlying mechanisms were further explored by Western blotting. RESULTS: The IHC assays showed that TRPM2-S, but not TRPM2-L, was prognostic in RPLS. Low TRPM2-S level was associated with poor disease-free survival (DFS). Calcium influx signal intensity was significantly decreased under TRPM2-S overexpression, which resulted in a decrease in the levels of FOXO3a and PTEN. Correspondingly, the levels of pERK, pAKT, pP65, pGSK-3ß, Bcl-2, and ß-catenin were upregulated, and cellular ROS was gently increased under TRPM2-S overexpression. Moreover, TRPM2-S slightly promoted cell proliferation and inhibited apoptosis of RPLS cell lines under normoxia, but largely increased apoptosis rates under oxidative stress. The cleaved caspase3 was significantly upregulated by TRPM2-S overexpression under oxidative stress. N-Acetyl-L-cysteine (NAC), a small molecule antioxidant, could largely rescue RPLS cells from the apoptosis induced by H2O2. CONCLUSION: TRPM2-S exerts Janus-faced effects in RPLS by increasing the ROS levels via inhibition on FOXO3a, which promotes cell proliferation under normoxia but induces apoptosis under oxidative stress. Video abstract.

Prevalence of frailty among patients with inflammatory bowel disease and its association with clinical outcomes: a systematic review and meta-analysis.

BACKGROUND: Studies have reported frailty as an independent risk factor of mortality in patients with inflammatory bowel disease (IBD). However, no systematic review and meta-analysis has been conducted to determine the relationship of frailty and IBD. We aimed to investigate the prevalence of frailty in patients with IBD and the impact of frailty on the clinical prognosis of these patients. METHODS: We systematically searched PubMed, Ovid (Medline), Embase, Web of Science, and Cochrane Library from database inception until October 2022. This systematic review included observational studies describing IBD and frailty. We performed meta-analysis for the frailty prevalence in patients with IBD. We analyzed primary outcomes (mortality) and secondary outcomes (infections, hospitalizations, readmission, and IBD-related surgery). RESULTS: Nine studies with a total of 1,495,695 participants were included in our meta-analysis. The prevalence of frailty was 18% in patients with IBD. The combined effect analysis showed that frail patients with IBD had a higher risk of mortality (adjusted hazard ratio = 2.25, 95% confidence interval: 1.11-4.55) than non-frail patients with IBD. The hazard ratio for infections (HR = 1.23, 0.94-1.60), hospitalizations (HR = 1.72, 0.88-3.36), readmission (HR = 1.21, 1.17-1.25) and IBD-related surgery (HR = 0.78, 0.66-0.91) in frail patients with IBD. CONCLUSIONS: We demonstrated that frailty is a significant independent predictor of mortality in patients with IBD. Our work supports the importance of implementing frailty screening upon admission in patients with IBD. More prospective studies are needed to investigate the influence of frailty on patients with IBD and improve the poor prognosis of patients with frailty and IBD.

Carbon Nanotube Field-Effect Transistor Biosensor for Ultrasensitive and Label-Free Detection of Breast Cancer Exosomal miRNA21.

Tumor-derived exosomal miRNAs may have important functions in the onset and progression of cancers and are potential biomarkers for early diagnosis and prognosis monitoring. Yet, simple, sensitive, and label-free detection of exosomal miRNAs remains challenging. Herein, an ultrasensitive, label-free, and stable field-effect transistor (FET) biosensor based on a polymer-sorted high-purity semiconducting carbon nanotube (CNT) film is reported to detect exosomal miRNA. Different from conventional CNT FETs, the CNT FET biosensors employed a floating gate structure using an ultrathin Y2O3 as an insulating layer, and assembled Au nanoparticles (AuNPs) on Y2O3 as linkers to anchor probe molecules. A thiolated oligonucleotide probe was immobilized on the AuNP surface of the sensing area, after which miRNA21 was detectable by monitoring the current change before and after hybridization between the immobilized DNA probe and target miRNA. This method achieved both high sensitivity (LOD: 0.87 aM) and high specificity. Furthermore, the FET biosensor was employed to test clinical plasma samples, showing significant differences between healthy people and breast cancer patients. The CNT FET biosensor shows the potential applications in the clinical diagnosis of breast cancer.

Dual-Aptamer Modified Graphene Field-Effect Transistor Nanosensor for Label-Free and Specific Detection of Hepatocellular Carcinoma-Derived Microvesicles.

Cancerous microvesicles (MVs), which are heterogeneous membrane-bound nanovesicles shed from the surfaces of cancer cells into the extracellular environment, have been widely recognized as promising "biofingerprints" for various cancers. High-performance identification of cancerous MVs plays a vital role in the early diagnosis of cancer, yet it is still technically challenging. Herein, we report a gold nanoparticle (AuNP)-decorated, dual-aptamer modified reduced graphene oxide (RGO) field-effect transistor (AAP-GFET) nanosensor for the label-free, specific, and sensitive quantification of HepG2 cell-derived MVs (HepG2-MVs). After GFET chips were fabricated, AuNPs were then decorated on the RGO surface. For specific capture and detection of HepG2-MVs, both sulfhydrylated HepG2 cell specific TLS11a aptamer (AptTLS11a) and epithelial cell adhesion molecule aptamer (AptEpCAM) were immobilized on the AuNP surface through an Au-S bond. This developed nanosensor delivered a broad linear dynamic range from 6 × 105 to 6 × 109 particles/mL and achieved a high sensitivity of 84 particles/µL for HepG2-MVs detection. Moreover, this AAP-GFET platform was able to distinguish HepG2-MVs from other liver cancer-related serum proteins (such as AFP and CEA) and MVs derived from human normal cells and other cancer cells of lung, pancreas, and prostate, suggesting its excellent method specificity. Compared with those modified with a single type of aptamer alone (AptTLS11a or AptEpCAM), such an AAP-GFET nanosensor showed greatly enhanced signals, suggesting that the dual-aptamer-based bio-nano interface was uniquely designed and could realize more sensitive quantification of HepG2-MVs. Using this platform to detect HepG2-MVs in clinical blood samples, we found that there were significant differences between healthy controls and hepatocellular carcinoma (HCC) patients, indicating its great potential in early HCC diagnosis.

Ultrasensitive Monolayer MoS2 Field-Effect Transistor Based DNA Sensors for Screening of Down Syndrome.

Field-effect transistor (FET) biosensors based on low-dimensional materials present the advantages of low cost, high speed, small size, and excellent compatibility with integrated circuits (ICs). In this work, we fabricated highly sensitive FET-based DNA biosensors based on chemical vapor deposition (CVD)-grown monolayer MoS2 films in batches and explored their application in noninvasive prenatal testing (NIPT) for trisomy 21 syndrome. Specifically, MoS2 was functionalized with gold nanoparticles (Au NPs) of an optimized size and at an ideal density, and then, probe DNAs for the specific capture of target DNAs were immobilized on the nanoparticles. The fabricated FET biosensors are able to reliably detect target DNA fragments (chromosome 21 or 13) with a detection limit below 100 aM, a high response up to 240%, and a high specificity, which satisfy the requirement for the screening of Down syndrome. In addition, a real-time test was conducted to show that the biosensor clearly responds to the target DNA at concentrations as low as 1 fM. Our approach shows the potential for detecting the over-expression of chromosome 21 in the peripheral blood of pregnant women and achieving Down syndrome screening.

Receptor-Mediated Field Effect Transistor Biosensor for Real-Time Monitoring of Glutamate Release from Primary Hippocampal Neurons.

Glutamate, one of the most important central excitatory neurotransmitters, plays crucial roles in nerve signal transduction and is implicated in several neurological disorders. However, no effective means has been developed for specific detection of glutamate released from primary cultured neurons. Here we present a reduced graphene oxide (RGO)-based field effect transistor (FET) biosensor functionalized with synthesized glutamate receptor for real-time monitoring of glutamate release from primary cultured rat hippocampus neurons. Metabotropic glutamate receptors (mGluR) was specifically synthesized and then immobilized on the RGO surface by 1-pyrenebutanoic acid succinimidyl ester (PASE) linker, after which target glutamate (pI = 3.22) could specifically bind to the synthesized mGluR in the neutral buffer, causing the charge density change. After the neurons were cultured on the sensing channel with a self-made liquid reservoir, the FET biosensor could discriminate glutamate in the femtomolar range in complete cell culture medium and generate encouraging results in real-time monitoring of glutamate release from primary rat hippocampus neurons. This work is the first report of specific and direct detection of glutamate molecules released from primary culture of differentiated central neurons, which may further help understand the nature of neuronal communication. Moreover, this work paves a way for the detection of electrochemically inactive small molecules released by cells.

Electrical and Label-Free Quantification of Exosomes with a Reduced Graphene Oxide Field Effect Transistor Biosensor.

Exosomes are small membrane-bound nanovesicles with a size of 50-150 nm which contain many functional biomolecules, such as nucleic acids and proteins. Due to their high homology with parental generation, they are of great significance in clinical diagnosis. At present, the quantitative detection of low concentrations of cancer-derived exosomes present in biofluids is still a great challenge. In this study, we develop an electrical and label-free method to directly detect exosomes with high sensitivity based on a reduced graphene oxide (RGO) field effect transistor (FET) biosensor. An RGO FET biosensor modified with specific antibody CD63 in the sensing area was fabricated and was used for electrical and label-free quantification of exosomes. The method achieved a low limit of detection down to 33 particles/µL, which is lower than that of many other available methods. In addition, the FET biosensor was employed to detect exosomes in clinical serum samples, showing significant differences in detecting healthy people and prostate cancer (PCa) patients. Different from other technologies, this study provides a unique technology capable of directly quantifying exosomes without labeling, indicating its potential as a tool for early diagnosis of cancer.

Microvesicle detection by a reduced graphene oxide field-effect transistor biosensor based on a membrane biotinylation strategy.

Unlike other extracellular vesicle (EV) subtypes such as exosomes, the lack of well-defined universal markers on the surface of microvesicles (MVs) has led to difficulty in the detection of the entire MV population. To design a universal MV detection method, we reported highly sensitive electrical detection of MVs using a reduced graphene oxide (RGO)-based field-effect transistor (FET) biosensor by the introduction of a membrane biotinylation strategy in this work. Biotinylated MVs (B-MVs) were obtained by supplying the culture medium with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[biotinyl(polyethylene glycol)-2000] (DSPE-PEG-biotin) while cultivating the cells. Excellent biotinylation efficiency of MVs (92.6%) was then realized. A streptavidin (SA) probe was subsequently modified onto the channel surface of the as-fabricated RGO-based FET device, which was capable of specifically recognizing B-MVs due to the high affinity between SA and biotin in a 1 : 4 recognition format. The results showed that the RGO-based FET biosensor could detect B-MVs in a wide range from 105 particles per mL to 109 particles per mL with a low detection limit down to 20 particles per µL, which was the lowest value compared with other previously reported results. This platform also allowed distinguishing B-MVs from other unbiotinylated EV types such as MVs and exosomes, exhibiting excellent specificity. Moreover, this FET biosensor demonstrated the capability of detecting B-MVs derived from different cell lines including cancer cells and normal cells, indicating its versatility and potential applications in the biomedical field.

A field effect transistor modified with reduced graphene oxide for immunodetection of Ebola virus.

The authors describe a field effect transistor (FET) based immunoassay for the detection of inactivated ebola virus (EBOV). An equine antibody against the EBOV glycoprotein was immobilized on the surface of the FET that was previously modified with reduced graphene oxide (RGO). The antibody against EBOV was immobilized on the modified FET, and the response to EBOV was measured as a function of the shift of Dirac voltage. The method can detect the EBOV over the concentration range from 2.4 × 10-12 g·mL-1 to 1.2 × 10-7 g·mL-1 and with a limit of detection as low as 2.4 pg·mL-1. The assay has satisfactory specificity and was applied to the quantitation of inactivated EBOV in spiked serum. Graphical abstract Schematic presentation of the field effect transistor (FET) modified with reduced graphene oxide (RGO) for Ebola Virus (EBOV) detection. Specific binding between EBOV and the anti-EBOV antibody (Ab) on the FET device leads to obvious current change.

Real-Time Monitoring of Nitric Oxide at Single-Cell Level with Porphyrin-Functionalized Graphene Field-Effect Transistor Biosensor.

An ultrasensitive and highly efficient assay for real-time monitoring of nitric oxide (NO) at single-cell level based on a reduced graphene oxide (RGO) and iron-porphyrin-functionalized graphene (FGPCs) field-effect transistor (FET) biosensor is reported. A layer-to-layer assembly of RGO and FGPCs on a prefabricated FET sensor surface through π-π stacking interaction allowed superior electrical conductivity caused by RGO, and highly catalytic specificity induced by metalloporphyrin, ensuring the ultrasensitive and highly specific detection of NO. The results demonstrated that the RGO/FGPCs FET biosensor was capable of real-time monitoring of NO in the range from 1 pM to 100 nM with the limit of detection as low as 1 pM in phosphate-buffered saline (PBS) and 10 pM in the cell medium, respectively. Moreover, the developed biosensor could be used for real-time monitoring of NO released from human umbilical vein endothelial cells (HUVECs) at single-cell level. Along with its miniaturized sizes, ultrasensitive characteristics, and fast response, the FET biosensor is promising as a new platform for potential biological and diagnostic applications.

Posttreatment with Ma-Xing-Shi-Gan-Tang, a Chinese medicine formula, ameliorates lipopolysaccharide-induced lung microvessel hyperpermeability and inflammatory reaction in rat.

OBJECTIVE: The aim of present study was to investigate the efficacy of MXSGT, a traditional Chinese medicine formula used for treatment of respiratory system diseases, in the LPS-induced rat ALI particularly with a focus on its effect on lung microvascular hyperpermeability and inflammatory reaction. METHODS: Male Sprague-Dawley rats were injected with LPS (7.5 mg/kg, 1.5 mg/mL) intraperitoneally. MXSGT (0.52 g or 2.61 g/kg) was given by gavage six hours after LPS injection. RESULTS: LPS stimulation resulted in a reduced survival rate, deteriorated vital signs, an increase in the number of leukocytes adhering to lung venules, the albumin leakage, the activity of MPO in lung tissues, the production of pro-inflammatory cytokines and lung perivascular edema. After LPS stimulation, western blot analysis revealed an increase in the expression of ICAM-1 and toll-like receptor 4, a decrease in tight junction proteins and an activation of cav-1, Src, and NF-κB. All the LPS-induced alterations were significantly attenuated by posttreatment with MXSGT. CONCLUSIONS: This study demonstrated MXSGT as a potential strategy for lung microvascular hyperpermeability and inflammatory reaction in ALI, and suggested that the beneficial role of MXSGT was correlated with toll-like receptor 4, Src, and NF-κB.

Reproducible, Accurate, and Sensitive Food Toxin On-Site Detection with Carbon Nanotube Transistor Biosensors.

Field-effect transistor (FET) biosensors based on nanomaterials are promising in the areas of food safety and early disease diagnosis due to their ultrahigh sensitivity and rapid response. However, most academically developed FET biosensors lack real-world reproducibility and comprehensive methodological validation to meet the standards of regulatory bodies. Here, highly uniform and well-packaged semiconducting carbon nanotube (CNT) FET biosensor chips were developed and assessed for the plug-and-play sensing for the rapid and highly sensitive detection of aflatoxin B1 (AFB1) in real food samples to meet international standards. In order to meet the requirements for reproducibility and stability, a scalable residual-free passivation and packaging process was developed for CNT FET biosensors. Portable detection systems were then constructed for on-site detection. The resulting packaged chips were functionalized with nucleic aptamers to enable highly selective detection of AFB1 in food samples with a detection limit (LOD) of 0.55 fg/mL (standard) for AFB1 and cross-reactivity coefficients to interferences as low as 1.8 × 10-7 in simulated solutions. Utilizing the portable detection system, on-site real food detection was achieved with a rapid response time less than 60 s, and LOD of 0.25 pg/kg (standard) in complex corn sample matrices. Single-blind tests demonstrated the ability of the chips to detect AFB1-positive food with 100% accuracy, using a set of 30 peanut samples. Validation experiments confirmed that the detection range, stability, and repeatability met international standards. This study showcased the accuracy, reliability, and potential practical applications of CNT FET biosensor chips in areas such as food safety and rapid biomedical testing.

Mobilization of phosphorus in sediments of eutrophic lakes induced by elevated sulfate levels.

Elevated sulfate levels in eutrophic lakes have been observed to induce the release of endogenous phosphorus. While previous studies have predominantly examined its impact on iron-bound phosphorus (FeP), the influence on organic phosphorus (OP), a crucial active phosphorus component in sediments, remains poorly understood. In this study, mesocosms were established with lactate supplementation and varying sulfate concentrations to explore sulfate reduction and its impacts on phosphorus mobilization in freshwater sediments. Lactate addition induced hypoxia and provided substrates, thereby stimulating sulfate reduction with a decline of sulfate levels, an increase of sulfide concentrations, and fluctuations of sulfate-reducing bacteria. Meanwhile, concentrations of total dissolved phosphorus and phosphate were dramatically promoted during lactate decomposition, with a higher sulfate concentration associated with greater phosphorus elevation, correlating with the decrease of total phosphorus in sediment. The increase in phosphorus of the overlying water was partly attributed to FeP release from the sediment, confirmed by a decrease in its sediment content. FeP release was ascribed to dissimilatory reduction of iron oxides or chemical reduction mediated by sulfides in anoxic sediments, leading to the desorption and subsequent release of phosphorus. Evidences included the proliferation of iron-reducing bacteria, a decrease in Fe(II) concentrations in sediment pore- water, and the continuous accumulation of solid iron sulfides in surface sediments. Furthermore, OP mineralization in sediment also contributed to the increase in phosphorus in water columns, confirmed by a reduction in its content and the abundance of fermentation bacteria in surface sediment. Notably, the decrease in OP content accounted for >80 % of the total phosphorus reduction in surface sediment in the end. Thus, sulfur cycling plays a critical role in iron and phosphorus cycling, significantly stimulating not only the mobilization of FeP but also OP in sediments, with OP mineralization potentially being the primary contributor to endogenous phosphorus release.

Ultra-sensitive and rapid detection of Salmonella enterica and Staphylococcus aureus to single-cell level by aptamer-functionalized carbon nanotube field-effect transistor biosensors.

Foodborne diseases caused by Salmonella enterica (S. enterica) and Staphylococcus aureus (S. aureus) significantly impact public health, underscoring the imperative for highly sensitive, rapid, and accurate detection technologies to ensure food safety and prevent human diseases. Nanomaterials hold great promise in the development of high-sensitivity transistor biosensors. In this work, field-effect transistor (FET) comprising high-purity carbon nanotubes (CNTs) were fabricated and modified with corresponding nucleic acid aptamers for the high-affinity and selective capture of S. enterica and S. aureus. The aptamer-functionalized CNT-FET biosensor demonstrated ultra-sensitive and rapid detection of these foodborne pathogens. Experimental results indicated that the biosensor could detect S. enterica at a limit of detection (LOD) as low as 1 CFU in PBS buffer, and S. aureus at an LOD of 1.2 CFUs, achieving single-cell level detection accuracy with exceptional specificity. The biosensor exhibited a rapid response time, completing single detections within 200 s. Even in the presence of interference from six complex food matrices, the biosensor maintained its ultra-sensitive (3.1 CFUs) and rapid response (within 200 s) characteristics for both pathogens. The developed aptamer-functionalized CNT-FET biosensor demonstrates a capability for low-cost, ultra-sensitive, label-free, and rapid detection of low-abundance S. enterica and S. aureus in both buffer solutions and complex environments. This innovation holds significant potential for applying this detection technology to on-site rapid testing scenarios, offering a promising solution to the pressing need for efficient and reliable pathogen monitoring in various settings.

Power and Sensitivity Management of Carbon Nanotube Transistor Glucose Biosensors.

Continuous glucose monitoring (CGM), which is significant for the daily management of diabetes, requires a low-power-consumption sensor system that can track low nanomolar levels of glucose in physiological fluids, such as sweat and tears. However, traditional electrochemical methods are limited to analytes in micromolar to millimolar ranges and entail high power consumption. Carbon nanotube (CNT) film field-effect transistors (FETs) are promising for constructing extremely sensitive biosensors, but their wide applications in CGM are limited by the strong screening effect of physiological fluids and the zero charge of glucose molecules. In this study, we demonstrate a glucose aptamer-modified CNT FET biosensor to realize a highly sensitive CGM system with sub-nW power consumption by applying a suitable gate voltage. A positive gate voltage can enlarge the effective Debye screening length at the double layer to reduce the local ion population nearby and then improve the sensitivity of the FET-based biosensors by 5 times. We construct CNT FET sensors for CGM with a limit of detection of 0.5 fM, a record dynamic range up to 109, and a power consumption down to ∼100 pW. The proposed field-modulated sensing performance scheme is applicable to other aptamer-based FET biosensors for detecting neutral or less charged molecules and opens opportunities to develop facilely modulated, highly sensitive, low-power, and noninvasive CGM systems.