A portable transistor immunosensor for fast identification of porcine epidemic diarrhea virus.

Widespread distribution of porcine epidemic diarrhea virus (PEDV) has led to catastrophic losses to the global pig farming industry. As a result, there is an urgent need for rapid, sensitive and accurate tests for PEDV to enable timely and effective interventions. In the present study, we develop and validate a floating gate carbon nanotubes field-effect transistor (FG CNT-FET)-based portable immunosensor for rapid identification of PEDV in a sensitive and accurate manner. To improve the affinity, a unique PEDV spike protein-specific monoclonal antibody is prepared by purification, and subsequently modified on FG CNT-FET sensor to recognize PEDV. The developed FET biosensor enables highly sensitive detection (LoD: 8.1 fg/mL and 100.14 TCID50/mL for recombinant spike proteins and PEDV, respectively), as well as satisfactory specificity. Notably, an integrated portable platform consisting of a pluggable FG CNT-FET chip and a portable device can discriminate PEDV positive from negative samples and even identify PEDV and porcine deltacoronavirus within 1 min with 100% accuracy. The portable sensing platform offers the capability to quickly, sensitively and accurately identify PEDV, which further points to a possibility of point of care (POC) applications of large-scale surveillance in pig breeding facilities.

Recent Progress of Ion-Modified TiO2 for Enhanced Photocatalytic Hydrogen Production.

Harnessing solar energy to produce hydrogen through semiconductor-mediated photocatalytic water splitting is a promising avenue to address the challenges of energy scarcity and environmental degradation. Ever since Fujishima and Honda's groundbreaking work in photocatalytic water splitting, titanium dioxide (TiO2) has garnered significant interest as a semiconductor photocatalyst, prized for its non-toxicity, affordability, superior photocatalytic activity, and robust chemical stability. Nonetheless, the efficacy of solar energy conversion is hampered by TiO2's wide bandgap and the swift recombination of photogenerated carriers. In pursuit of enhancing TiO2's photocatalytic prowess, a panoply of modification techniques has been explored over recent years. This work provides an extensive review of the strategies employed to augment TiO2's performance in photocatalytic hydrogen production, with a special emphasis on foreign dopant incorporation. Firstly, we delve into metal doping as a key tactic to boost TiO2's capacity for efficient hydrogen generation via water splitting. We elaborate on the premise that metal doping introduces discrete energy states within TiO2's bandgap, thereby elevating its visible light photocatalytic activity. Following that, we evaluate the role of metal nanoparticles in modifying TiO2, hailed as one of the most effective strategies. Metal nanoparticles, serving as both photosensitizers and co-catalysts, display a pronounced affinity for visible light absorption and enhance the segregation and conveyance of photogenerated charge carriers, leading to remarkable photocatalytic outcomes. Furthermore, we consolidate perspectives on the nonmetal doping of TiO2, which tailors the material to harness visible light more efficiently and bolsters the separation and transfer of photogenerated carriers. The incorporation of various anions is summarized for their potential to propel TiO2's photocatalytic capabilities. This review aspires to compile contemporary insights on ion-doped TiO2, propelling the efficacy of photocatalytic hydrogen evolution and anticipating forthcoming advancements. Our work aims to furnish an informative scaffold for crafting advanced TiO2-based photocatalysts tailored for water-splitting applications.

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.

Progress and perspectives of sorption-based atmospheric water harvesting for sustainable water generation: Materials, devices, and systems.

Establishing alternative methods for freshwater production is imperative to effectively alleviate global water scarcity, particularly in land-locked arid regions. In this context, extracting water from the ubiquitous atmospheric moisture is an ingenious strategy for decentralized freshwater production. Sorption-based atmospheric water harvesting (SAWH) shows strong potential for supplying liquid water in a portable and sustainable way even in desert environments. Herein, the latest progress in SAWH technology in terms of materials, devices, and systems is reviewed. Recent advances in sorbent materials with improved water uptake capacity and accelerated sorption-desorption kinetics, including physical sorbents, polymeric hydrogels, composite sorbents, and ionic solutions, are discussed. The thermal designs of SAWH devices for improving energy utilization efficiency, heat transfer, and mass transport are evaluated, and the development of representative SAWH prototypes is clarified in a chronological order. Thereafter, state-of-the-art operation patterns of SAWH systems, incorporating intermittent, daytime continuous and 24-hour continuous patterns, are examined. Furthermore, current challenges and future research goals of this cutting-edge field are outlined. This review highlights the irreplaceable role of heat and mass transfer enhancement and facile structural improvement for constructing high-yield water harvesters.

Ultraflexible, cost-effective and scalable polymer-based phase change composites via chemical cross-linking for wearable thermal management.

Phase change materials (PCMs) offer great potential for realizing zero-energy thermal management due to superior thermal storage and stable phase-change temperatures. However, liquid leakage and solid rigidity of PCMs are long-standing challenges for PCM-based wearable thermal regulation. Here, we report a facile and cost-effective chemical cross-linking strategy to develop ultraflexible polymer-based phase change composites with a dual 3D crosslinked network of olefin block copolymers (OBC) and styrene-ethylene-butylene-styrene (SEBS) in paraffin wax (PW). The C-C bond-enhanced OBC-SEBS networks synergistically improve the mechanical, thermal, and leakage-proof properties of PW@OBC-SEBS. Notably, the proposed peroxide-initiated chemical cross-linking method overcomes the limitations of conventional physical blending methods and thus can be applicable across diverse polymer matrices. We further demonstrate a portable and flexible PW@OBC-SEBS module that maintains a comfortable temperature range of 39-42 °C for personal thermotherapy. Our work provides a promising route to fabricate scalable polymer-based phase change composite for wearable thermal management.

Functionalized carbon nanotube field-effect transistor biosensor for highly sensitive detection of exosomal protein.

Since the exosomal protein level is related to many diseases, sensitive detection of exosomal protein is highly desirable. Here, we describe a polymer-sorted high-purity semiconducting carbon nanotubes (CNTs) films-based field-effect transistor (FET) biosensor for ultrasensitive and label-free detection of MUC1, a transmembrane protein highly expressed in breast cancer exosomes. Polymer-sorted semiconducting CNTs hold advantages including high purity (>99%), high CNT concentration, and short processing time (<1 h), but they are difficult to be stably functionalized with biomolecules because of lacking hanging bonds on their surface. To solve this issue, poly-lysine (PLL) was employed to modify the CNT films after they were deposited on the sensing channel surface of the fabricated FET chip. To specifically recognize the exosomal protein, sulfhydryl aptamer probes were immobilized on the gold nanoparticles (AuNPs) surface that was assembled on PLL substrate. The aptamer-modified CNT FET was capable of sensitively and selectively detecting exosomal MUC1 as high as 0.34 fg/mL. Moreover, the CNT FET biosensor was able to recognize breast cancer patients from healthy individuals by comparing the expression level of exosomal MUC1. The developed CNT FET biosensor is expected to be a novel assay for early diagnosis of cancer.

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.

A micro-carbon nanotube transistor for ultra-sensitive, label-free, and rapid detection of Staphylococcal enterotoxin C in food.

Staphylococcal enterotoxin C (SEC) is an enterotoxin produced by Staphylococcus aureus, which can cause intestinal diseases. Therefore, it is of great significance to develop a sensitive detection method for SEC to ensure food safety and prevent foodborne diseases in humans. A field-effect transistor (FET) based on high-purity carbon nanotubes (CNTs) was used as a transducer, and a nucleic acid aptamer with high affinity was used for recognition to capture the target. The results indicated that the biosensor achieved an ultra-low theoretical detection limit of 1.25 fg/mL in PBS, and its good specificity was verified by detecting target analogs. Three typical food homogenates were used as the solution to be measured to verify that the biosensor had a swift response time (within 5 min after sample addition). An additional study with a more significant basa fish sample response also showed excellent sensitivity (theoretical detection limit of 8.15 fg/mL) and a stable detection ratio. In summary, this CNT-FET biosensor enabled the label-free, ultra-sensitive, and fast detection of SEC in complex samples. The FET biosensors could be further used as a universal biosensor platform for the ultrasensitive detection of multiple biological toxic pollutants, thus considerably stopping the spread of harmful substances.

A pH-sensitive field-effect transistor for monitoring of cancer cell external acid environment.

The external acid environment of cancer cells is different from that of normal cells, making a profound impact on cancer progression. Here we report a simple poly-l-lysine-modified graphene field-effect transistor (PLL@G-FET) for in situ monitoring of extracellular acidosis around cancer cells. PLL is a well-known material with good biocompatibility and is rich in amino groups that are sensitive to hydrogen ions. After a simple drop-casting of PLL on the reduced graphene oxide (RGO) FET surface, the PLL@G-FET was able to realize the real-time monitoring of the localized pH change of cancer cells after the cancer cells were grown on the device. The PLL@G-FET sensor achieved a Nernstian value of 52.9 mV/pH in phosphate buffer saline from pH 4.0 to 8.0. In addition, the sensor exhibited excellent biocompatibility as well as good anti-interference ability in the cell culture medium. Furthermore, the device was used to real-time monitor the extracellular pH changes of MCF-7 cells under the intervention of different concentrations of drugs. This developed pH-sensitive FET provides a new method to study the extracellular acid environment in situ and helps us to enhance our understanding of cancer cell metabolism.

Simultaneous atmospheric water production and 24-hour power generation enabled by moisture-induced energy harvesting.

Water and electricity scarcity are two global challenges, especially in arid and remote areas. Harnessing ubiquitous moisture and sunlight for water and power generation is a sustainable route to address these challenges. Herein, we report a moisture-induced energy harvesting strategy to realize efficient sorption-based atmospheric water harvesting (SAWH) and 24-hour thermoelectric power generation (TEPG) by synergistically utilizing moisture-induced sorption/desorption heats of SAWH, solar energy in the daytime and radiative cooling in the nighttime. Notably, the synergistic effects significantly improve all-day thermoelectric power density (~346%) and accelerate atmospheric water harvesting compared with conventional designs. We further demonstrate moisture-induced energy harvesting for a hybrid SAWH-TEPG device, exhibiting high water production of 750 g m-2, together with impressive thermoelectric power density up to 685 mW m-2 in the daytime and 21 mW m-2 in the nighttime. Our work provides a promising approach to realizing sustainable water production and power generation at anytime and anywhere.

Acupuncture Needle-Based Transistor Neuroprobe for In Vivo Monitoring of Neurotransmitter.

Chemical communication via neurotransmitters is central to brain functions. Nevertheless, in vivo real-time monitoring of neurotransmitters released in the brain, especially the electrochemically inactive molecules, remains a great challenge. In this work, a novel needle field-effect transistor (FET) microsensor based on an acupuncture needle is proposed, which is demonstrated to be capable of real-time monitoring dopamine molecules as well as neuropeptide Y in vivo. The FET microstructure is fabricated by successively wrapping an insulating layer and a gold layer on the top of the needle, where the needle and the Au served as the source and drain, respectively. After assembling reduced graphene oxide (RGO) between the source and drain electrodes, the specific aptamer is immobilized on the RGO, making this needle-FET biosensor highly selective and sensitive to real-time monitor neurotransmitters released from rat brain, even in a Parkinson's diseases model. Furthermore, the needle-FET biosensor is applied to detect a variety of targets including hormones, proteins, and nucleic acid. By constructing a FET sensing interface on an acupuncture needle and implanting the sensor in a rat's brain for in vivo detection, this work provides a new sight in the FET domain and further expands the species of real-time in vivo detection.

Tandem Cas13a/crRNA-Mediated CRISPR-FET Biosensor: A One-for-All Check Station for Virus without Amplification.

The path toward field-effect transistor (FET) application from laboratory to clinic has delivered a compelling push in the biomedical domain, yet ultrasensitive and timely pathogen identification without PCR remains a long-lasting challenge. Herein, we create a generic check station termed "CRISPR-FET", first incorporating the CRISPR/Cas13a system within the FET modality, for accelerated and unamplified detection of viral RNA. Unlike conventional FETs bearing target-specific receptors, this sensor holds three unique advancements: (i) an ingenious sensing mechanism is used, which converts the signal of a large-sized analyte into an on-chip cleavage response of an immobilized CRISPR reporter, enabling signal generation events to occur all within the Debye length; (ii) the multipurpose inspection of the CoV ORF1ab, CoV N gene, and HCV RNA unveils the potential for "one-for-all" scalable FET-based molecular diagnostics; and (iii) it is shown that Cas13a-crRNAs targeting different sites of the viral genome can be deployed in tandem to amplify the FET response, empowering the detection limit down to 1.56 aM, which is a world-record level of sensitivity in the FET for direct viral gene sensing. Notably, a brilliant clinical applicability was made in distinguishing HCV-infected patients from normal controls. Overall, this study sheds new insights into FET-based nucleic acid sensing technology and invokes a vision for its possible future roles in diagnosis of various viral diseases.

A rechargeable molecular solar thermal system below 0 °C.

An optimal temperature is crucial for a broad range of applications, from chemical transformations, electronics, and human comfort, to energy production and our whole planet. Photochemical molecular thermal energy storage systems coupled with phase change behavior (MOST-PCMs) offer unique opportunities to capture energy and regulate temperature. Here, we demonstrate how a series of visible-light-responsive azopyrazoles couple MOST and PCMs to provide energy capture and release below 0 °C. The system is charged by blue light at -1 °C, and discharges energy in the form of heat under green light irradiation. High energy density (0.25 MJ kg-1) is realized through co-harvesting visible-light energy and thermal energy from the environment through phase transitions. Coatings on glass with photo-controlled transparency are prepared as a demonstration of thermal regulation. The temperature difference between the coatings and the ice cold surroundings is up to 22.7 °C during the discharging process. This study illustrates molecular design principles that pave the way for MOST-PCMs that can store natural sunlight energy and ambient heat over a wide temperature range.

Ultrasensitive detection of exosomal miRNA with PMO-graphene quantum dots-functionalized field-effect transistor biosensor.

Compared with the conventional DNA probe immobilization on the planar surface, nanoparticles-based DNA probes enable more RNA molecules to be anchored to the sensor surface, thereby improving the detection sensitivity. In this work, we report phosphorodiamidate morpholino oligomers (PMO)-graphene quantum dots (GQDs)-functionalized reduced graphene oxide (RGO) field effect transistor (FET) biosensors for ultrasensitive detection of exosomal microRNAs. After the RGO FET sensor was fabricated, polylysine (PLL) film was deposited onto the RGO surface. GQDs-PMO hybrid was prepared and covalently bound to PLL surface, enabling detection of exosomal microRNAs (miRNAs). The method achieved a detection limit as low as 85 aM and high specificity. Furthermore, the FET sensor was able to detect exosomal miRNAs in plasma samples and distinguish breast cancer samples from healthy samples. Compared with other methods, we use GQDs to further improve the sensitivity of FET, making it a potential tool for early diagnosis of breast cancer.

Ultralow-temperature-driven water-based sorption refrigeration enabled by low-cost zeolite-like porous aluminophosphate.

Thermally driven water-based sorption refrigeration is considered a promising strategy to realize near-zero-carbon cooling applications by addressing the urgent global climate challenge caused by conventional chlorofluorocarbon (CFC) refrigerants. However, developing cost-effective and high-performance water-sorption porous materials driven by low-temperature thermal energy is still a significant challenge. Here, we propose a zeolite-like aluminophosphate with SFO topology (EMM-8) for water-sorption-driven refrigeration. The EMM-8 is characterized by 12-membered ring channels with large accessible pore volume and exhibits high water uptake of 0.28 g·g-1 at P/P0 = 0.2, low-temperature regeneration of 65 °C, fast adsorption kinetics, remarkable hydrothermal stability, and scalable fabrication. Importantly, the water-sorption-based chiller with EMM-8 shows the potential of achieving a record coefficient of performance (COP) of 0.85 at an ultralow-driven temperature of 63 °C. The working performance makes EMM-8 a practical alternative to realize high-efficient ultra-low-temperature-driven refrigeration.

Dual-Encapsulated Highly Conductive and Liquid-Free Phase Change Composites Enabled by Polyurethane/Graphite Nanoplatelets Hybrid Networks for Efficient Energy Storage and Thermal Management.

Phase change materials (PCMs) are regarded as promising candidates for realizing zero-energy thermal management of electronic devices owing to their high thermal storage capacity and stable working temperature. However, PCM-based thermal management always suffers from the long-standing challenges of low thermal conductivity and liquid leakage of PCMs. Herein, a dual-encapsulation strategy to fabricate highly conductive and liquid-free phase change composites (PCCs) for thermal management by constructing a polyurethane/graphite nanoplatelets hybrid networks is reported. The PCM of polyethylene glycol (PEG) is first infiltrated into the cross-linked network of polyurethane (PU) to synthesize hybridized semi-interpenetrated composites (PEG@PU), and then incorporated with reticulated graphite nanoplatelets (RGNPs) via pressure-induced assembly to fabricate highly conductive PCCs (PEG@PU-RGNPs). The hybrid networks enable the PCCs to show excellent mechanical strength, liquid-free phase change, and stable thermal property. Notably, the dual-encapsulated PCCs exhibit high thermal and electrical conductivities up to 27.0 W m-1 K-1 and 51.0 S cm-1 , superior to the state-of-the-art PEG-based PCCs. Furthermore, the PCC-based energy device is demonstrated for efficient battery thermal management toward versatile demands of active preheating at a cold environment and passive cooling at a hot ambient. Overall, this work provides a promising route for fabricating highly conductive and liquid-free PCCs toward thermal management.

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-Functional Aligned and Interconnected Graphite Nanoplatelet Networks for Accelerating Solar Thermal Energy Harvesting and Storage within Phase Change Materials.

Solar thermal energy conversion and storage within phase change materials (PCMs) can overcome solar radiation intermittency to enable continuous operation of many heating-related processes. However, the energy-harvesting performance of current storage systems is always limited by low efficiencies in either solar thermal energy conversion or thermal transport within PCMs. Although PCM-based nanocomposites can address one or both of these issues, achieving high-performance composites with simultaneously enhanced photothermal performance and thermal transport capacity remains challenging. Here, we demonstrate that dual-functional aligned and interconnected graphite nanoplatelet networks (AIGNNs) yield the synergistic enhancement of interfacial photothermal conversion and thermal transport within PCMs to accelerate the solar thermal energy harvesting and storage. The AIGNNs include the naked part as the three-dimensional optical absorber and the incorporated part as thermally conductive pathways within PCMs. First, a phase change composite composed of the AIGNNs and the solid-solid PCM of polyhydric alcohol is synthesized using a facile three-step method, and shows 400% thermal conductivity enhancement for per 1 wt % graphite loading compared to pristine PCMs. After the elaborate surface treatment, a small part of the graphite networks is in situ exposed as the 3D optical absorber to boost the surface full-spectrum sunlight absorptivity up to 95%. This dual function design takes full advantage of the integrated AIGNNs in terms of both photothermal conversion and thermal transport capacities, superior to the traditional coating-enhanced photothermal conversion. This work offers a promising route to accelerating solar thermal energy harvesting and storage within PCMs.

Rapid and unamplified identification of COVID-19 with morpholino-modified graphene field-effect transistor nanosensor.

SARS-CoV-2 RNA is identified as a pivotal player to bolster energizing zones of COVID-19 detection. Herein, we develop a rapid and unamplified nanosensing platform for detection of SARS-CoV-2 RNA in human throat swab specimens. A gold nanoparticle (AuNP)-decorated graphene field-effect transistor (G-FET) sensor was fabricated, after which complementary phosphorodiamidate morpholino oligos (PMO) probe was immobilized on the AuNP surface. This sensor allowed for highly sensitive testing of SARS-CoV-2 RdRp as PMO does not have charges, leading to low background signal. Not only did the method present a low limit of detection in PBS (0.37 fM), throat swab (2.29 fM), and serum (3.99 fM), but also it achieved a rapid response to COVID-19 patients' samples within 2 min. The developed nanosensor was capable of analyzing RNA extracts from 30 real clinical samples. The results show that the sensor could differentiate the healthy people from infected people, which are in high agreement with RT-PCR results (Kappa index = 0.92). Furthermore, a well-defined distinction between SARS-CoV-2 RdRp and SARS-CoV RdRp was also made. Therefore, we believe that this work provides a satisfactory, attractive option for COVID-19 diagnosis.