The fast spread of SARS-CoV-2 has severely threatened the public health. Establishing a sensitive method for SARS-CoV-2 detection is of great significance to contain the worldwide pandemic. Here, we develop a graphene field-effect transistor (g-FET) biosensor and realize ultrasensitive SARS-CoV-2 antibody detection with a limit of detection (LoD) down to 10 −18 M (equivalent to 10 −16 g mL −1 ) level. The g-FETs are modified with spike S1 proteins, and the SARS-CoV-2 antibody biorecognition events occur in the vicinity of the graphene surface, yielding an LoD of ∼150 antibodies in 100 μL full serum, which is the lowest LoD value of antibody detection. The diagnoses time is down to 2 min for detecting clinical serum samples. As such, the g-FETs leverage rapid and precise SARS-CoV-2 screening and also hold great promise in prevention and control of other epidemic outbreaks in the future.
Due to the complexity of detection environments, field‐effect transistor (FET) sensors face the problem of fouling in practical applications. Existing antifouling strategies normally block the sensing sites and decrease the detection sensitivity. It remains a great challenge to achieve antifouling and sensitive detection. Here, a strategy is developed to use covalent organic frameworks (COFs) as the sensing interface. Owing to their unique crystalline mesoporous structure, the COFs not only encapsulate and prevent the channel from being fouled but also provide a large specific surface area modified with receptors. This approach enables the detection of 10−10 m Hg2+ within 50 ms in a ≈30 ppm poly‐(3,4‐ethylenedioxythiophene):poly‐(styrenesulfonate) solution and weak neural potential signals in complex bio‐environment, which is among the best performance for antifouling FET sensors. The COF interface enables highly sensitive and antifouling detection together with a fast response and large response range, which shows its great potential in high‐performance antifouling FET sensors.
Owing to high resolution, reliability, and industrial compatibility, all-photolithography is a promising strategy for industrial manufacture of organic electronics. However, it receives limited success due to the absence of a semiconducting photoresist with high patterning resolution, mobility, and performance stability against photolithography solution processes. Here, we develop a comprehensive semiconducting photoresist with nano-interpenetrating structure. After photolithography, nanostructured cross-linking networks interpenetrate with continuous phases of semiconducting polymers, enabling submicrometer patterning accuracy and compact molecular stacking with high thermodynamic stability. The mobility reaches the highest values of photocrosslinkable organic semiconductors and maintains almost 100% after soaking in developer and stripper for 1000 min. Owing to the comprehensive performance, all-photolithography is achieved, which fabricates organic inverters and high-density transistor arrays with densities up to 1.1 × 105 units cm−2 and 1 to 4 orders larger than conventional printing processes, opening up a new approach toward manufacturing highly integrated organic circuits and systems.
The growth of covalent organic frameworks (COFs) normally goes through a fast polymerization process, which quickly forms amorphous powder and then slowly crystallizes to obtain nanometer-sized crystals. Until now, it is still a challenge to modulate the growth process of COFs, which hampers the controllable synthesis for practical applications. Here, we develop a repolymerization strategy which realizes the self-controlled growth of COFs for the first time. COFs powder is used as starting material that can slowly decompose and release monomers and oligomers. At a self-established equilibrium state of reversible polymerization− decomposition−repolymerization reactions, the monomers and oligomers controllably repolymerize to form a thin crystalline COF film on substrates. The resulting COF film can be directly used as the sensing interface of graphene transistor sensors, which detect NH 3 down to 100 ppt, showing the great potential of this strategy in future applications.
Transition-metal dichalcogenides (TMDs) have been considered potential materials for the next generation of semiconductors. Realizing controllable growth of TMD crystals is a prerequisite for their future applications, which remains challenging. Here, we reveal a new mechanism of self-expanding molten salt-driven growth for a salt-assisted method and achieve the patterned growth of TMD single-crystal arrays with a size of hundreds of micrometers. Time-of-flight secondary ion mass spectroscopy and other spectroscopy characterizations identify the component of the molten salt solution. Microscopic characterizations reveal the existence of salt solution as an interlayer between a TMD monolayer and the silicon substrate as well as particles along the crystal edge. The edged salt solution serves as a self-expanding liquid substrate, which confines the reactive sites to the localized liquid surface, thus avoiding random nucleation. The surface reaction also assures monolayer crystal formation due to self-limiting growth. Besides, the liquid substrate affords sources and spreads itself continuously owing to the nonwetting effect on TMD crystals, thereby facilitating the continuous extension of the TMD monolayer. This work provides novel insights into the controllable synthesis of TMD monolayers and paves the way for the fabrication of TMD-based integrated functional devices.
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