Open-Bandgap Graphene-Based Field-Effect Transistor Using Oligo(phenylene-ethynylene) Interfacial Chemistry

Bioelectronics based on antibody-conjugated graphene field-effect transistor for response of Staphylococcal enterotoxin B as a biological weapon

Staphylococcal enterotoxin B (SEB) is a potent toxin that is produced by Staphylococcus aureus and is classified as an agent for biological weapons. Various nanotechnology-based biosensors have been developed to respond to SEB-based biological weapons; however, these biosensors exhibit various limitations. A novel chimeric antibody was developed from SEB-specific hybridoma clones that were generated using native-like SEB antigen expressed via a baculovirus system. The chimeric antibody exhibited high binding specificity and subnanomolar affinity and was subsequently conjugated onto a graphene field-effect transistor-based bioelectronic (SEB bioelectronic). This device exhibited high performance with a limit of detection of 1 pg/mL and a detection range of 1 pg/mL to 100 ng/mL, demonstrating superior specific detection performance even in the presence of various interference toxin substances at 103 times higher concentrations. Moreover, the SEB bioelectronic was evaluated using nonhuman primate infection models, and the detection performance was investigated based on those for standard SEB substances. These results indicate that the SEB bioelectronic can be utilized for noncontact SEB detection in SEB-exposed onsite locations and can be applied for bioelectronic development to respond to other biological weapons through bioprobe exchanges.

Plasmon-Driven Gold Nanopillar Multiarrayed Gene Amplification Methodology for the High-Throughput Discrimination of Pathogens

Molecular diagnosis limitations, including complex treatment processes, low cost-effectiveness, and operator-dependent low reproducibility, interrupt the timely prevention of disease spread and the development of medical devices for home and outdoor uses. A newly fabricated gold nanopillar array-based film is presented for superior photothermal energy conversion. Magnifying the metal film surface-to-volume ratio increases the photothermal energy conversion efficiency, resulting in a swift reduction in the gene amplification reaction time. Plasmonic energy-based ultrafast gene amplification and facile confirmation methodology offer a rapid disease discrimination platform for high-throughput multiplexed diagnosis. The superior performance of the gold nanopillar arrayed film is demonstrated by measuring the amount of pathogen (Vibrio cholerae) with a sensitivity of 101 cfu mL-1 in 5.5 min. The newly engineered gold nanopillar arrayed film can be utilized to diagnose universal pathogens to achieve an increasingly successful complete cure.

TRPA1 nanovesicle-conjugated receptonics for rapid biocide screening

Although biocides are important materials in modern society and help protect human health and the environment, increasing exposure to combined biocides can cause severe side effects in the human body, such as lung fibrosis. In this study, we developed a receptonics system to screen for biocides in combined household chemical products based on biocides. The system contains transient receptor potential ankyrin 1 (TRPA1) nanovesicles (NVs) to sense biocides based on pain receptors and a side-gated field-effect transistor (SGFET) using a single-layer graphene (SLG) micropattern channel. The binding affinities between the TRPA1 receptor and the various biocides were estimated by performing biosimulation and using a calcium ion (Ca2+) assay, and the sensitivity of the system was compared with that of TRPA1 NV receptonics systems. Based on the results of the TRPA1 NV receptonics system, the antagonistic and potentiation effects of combined biocides and household chemical products depended on the concentration. Finally, the TRPA1 NV receptonics system was applied to screen for biocides in real products, and its performance was successful. Based on these results, the TRPA1 NV receptonics system can be utilized to perform risk evaluations and identify biocides in a simple and rapid manner.

In Situ Local Band Engineering of Monolayer Graphene Using Triboelectric Plasma

Graphene, a promising material with excellent properties, suffers from a major limitation in electronics due to its zero bandgap. The gas molecules adsorption has proven to be an effective approach for band regulation, which usually requires a harsh environment. Here, O2 - ions produced with triboelectric plasma are used for in situ regulation of graphene, and the switching ratio can reach 1010. The O2 - ions physical adsorption will reduce the Fermi-level (EF) of graphene. As the EF of graphene is lower than the lowest unoccupied molecular orbital (LUMO) level of O2-, the adsorption of O2 - changes from uniform physical adsorption to local chemical adsorption, thereby realizing the semiconductor properties of graphene. The local graphene bandgap is calculated to be 83.4 meV by the variable-temperature experiment. Furthermore, annealing treatment can restore to 1/10 of the initial conductance. The C─O bond formed by O2 - adsorption has low bond energy and is easy to desorb, while the C═O bond formed by adsorption on defects and edges has higher bond energy and is difficult to desorb. The study proposes a simple in situ method to investigate the microscopic process of O2 - adsorption on the graphene surface, demonstrating a new perspective for local energy band engineering of graphene.

Synchronous Diagnosis of Respiratory Viruses Variants via Receptonics Based on Modeling Receptor-Ligand Dynamics

The transmission and pathogenesis of highly contagious fatal respiratory viruses are increasing, and the need for an on-site diagnostic platform has arisen as an issue worldwide. Furthermore, as the spread of respiratory viruses continues, different variants have become the dominant circulating strains. To prevent virus transmission, the development of highly sensitive and accurate on-site diagnostic assays is urgently needed. Herein, a facile diagnostic device is presented for multi-detection based on the results of detailed receptor-ligand dynamics simulations for the screening of various viral strains. The novel bioreceptor-treated electronics (receptonics) device consists of a multichannel graphene transistor and cell-entry receptors conjugated to N-heterocyclic carbene (NHC). An ultrasensitive multi-detection performance is achieved without the need for sample pretreatment, which will enable rapid diagnosis and prevent the spread of pathogens. This platform can be applied for the diagnosis of variants of concern in clinical respiratory virus samples and primate models. This multi-screening platform can be used to enhance surveillance and discriminate emerging virus variants before they become a severe threat to public health.

Plasmonic digital PCR for discriminative detection of SARS-CoV-2 variants

We developed a novel strategy for discriminative detection of SARS-CoV-2 variants based on the plasmonic photothermal effect of gold nanofilms and digital polymerase chain reaction (dPCR) technology. This method consists of the gold nanofilm-based dPCR chip fabrication for ultrafast heating and cooling cycles by the plasmonic photothermal effect, the LED quencher immobilization through the interfacing compound on the surface of the gold nanofilm to prevent photoquenching of PCR signaling dye, and the discriminative detection of the variant viruses from the COVID-19 clinical samples by photothermal cycles with fabricated dPCR chips and a portable plasmonic PCR device. Compared to conventional sequencing or RT-qPCR-based variant detection methods, this technology can be effectively applied to point-of-care testing by enabling ultrafast quantitative analysis with a small device. With this method, we successfully detected the delta variant and the omicron variant with a high sensitivity of 10 copies from COVID-19 patients' clinical samples within 25 min, including reverse transcription. This method can be applied universally to rapid and accurate point-of-care testing for various pandemic viruses as well as the coronavirus.