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Two-dimensional (2D) transition metal dichalcogenide (TMD) hetero PN junctions with a van der Waals (vdW) interface have received much attention, because PN diodes are basically important to control the vertical current across the junction. Interestingly, the same vdW PN junction structure can be utilized for junction field-effect transistors (JFETs) where in-plane current is controlled along the junction. However, 2D vdW JFETs seem rarely reported, despite their own advantages to achieve when good vdW junction is secured. Here, we present high-performance p-MoTe2 JFETs using almost perfect vdW organic Alq3/p-MoTe2 junctions and demonstrate organic NPB/n-MoS2 JFETs. The p- and n-channel JFETs stably show high mobilities of 60-80 and ∼800 cm2/V s, respectively, along with a high ON/OFF current ratio (>1 × 105) and minimal gate leakage at 5 V even after a few months. Such performances are attributed to a quality vdW junction at organic layer/TMD interfaces.

Very recently, stacked two-dimensional materials are studied, focusing on the van der Waals interaction at their stack junction interface. Here, we report field effect transistors (FETs) with stack...

Since transition metal dichalcogenide (TMD) semiconductors are found as two-dimensional van der Waals materials with a discrete energy bandgap, many TMD based field effect transistors (FETs) are reported as prototype devices. However, overall reports indicate that threshold voltage (Vth) of those FETs are located far away from 0 V whether the channel is p- or n-type. This definitely causes high switching voltage and unintended OFF-state leakage current. Here, a facile way to simultaneously modulate the Vth of both p- and n-channel FETs with TMDs is reported. The deposition of various organic small molecules on the channel results in charge transfer between the organic molecule and TMD channels. Especially, HAT-CN molecule is found to ideally work for both p- and n-channels, shifting their Vth toward 0 V concurrently. As a proof of concept, a complementary metal oxide semiconductor (CMOS) inverter with p-MoTe2 and n-MoS2 channels shows superior voltage gain and minimal power consumption after HAT-CN deposi...

Nanofiber membranes for biomedical filtration devices require antibacterial activity to prevent bacterial contamination under moisture conditions while exhibiting biocompatibility. Here, we propose an antibacterial membrane filter composed of electrospun polyacrylonitrile (PAN) nanofibers with a surface functionalized with silver nanoparticles (AgNPs) by a facile wetting process for in situ silver reduction under physiologically mild conditions. Sequential wetting of thermally stabilized PAN nanofibers in silver nitrate (AgNO3) and sodium hydroxide (NaOH) solutions enabled direct control of the amount of synthesized AgNPs and their release behaviors in an aqueous environment. The fabricated AgNPs-functionalized PAN nanofibers (PAN-AgNPs) exhibit the appreciable antibacterial efficiency against Escherichia coli and Staphylococcus aureus bacteria with considerable sustainability for repetitive use. In addition, the generated AgNPs on PAN nanofiber membranes in an adequate loading range also revealed good biocompatibility with mammalian cells. Thus, PAN-AgNPs nanofibers can be practically applied as a promising disinfecting membrane filter for biomedical and hygienic applications.

Two-dimensional (2D) transition metal dichalcogenides (TMDs)-based van der Waals (vdW) PN junctions have been used for heterojunction diodes, which basically utilize out-of-plane current across the junction interface. In fact, the same vdW PN junction structure can be utilized for another important device application, junction field effect transistors (JFETs), where in-plane current is possible along with 2D–2D heterojunction interface. Moreover, the 2D TMD-based JFET can use both p- and n-channel for low voltage operation, which might be its unique feature. Here we report vdW JFETs as an in-plane current device with heterojunction between semiconducting p- and n-TMDs. Since this vdW JFET would have low-density traps at the vdW interface unlike 2D TMD-based metal insulator semiconductor field effect transistors (MISFETs), little hysteresis of 0.0–0.1 V and best subthreshold swing of ~100 mV/dec were achieved. Easy saturation was observed either from n-channel or p-channel JFET as another advantage over 2D MISFETs, exhibiting early pinch-off at ~1 V. Operational gate voltage for threshold was near 0 V and our highest mobility reaches to ~>500 cm2/V·s for n-channel JFET with MoS2 channel. For 1 V JFET operation, our best ON/OFF current ratio was observed to be ~104. Van der Waals heterostructures of atomically thin semiconductors enable junction field effect transistors (JFETs). A team led by Seongil Im at Yonsei University fabricated JFETs using a heterojunction of semiconducting p-MoTe2 (or p-WSe2) and n-MoS2. The p-type transition metal dichalcogenide (TMDC) works as a gate for the n-type TMDC channel, whereas the n-type TMDC operates as a gate for the p-type TMDC channel. Owing to the low density of traps at the van der Waals interface, the devices exhibit low hysteresis of 0.05–0.1 V and achieve a subthreshold swing of ~100 mV/decade. The highest mobility reaches 500 cm2/V·s for the n-channel JFET with MoS2, whereas the p-channel JFET with MoTe2 is characterized by a much lower mobility of ~13 cm2/V·s. The highest ON/OFF current ratio was observed to be >104.

Despite the great promise of immune checkpoint blockade (ICB) therapy for cancer treatment, the currently available options for ICB treatment pose major clinical challenges, including the risk of severe systemic autoimmune responses. Here, we developed a novel localized delivery platform, immuno-bioglue (imuGlue), which is inspired by the intrinsic underwater adhesion properties of marine mussels and can allow the optimal retention of anti-PD-L1 drugs at tumor sites and the on-demand release of drugs in response to the tumor microenvironment. Using a triple-negative breast cancer and melanoma models, we found that imuGlue could significantly enhance anti-tumor efficacy by eliciting a robust T cell-mediated immune response while reducing systemic toxicity by preventing the rapid diffusion of anti-PD-L1 drugs into the systemic circulation and other tissues. It was also demonstrated that imuGlue could be successfully utilized for combination therapy with other immunomodulatory drugs to enhance the anti-tumor efficacy of ICB-based immunotherapy, demonstrating its versatility as a new treatment option for cancer immunotherapy.

Following surgical resection for primary treatment of solid tumors, systemic chemotherapy is commonly used to eliminate residual cancer cells to prevent tumor recurrence. However, its clinical outcome is often limited due to insufficient local accumulation and the systemic toxicity of anticancer drugs. Here, we propose a sprayable adhesive nanoparticle (NP)-based drug delivery system using a bioengineered mussel adhesive protein (MAP) for effective locoregional cancer therapy. The MAP NPs could be administered to target surfaces in a surface-independent manner through a simple and easy spray process by virtue of their unique adhesion ability and sufficient dispersion property. Doxorubicin (DOX)-loaded MAP NPs (MAP@DOX NPs) exhibited efficient cellular uptake, endolysosomal trafficking, and subsequent low pH microenvironment-induced DOX release in cancer cells. The locally sprayed MAP@DOX NPs showed a significant inhibition of tumor growth in vivo, resulting from the prolonged retention of the MAP@DOX NPs on the tumor surface. Thus, this adhesive MAP NP-based spray therapeutic system provides a promising approach for topical drug delivery in adjuvant cancer therapy.

Perovskite photovoltaic (PV) cell researches have been extensively conducted due to its unprecedentedly excellent power conversion efficiencies (PCEs), which are reported to be over 23.7% in maximum. Despite the high PCEs, there are several unresolved issues on optimal interface states in the cell and device stabilities. Moreover, beyond the simple PV device issues, extended device or circuit applications have rarely been reported although it seems equally important to fully reveal the self-power energy harvesting functions of the perovskite cells to modern ubiquitous environment. Here, we integrate a realistic self-power circuit utilizing a few nm-thin molybdenum ditelluride (MoTe2) field effect transistors (FETs) as well as perovskite PV cells. The PV cells intrinsically show more than 0.9 V of open circuit voltage (VOC) under artificial sun (AM 1.5) or visible photon illumination, so we thus used a red-light emitting diode (LED) to simply generate ~1 V of photovoltage. Two modes for practical operation were consequently observed from the circuit, depending on the light intensity: self-power current/voltage source mode (high intensity) and photosensor mode (low intensity). We now conclude that our self-power circuit approaches integrating perovskite cells and 2D MoTe2 FET could attract much attention for future ubiquitous electronics and energy harvest applications.