Ultrahighly Sensitive and Selective Glutathione Sensor Based on Carbon Dot-Functionalized Solution-Gate Graphene Transistor.

A new type of carbon dot (CD)-functionalized solution-gated graphene transistor (SGGT) sensor was designed and fabricated for the highly sensitive and highly selective detection of glutathione (GSH). The CDs were synthesized via a one-step hydrothermal method using DL-thioctic acid and triethylenetetramine (TETA) as sources of S, N, and C. The CDs have abundant amino and carboxyl groups and were used to modify the surface of the gate electrode of SGGT as probes for detecting GSH. Remarkably, the CDs-SGGT sensor exhibited excellent selectivity and ultrahigh sensitivity to GSH, with an ultralow limit of detection (LOD) of up to 10-19 M. To the best of our knowledge, the sensor outperforms previously reported systems. Moreover, the CDs-SGGT sensor shows rapid detection and good stability. More importantly, the detection of GSH in artificial serum samples was successfully demonstrated.

Iron Vacancy Tunable Superconductor-Insulator Transition in FeSe/SrTiO_{3} Monolayer.

The Fe_{4}Se_{5} with a sqrt[5]×sqrt[5] Fe vacancy order is suggested to be a Mott insulator and the parent state of bulk FeSe superconductor. The iron vacancy ordered state has been considered as a Mott insulator and the parent compound of bulk FeSe-based superconductors. However, for the superconducting FeSe/SrTiO_{3} monolayer (FeSe/STO) with an interface-enhanced high transition temperature (T_{c}), the electronic evolution from its Fe vacancy ordered parent phase to the superconducting state, has not been explored due to the challenge to realize an Fe vacancy order in the FeSe/STO monolayer, even though important to the understanding of superconductivity mechanism. In this study, we developed a new method to generate Fe vacancies within the FeSe/STO monolayer in a tunable fashion, with the assistance of atomic hydrogen. As a consequence, an insulating sqrt[5]×sqrt[5] Fe vacancy ordered monolayer is realized as the parent state. By using scanning tunneling microscopy and scanning tunneling spectroscopy, the spectral evolution from superconductivity to insulator is fully characterized. Surprisingly, a prominent spectral weight transfer occurs, thus implying a strong electron correlation effect. Moreover, the Fe vacancy induced insulating gap exhibits no Mott gap-like features. This work provides new insights in understanding the high-T_{c} superconductivity in FeSe/STO monolayer.

Construction of highly efficient carbon dots-based polymer photonic luminescent solar concentrators with sandwich structure.

The enhancement of photoluminescence (PL) emission and waveguide play a key role in improving the optical efficiency of luminescent solar concentrators (LSCs). In this work, to boosting PL emission and waveguide simultaneously, one photonic crystal (PC) structure (crystalline colloid arrays (CCAs)) was introduced into carbon dots (CDs)-based polymer LSCs. A sandwich-structured CDs-based polymer photonic LSC, comprising glass/CDs-based polymer PC film/glass, was created. First, CDs-based colloidal crystal suspensions were prepared by co-assembly of monodispersed p(MMA-NIPAm) colloids and multicolor-emitting CDs in HEMA monomer induced by the evaporation-driven assembly. The obtained suspensions not only had uniform PL and structural colors, but showed enhanced PL emission. Second, the above suspensions were sandwiched between two glass sheets and finally a photonic polymer LSC with sandwiched structure (25 × 25 × 1.8 mm3) were formed via one-step photopolymerization technique. Remarkably, the optimal CDs-based polymer photonic LSCs with sandwiched structure not only had high transparence at visible range (>60%), but exhibited PL emission enhancement (at least 2 times). Furthermore, the maximum external optical efficiency (ηopt) of 5.84% could be achieved based on yellow-emitting CDs-based polymer photonic LSC. The high external optical efficiency was mainly attributed to the PL emission enhancement and good PC waveguide.

Tuning the Electronic Structure of an α-Antimonene Monolayer through Interface Engineering.

The interfacial charge transfer from the substrate may influence the electronic structure of the epitaxial van der Waals (vdW) monolayers and, thus, their further technological applications. For instance, the freestanding Sb monolayer in the puckered honeycomb phase (α-antimonene), the structural analogue of black phosphorene, was predicted to be a semiconductor, but the epitaxial one behaves as a gapless semimetal when grown on the Td-WTe2 substrate. Here, we demonstrate that interface engineering can be applied to tune the interfacial charge transfer and, thus, the electron band of the epitaxial monolayer. As a result, the nearly freestanding (semiconducting) α-antimonene monolayer with a band gap of ∼170 meV was successfully obtained on the SnSe substrate. Furthermore, a semiconductor-semimetal crossover is observed in the bilayer α-antimonene. This study paves the way toward modifying the electron structure in two-dimensional vdW materials through interface engineering.

Erratum: Realization of a Metallic State in 1T-TaS_{2} with Persisting Long-Range Order of a Charge Density Wave [Phys. Rev. Lett. 123, 206405 (2019)].

This corrects the article DOI: 10.1103/PhysRevLett.123.206405.

Realization of a Metallic State in 1T-TaS_{2} with Persisting Long-Range Order of a Charge Density Wave.

Metallization of 1T-TaS_{2} is generally initiated at the domain boundary of a charge density wave (CDW), at the expense of its long-range order. However, we demonstrate in this study that the metallization of 1T-TaS_{2} can be also realized without breaking the long-range CDW order upon surface alkali doping. By using scanning tunneling microscopy, we find the long-range CDW order is always persisting, and the metallization is instead associated with additional in-gap excitations. Interestingly, the in-gap excitation is near the top of the lower Hubbard band, in contrast to a conventional electron-doped Mott insulator where it is beneath the upper Hubbard band. In combination with the numerical calculations, we suggest that the appearance of the in-gap excitations near the lower Hubbard band is mainly due to the effectively reduced on-site Coulomb energy by the adsorbed alkali ions.

Characterization and Genome Analysis of a Novel Alteromonas Phage JH01 Isolated from the Qingdao Coast of China.

A novel Alteromonas phage JH01, with the host strain identified to be Alteromonas marina SW-47(T), was isolated from the Qingdao coast during the summer of 2017. Transmission electron microscopy analysis showed that phage JH01 can be categorized into the Siphoviridae family, with an icosahedral head of 62 ± 5 nm and a long contractile tail of 254 ± 10 nm. The bioinformatic analysis shows that this phage consists of a linear, double-stranded 46,500 bp DNA molecule with a GC content of 44.39%, and 58 ORFs with no tRNA genes. The ORFs are classified into four groups, including phage packaging, phage structure, DNA replication and regulation, and hypothetical protein. The phylogenetic tree, constructed using neighbor-joining analysis, shows that phage JH01 has altitudinal homology with some Vibrio and Pseudoalteromonas phage B8b. Comparative analysis reveals the high similarity between phage JH01 and phage B8b. Additionally, our study of phage JH01 provides useful information for further research on the interaction between Alteromonas phages and their hosts.

Thermal accelerated urease-driven hyaluronan-targeted melanin nano-missile for bio-radar detection and chemodrug-free phototherapy.

Polymer-based nanomotors are attracting increasing interest in the biomedical field due to their microscopic size and kinematic properties which support overcoming biological barriers, completing cellular uptake and targeted blasting in limited spaces. However, their applications are limited by the complex viscous physiological environment and lack of sufficient biocompatibility. This manuscript firstly reports a natural melanin nano-missile of MNP@HA-EDA@Urease@AIE PS (MHUA) based on photothermally accelerated urease-driven to achieve chemodrug-free phototherapy. Compared to conventional nano-missiles that only provide driving force, this photothermally accelerated urease-driven nanomotor is independent of chemodrug to maximise biocompatibility, and achieve ideal therapeutic effect through targeted PTT/PDT. In particular, the thermal effect can not only boost the catalytic activity of urease but also achieve ideally anti-tumor effect. In addition, guided by and AIE PS, the nanomotor can generate 1O2 to achieve PDT and be traced in real time serving as an effective fluorescent bio-radar for intracellular self-reporting during cancer treatment. Finally, the targeting ability of MUHA is provided by hyaluronan. Taken together, this MHUA platform provides a simple and effective strategy for target/fluorescence radar detective-guided PTT/PDT combination, and achieves good therapeutic results without chemodrug under thermal accelerated strategy, providing a new idea for the construction of chemodrug-free nanomotor-therapy system.

Thermal-Accelerated Urease-Driven Bowl-Like Polydopamine Nanorobot for Targeted Photothermal/Photodynamic Antibiotic-Free Antibacterial Therapy.

The problem of antibiotic resistance seriously affects the treatment of bacterial infections, so there is an urgent need to develop novel antibiotic-independent antimicrobial strategies. Herein, a urease-driven bowl-like mesoporous polydopamine nanorobot (MPDA@ICG@Ur@Man) based on single-wavelength near-infrared (NIR) remote photothermal acceleration to achieve antibiotic-free phototherapy(photothermal therapy, PTT, plus photodynamic therapy, PDT) is first reported. The smart nanorobots can perform active movement by decomposing urea to produce carbon dioxide and ammonia. Particularly, the elevated local temperature during PTT can increase urease activity to enhance the autonomous movement and thus increase the contact between the antimicrobial substance and bacteria. Compared with a nanomotor propelled by urea only, the diffusion coefficient (De) of photothermal-accelerated nanorobots is increased from 1.10 to 1.26 µm2 s-1. More importantly, urease-driven bowl-like nanorobots with photothermal enhancement can specifically identify Escherichia coli (E. coli) and achieve simultaneous PTT/PDT at a single wavelength with 99% antibactericidal activity in vitro. In a word, the urease-driven bowl-like nanorobots guided by photothermal-accelerated strategy could provide a novel perspective for increasing PTT/PDT antibacterial therapeutic efficacy and be promising for various antibiotic-free sterilization applications.

Realization of monolayer ZrTe5 topological insulators with wide band gaps.

Two-dimensional topological insulators hosting the quantum spin Hall effect have application potential in dissipationless electronics. To observe the quantum spin Hall effect at elevated temperatures, a wide band gap is indispensable to efficiently suppress bulk conduction. Yet, most candidate materials exhibit narrow or even negative band gaps. Here, via elegant control of van der Waals epitaxy, we have successfully grown monolayer ZrTe5 on a bilayer graphene/SiC substrate. The epitaxial ZrTe5 monolayer crystalizes in two allotrope isomers with different intralayer alignments of ZrTe3 prisms. Our scanning tunneling microscopy/spectroscopy characterization unveils an intrinsic full band gap as large as 254 meV and one-dimensional edge states localized along the periphery of the ZrTe5 monolayer. First-principles calculations further confirm that the large band gap originates from strong spin-orbit coupling, and the edge states are topologically nontrivial. These findings thus provide a highly desirable material platform for the exploration of the high-temperature quantum spin Hall effect.

Photothermal-accelerated urease-powered human serum albumin nanomotor for rapid and efficient photothermal and photodynamic cancer combination therapy.

Nanomotors, as a new type of micro-device, show good performance in terms of rapid transportation and deep penetration through their autonomous motion. However, their ability to efficiently break physiological barriers still remains a great challenge. Herein, we first developed a thermal-accelerated urease driven human serum albumin (HSA) nanomotor based on photothermal intervention (PTI) to achieve chemotherapy drugfree-phototherapy. The HANM@FI (HSA-AuNR@FA@Ur@ICG) is composed of a main body of biocompatible HSA, modified by gold nanorods (AuNR) and loaded with functional molecules of folic acid (FA) and indocyanine green (ICG). It promotes its own motion by breaking down urea to produce carbon dioxide and ammonia. In particular, the nanomotor is conveniently operated via near-infrared combined photothermal therapy (PTT)/ photodynamic therapy (PDT) to achieve an accelerated De value from 0.73 µm2s-1 to 1.01µm2s-1, and ideal tumor ablation at the same time. In contrast to customary urease-driven nanodrug-stacked engine, this HANM@FI has both targeting and imaging-guided capabilities, and finally achieves superior anti-tumor effects without chemotherapy drugs, through a "two-in-one" (motor mobility plus unique phototherapy in chemotherapy-drugfree phototherapy) strategy. This PTI effect with urease-driven nanomotors may offer further possibilities for future clinical applications of nanomedicines by enabling deep penetration and a subsequent chemotherapy-drugfree combination therapy strategy.

Unamplified and Real-Time Label-Free miRNA-21 Detection Using Solution-Gated Graphene Transistors in Prostate Cancer Diagnosis.

The incidence of prostate cancer (PCa) in men globally increases as the standard of living improves. Blood serum biomarker prostate-specific antigen (PSA) detection is the gold standard assay that do not meet the requirements of early detection. Herein, a solution-gated graphene transistor (SGGT) biosensor for the ultrasensitive and rapid quantification detection of the early prostate cancer-relevant biomarker, miRNA-21 is reported. The designed single-stranded DNA (ssDNA) probes immobilized on the Au gate can hybridize effectively with the miRNA-21 molecules targets and induce the Dirac voltage shifts of SGGT transfer curves. The limit of detection (LOD) of the sensor can reach 10-20  M without amplification and any chemical or biological labeling. The detection linear range is from 10-20 to 10-12  M. The sensor can realize real-time detection of the miRNA-21 molecules in less than 5 min and can well distinguish one-mismatched miRNA-21 molecule. The blood serum samples from the patients without RNA extraction and amplification are measured. The results demonstrated that the biosensor can well distinguish the cancer patients from the control group and has higher sensitivity (100%) than PSA detection (58.3%). Contrastingly, it can be found that the PSA level is not directly related to PCa.

Self-healing/pH-responsive/inherently antibacterial polysaccharide-based hydrogel for a photothermal strengthened wound dressing.

Hydrogels have been used widely as wound dressings for maintaining a moist environment to rapid wound healing. However, the lack of antibacterial effect limits their further applications. Herein, we developed a polysaccharide-based hydrogel that can achieve photothermal-assisted bacterial inactivation. The hydrogel has inherent antibacterial activity due to introduction of quaternised chitosan (QCS) with a protonated amine group-modified hydrophilic polycationic structure. Under near infrared (NIR) irradiation, the antibacterial effect of the hydrogel was significantly improved because thermal ablation could also combat bacteria. The hydrogel showed self-healing property through reversible Schiff base bonds between QCS and oxidized hyaluronic acid (OHA). The hydrogel is also pH-sensitive to release drugs in acidic wound. The full-thickness skin defect model showed it had a promoting effect on wound healing. Overall, we provide a theoretical basis for a promising wound dressing based on a photothermally improved polysaccharide-based hydrogel with self-healing/pH-responsive/inherently antibacterial capacity.

Rapid and Unamplified Detection of SARS-CoV-2 RNA via CRISPR-Cas13a-Modified Solution-Gated Graphene Transistors.

The disease caused by severe acute respiratory syndrome coronavirus, SARS-CoV-2, is termed COVID-19. Even though COVID-19 has been out for more than two years, it is still causing a global pandemic. Due to the limitations of sample collection, transportation, and kit performance, the traditional reverse transcription-quantitative polymerase chain reaction (RT-qPCR) method has a long detection period and high testing costs. An increased risk of infection is inevitable, since many patients may not be diagnosed in time. The CRISPR-Cas13a system can be designed for RNA identification and knockdown, as a promising platform for nucleic acid detection. Here, we designed a solution-gated graphene transistor (SGGT) biosensor based on the CRISPR-Cas13a system. Using the gene-targeting capacity of CRISPR-Cas13a and gate functionalization via multilayer modification, SARS-CoV-2 nucleic acid sequences can be quickly and precisely identified without the need for amplification or fluorescence tagging. The limit of detection (LOD) in both buffer and serum reached the aM level, and the reaction time was about 10 min. The results of the detection of COVID-19 clinical samples from throat swabs agree with RT-PCR. In addition, the interchangeable gates significantly minimize the cost and time of device fabrication. In a nutshell, our biosensor technology is broadly applicable and will be suitable for point-of-care (POC) testing.

The prevalence, predictors, and outcomes of spontaneous echocardiographic contrast or left ventricular thrombus in patients with HFrEF.

AIMS: This study aimed to determine prevalence, predictors, and association with ischaemic stroke risk of spontaneous echocardiographic contrast (SEC) or left ventricular thrombus (LVT) in patients with heart failure with reduced ejection fraction (HFrEF). METHODS AND RESULTS: Clinical, echocardiographic, and follow-up data from January 2009 through February 2019 were retrospectively extracted from electronic medical records of patients with heart failure with left ventricular ejection fraction < 40% by echocardiography on admission, with follow-up to February 2020. Of 9485 consecutive patients with HFrEF, 123 (1.3%) presented LVT and 331 (3.5%) presented SEC. Patients with vs. those without SEC/LVT had larger left ventricular end-diastolic volume (199.5 ± 77.7 vs. 165.8 ± 61.3 mL, P < 0.001), lower left ventricular ejection fractions (29.5 ± 7.0% vs. 33.7 ± 5.5%, P < 0.001), and more often ischaemic cardiomyopathy, apical aneurysm, chronic kidney diseases, and smoking habit. In Cox regression analysis, SEC and LVT were independent predictors for ischaemic stroke occurrence [hazard ratio (HR) = 2.40, 95% confidence interval (CI): 1.74-3.31; HR = 4.52, 95% CI: 2.77-7.40, both P < 0.001]. In patients with those without SEC or LVT, stroke risk was higher among those not on anticoagulants (HR = 2.55, 95% CI: 1.85-3.53; HR = 4.71, 95% CI: 2.84-7.81, both P < 0.001), but similar among those on anticoagulants (P > 0.05). In patients with sinus rhythm, the associations between SEC/LVT and ischaemic stroke persist with HRs of 2.57 (95% CI: 1.69-3.92) and 5.74 (95% CI: 3.38-9.75). CONCLUSIONS: In patients with HFrEF, SEC was not uncommon and increased risk of ischaemic stroke as well as LVT. Anticoagulants could play a role in the reduction of stroke risk, suggesting that patients with SEC/LVT, even those in sinus rhythm, would benefit from systemic anticoagulation treatment.

A novel risk model to predict first-ever ischemic stroke in heart failure with reduced ejection fraction.

Patients with heart failure are at increased risk for ischemic stroke. We aim to develop a more accurate stroke risk prediction tools identify high-risk patients with heart failure with reduced ejection fraction (HFrEF). Patient data were extracted retrospectively from the electronic medical database between January 2009 and February 2019. Univariate and multivariate Cox regression analysis were performed to identify independent predictors, which were utilized to construct a nomogram for predicting ischemic stroke. AUROC analysis was used to compare the prognostic value between the new risk score and CHADS2/CHA2DS2-VASc scores. In 6087 patients with HFrEF, the risk of first-ever ischemic stroke was 5.8% events/pts-years (n=468) during 8007.2 person-years follow-up. A nomogram constructed by integrating 6 variables, including age, atrial fibrillation (AF), deep vein thrombosis (DVT), d-dimer, anticoagulant use and spontaneous echocardiographic contrast (SEC)/left ventricular thrombus (LVT), exhibited a greater area under the curve of 0.727, 0.728 and 0.714 than that by CHADS2 score (0.515, 0.522 and 0.540), and by CHA2DS2-VASc score (0.547, 0.553 and 0.562) for predicting first-ever ischemic stroke at hospitalization, 30-day and 6-month follow-up (all p<0.001). This novel stroke risk score performed better than existing CHADS2/ CHA2DS2-VASc scores and showed improvement in predicting first-ever ischemic stroke in HFrEF patients.

Clinical characteristics and outcomes in patients with echocardiographic left ventricular spontaneous echo contrast.

BACKGROUND: Spontaneous echo contrast (SEC) is a known precursor to thrombus formation and thromboembolic events. This study aims to demonstrate the clinical characteristics and outcomes of patients with left ventricular spontaneous echo contrast (LV-SEC). METHODS: Patients with consecutive echocardiogram performed from October 2009 to September 2019 were enrolled in this retrospective, single-center study. Those with LV-SEC were included, while patients complicated by left ventricular thrombus, with history of infective endocarditis, prosthetic valves, or lost to follow-up were excluded. The clinical endpoint was 1-year thromboembolic events (i.e. stroke and peripheral embolism). RESULTS: Among 417 patients (mean age 63.5 ± 14.7 years; 86.8% men) with LV-SEC, the incidence of 1-year embolism was 12.9%. In multivariate Cox proportional hazard model, significant risk factors for thromboembolic event were age [hazard ratio (HR) = 1.022, 95% confidence interval (CI): 1.000-1.045], atrial fibrillation (AF) (HR = 2.292, 95% CI: 1.237-4.244), hemoglobin (HR = 1.032, 95% CI: 1.017-1.047), left ventricular ejection fraction (LVEF) (HR = 1.021, 95% CI: 1.002-1.041), and anticoagulant therapy (HR = 0.310, 95% CI: 0.168-0.572). For patients with repeated measurements for echocardiography, D-dimer (HR = 1.137, 95% CI: 1.051-1.231), and △LVEF (HR = 0.961, 95% CI: 0.928-0.996) were independently associated with the persistent LV-SEC. CONCLUSION: The present study reported a high incidence of 1-year thromboembolic event in patients with LV-SEC. Age, AF, hemoglobin, LVEF were independent risk factors for 1-year embolism and a reduced risk of embolism was observed among patients with anticoagulation therapy. Additionally, D-dimer and △LVEF are independently associated with the persistent LV-SEC.

The isolation and genome sequencing of a novel cyanophage S-H68 from the Bohai Sea, China.

Cyanobacteria, also known as bule-green algae, are capable of photosynthesis and have a fixed carbon and nitrogen effect. The virus that specifically infects cyanobacteria is called the cyanophage. Cyanophages play a key role in building microbial communities. However, only a small number of cyanophages have been reported so far. In this study, a novel Synechococcus cyanophage S-H68 was isolated from the Bohai Sea of China. Transmission electron microscope observations showed that S-H68 has an icosahedral head, 66 ± 1 nm in diameter, and a tail with a length of 107 ± 1 nm, and should be grouped into the family Siphoviridae. To better understand the genetic diversity of this cyanophage, the complete genome was characterized. It consists of 79,639 -bp -length double-stranded DNA with a GC content of 59.8% and is predicted to have 117 open reading frames (ORFs) with an average length of 655 nucleotides. Using the BLASTN tool in the NCBI database for genome comparison, there was no significant similarity between S-H68 and other known cyanophages. So the present study added a new Siphoviridae cyanophage to the marine phage dataset.

Kinetics-Limited Two-Step Growth of van der Waals Puckered Honeycomb Sb Monolayer.

Puckered honeycomb Sb monolayer, the structural analog of black phosphorene, has been recently successfully grown by means of molecular beam epitaxy. However, little is known to date about the growth mechanism for such a puckered honeycomb monolayer. In this study, by using scanning tunneling microscopy in combination with first-principles density functional theory calculations, we unveil that the puckered honeycomb Sb monolayer takes a kinetics-limited two-step growth mode. As the coverage of Sb increases, the Sb atoms first form the distorted hexagonal lattice as the half layer, and then the distorted hexagonal half-layer transforms into the puckered honeycomb lattice as the full layer. These results provide the atomic-scale insight in understanding the growth mechanism of puckered honeycomb monolayer and can be instructive to the direct growth of other monolayers with the same structure.