Nitric oxide releasing nanofiber stimulates revascularization in response to ischemia via cGMP-dependent protein kinase.

Nitric oxide (NO) promotes angiogenesis via various mechanisms; however, the effective transmission of NO in ischemic diseases is unclear. Herein, we tested whether NO-releasing nanofibers modulate therapeutic angiogenesis in an animal hindlimb ischemia model. Male wild-type C57BL/6 mice with surgically-induced hindlimb ischemia were treated with NO-releasing 3-methylaminopropyltrimethoxysilane (MAP3)-derived or control (i.e., non-NO-releasing) nanofibers, by applying them to the wound for 20 min, three times every two days. The amount of NO from the nanofiber into tissues was assessed by NO fluorometric assay. The activity of cGMP-dependent protein kinase (PKG) was determined by western blot analysis. Perfusion ratios were measured 2, 4, and 14 days after inducing ischemia using laser doppler imaging. On day 4, Immunohistochemistry (IHC) with F4/80 and gelatin zymography were performed. IHC with CD31 was performed on day 14. To determine the angiogenic potential of NO-releasing nanofibers, aorta-ring explants were treated with MAP3 or control fiber for 20 min, and the sprout lengths were examined after 6 days. As per either LDPI (Laser doppler perfusion image) ratio or CD31 capillary density measurement, angiogenesis in the ischemic hindlimb was improved in the MAP3 nanofiber group; further, the total nitrate/nitrite concentration in the adduct muscle increased. The number of macrophage infiltrations and matrix metalloproteinase-9 (MMP-9) activity decreased. Vasodilator-stimulated phosphoprotein (VASP), one of the major substrates for PKG, increased phosphorylation in the MAP3 group. MAP3 nanofiber or NO donor SNAP (s-nitroso-n-acetyl penicillamine)-treated aortic explants showed enhanced sprouting in an ex vivo aortic ring assay, which was partially abrogated by KT5823, a potent inhibitor of PKG. These findings suggest that the novel NO-releasing nanofiber, MAP3 activates PKG and promotes therapeutic angiogenesis in response to hindlimb ischemia.

Clinical Outcome after Clavicular Hook Plate Fixation for Displaced Medial-End Clavicle Fractures.

Background: Surgery of the medial end of the clavicle remains a challenge for orthopedic surgeons. Moreover, there is no standard surgical procedure for treating displaced fractures or dislocation of the medial clavicle. Thus, the present study aimed to evaluate the safety and efficacy of using a hook plate for treating medial-end clavicular fractures and present functional outcomes. Methods: We retrospectively investigated 18 patients who underwent surgery with a hook plate from July 2016 to December 2021. There were 14 men and 4 women with a mean age of 57.4 years. Fracture union was assessed at follow-up by computed tomography (CT). Other outcome parameters were complications, including implant failure, infection, nonunion, osteolysis of sternal manubrium, and migration of the hook portion. Range of motion (ROM), visual analog scale (VAS), Quick Disabilities of the Arm, Shoulder and Hand (Quick DASH), and American Shoulder and Elbow Society (ASES) scores were evaluated 6 months postoperatively and at the last follow-up. Results: The mean operation time was 43.8 minutes (range, 35-50 minutes) and the mean follow-up was 22.8 months (range, 12-42 months). Bone union was confirmed in all cases. The mean union time was 6.2 months (range, 6-7 months). Implant removal was performed routinely according to the clinical course in 17 cases. The mean implant removal time was 10.0 months (range, 6-14 months). Clinical and functional outcomes measured at the last follow-up were significantly improved compared to those at 6 months postoperatively (p < 0.05). Regarding complications, there were 6 cases (33.3%) of osteolysis of the sternal manubrium. Although the anteroposterior length of the manubrium and hook depth showed significant differences between the non-osteolysis group and the osteolysis group (p = 0.024), ROM, VAS, Quick DASH, and ASES scores were not significantly different between the two groups (all p > 0.05). Conclusions: Clavicle hook plating can be a safe and effective method that can be easily applied with good outcomes if it is used with appropriate surgical planning and technique for medial-end clavicle fracture. CT scans are useful for preoperative planning and postoperative evaluation of bone union or complications.

Delayed dislocation of the radial head associated with malunion of distal radial fracture: A case report.

BACKGROUND: Traumatic radial head dislocation (RHD) is a well-described injury in the pediatric population. It is usually associated with an injury to the ulna in Monteggia fracture-dislocation, although it can occur as an isolated injury. Traumatic RHD with ipsilateral radial shaft fracture has rarely been reported. Delayed RHD secondary to the malunion of an isolated radial shaft fracture is extremely rare. CASE SUMMARY: We report a 9-year-old boy with limited pronation of the right elbow. The patient was diagnosed with delayed RHD associated with the malunion of a distal radial fracture. Since the annular ligament was disrupted with forearm rotation causing subluxation of the radial head, a modified double-strip Bell Tawse procedure was performed to reconstruct the annular ligament without corrective osteotomy for the malunited site. Four years after surgery, the angulation deformity of the distal radius was corrected with the restoration of the normal curvature of the radius. There was no recurrence of RHD. CONCLUSION: Annular ligament reconstruction without corrective osteotomy could reduce RHD and restore the normal curve of the radial shaft in children with delayed dislocation of the radial head associated with malunion of the radial shaft. Annular reconstruction using double triceps tendon strips might be useful for maintaining a more stable reduction by augmenting anterolateral parts.

Breast Tissue Reconstruction Using Polycaprolactone Ball Scaffolds in a Partial Mastectomy Pig Model.

BACKGROUND: Breast cancer patients suffer from lowered quality of life (QoL) after surgery. Breast conservancy surgery (BCS) such as partial mastectomy is being practiced and studied as an alternative to solve this problem. This study confirmed breast tissue reconstruction in a pig model by fabricating a 3-dimensional (3D) printed Polycaprolactone spherical scaffold (PCL ball) to fit the tissue resected after partial mastectomy. METHODS: A 3D printed Polycaprolactone spherical scaffold with a structure that can help adipose tissue regeneration was produced using computer-aided design (CAD). A physical property test was conducted for optimization. In order to enhance biocompatibility, collagen coating was applied and a comparative study was conducted for 3 months in a partial mastectomy pig model. RESULTS: In order to identify adipose tissue and fibroglandular tissue, which mainly constitute breast tissue, the degree of adipose tissue and collagen regeneration was confirmed in a pig model after 3 months. As a result, it was confirmed that a lot of adipose tissue was regenerated in the PCL ball, whereas more collagen was regenerated in the collagen-coated Polycaprolactone spherical scaffold (PCL-COL ball). In addition, as a result of confirming the expression levels of TNF-a and IL-6, it was confirmed that PCL ball showed higher levels than PCL-COL ball. CONCLUSION: Through this study, we were able to confirm the regeneration of adipose tissue through a 3-dimensional structure in a pig model. Studies were conducted on medium and large-sized animal models for the final purpose of clinical use and reconstruction of human breast tissue, and the possibility was confirmed.

Breast Tissue Restoration after the Partial Mastectomy Using Polycaprolactone Scaffold.

As breast conserving surgery increases in the surgical treatment of breast cancer, partial mastectomy is also increasing. Polycaprolactone (PCL) is a polymer that is used as an artifact in various parts of the human body based on the biocompatibility and mechanical properties of PCL. Here, we hypothesized that a PCL scaffold can be utilized for the restoration of breast tissue after a partial mastectomy. To demonstrate the hypothesis, a PCL scaffold was fabricated by 3D printing and three types of spherical PCL scaffold including PCL scaffold, PCL scaffold with collagen, and the PCL scaffold with breast tissue fragment were implanted in the rat breast defect model. After 6 months of implantation, the restoration of breast tissue was observed in the PCL scaffold and the expression of collagen in the PCL scaffold with collagen was seen. The expression of TNF-α was significantly increased in the PCL scaffold, but the expression of IL-6 showed no significant difference in all groups. Through this, it showed the possibility of using it as a method to conveniently repair tissue defects after partial mastectomy of the human body.

Large-Area Uniform 1-nm-Level Amorphous Carbon Layers from 3D Conformal Polymer Brushes. A "Next-Generation" Cu Diffusion Barrier?

A reliable method for preparing a conformal amorphous carbon (a-C) layer with a thickness of 1-nm-level, is tested as a possible Cu diffusion barrier layer for next-generation ultrahigh-density semiconductor device miniaturization. A polystyrene brush of uniform thickness is grafted onto 4-inch SiO2 /Si wafer substrates with "self-limiting" chemistry favoring such a uniform layer. UV crosslinking and subsequent carbonization transforms this polymer film into an ultrathin a-C layer without pinholes or hillocks. The uniform coating of nonplanar regions or surfaces is also possible. The Cu diffusion "blocking ability" is evaluated by time-dependent dielectric breakdown (TDDB) tests using a metal-oxide-semiconductor (MOS) capacitor structure. A 0.82 nm-thick a-C barrier gives TDDB lifetimes 3.3× longer than that obtained using the conventional 1.0 nm-thick TaNx diffusion barrier. In addition, this exceptionally uniform ultrathin polymer and a-C film layers hold promise for selective ion permeable membranes, electrically and thermally insulating films in electronics, slits of angstrom-scale thickness, and, when appropriately functionalized, as a robust ultrathin coating with many other potential applications.

High-Resolution Colloidal Quantum Dot Film Photolithography via Atomic Layer Deposition of ZnO.

High-resolution patterning of quantum dot (QD) films is one of the preconditions for the practical use of QD-based emissive display platforms. Recently, inkjet printing and transfer printing have been actively developed; however, high-resolution patterning is still limited owing to nozzle-clogging issues and coffee ring effects during the inkjet printing and kinetic parameters such as pickup and peeling speed during the transfer process. Consequently, employing direct optical lithography would be highly beneficial owing to its well-established process in the semiconductor industry; however, exposing the photoresist (PR) on top of the QD film deteriorates the QD film underneath. This is because a majority of the solvents for PR easily dissolve the pre-existing QD films. In this study, we present a conventional optical lithography process to obtain solvent resistance by reacting the QD film surface with diethylzinc (DEZ) precursors using atomic layer deposition. It was confirmed that, by reacting the QD surface with DEZ and coating PR directly on top of the QD film, a typical photolithography process can be performed to generate a red/green/blue pixel of 3000 ppi or more. QD electroluminescence devices were fabricated with all primary colors of QDs; moreover, compared to reference QD-LED devices, the patterned QD-LED devices exhibited enhanced brightness and efficiency.

Arthroscopic-assisted bone grafting and percutaneous K-wires fixation for the treatment of scaphoid nonunion in the skeletally immature patient: Three cases report.

RATIONALE: The treatment methods of pediatric scaphoid nonunion are still controversial. To our knowledge, arthroscopic-assisted treatments for pediatric scaphoid nonunion has not been reported in the English-language literature. Therefore, the purpose of this study is to report the use of arthroscopic-assisted bone grafting for scaphoid nonunion fracture in 3 patients and present a literature review. PATIENTS CONCERNS: Two 15-year-old patients developed carpal joint injuries over a year, prior to their hospital presentation, since they had not received adequate treatment. The third patient, 12 years of age, was diagnosed with scaphoid fracture after a traffic accident and underwent conservative treatment but presented to the hospital due to issues related with bone union. DIAGNOSIS: All 3 patients were diagnosed with scaphoid nonunion at our hospital, using plain wrist radiographs and computed tomography. INTERVENTIONS: All the patients underwent arthroscopic debridement; 2 patients received autogenous iliac cancellous bone graft, while the other patient received a bone substitute graft. The internal fixation of the scaphoid was performed with K-wires. OUTCOMES: Bone unions were achieved in all patients, and the final follow-up resulted in successful outcomes. LESSONS: Arthroscopic-assisted bone grafting and percutaneous K-wire fixation can be considered as a good method for the treatment of pediatric scaphoid nonunion fractures. Therefore, it is a primary treatment option for symptomatic scaphoid nonunion fracture and displaced fractures.

Tertiary RNA Folding-Targeted Drug Screening Strategy Using a Protein Nanopore.

Bacterial riboswitch RNAs are attractive targets for novel antibiotics against antibiotic-resistant superbacteria. Their binding to cognate metabolites is essential for the regulation of bacterial gene expression. Despite the importance of RNAs as therapeutic targets, the development of RNA-targeted, small-molecule drugs is limited by current biophysical methods. Here, we monitored the specific interaction between the adenine-sensing riboswitch aptamer domain (ARS) and adenine at the single-molecule level using α-hemolysin (αHL) nanopores. During adenine-induced tertiary folding, adenine-bound ARS intermediates exhibited characteristic nanopore events, including a two-level ionic current blockade and a ∼ 5.6-fold longer dwell time than that of free RNA. In a proof-of-concept experiment, tertiary RNA folding-targeted drug screening was performed using a protein nanopore, which resulted in the discovery of three new ARS-targeting hit compounds from a natural compound library. Taken together, these results reveal that αHL nanopores are a valuable platform for ultrasensitive, label-free, and single-molecule-based drug screening against therapeutic RNA targets.

A preclinical trial of perventricular pulmonary valve implantation: Pericardial versus aortic porcine valves mounted on self-expandable stent.

Perventricular pulmonary valve implantation (PPVI) of a xenograft valve can be a less invasive technique that avoids cardiopulmonary bypass in patients who require pulmonary valve replacement. We compared the hemodynamics, durability, and histologic changes between two different xenogenic valves (pericardial vs. aortic valve porcine xenografts) implanted into the pulmonary valve position using a PPVI technique and evaluated the safety and efficacy of PPVI as a preclinical study. In 18 sheep, pericardial (group porcine pericardial [PP], n = 9) or aortic valve (group porcine aortic valve [PAV], n = 9) xenogenic porcine valves manufactured as a stented valve were implanted using a PPVI technique. The porcine tissues were decellularized, alpha-galactosidase treated, fixed with glutaraldehyde after space-filler treatment, and detoxified to improve durability. Hemodynamic and immunohistochemical studies were performed after the implantation; radiologic and histologic studies were performed after a terminal procedure. All stented valves were positioned properly after the implantation, and echocardiography and cardiac catheterization demonstrated good hemodynamic state and function of the valves. All the anti-α-Gal IgM and IgG titers were below 0.3 optical density. Computed tomography of extracted valves demonstrated no significant differences in the degree of calcification between the two groups (P = .927). Microscopic findings revealed a minimal amount of calcification and no significant infiltration of macrophage or T-cell in both groups, regardless of the implantation duration. The PPVI is a feasible technique. Both stented valves made of PP and PAV showed no significant differences in hemodynamic profile, midterm durability, and degree of degenerative dystrophic calcification.

Effect of the Bilayer Period of Atomic Layer Deposition on the Growth Behavior and Electrical Properties of the Amorphous In-Zn-O Film.

This study reports on the effect of a bilayer period on the growth behavior, microstructure evolution, and electrical properties of atomic layer deposition (ALD) deposited In-Zn-O (IZO) films, fixing the ALD cycle ratio of In-O/Zn-O as 9:1. Here, the bilayer period is defined as the total number of ALD cycles in one supercycle of In-O and Zn-O by alternately stacking Zn-O and In-O layers at a temperature of 220 °C. IZO films with a bilayer period from 10 to 40 cycles, namely, IZO[In-O/Zn-O = 9:1] to IZO[36:4], result to form an amorphous phase with a resistivity of 4.94 × 10-4 Ω·cm. However, by increasing the bilayer period above 100 cycles, the IZO films begin to form a mixed amorphous-nanocrystalline microstructure, resulting from the limited intermixing at the interfaces. Concomitantly, the overall film resistivity is considerably increased with a simultaneous decrease in both the carrier mobility and the concentration. These results not only reveal the importance of the bilayer period in designing the ALD stacking sequence in the ALD-IZO, but also provide the possibility of forming various multilayered materials with different electrical properties.

Treatment Outcomes at Skeletal Maturity after Calcaneo-Cuboid-Cuneiform Osteotomy for Symptomatic Flatfoot Deformity in Children.

BACKGROUND: The purpose of this study was to evaluate clinical and radiological outcomes at skeletal maturity after a calcaneo-cuboid-cuneiform osteotomy (triple C osteotomy) for symptomatic flatfoot deformity compared with healthy young adult controls. METHODS: Nineteen patients (30 feet) who undergone a triple C osteotomy for idiopathic symptomatic flatfeet from July 2006 to April 2013 were compared with 19 controls (38 feet). Radiographic measurements at preoperative examination, 1-year postoperative follow-up, and follow-up at skeletal maturity were evaluated. Functional outcomes were assessed by using the validated visual analog scale foot and ankle (VAS-FA) and the modified American Orthopaedic Foot and Ankle Surgery (AOFAS) score. RESULTS: In the triple C osteotomy group, 11 of 12 radiographic measurements were significantly improved at 1 year postoperatively and the last follow-up (p < 0.001). There was no recurrence at skeletal maturity (p > 0.05). There were no significant differences in nine of 12 radiographic measurements between the triple C osteotomy group at maturity and the control group (p > 0.05). Average VAS-FA and AOFAS scores were significantly improved at the time of skeletal maturity (p < 0.001). CONCLUSIONS: Surgical correction of symptomatic flatfoot deformity in childhood resulted in favorable outcomes after the triple C osteotomy. Deformity correction was also maintained during follow-up at skeletal maturity.

Sheet Resistance Analysis of Interface-Engineered Multilayer Graphene: Mobility Versus Sheet Carrier Concentration.

Both interlayer-undoped and interlayer-doped multilayer graphenes were prepared by the multiple transfers of graphene layers with multiple Cu etching (either dopant-free or doped during etching) and transfer, and the effect of interface properties on the electrical properties of multilayer graphene was investigated by varying the number of layers from 1 to 12. In both the cases, the sheet resistance decreased with increasing number of layers from 700 to 104 Ω/sq for the interlayer-undoped graphene and from 280 to 25 Ω/sq for the interlayer-doped graphene. Further, Hall measurements revealed that the origins of the sheet resistance reduction in the two cases are different. In the interlayer-undoped graphene, the sheet resistance decreased because of the increase in mobility with the addition of inner layers, which has a low carrier density and a high carrier mobility. On the other hand, it decreased because of the increase in sheet carrier density in the interlayer-doped multilayer graphene. The mobility and carrier density variations in both the cases were confirmed by fitting with the model of Hall effect in the heterojunction. In addition, we found that surface property modification by the doping of the top layer and the formation of double-layer graphene with different partial coverages allow the separate control of carrier density and mobility. Our study provides an effective approach for controlling the properties of multilayer graphene for electronic applications.

An electrophoretic DNA extraction device using a nanofilter for molecular diagnosis of pathogens.

Rapid and efficient nucleic acid (NA) extraction and concentration are required for point-of-care analysis in order to prevent an epidemic/pandemic disease outbreak. Typical silica-based NA extraction methods have limitations such as being time-consuming, requiring human intervention, and resulting in a low recovery yield. In this study, we have developed a pathogenic DNA extraction device based on electrokinetic separation incorporated with a silicon nitride (SiNx) nanofilter, which expedites the DNA extraction procedure with advantages of being convenient, efficient, and inexpensive. This DNA extraction device consists of a computer numerical control (CNC) milled-Teflon gadget with a cis-chamber as a cell lysate reservoir and a trans-chamber as a elution solution reservoir, with the SiNx nanofilter being inserted between the two chambers. The SiNx nanofilter was fabricated using a photolithographic method in conjunction with nanoimprinting. Approximately 7.2 million nanopores of 220 nm diameter were located at the center of the nanofilter. When a DC electric field is applied through the nanopores, DNA is transferred from the cis-chamber to the trans-chamber to isolate the DNA from the cell debris. To demonstrate the DNA extraction performance, we measured the absorbances at 260 and 280 nm and performed a real-time polymerase chain reaction (real-time PCR) using the recovered DNA to verify its feasibility for downstream genetic analysis. Moreover, the DNA extraction device was successfully operated using a 1.5 V alkaline battery, which verifies the portability of the device for point-of-care testing. Such an advanced DNA extraction system can be utilized in various fields including clinical analysis, pathogen detection, forensic analysis, and on-site detection.

Selective Atomic Layer Deposition of Metals on Graphene for Transparent Conducting Electrode Application.

Although graphene has considerable potential as a next-generation transparent conducting electrode (TCE) material owing to its excellent optical transparency and flexibility, its electrical properties require further improvement for industrial application. This study reports a pathway of doping graphene by selective atomic layer deposition (ALD) of metals to elevate the electrical conductivity of graphene. Introduction of a novel Pt precursor [dimethyl(N,N-dimethyl-3-butene-1-amine-N)platinum(II); C8H19NPt; DDAP] facilitates a low-temperature (165 °C) process. The sheet resistance (Rs) of graphene is reduced significantly from 471 to 86.8 Ω sq-1 after 200 cycles of Pt ALD, while the optical transmittance at 550 nm (T) is maintained above 90% up to 200 cycles due to the selective growth of Pt on the defects of graphene. Furthermore, comprehensive analysis, including metal (Ru, Pt, and Ni) ALD on graphene, metal (Ru, Pt, Ni, Au, and Co) evaporation on graphene, and change in the ALD chemicals, demonstrates that ALD allows efficient graphene doping and the oxygen affinity of the metal is one of the key properties for efficient graphene doping. Finally, Pt ALD is applied to a multilayer graphene to further reduce Rs down to 75.8 Ω sq-1 yet to be highly transparent (T: 87.3%) after 200 cycles. In summary, the selective ALD of metals opens a way of improving the electrical properties of graphene to a level required for the industrial TCE application and has the potential to promote development of other types of functional metal-graphene composites.

Surface modification of solid-state nanopore by plasma-polymerized chemical vapor deposition of poly(ethylene glycol) for stable device operation.

Biopolymer adsorption onto a membrane is a significant issue in the reliability of solid-state nanopore devices, since it degrades the device performance or promotes device failure. In this work, a poly(ethylene glycol) (PEG) layer was coated on a silicon nitride (SiNx) membrane by plasma-polymerized vapor deposition to inhibit biopolymer adsorption. From optical observations, the deposited PEG layer demonstrated increased hydrophilicity and anti-adsorption property compared to the SiNx surface. Electrical properties of the PEG/SiNx nanopore were characterized, showing Ohmic behavior and a 6.3 times higher flicker noise power due to the flexible conformation of PEG in water. Antifouling performance of each surface was analyzed by measuring the average time from voltage bias to the first adsorption during DNA translocation experiments, where the modified surface enabled two times prolonged device operation. The time to adsorption was dependent on the applied voltage, implying adsorption probability was dominated by the electrophoretic DNA approach to the nanopore. DNA translocation behaviors on each surface were identified from translocation signals, as the PEG layer promoted unfolded and fast movement of DNA through the nanopore. This work successfully analyzed the effect of the PEG layer on DNA adsorption and translocation in solid-state nanopore experiments.

Direct electrophoretic microRNA preparation from clinical samples using nanofilter membrane.

A method to directly collect negatively charged nucleic acids, such as DNA and RNA, in the biosamples simply by applying an electric field in between the sample and collection buffer separated by the nanofilter membrane is proposed. The nanofilter membrane was made of low-stress silicon nitride with a thickness of 100 nm, and multiple pores were perforated in a highly arranged pattern using nanoimprint technology with a pore size of 200 nm and a pore density of 7.22 × 108/cm2. The electrophoretic transport of hsa-mir-93-5p across the membrane was confirmed in pure microRNA (miRNA) mimic solution using quantitative reverse transcription-polymerase chain reactions (qRT-PCR). Consistency of the collected miRNA quantity, stability of the system during the experiment, and yield and purity of the prepared sample were discussed in detail to validate the effectiveness of the electrical protocol. Finally, in order to check the applicability of this method to clinical samples, liquid biopsy process was demonstrated by evaluating the miRNA levels in sera of hepatocellular carcinoma patients and healthy controls. This efficient system proposed a simple, physical idea in preparation of nucleic acid from biosamples, and demonstrated its compatibility to biological downstream applications such as qRT-PCR as the conventional nucleic acid extraction protocols.

Cu oxidation kinetics through graphene and its effect on the electrical properties of graphene.

The oxidation kinetics of Cu through graphene were evaluated from the surface coverage of Cu oxide (F ox) by varying the oxidation time (t ox = 10-360 min) and temperature (T ox = 180-240 °C) under an air environment. F ox, as a function of time, well followed the Johnson-Mehl-Avrami-Kolmogorov equation; thus, the activation energy of Cu oxidation was estimated as 1.5 eV. Transmission electron microscopy studies revealed that Cu2O formed on the top of the graphene at grain boundaries (G-GBs), indicating that Cu2O growth was governed by the out-diffusion of Cu through G-GBs. Further, the effect of Cu oxidation on graphene quality was investigated by measuring the electrical properties of graphene after transferring. The variation of the sheet resistance (R s) as a function of t ox at all T ox was converted into one curve as a function of F ox. R s of 250 Ω sq-1 was constant, similar to that of as-grown graphene up to F ox = 15%, and then increased with F ox. The Hall measurement revealed that the carrier concentration remained constant in the entire range of F ox, and R s was solely related to the decrease in the Hall mobility. The variation in Hall mobility was examined according to the graphene percolation probability model, simulating electrical conduction on G-GBs during Cu2O evolution. This model well explains the constant Hall mobility within F ox = 15% and drastic F ox degradation of 15-50% by the concept that the electrical conduction of graphene is disconnected by Cu2O formation along with the G-GBs. Therefore, we systematically developed the oxidation kinetics of Cu through graphene and simultaneously examined the changes in the electrical properties of graphene.

Nanopore Analysis on the Drug-Induced Conformation Change of a p53-Linker-Mouse Double Minute 2 Protein Complex.

Detection of conformational changes in proteins by protein-protein interaction (PPI) is a key issue in developing drug screening platforms. In order to effectively investigate the conformational change in a protein at a single-molecule level, we propose the use of nanopore detection to identify protein conformational changes resulting from protein-protein interactions and their inhibition by Nutlin-3. We designed a protein complex comprising a p53 peptide and a mouse double minute 2 (MDM2) linked by 6 amino acids, transforming its shape from globular to dumbbell structure by inhibition of interaction between p53 peptide and MDM2. In the NMR experiment, no distinguished crosspeaks were observed upon Nutlin-3 addition. However, the nanopore experiment clearly showed double-peak signals with the addition of Nutlin-3. The observed fraction of the double-peak among single-peak signals increased from 8.77% to 22.03% with a concurrent increase in the Nutlin-3 concentration from a molar ratio of 1 to 10-fold. From the nanopore data, we estimated the dwell time for the elongated form of Nutlin-3-bound protein, which traverses for a longer duration (∼2 times) than the globular form. Finally, the hydrodynamic diameter of the local peak of the double-peak signal was calculated and compared with the X-ray crystallography results. This approach shows feasibility of the nanopore detection to verify the protein conformational change by inhibition of protein-protein interaction at a single-molecule level.

Comparison of Growth Behavior and Electrical Properties of Graphene Grown on Solid and Liquid Copper by Chemical Vapor Deposition.

We study the graphene growth behavior above and below the copper (Cu) melting point (1083 °C) by only changing the growth temperature from 1020 °C to 1100 °C at intervals of 40 °C, to investigate the effect of the Cu phase as a catalyst layer in graphene growth. We investigate the graphene growth behavior by observing the changes in nucleation density and grain size with growth time. As the phase of the Cu catalyst changes from solid to liquid, the grain size of graphene increases by 2 orders of magnitude from 0.4 to 40 µm, while the nuclei density decreases by 4 orders of magnitude from 3.02/µm2 to 0.0004/µm2. Additionally, as in previous studies, graphene growth shows a well-aligned hexagonal shape on liquid Cu although graphene on solid Cu shows an irregular shape under the same growth conditions. The effect of the smooth surface of the liquid metal catalyst on graphene growth is remarkable even after considering the temperature difference. The reduction of defect density arising from the increase of the graphene grain size is confirmed by Raman spectroscopy. Additionally, the improvement in electrical properties is also investigated by Hall measurements.