Surface Functionalized Graphene Biosensor on Sapphire for Cancer Cell Detection.

Graphene has several unique physical, optical and electrical properties such as a two-dimensional (2D) planar structure, high optical transparency and high carrier mobility at room temperature. These make graphene interesting for electrical biosensing. Using a catalyst-free chemical vapor deposition (CVD) method, graphene film is grown on a sapphire substrate. There is a single or a few sheets as confirmed by Raman spectroscopy and atomic force microscopy (AFM). Electrical graphene biosensors are fabricated to detect large-sized biological analytes such as cancer cells. Human colorectal carcinoma cells are sensed by the resistance change of an active bio-functionalized graphene device as the cells are captured by the immobilized antibody surface. The functionalized sensors show an increase in resistance as large as ~20% of the baseline with a small number of adhered cells. This study suggests that the bio-functionalized electrical graphene sensors on sapphire, which is a highly transparent material, can potentially detect circulating tumor cells (CTCs) and monitor cellular electrical behavior while being compatible with fluorescence-based optical-detection bioassays.

Metal free growth of graphene on quartz substrate using chemical vapor deposition (CVD).

Graphene was grown on (0001) quartz substrate (z-cut) using catalyst free Chemical Vapor Deposition (CVD). Methane was used as a carbon source and hydrogen was introduced independently to optimize the growth. The effect of growth temperature was investigated while varying the temperature between 1000 and 1300 degrees C. With an optimized condition, a thin (< or = 2 mono-layer) continuous graphene film was grown as confirmed by Raman spectroscopy, optical transmission, and electrical measurements. The best quality film showed the Raman D-peak to G-peak intensity ratio of approximately 0.8 with the 2D-peak width of approximately 60 cm(-1). High resolution X-ray Photoelectron Spectroscopy (XPS) revealed that the grown graphene is slightly oxidized but there is no detectable Si--C chemical bond in the graphene/quartz system. Hall effect measurements exhibited a carrier mobility of approximately 400 cm2/V x s with a sheet carrier density of approximately 5 x 10(12) cm(-2).

Changes in quality characteristics and biogenic amine contents in beef by cooking methods.

This study aimed to evaluate the changes in imported beef loin before and after cooking, depending on cooking methods, through quality characteristics, biogenic amine (BA) content analysis, and electronic tongue system. Sous-vide (SV), characterized by the least cooking loss, exhibited the highest water content at 64.11%. Pan-grilling (PG), air-frying (AF), and IR-grilling (IR) methods showed a range of water content from 46.90 to 54.19%. In the taste results by the electronic tongue, umami and saltiness were higher in the high cooking temperature methods (PG, AF, IR, and combined sous-vide + pan-grilling [SVP]) than SV (p < 0.05). Compared to the control, total BAs concentrations decreased by 67.32% (SV), 64.90% (AF), 62.46% (IR), and 50.64% (PG), and SVP showed the largest decrease of 68.64% (p < 0.05). Therefore, SVP was considered the most effective cooking method for reducing BAs and maintaining the quality characteristics of beef loin. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-024-01650-9.

Effects of cooking methods on antioxidant activity and acrylamide formation in red bell pepper (Capsicum annuum L.).

Red bell pepper (Capsicum annuum L.) is a popular and nutritious vegetable. In this study, oven cooking (OV), air-frying (AF), and infrared grilling (IR) were used to cook red bell peppers at different temperatures (170, 180, 190, and 200 °C). Changes in the total phenolic content, ascorbic acid content, antioxidant activity, and sugar and acrylamide content in red bell peppers were evaluated before and after cooking. The total phenolic and ascorbic acid contents decreased significantly after cooking (p < 0.05). Among the three evaluated methods, OV-cooked red bell peppers exhibited the highest antioxidant activity. The acrylamide content showed the lowest levels in OV 170 °C (93.67 ± 3.22 µg/kg dw) and the highest in AF 200 °C (1985.38 ± 76.39 µg/kg dw) samples. Compared to the AF and IR methods, OV was identified as the best way to preserve the antioxidant activity of red bell peppers while reducing acrylamide production. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-024-01623-y.

Evaluation of umami taste in Hanwoo with different feed sources by chemical analysis, electronic tongue analysis, and sensory evaluation.

This study aimed to evaluate umami taste in Hanwoo with different feed by chemical analysis, sensory evaluation and an electronic tongue system. Hanwoo cattle were divided into three groups: control group (fed only total mixed ration [TMR]), T1 (fed soybean meal + TMR), and T2 (fed soybean meal + corn-dried distiller's grain with solubles [Corn DDGS] + TMR). The three most abundant fatty acids (C18:1n-9, C16:0, and C18:0) in the T1, T2, and control groups accounted for 83.63%, 86.07%, and 85.52% of the total fatty acid content, respectively. Umami taste-related glutamic acid levels were significantly high in T1 (109.89 mg/kg), followed by T2 (66.66 mg/kg) and control (47.27 mg/kg). Fatty acid levels showed a high correlation with umami taste. The results of this study showed that the amino acid and fatty acid levels had been affected by feed types and soybean- or Corn DDGS-based feed potentially enhanced Hanwoo's umami flavor.

Improvement of carrier mobility of top-gated SiC epitaxial graphene transistors using a PVA dielectric buffer layer.

The effects of treatment with polyvinyl alcohol (PVA) and a dielectric film of HfO(2) on the properties of SiC based epitaxial graphene have been explored and analyzed. We have characterized the carrier mobility of graphene on Si-face and C-face SiC with a layer of HfO(2), with or without an initial PVA treatment on the device active layer. Epitaxial graphene grown on the C-face displays a higher mobility than a film grown on the silicon face. Also, the mobility in the presence of the PVA treatment with HfO(2) dielectric layer has been improved, compared with the mobility after deposition of only gate dielectric: ∼20% in C-face graphene and ∼90% in Si-face graphene. This is a major improvement over the degradation normally observed with dielectric/graphene systems.

Charge trapping devices using a bilayer oxide structure.

This experiment is the first exploration of use of charge traps in the bulk of deposited top oxide and at the interface between thermal oxide and deposited top oxide. We report the operational characteristics of SiO2/SiO2 device structures with 0.5 microm gate width and length. Low power operations are achieved through very thin gate stacks of 3 nm of thermally grown oxide and 7 nm of deposited oxide. However, narrow memory windows have been acquired comparing with conventional silicon-oxide-nitride-oxide-silicon (SONOS) memory cells due to a low trap density at the interface between a grown oxide and a deposited oxide. Additionally, the electric field between the channel and the charge is determined by solving 1D Poisson equation at a given write voltage, then total tunneling current density is calculated to make a program modeling for charge trapping devices. Tunneling/trapping simulation based on Fowler-Nordheim (F-N) tunneling performed and it fits the programming curves well. The memory window is almost constant after 100,000 cycles, and the retention characteristics are deteriorated rapidly.

Muffins enriched with dietary fiber from kimchi by-product: Baking properties, physical-chemical properties, and consumer acceptance.

This study aimed to evaluate the effects of dietary fiber from Chinese cabbage outer-leaf powder, which is a main by-product of kimchi, on the quality, texture properties, and sensory evaluation of muffins. The kimchi by-product powder (KBP, 36.2% dietary fiber) was added at 1%-4% dietary fiber content, by replacing wheat flour (w/w basis). The physico-chemical and sensory properties of the baked muffins were measured. The height and volume of the muffins decreased with the addition of KBP. Increasing the KBP content resulted in increased hardness and reduced chewiness. No significant difference was observed in the overall acceptance among the muffins, up to the 2% added dietary fiber group, and the positive effect of the incorporated KBP was also confirmed in the sensory evaluation. These results indicate that it is possible to produce functional muffins with increased dietary fiber content by adding KBP in place of flour.

Inhibitory effect of Au@Pt-NSs on proliferation, migration, and invasion of EJ bladder carcinoma cells: involvement of cell cycle regulators, signaling pathways, and transcription factor-mediated MMP-9 expression.

BACKGROUND: Although the diverse biological properties of nanoparticles have been studied intensively, research into their mechanism of action is relatively rare. In this study, we investigated the molecular mechanisms of the anticancer activity of heterometallic Au@Pt-nanoseeds (NSs) against bladder cancers. MATERIALS AND METHODS: Mode of action of Au@Pt-NSs was investigated through MTT assay, flow cytometry analysis, Western immunoblots, real-time qPCR, wound-healing migration and invasion assays, zymography, and electrophoretic mobility shift assay (EMSA). RESULTS: Treatment with Au@Pt-NSs significantly inhibited the proliferation of EJ cells in a dose-dependent manner by inducing G1 phase cell cycle arrest. Among the regulators associated with the G1 cell cycle phase, CDK2, CDK4, cyclin D1, cyclin E, and p21WAF1 were shown to participate in the inhibitory pathways of Au@Pt-NSs. In addition, treatment with Au@Pt-NSs led to upregulation of phospho-p38 MAPK and downregulation of phospho-AKT in EJ cells. Interestingly, Au@Pt-NSs inhibited the migratory and invasive potential of the cells, which was attributed to the suppression of the enzymatic activity of matrix metalloproteinase-9 (MMP-9). Using MMP-9-specific oligonucleotides, we showed that transcription factors such as NF-κB and Sp-1 were responsible for the MMP-9-mediated metastatic potential of EJ cells. CONCLUSION: Au@Pt-NSs significantly limited the progression, migration, and invasion of bladder cancer EJ cells. Our data represent a novel insight into developing cisplatin-like chemotherapeutic reagents with fewer side effects and provide useful information on molecular markers to monitor patients under Au@Pt-NSs-based chemotherapy.

Effect of Pleurotus eryngii Mushroom ß-Glucan on Quality Characteristics of Common Wheat Pasta.

The objective of this study was to evaluate the effect of ß-glucan-rich fractions (BGRFs) from Pleurotus eryngii mushroom powder on the quality, textural properties, and sensory evaluation of common wheat pasta. Pasta was prepared from semolina flour and common wheat flour by replacing common wheat flour at 2%, 4%, and 6% with BGRFs. Semolina flour showed significantly higher viscosities than common wheat flour samples. However, all viscosities, except the breakdown viscosity, were reduced with increasing percentages of BGRFs. Replacement of the common wheat flour with BGRFs resulted in a reddish brown colored pasta with a lower L* value and a higher a* value. The common wheat pastas containing up to 4% BGRFs were not significantly different from semolina pasta with regard to cooking loss. Addition of up to 2% BGRFs had no significant impact on swelling index and water absorption. The addition of BGRFs in common wheat flour had a positive effect on the quality of common wheat pasta and resulted in hardness values similar to those of semolina pasta. In a sensory evaluation, cooked pasta with 2% BGRFs had the highest overall acceptability score. In summary, the results showed that common wheat flour containing 4% BGRFs could be used to produce pasta with an improved quality and texture properties similar to semolina pasta.

Combined Application of Antibrowning, Heat Treatment and Modified-Atmosphere Packaging to Extend the Shelf Life of Fresh-Cut Lotus Root.

This work aimed to determine the effects of different concentrations of antibrowning treatments (that is, distilled water [DW], 1% ascorbic acid [AA], 0.5% chamomile [CM], and 1% AA + 0.5% CM) and heat-treatment (55 °C for 45 s) combined with packaging under 4 different modified-atmosphere gas compositions (that is, air, vacuum, 100% CO2 , 50% CO2 /50% N2 ) on the quality and microbiological characteristics of fresh-cut lotus root. The quality characteristics (that is, color, weight loss, texture, pH, polyphenoloxidase activity, and total phenolic content) of the AA + CM-dipped sample in 100% CO2 packaging were maintained significantly better than those of the other samples (P < 0.05). The microbiological counts observed in the DW-dipped sample during storage were higher than those of the AA, CM, and AA + CM samples, and heat-treatment retarded the microbiological deterioration of fresh-cut lotus root. Therefore, the results revealed that dipping in an antibrowning treatment (AA + CM), and 100% CO2 MAP with heat treatment effectively extend the shelf life of fresh-cut lotus root to 21 d at 5 °C.

SiC surface orientation and Si loss rate effects on epitaxial graphene.

We have explored the properties of SiC-based epitaxial graphene grown in a cold wall UHV chamber. The effects of the SiC surface orientation and silicon loss rate were investigated by comparing the characteristics of each formed graphene. Graphene was grown by thermal decomposition on both the silicon (0001) and carbon (000-1) faces of on-axis semi-insulating 6H-SiC with a "face-down" and "face-up" orientations. The thermal gradient, in relation to the silicon flux from the surface, was towards the surface and away from the surface, respectively, in the two configurations. Raman results indicate the disorder characteristics represented by ID/IG down to < 0.02 in Si-face samples and < 0.05 in C-faces over the 1 cm2 wafer surface grown at 1,450°C. AFM examination shows a better morphology in face-down surfaces. This study suggests that the optimum configuration slows the thermal decomposition and allows the graphene to form near the equilibrium. The Si-face-down orientation (in opposition to the temperature gradient) results in a better combination of low disorder ratio, ID/IG, and smooth surface morphology. Mobility of Si-face-down orientation has been measured as high as approximately 1,500 cm2/Vs at room temperature. Additionally, the field effect transistors have been fabricated on both Si-face-down and C-face-down showing an ambipolar behavior with more favorable electron conduction.