Flexible chemical sensors utilizing chemically sensitive nanomaterials are of great interest for wearable sensing applications. However, obtaining high performance flexible chemical sensors with high sensitivity, fast response, transparency, stability, and workability at ambient conditions is still challenging. Herein, a newly designed flexible and transparent chemical sensor of reduced graphene oxide (R‐GO) coupled with organic dye molecules (bromophenol blue) is introduced. This device has promising properties such as high mechanical flexibility (>5000 bending cycles with a bending radius of 0.95 cm) and optical transparency (>60% in the visible region). Furthermore, stacking the water‐trapping dye layer on R‐GO enables a higher response as well as workability in a large relative humidity range (up to 80%), and dual‐mode detection capabilities of colorimetric and electrical sensing for NH3 gas (5–40 ppm). These advantageous attributes of the flexible and transparent R‐GO sensor coupled with organic dye molecules provide great potential for real‐time monitoring of toxic gas/vapor in future practical chemical sensing at room conditions in wearable electronics.
Acrylic-based denture materials have several common weak points, such as shrinkage after curing, lack of strength and toxicity. In order to solve these problems, we adapted a hybrid system using acrylic polymer and polyhedraloligosilsesquioxane (POSS). The aim of the study was to investigate the biocompatibility of a reinforced acrylic-based hybrid denture composite resin with POSS. Specimens of a novel polymeric denture base resin, in which POSS was used to partially replace the commonly used base monomer, were fabricated. In order to examine changes in biocompatibility with time, fresh specimens, along with specimens soaked in distilled water for 24 and 72 h were fabricated. Three other types of acrylic denture base resins were used to prepare the resin specimens. Biocompatibility (as measured by a metabolic assay, an agar overlay test, and a mutagenesis assay) of the composites was tested. The metabolic and mutagenesis assays were conducted with pure culture medium as a control. In this study, the reinforced acrylic-based hybrid denture composite resin with POSS showed improved biocompatibility and lower mutagenicity than the control. Statistical examinations showed the cell metabolic activity of the novel polymeric denture base resin in the 72-h immersion case as having almost the same inclination as the control. We hope that these results might aid in the development of a reinforced acrylic-based denture resin.
Gelatin nanofibers can be used in the development of a biomimicking artificial extra cellular matrix(ECM) for tissue engineering, wound healing dressings and drug release. However, gelatin nanofibers are water soluble and have weak mechanical strength. Two different cross-linking methods for preparing gelatin nanofibers were used to render gelatin nanofibres insoluble: 1) UV radiation for modified gelatin nanofibers by trans-cinnamic acid; and 2) electrospun gelatin nanofibers cross-linked with genipin. A photo cross-linking method was used to examine the effects of ultraviolet (UV) radiation on the modified gelatin nanofiber scaffolds. A modified gelatin solution containing gelatin, trans-cinnamic acid and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) at a molar ratio of 1:3:30 was prepared. The results showed that the degree of modification in gelatin molecules was 14.5 groups per mol. The modified gelatin was dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol at 20%(w/v) and nanofibrous meshes were obtained by electrospinning. After drying, the nanofibrous meshes were exposed to a commercial germicide UV (=254 nm) lamp for different times. The swelling ratio of each nanofibrous mesh was decreased from 195% to 105% with increasing UV exposure time from 1 h to 10 h. A cross-linking agent method was used to evaluate the effects of the cross-linked gelatin nanofiber scaffolds with genipin. The swelling ratios decreased from 725% to 445% with increasing genipin solution concentration from 0.5%(w/ v) to 2%(w/v). The results of the cell culture suggest that cross-linking gelatin nanofibers with 0.5%(w/v) genipin improves the level of cell proliferation with increasing cell culture time from 1 day to 5 days. Moreover, the cell viability of each nanofiber increased with increasing cell culture time. However, the cell viability decreased with increasing genipin solution concentration.
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