Applied Mechanics and Materials Vol. 804

Abstract: Synthesis of Diamond-Like-Carbon (DLC) films as the coating prototype for biomedical materials was fabricated by direct current (DC) magnetron sputtering at working pressure of 1.0x10^-3 Torr, DC power between 50-150 W, and coating time between 60-180 sec. Polystyrene and Graphite were used as a substrate and target, respectively. The results showed that the surface roughness increased with increasing of the power and the coating time. These changes influenced the contact angle of DLC films, and the time of blood clotting. Blood clotting time of the blood samples with the fabricated surface was faster than that of the blood samples without the surfaces.

Abstract: Silk sericin/chitosan composite films were successfully prepared for possible future wound dressing applications. To prepare the chitosan, shrimp shells were first washed and finely ground to obtain a fine powder before extracting the chitosan using a chemical reaction method. The sericin was extracted from Thai raw cocoons of Bombyx mori silk worm via boiling and drying. To prepare the silk sericin/chitosan composite films, the silk sericin and chitosan solutions with varying volume ratios were mixed in a magnetic stirrer for 30 minutes. They were then dropped on to a plastic mold. The sample was dried at a temperature of 50 °C. The prepared composite films were characterized using UV-VIS spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The results from our studies could provide a method for future composite film development.

Abstract: Titanium dioxide (TiO₂) is coated onto the materials (e.g. glass ceramic) to inhibit the bacteria growth. TiO₂ has become a popular photocatalyst for both air and water purification. It has also shown to be very active for bacterial destruction even under UV light. The photocatalytic of TiO₂ involves the light-induced catalysis of reducing and oxidizing reactions on the surface of materials. The spray pyrolysis technique for material synthesis in thin-film configuration is an interesting option due to the use of inexpensive precursor materials and low-cost equipment suitable for large-area coatings. In this research, TiO₂ thin films were deposited onto glass substrates using spray pyrolysis technique. Escherichia coli (E.coli) was used as testing bacteria. TiO₂ thin films showed some antibacterial effect in the halo test.

Abstract: The objective of this research is to compare the characteristic of gelatin prepared from waste fish scales. White perch, java barb, red tilapia and nile tilapia scales were cleaned and treated with 1.0 M NaOHfor 2 h at room temperature to remove fat and then treated 0.8 M acetic acid to restructure of fish scales. Gelatin from waste fish scales were exacted using heating the cleaned fish scales in the distilled water at 70 °C for 2 h. Gelatins were characterization by UV-vis spectrometer, viscometer, X-ray diffraction (XRD), fourier transform infrared spectrophotometer (FT-IR) and scanning electron microscopy (SEM). The results shown the amount of gelatin and percent transmittance of light of gelatin from white perch was more than that of other waste fish scales. The viscosities of all gelatins decreased with increasing temperature. The gelatin from java bard was more viscosity than that from other fish scales due to more amounts of aspartic and glutamic acid. The XRD intensity of gelatin from white perch scales and java barb scales had higher than that from other fish scales confirming the higher crystallinity of gelatin. The FT-IR resultsindicated the same function groupsof all gelatins. SEM results revealed the porous structure of all gelatins. The all results concluded that gelatin property of nile tilapia scales had less than that of other fish scales which could be used in different industry.

Abstract: Present study consisted a possible novel natural antimicrobial agent replacing chemicals for preventing the microbial growth and microbial biofilm accumulated on silicone. Since squid ink has long proved to play various primary roles in wide ranges of alternative therapeutic medicine and food applications. This research was designed to report the potential antimicrobial effects of squid ink especially after heat treatment against the microorganisms causing biofilms. Various temperature conditions comprising room temperature (RT), 40, 60, 80, and 100°C were applied to the crude squid ink. Two fresh ink samples isolated from splendid squid (Loligo duvauceli) and soft cuttlefish (Sepioteuthis lessoniana) were determined for their antimicrobial activities after heat treatment on most reported microbes causing biofilms on these plastic substrates. The results showed that after pretreatment at RT-50°C for 15 min, fresh crude ink of L. duvauceli consistently presented higher bioactive activity (> 15 mm diameter) than S. lessoniana(5-10 mm diameter), based on a zone of inhibition of disc diffusion method. From this study, both squid inks could definitely be future applied as active antimicrobial ingredients into silicone.

Abstract: Flavonoids are compounds which act as antioxidants in both plant and human. These substances are found in reproductive tissues. Tobaccos expressing ORF of PRODUCTION OF ANTHOCYANIN PIGMENT 1 (PAP1) involved in flavonoid biosynthesis were used for investigating the flavonoid profiles and antioxidant activity of petals and compared to wild type (WT) tobacco. Approximately two months, the tobacco grown in a culturing room had produced flowers for harvesting. The petal tissues were extracted with the solvent of acidic methanol and water. These extracts were measured the specific wavelength of flavonoid derivatives by using a spectrophotometer. The petal extract of H7 line showed the highest content of all detected flavonoid subgroups. However the petal extract of transgenic line H5 and H7 had significantly higher levels of anthocyanin (pelargonidin) than those of the other transgenic and WT tobaccos. An antioxidant activity of the petal extract was evaluated by 2,2-diphenyl-1-picrylhydrazyl radical (DPPH^•) assay. An effective concentration of the extract which scavenged DPPH radical by 50% (EC₅₀) was presented. EC₅₀ of the H5 and H7 transgenic extracts was approximately two folds less than that of WT extract Therefore anthocyanin may highly affect on antioxidant activities.

Abstract: We present a nanograting optical biosensor device, fabricated by photolithography, which is sensitive to changes in refractive index at the sensor surface. via changes in the reflectivity spectra. The grating was created by etching of a silicon nitride (Si₃N₄) film, which has a refractive index of 2.01, resulting in an array of Si₃N₄ pillars. The grating was coated by the high quality spin on glass material which has a low effective refractive index <1.50. The surface was functionalised with a layer of probe biomolecules for specific binding of the target DNA. Immobilization of the probe molecules was carried out via streptavidin – biotin interaction, the biotin modified ssDNA oligonucleotide probes were 23 bases in length (10¹⁰ copies/μl) and the sequence of the complementary ssDNA was 5’-TAC TCA TAC TTG AGG TTG AAA TT-3’(10, 100 and 1000 copies/μl). Results of the experiment showed that when molecules attached to the surface of the device, the position of the reflectance spectrum shifted due to the change of the optical path of light that is coupled into the nanograting structure. The extent of the wavelength shift (Δλ) of the peaks could be used to quantify the amount of materials bound to the sensor surface.

Abstract: Chitosan is the second most abundant polysaccharide in nature, non-toxic, biocompatible, biodegradable, and bacteriostatic and fungistatic. Many researches have devoted on the development of new biodegradable materials especially films and coatings with its polysaccharides causing film-forming properties. The heating process during plasticization has been long known for its detrimental effects on a shelf life of chitosan and possibly its antimicrobial activity. In the study, we were interested in understanding of antimicrobial activity of chitosan after mixing with various amounts of plasticizer polyethylene glycol (PEG) under various temperatures but not further be plasticized chitosan films. From fifty percentages of chitosan obtained by deacetylation of chitin which was extracted from shrimp wastes. Chitosan was mixed with plasticizer PEG, incubated at room temperature, 40, 60, 80, or 100°C for 15 min, and observed for their microbial susceptibility. The results exhibited comparable effectiveness of the antimicrobial properties in chitosan and even quite lower in chitosan blended with PEG, in exhibiting antimicrobial activity. Additionally, antibacterial activities of chitosan blended with PEG were heat dependent. These overall data will be essential information for the development of antimicrobial films and coatings in food packaging with the extending shelf life.

Abstract: Cotton fabric samples were printed with pigment dye using warp yarn printing technique has been investigated. The color fastness was evaluated to testing in with washing, light, rubbing, water, and perspiration of the printed samples, the test were determined according to ISO 105-C06 A1S: 2010, ISO 105-B02: 1994, ISO 105-X12: 2001, ISO 105-E01: 2010, and ISO 105-E04: 2008 respectively. The results showed that the colour fastness to washing, water, and perspiration were in very good level whereas colour fastness to rubbing was in good. The results indicated that the properties of printed samples (handling and sharpness) were good to very good level.

Abstract: In this study, nanofibres consisting of silk fibroin (SF) and gelatin (GP) with different composition ratio were fabricated by needleless electrospinning method. The influences of SF/GP blending ratio on the properties of spinning solution and the morphology of electrospun fibres were investigated. A variety of compositions of the silk fibroin/gelatin blend solutions were successfully electrospun into nanofibres sheet. The morphology of electrospun fibre was characterized by a scanning electron microscope (SEM) which indicates that the morphology of obtained fibres was influenced by the weight ratio of gelatin to silk fibroin in the spinning solution. It was observed that the blending ratio of gelatin to silk fibroin in spinning solution played an important role in spinning performance of the process and the diameter of obtained fibres. An increasing in gelatin content in blended solution resulted in bigger diameter of the obtained electrospun fibres. The silk fibroin/gelatin electrospun fibres had diameters ranging from 200 to 660 nm.