Krit Sutjarittangtham

Antibacterial Activity and Inhibition of Adherence of Streptococcus mutans by Propolis Electrospun Fibers

Mouth-dissolving fibers with antibacterial activity for the oral cavity were prepared by an electrospinning technique. Propolis extract was used as an active ingredient and polyvinylpyrrolidone (PVP) K90 as the polymer matrix. The morphology and diameter of the fibers were characterized by scanning electron microscopy. Antibacterial activity against Streptococcus mutans and the inhibition of S. mutans adhesion on a smooth glass surface during the biofilm formation were tested. Propolis, 5% (w/v), was combined with a PVP K90 solution, 8% (w/v), with or without Tween 80 including flavor additives and electrospun with an applied voltage of 15 kV. Uniform and smooth fibers of propolis-PVP K90 were obtained. The results showed that electrospun fibers with propolis extract can dissolve and release the propolis in water. Propolis-PVP electrospun fibers showed better antibacterial activity by reduction of bacteria adhesion on a smooth glass surface when compared to some commercial mouthwash products. These results indicated the potential of electrospun fibers to be used as mouth-dissolving fibers for effective antibacterial activity in the oral cavity.

Influence of seed nano-crystals on electrical properties and phase transition behaviors of Ba0.85Sr0.15Ti0.90Zr0.10O3 ceramics prepared by seed-induced method

This work studied the effects of seed nano-crystal on the electrical properties and the phase transition behaviors of Ba0.85Sr0.15Ti0.90Zr0.10O3 (BSZT) ceramics. The BSZT ceramics were prepared by the seed-induced method. The seed nano-crystal were prepared by the molten salt technique, and NaCl-KCl (1:1 by mole) eutectic mixtures were used as the flux.[1] The ceramic powders were prepared by using a conventional method which added seed nano-crystals at various ratios. Results indicated that seed nano-crystals enhanced the electrical properties of ceramics. The sample with a 20 wt. % seed nano crystals has excellent value of dielectric constant (µr) of 34698 at maximum temperature. The phase transition temperature was observed at 60°C. The morphology was found that the grain size increasing significantly with an increased of seed nano crystals. The relaxor ferroelectric phase transition behavior was shown by a diffuseness parameter (³). An increase in the BSZT-seed showed a decreased in ³ value from 1.61 to 1.44. Thus the ferroelectric of the BSZT ceramics can be confirmed by hysteresis loop.

Bactericidal effects of propolis/polylactic acid (PLA) nanofibres obtained via electrospinning

Summary Electrospinning of propolis/polylactic acid (PLA) fibres was investigated for propolis concentrations from 0–10% (w/v). Solutions could not be spun when the amount of propolis was over 8% (w/v). Mechanical characterization indicated that propolis reduced the tensile strength. The fibre mats exhibited poorer mechanical performance when the propolis concentration was increased. At propolis concentrations of 2–6% (w/v), the fibres were smooth, bead-free and homogeneous. When the concentration of propolis was more than 6% (w/v), the fibres changed from ductile to brittle. The fibres containing 2% (w/v) propolis showed bactericidal effects on Staphylococcus aureus, Staphylococcus epidermidis, Proteus mirabilis and Escherichia coli. At a propolis concentration of 4% (w/v) they also inhibited Bacillus cereus.

Preparation of glutinous rice starch nanofibers by electrospinning

Glutinous rice starch (GRS) is produced from glutinous rice which is commonly cultivated in the Northeast of Thailand. GRS contains two types of glucose polymers which are amylose and amylopectin. Glutinous rice starch nanofibers (GNF) can be produced by an electrospinning technique. This is not a complicated method but needs a high voltage power supply. The aim of this study was to understand the production of GNF and physical-chemical properties of GNF. The morphology of GNF was examined by scanning electron microscopy. The characteristics of GNF are high porosity, flake multi-layers and a high swelling power. The Electrospinning technique did not change the chemical structure of GRS based on an FT-IR evaluation. This research revealed the basic characteristics of electrospun glutinous starch for use in various applications in the future.

Ultrasonic extraction of thai propolis for antimicrobial and antioxidant properties

Propolis is the mixture of resins that honeybees collect from plant buds, leaves and exudates. Antimicrobial and antioxidant properties of propolis have been widely studied, however, there have few reports on Thai propolis. To increase the efficient extraction of organic propolis compounds, extraction methods have been developed. We applied the ultrasound technology to reduce extraction time and increase extraction yields of propolis. The propolis was extracted using ultrasound technology for 15-60 minutes and the propolis extracts were examined to compare their biological activities. Antimicrobial activities of the propolis were investigated using the agar well diffusion method. The free radical-scavenging and antioxidant activities of propolis extracts were measured using the DPPH and FolinCiocalteau colorimetric methods. The propolis extracted using ultrasound for 15 and 30 minutes showed inhibitory effects on tested fungi and bacteria as well as antioxidant activities.

Antimicrobial Effect of Brazillian Propolis/Polycaprolactone Polymer on some Human Pathogenic Bacteria

The antimicrobial activities of propolis against some bacterial strains have been studied. However, there are few reports on biopolymers from propolis. Polycaprolactone (PCL) is a biodegradable polymer that has a long history of use in the biomedical field. In this work, the polymer nanofiber was grown from a Brazillian propolis extract solution on PCL using an electrospinning technique. Antimicrobial activities were investigated by the disc diffusion method. The propolis extract and polymer nanofiber could inhibit some human pathogenic bacteria. In addition, the inhibitory effects on tested microorganism depended on the concentration of propolis extract mixed with the polymer nanofiber. Such properties of the propolis/PCL nanofiners can be further developed for biomedical applications.

Preparation of polycaprolactone/ethanolic extract propolis nanofibers films

Recent years, propolis has plenty of biological and pharmacological properties and its mechanisms of action have been widely investigated. There is a substantive database on the biological activity and toxicity of propolis indicating it may have many antibiotic, antifungal, antiviral and antitumor properties, among other attributes. The one-step incorporation of propolis into nanofibrous mats of polycaprolactone (PCL) by electrospinning was demonstrated. In this research, the preparation of the PCL nanofibers films added ethanolic extract propolis (EEP) by electrospinning technique was studied. The EEP content was varied from 0, 2, 4, 6, 8 and 10%. The morphology was observed by a scanning electron microscope (SEM). The functional group was investigated by FT-IR

Nanofiber Production Using Polyvinylalcohol (PVA) and Thai Honey and its Properties

Nanofibers are currently used in modern medicine. Various materials including biodegradable, non-degradable, and natural materials have been used to produce the novel nanofibers. Electrospinning technique enables the creation of continuous fibers with dimensions on the scale of nanometers from a wide range of natural and synthetic polymers. Our research was focused on producing nanofibers from the mixture polyvinylalcohol (PVA) and Thai honey by using the elecotrospinning method. The morphology of fibers was observed by SEM. Also, the biological properties (antibacterial and antioxidant properties) were described.

Effects of B-site doping on piezoelectric and ferroelectric properties of Pb0.88Sr0.12(Zr0.54Ti0.44Sb 0.02)(1-y)-(Zn1/3Nb2/3) yO3 ceramics

Pb0.88Sr0.12(Zr0.54Ti0.44Sb0.02)(1-y) – (Zn1/3Nb2/3)yO3 ceramics where y = 0.00–0.10 were prepared by a solid state reaction method. Doping of Zn and Nb (co-doped) at B-site produced a phase transformation from tetragonal to rhombohedral phase. Highest piezoelectric coefficient d33 of 632 pC/N was recorded for the y = 0.04 sample. The piezoelectric result was correlated with the phase formation and the ferroelectric properties. Dielectric constant and loss tangent slightly increased with increasing the co- doped content. However, loss tangent values were less than 0.06 for all samples. These results indicated that the piezoelectric and dielectric properties of the ceramics could be improved by the co-doping.

Dielectric and Piezoelectric Properties of Sr Doped 0.8PZT-0.2PNN Ceramics

The solid solution of 0.8(Pb(Zr 1/2 Ti 1/2 )O 3 ) – 0.2(Pb(Ni 1/2 Nb 2/3 )O 3 ) doped with Sr were prepared by solid state route. Effect of Sr dopant on dielectric and piezoelectric properties was investigated. The dielectric constant at room temperature of the ceramics was found to increase with increasing Sr concentration. An increase in tunability was observed for the samples doped with higher Sr concentration. However, the maximum piezoelectric coefficient (d 33 ) was observed for the ceramic doped with 0.6 mol% Sr.