Papers by Author: Sukum Eitssayeam

Abstract: 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.

Abstract: In this work, the effects of crystalline morphology on the mechanical properties of polycaprolactone/polyvinyl alcohol/ butterfly pea extract (PPB) nanofiber composite were investigated. Biopolymer nanofiber composite of PPB was fabricated by electrospinning technique using polycaprolactone concentration and distance of nozzle to ground collector of 7 wt% and 20 cm, respectively. The influence of applied voltage (vary from 15-25 kV) on the stress-strain curves was also observed. The structure and morphology of electrospun PPB nanofibers were investigated by x-ray diffraction (XRD) and scanning electron microscopy (SEM). It was found that, the degree of crystallinity increased with applied voltage and the mechanical properties was affected by the morphology of PPB nanofiber.

Abstract: 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.

Abstract: 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

Abstract: In this work, thepreparation and morphology of biphasic calcium phosphate (BCP) have been studied. The biphasic calcium phosphate (BCP) ceramics were prepared by mixing between hydroxyapatite (HA) and Beta-tricalcium phosphate (β-TCP) powderby ball milling technique with different ratios (100:0,80:20,60:40,50:50,40:60, 20:80 and 0:100). After that the mixtures were forming by Gel casting method and then sintered at 1200°C, respectively. The phase formation of the biphasic calcium phosphateceramics were studied by X-ray diffraction (XRD) and their ceramic microstructure,shrinkage and density were investigated.

Abstract: In this research, the two-step sintering method was employed to develop the physical properties of Hydroxyapatite (HA) ceramics. HA powder was extracted from bovine bone and vibro-milling method was used to make the fine particles. For the two-step sintering process, the samples were heated up to the first step temperature (T₁=1200^°C) for 6 min then the temperature was lowered down to second step temperatures (T₂=1150^°C and 1100^°C) for 5, 10 and 15 h. Another set of samples were heated up to the first step temperature (T₁=1250^°C) for 6 min then the temperature was lowered down to second step temperature (T₂=1150^°C) for 5, 10 and 15 h. X-ray diffraction (XRD) was carried out for investigating the phase formation in the prepared ceramics. Physical properties of the prepared ceramics were studied such as porosity, density by Archimedess principle. It is found that most of the samples exhibit Ca₅(PO₄)₃(OH) phase with JCPDS number 09-0432. The first step temperature plays the most roles on controlling the density of HA ceramics than T₂ and dwell times. Microstructures of the HA powder and ceramics were characterized using scanning electron microscope (SEM).The feasibility in using the prepared ceramics for bone replacement applications was discussed.

Abstract: Hydroxyapatite (HA) is classified as one of the important bioceramics, which has been used in orthopedics, medical and dental applications. It has bioactivity and good biocompatibility with the human organism, which is suitable in medical applications as an implant or coating on prostheses such as metal. In this study, the effects of calcinations temperatures on phase formation and physical properties of HA particles were investigated. The HA particles synthesized from bovine bone were cleaned and fired at 800°C and subsequently ball milled for 24 h. Then received HA particles were divided into two parts. The first one was calcined at various temperatures from 900 to 1400°C and the second one was vibratory milled for 4 h and subsequently calcined at various temperatures from 900 to 1400°C. The calcined HA particles were characterized by X-ray diffraction (XRD) for their crystal structure and particle size analysis. Scanning electron microscope (SEM) was used for microstructural.

Abstract: The aim of this study was to investigate the effect of BaZr_0.05Ti_0.95O₃ (BZT) addition on the microstructure, physical, dielectric and piezoelectric properties of hydroxyapatite (HA), and develop new biomaterials which have potential applications in the support for cellular growth and in the system for bone regeneration. In this case the BaZr_0.05Ti_0.95O₃- HA composites (HABZT) were prepared by conventional sintering method. The BZT were added to HA with ratio 0, 10, 20 and 30 %wt. Then the mixed powders were pressed and subsequently sintered at the temperature ranging from 1150 to 1350°C. The result showed that the dielectric and piezoelectric properties were improved by the addition of BZT. Moreover, the bioactivity of the HA improved with addition of BZT especially at 10% as evident by the formation of bone like apatite layers on the surface of all BCZT composites after soaking in simulated body fluid (SBF) for 15 days. The results confirmed the possibility of using these bioactive composites for treatment within the human body.

Abstract: 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.