Yi Fan Goh

Electrospun fibers for tissue engineering, drug delivery, and wound dressing

Electrospinning, a technique well known for fabricating nanoscale fibers, has recently been studied extensively due to its various advantages such as high surface-to-volume ratio, tunable porosity, and ease of surface functionalization. The resulting fibers are extremely useful for applications in the fields of tissue engineering, drug delivery, and wound dressing. Since electrospun fiber mimic extracellular matrix of tissue in terms of scale and morphology, its potential to be used as scaffold is continuously explored by researchers, especially in the field of vascular, nerve, bone, and tendon/ligament tissue engineering. Besides morphology, physical, and chemical properties, electrospun scaffolds are often evaluated through various cell studies. Researchers have adopted approaches such as surface modification and drug loading to enhance the property and function of scaffold. This review gives an overview of some current aspects of various applications of electrospun fibers, particularly in biomedical fields, how researchers have enhanced electrospun fibers with different methods and attempted to overcome the inherent limitation of electrospinning by using novel techniques.

Continuous microwave flow synthesis of mesoporous hydroxyapatite

We have successfully used continuous microwave flow synthesis (CMFS) technique for the template free synthesis of mesoporous hydroxyapatite. The continuous microwave flow reactor consisted of a modified 2.45GHz household microwave, peristaltic pumps and a Teflon coil. This cost effective and efficient system was exploited to produce semi-crystalline phase pure nano-sized hydroxyapatite. Effect of microwave power, retention time and the concentration of reactants on the phase purity, degree of crystallinity and surface area of the final product was studied in detail. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to study the phase purity and composition of the product, while transmission electron microscopy (TEM) was used to study the effect of process parameters on the morphology of hydroxyapatite. The TEM analysis confirmed the formation of spherical particles at low microwave power; however the morphology of the particles changed to mesoporous needle and rod-like structure upon exposing the reaction mixture to higher microwave power and longer retention time inside the microwave. The in-vitro ion dissolution behavior of the as synthesized hydroxyapatite was studied by determining the amount of Ca(2+) ion released in SBF solution.

Synthesis, characterization and in vitro study of magnetic biphasic calcium sulfate-bioactive glass

Calcium sulfate-bioactive glass (CSBG) composites doped with 5, 10 and 20 mol% Fe were synthesized using quick alkali sol-gel method. X-ray diffraction (XRD) data of samples heated at 700 °C revealed the presence of anhydrite, while field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) characterization confirmed the formation of nano-sized CSBGs. The UV-vis studies confirmed that the main iron species in 5% Fe and 10% Fe doped CSBGs were tetrahedral Fe(III) whereas that in 20% Fe doped CSBG were extra-framework FeOx oligomers or iron oxide phases. Measurement of magnetic properties of the samples by vibrating sample magnetometer (VSM) showed very narrow hysteresis loop with zero coercivity and remanence for 10% Fe and 20% Fe doped CSBG, indicating that they are superparamagnetic in nature. All samples induced the formation of apatite layer with Ca/P ratio close to the stoichiometric HA in simulated body fluid (SBF) assessment.