Dhewa Edikresnha

Correlation between Structures and Antioxidant Activities of Polyvinylpyrrolidone/Garcinia mangostana L. Extract Composite Nanofiber Mats Prepared Using Electrospinning

Nanofiber mats of polyvinyl(pyrrolidone) (PVP) with Garcinia mangostana extract (GME) as the encapsulated drug have been developed using electrospinning. SEM images of all electrospun PVP/GME composite nanofiber mats showed that they had similar and smooth morphology, no beads, and spindle shape. Its average diameter decreased and its surface area therefore increased with the decrease of its PVP concentration. The benefit of high surface area is obvious in drug delivery systems for poorly water-soluble drugs. Their FTIR spectra indicated that PVP and GME interacted intermolecularly via hydrogen bonds in the composite nanofiber mats. A conformational change in the C-H chain of PVP occurred in the composite nanofiber mats due to the intermolecular interactions. Their XRD patterns confirmed that they were amorphous because of amorphization during electrospinning. The XRD analyses also strengthened the FTIR studies; namely, GME and PVP formed intermolecular interactions in the electrospun composite nanofiber mats. As a result, GME as the encapsulated drug was molecularly dispersed in the electrospun PVP nanofiber matrix that functioned as a drug delivery system. From the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, the composite nanofiber mats exhibited very high antioxidant activities despite having been exposed to high voltage during electrospinning. Therefore, they are potential antioxidant products for food and pharmaceutics.

Synthesis of Styrofoam Fibers Using Rotary Forcespinning Technique

Development of rotary forcespinning (RF) to synthesize fibers has been done. High speed motor driven centrifugal force becomes a major factor in the formation of fibers. RF apparatus consists of three main parts namely the motor system, the collector, and the heating system that serves to regulate the temperature and humidity around the motor. The liquid polymer was poured in the motor holder and rotated at high speed so that the liquid was dropped from the tip of the needle to the collector in the form of fibers. In this study, the liquid polymer was from waste polystyrene foam (styrofoam) soaked in acetone at a certain ratio. The observation was done with the digital microscope up to 1000 times of magnification. The produced styrofoam fibers were similar to homogeneous and smooth cotton with an average fiber diameter in micrometer. The utilization of waste styrofoam into the fibers is expected to reduce the environmental problems caused by waste styrofoam.

Electrospun Polyvinylpyrrolidone (PVP) Nanofiber Mats Loaded by Garcinia mangostana L. Extracts

Composite nanofibers of polyvinylpyrrolidone (PVP) and Garcinia mangostana L. extract (GME) have been synthesized through electrospinning method for application in drug delivery systems. The precursor solution of 10 mL PVP 10% w/w and GME 2% w/w was then electrospun collected at the rotating collector at the following optimum parameters: a voltage of 15 kV, a collector-nozzle distance of 12 cm, and a flow rate of 1 mL/hour. SEM images showed that the average diameters were 476 nm and 690 nm for the PVP and PVP-GME composite nanofibers, respectively. To some degree, the addition of GME into PVP nanofibers increased the average diameter size of nanofibers. Moreover, the release studies, it was shown that 80% of the GME was released within 30 minutes. Therefore, the PVP-GME composite nanofibers can be applied as the drug delivery systems.

Electrospun Polyvinylpyrrolidone as a Carrier for Leaves Extracts of Anredera cordifolia (Ten.) Steenis

Nanofibers produced by electrospinning method have high porosity, large surface area, long size, and their dimensions are ranging from nanometers to micrometers. The synthesis process was straightforward, uncomplicated and it can be processed from various type of materials and the nanofibers can be used as drug release. The polymer matrix acts as a carrier of other materials that will be spun. The purpose of this study was to to prepare electrospun fiber mats and to incorporate extracts from the leaves of Anredera cordifolia (Ten.) Steenis plant (Binahong). Polyvinylpyrrolidone (PVP) was used as a carrier matrix. Binahong leaf extract was added to a solution of PVP. The solution was then electrospun using a single nozzle and drum collector system under condition of voltage 12.5 kV, nozzle collector distance of 12 cm, and flow rate 10 μl /minute. In this study, the composite of Binahong extract and PVP solution was succesfully made into nanofiber.

Simply Electrospun Gelatin/Cellulose Acetate Nanofibers and their Physico-Chemical Characteristics

Gelatin in fibers form can be used for tissue engineering, wound dressing, or drug carrier. However, it is easily damaged if exposed to water. Thus, it was blended with cellulose acetate. Acetic acid was used as a solvent because it is less toxic. The mass ratios of gelatin to cellulose acetate of 10:0, 8:2, and 6:4 were as precursor solutions. Simple electrospinning was employed to produce gelatin/cellulose acetate fibers. From SEM images, it was shown that the average diameters of gelatin/cellulose acetate fibers from the precursor solutions of 10:0, 8:2, and 6:4 were 534, 649, and 765 nm, respectively. The addition of cellulose acetate increased the viscosity of gelatin/cellulose acetate solution. Moreover, gelatin mass reduction caused a decrease in conductivity of gelatin/cellulose acetate solution. Therefore, increasing in the viscosity or reducing in the conductivity of the precursor solution increased the average diameter of the gelatin/cellulose acetate fibers. The analysis of FTIR spectra showed that the structural changes of gelatin and cellulose acetate occurred after being transformed into gelatin/cellulose acetate nanofibers.

Mangosteen pericarp extract embedded in electrospun PVP nanofiber mats: physicochemical properties and release mechanism of α-mangostin

Background α-Mangostin is a major active compound of mangosteen (Garcinia mangostana L.) pericarp extract (MPE) that has potent antioxidant activity. Unfortunately, its poor aqueous solubility limits its therapeutic application. Purpose: This paper reports a promising approach to improve the clinical use of this substance through electrospinning technique. Methods Polyvinylpyrrolidone (PVP) was explored as a hydrophilic matrix to carry α-mangostin in MPE. Physicochemical properties of MPE:PVP nanofibers with various extract-to-polymer ratios were studied, including morphology, size, crystallinity, chemical interaction, and thermal behavior. Antioxidant activity and the release of α-mangostin, as the chemical marker of MPE, from the resulting fibers were investigated. Results It was obtained that the MPE:PVP nanofiber mats were flat, bead-free, and in a size range of 387–586 nm. Peak shifts in Fourier-transform infrared spectra of PVP in the presence of MPE suggested hydrogen bond formation between MPE and PVP. The differential scanning calorimetric study revealed a noticeable endothermic event at 119°C in MPE:PVP nanofibers, indicating vaporization of moisture residue. This confirmed hygroscopic property of PVP. The absence of crystalline peaks of MPE at 2θ of 5.99°, 11.62°, and 13.01° in the X-ray diffraction patterns of electrospun MPE:PVP nanofibers showed amorphization of MPE by PVP after being electrospun. The radical scavenging activity of MPE:PVP nanofibers exhibited lower IC50 value (55–67 µg/mL) in comparison with pure MPE (69 µg/mL). The PVP:MPE nanofibers tremendously increased the antioxidant activity of α-mangostin as well as its release rate. Applying high voltage in electrospinning process did not destroy the chemical structure of α-mangostin as indicated by retained in vitro antioxidant activity. The release rate of α-mangostin significantly increased from 35% to over 90% in 60 minutes. The release of α-mangostin from MPE:PVP nanofibers was dependent on α-mangostin concentration and particle size, as confirmed by the first-order kinetic model as well as the Hixson–Crowell kinetic model. Conclusion We successfully synthesized MPE:PVP nanofiber mats with enhanced antioxidant activity and release rate, which can potentially improve the therapeutic effects offered by MPE.

Synthesis of High-Impact Polystyrene Fibers using Electrospinning

Synthesis of fibers from waste high-impact polystyrene (HIPS) have been successfully done using electrospinning method. The HIPS solutions were made with a single solvent (DMF or d-limonene), a mixed solvent (d-limonene/DMF), and with the addition of acetone to the previously stated solvents. The effects of HIPS concentration, a mix of solvent, and the addition of acetone on the morphology and the diameter of fibers were observed. The morphological change from particles to fibers took place along with the increasing concentration of HIPS in d-limonene. For other precursor solutions using DMF solvent, bead free fibers could be obtained even at low levels. The average diameter of fibers increased along with the increase of the HIPS concentration in DMF. At the concentrations of 15, 20, 25, 30, and 35 wt.%, the average diameters were 1.85, 2.09, 2.66, 3.59, and 7.38 μm, respectively. For the precursor solutions with the combination of different solvents (HIPS/DMF), the existence of beads was influenced by the ratio of solvents. When the ratio of d-limonene/DMF was 75:25, the obtained beaded fibers had a relatively large amount of beads. At the ratio of 50:50, fewer beads were found. Bead-free fibers were finally reached when the ratio of HIPS / DMF was 25:75. The addition of acetone reduced the diameter of the produced fibers. However, too much addition of acetone caused the fibers to be wet. Additionally, the diameter became larger if the addition of acetone surpassed a certain amount of volume.

Synthesis of Polyvinylpyrrolidone (PVP)-Green Tea Extract Composite Nanostructures using Electrohydrodynamic Spraying Technique

Green Tea Extract (GTE) as an active substance has successfully loaded to PVP nanostructures using electrohydrodynamic spraying technique. The precursor solution was the mixture of ethanolic polyvinylpyrrolidone (PVP) with a molecular weight of 1,300 kg/mol and ethanolic GTE solutions at a weight concentration of 4 wt.% and 2 wt.%, respectively, and it was estimated that the entanglement number was 2. The electrospraying was conducted at the voltage of 15 kV, the flow rate of 10 µL/min., and the distance between the collector and the tip of the nozzle of 10 cm. The SEM images showed that the PVP/GTE nanostructures had a combination of agglomerated beads (less spherical particles) and nanofibers. This occurred because if the PVP concentration is low, the PVP/GTE composite has weak core structures that cause the shell to be easily agglomerated each other. The intermolecular interaction between PVP and GTE in the PVP/GTE nanostructures occurred as confirmed by the peak at 3396 cm-1, which is the carboxyl group, proving that the PVP/GTE nanostructures contained water, alcohols, and phenols. The peak at 1040 cm-1, which is the stretching of C-O group in amino acid, gave another proof to the intermolecular interaction.

Rotary forcespun styrofoam fibers as a soilless growing medium

To make styrofoam fibers from used styrofoam, rotary forcespinning technique was used because it offers high production rate and affordable production cost. The used styrofoam was dissolved in acetone to obtain styrofoam solution as a precursor of syrofoam fibers. Since the technique utilizes centrifugal force, the precursor was thrown out and its phase changed to be solid following acetone solvent evaporation. Long, clean and light styrofoam fibers were then produced. To determine if the styrofoam fibers is a good soilless growing medium, physico-chemical properties including pH and electrical conductivity, bulk density, water retention and wettability were measured. Rockwool, which is the most popular soilless growing medium and easily obtained from local farm suppliers, was selected as a benchmark to evaluate the styrofoam fibers.

Generation of Submicron Bubbles using Venturi Tube Method

In this experiment, submicron bubbles that have diameters less than 1 millimeter were generated by mixing water and gas by hydrodynamic cavitation method. The water was forced to pass through a venturi tube in which the speed of the water will increase in the narrow section, the throat, of the venturi. When the speed of water increased, the pressure would drop at the throat of the venturi causing the outside air to be absorbed via the gas inlet. The gas was then trapped inside the water producing bubbles. The effects of several physical parameters on the characteristics of the bubbles will be discussed thoroughly in this paper. It was found that larger amount of gas pressure during compression will increase the production rate of bubbles and increase the density of bubble within water.