Papers by Keyword: Hydrogel

Abstract: Flexible and wearable electronics are increasingly popular and utilized in various forms. Batteries have become essential as an energy source for wearable electronics. To meet demands of such electronics, these batteries must remain flexible, lightweight, possess good electrochemical performance, customizable shape, and ensure safety. Zinc-ion batteries (ZIBs) have emerged as a promising energy source for these applications. However, ZIBs encounter challenges due to the lack of flexible electrolytes. Polyacrylamide (PAM) is a polymer widely used as gel polymer electrolytes (GPEs) owing to its versatile electrical conductivity and excellent flexibility. However, PAM alone lacks the mechanical strength required to support flexible and wearable electronics adequately. To address this limitation, alginate (Alg), a polysaccharide with good compatibility with PAM, is incorporated in varying concentrations (0-3 %wt.) to form interpenetrating networks (IPN) hydrogels, with a chemical network of PAM and a physical network of alginate to enhance the overall mechanical properties. Following this, the 3D-printed PAM/Alg hydrogels are immerged in a 2M ZnSO₄ electrolyte to create PAM/Alg gel polymer electrolytes (PAM/Alg-GPEs). This process significantly improves the mechanical properties of PAM/Alg-GPEs. Subsequently, the ionic conductivity of these 3D-printed PAM/Alg-GPEs is evaluated using electrochemical impedance spectroscopy (EIS). The results demonstrate that PAM/Alg-GPEs exhibit the desired flexibility along with sufficient electrochemical performance, making them promising candidates for use as wearable electrolytes in zinc-ion batteries.

Abstract: This study focused on the preparation of hydrogels of poly (vinyl alcohol) and cellulose extracted from hemp fibers with the aid of borax as a cross-linking agent. Cellulose extracted from hemp fibers was initially dissolved in a mixed solution of urea and NaOH to obtain a cellulose solution. In the meantime, PVA was also dissolved in the urea and NaOH. These two solutions were mixed, and various loadings of borax were introduced. Moreover, the effect of borax loadings on equilibrium water content (EWC) and compression properties of the cross-linked hydrogels was investigated. The cross-linked hydrogels showed an EWC of 95.76% and a compression set of 9.71%, compared to those of the physical cross-linked hydrogels which had an EWC of 92.40% and a compression set of 29.96%. It was found that the chemically crosslinked hydrogels exhibited greater stability compared with physical ones owing to the stronger interaction induced by borax. Therefore, The PVA/cellulose hydrogels cross-linked with borax hold potential in various applications such as wound dressing, wastewater treatment, and agricultural fields.

Abstract: Hydrogels are polymers with soft and high-water absorption characteristics similar to biological tissues, leading to several potential applications, such as artificial organs, drug delivery, tissue engineering, and strain sensor. Interestingly, hydrogels can be designed to heal themselves after being damaged. In this research, hydrogels with self-healing ability from pectin and polyvinyl alcohol were prepared by simple physical mixing. Borax was used as a crosslinking agent to obtain crosslinked hydrogel structure by the formation of dynamic boron ester bonds. Glycerol was also added to the hydrogels as an anti-freezing agent and a stabilizer. The microstructures, mechanical properties, self-healing ability and swelling properties of the pectin/PVA-borax hydrogels were characterized. The results indicate that the size of microporous structure, modulus, tensile strength, self-healing time, swelling, and equilibrium water content of the pectin/PVA hydrogels increases with the increasing borax contents.

Abstract: Porang (Amorphophallus muelleri Blume), a plant belonging to the Araceae family, has the main content of glucomannan and calcium oxalate which is quite high. This study aims to determine the characteristic values ​​of glucomannan and calcium oxalate content from porang flour so that it can be used for various applications, especially hydrogel. The characteristics of glucomannan obtained from porang flour will be compared with commercial glucomannan from konjac using 3,5-DNS analysis, permanganate titration method, Fourier Transforms Infrared spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). The results showed that the glucomannan content of porang flour was 99.84% dry basic (db) and the calcium oxalate content of porang flour was 0.005% wet basic (wb). The characterization results show that the glucomannan content in porang flour is higher than the commercial glucomannan content from konjac, so that porang flour has good potential as a candidate for hydrogel materials.

Abstract: A phycocolloidal hydrogel patch is studied as a potential material for the transdermal delivery device for vitamin B12. The vitamin release kinetics from an agar/κ-carrageenan hydrogel blend as a function of mass ratio and vitamin loading. Concentration measurements were done using a colorimetric method, and the experimental data were fitted into the Korsmeyer-Peppas model, Peppas-Sahlin model, and Berens-Hopfenberg model. From the curve fitting, parameters such as first-order polymer relaxation constant and diffusivity constant were obtained. The results showed that for the Korsmeyer-Peppas model and the Peppas-Sahlin model, the release mechanism followed Fickian diffusion predominantly. On the other hand, the Berens-Hopfenberg model fit shows that the release mechanism predominantly follows non-Fickian diffusion and may need to be modified.

Abstract: Zeolitic imidazolate frameworks-8 (ZIF-8), a type of metal-organic frameworks (MOFs), displays high porosity, large surface areas, and tunable functionality in nanocomposites, promising carrier for drug delivery applications. In this work, ZIF-8 nanomaterials were synthesized via precipitation under three different conditions and subsequently loaded onto chitosan/pluronic F-127 (CS/PL) hydrogels. The ZIF-8 materials prepared in NH₄OH solution (ZIF-8-NH₄OH) showed a regular cubic shape with a large particle size of approximately 963 nm due to the acceleration of crystal growth in a basic medium. Meanwhile, the ZIF-8 species prepared in H₂O and MeOH (ZIF-8-H₂O and ZIF-8-MeOH, respectively) displayed crystal sizes of approximately 152 and 240 nm, respectively. The overall toxicity of the ZIF-8 nanomaterials was determined with an XTT assay against the L929 mouse fibroblast cell line. The morphology of the cells was altered at a concentration of over 30 µg/mL due to cell membrane deformations. This result correlated with the lactate dehydrogenase (LDH) release study by detection of LDH release at a concentration of over 25 µg/mL (50% LDH release). To reduce the toxicity of the ZIF-8 materials, CS/PL hydrogels were appropriately prepared and used to encapsulate the ZIF-8 at 0.095% w/w. Cytotoxicity results of the ZIF-8-loaded CS/PL hydrogels indicated over 75% cell viability of the L929 cells. These results presented significant implications for future applications of the ZIF-8 particles in the delivery of drugs or other compounds.

Abstract: Alginate is natural biodegradable polymers often used for wound treatments and drug delivery purposes. Due to thestructural characteristics, alginate polymers are able to form hydrogel. Alginate nanoparticles are obtained by diverse methodologies and the physical and chemical properties can be affected by production techniques and the molecules incorporated. Alginate possesses unique bioactivities such as biocompatibility, biodegradability, hydrophilicity and non-toxicity, so it has great potential for biomedical applications. Alginate based hydrogels and nanoparticles carrying active compounds are able to supply the optimal environments for wound healing and controlled drug administration including targeted or localized drug-delivery systems. In this review, the recent researches about the alginate and alginate-complex nanoparticles as potential tools for wound dressing membrane and drug delivery carriers are studied.

Abstract: Application of the adapted methylene blue (MB) adsorption method in determining specific surface area was investigated on particles containing hydrogels obtained from purified (99 wt%) and unpurified (60 wt%) betulin samples. In order to study the adsorption isotherms of MB on betulin particles in aqueous dispersions, initial concentration of MB was varied. An analysis of the adsorption process with the Langmuir adsorption model was performed. The results indicate that the experimental data fits very well with the Langmuir adsorption model. Straight isotherms are obtained with very good determination coefficients (R²=0.99; R²=1.00), which means that the surface of purified and unpurified betulin particles is homogeneous energetically and a monomolecular coverage forms during adsorption. The MB adsorption method adapted for betulin particles is simple and requires less complex apparatus and time than other methods. The determined specific surface area can be used to characterize the surface properties of betulin particles.

Abstract: Dynamic light scattering (DLS) is a well-established technique to analyze particle size in a liquid medium and sample preparation is an essential step of the analysis to obtain reliable data. In this study, the pretreatment of an aqueous suspension containing betulin particles was studied to characterize the colloidal betulin particles in supramolecular hydrogels obtained by the liquid antisolvent precipitation from purified and unpurified betulin samples. Parameters of two-step homogenization process using rotor and ultrasonic homogenizer, particle concentration, and pH were systematically varied to obtain stable aqueous suspensions that meet the requirements of DLS technique for good particle size analysis. It was found that the purified betulin particles have a higher tendency to agglomerate and their suspension is stable in a narrower concentration and pH range than unpurified. Particle size analysis in suspensions prepared independently shows good reproducibility of sample preparation.

Abstract: A novel leaky waveguide grating (LWG) biosensor is reported where a continuous waveguide film of chitosan was photo patterned, resulting in a periodic modulation of the concentration of recognition elements (streptavidin in this case). This resulted in a periodic variation in the refractive index of the waveguide film, forming a phase grating at resonance angles of the LWG. Thus, a diffraction pattern was observed at resonance angles, but not at other angles. The position of resonance angles and hence diffraction pattern was a function of the refractive index of chitosan waveguide strips, forming the basis of biosensing and quantitative measurements.