A polyvinyl alcohol (PVA) hydrogel loaded with guava leaf extract (GLE) has potential applications as a wound dressing with good antibacterial activity.
Andrographolide (AG) is one of the compounds in Andrographis
paniculata, which has a high antibacterial activity. This
paper reports the freeze–thaw method’s use to synthesize
polyvinyl alcohol (PVA) hydrogels loaded with AG and its characterization.
From the morphological examination, the porosity of the PVA/AG hydrogel
was found to increase with the increasing AG concentration. The swelling
degree test revealed that the hydrogels’ maximum swelling degrees
were generally greater than 100%. The composite hydrogel with the
highest fraction of andrographolide (PAG-4) showed greater weight
loss than the hydrogel without AG (PAG-0). The molecular interaction
between PVA and AG resulted in the narrowing of the band attributed
to the O–H and CO stretching bonds and the emergence
of an amorphous domain in the composite hydrogels. The loading of
AG disrupted the formation of hydroxyl groups in PVA and interrupted
the cross-linking between PVA chains, which lead to the decrease of
the compression strength and the crystallinity increased with increasing
AG. The antibacterial activity of the composite hydrogel increased
with increasing AG. The PAG-4 hydrogel had the highest antibacterial
activity of 37.9 ± 4.6b %. Therefore, the PVA/AG hydrogel
has the potential to be used as an antibacterial device.
Hydrogel is being broadly studied due to their tremendous properties, such as swelling ability and biocompatibility. Numerous review articles have discussed hydrogel polymer types, hydrogel synthesis methods, hydrogel properties, and hydrogel applications. Hydrogel can be synthesized by physical and chemical cross-linking methods. One type of the physical cross-linking method is freeze-thaw (F–T), which works based on the crystallization process of the precursor solution to form a physical cross-link. To date, there has been no review paper which discusses the F–T technique specifically and comprehensively. Most of the previous review articles that exposed the hydrogel synthesis method usually mentioned the F–T process as a small part of the physical cross-linking method. This review attempts to discuss the F–T hydrogel specifically and comprehensively. In more detail, this review covers the basic principles of hydrogel formation in an F–T way, the parameters that influence hydrogel formation, the properties of the hydrogel, and its application in the biomedical field.
Hydrogel is composed of a three-dimensional network of hydrophilic polymers and can swell when placed in an aqueous media. Polyvinyl alcohol (PVA) is a common polymer used to produce hydrogels because it has biocompatibility, non-toxicity, chemical stability, low cost, and excellent mechanical strength. In this study, the PVA solutions were prepared with concentrations of 6%, 8%, 10%, and 12% in distilled water. The precursor solutions underwent a freeze-thaw cycle with a freezing temperature of -25 °C for 20 hours and a thawing temperature of 37 °C for 4 hours and carried out for 6 cycles. The swelling degree and the gel fraction of the hydrogel were then determined. From the swelling degree results, the increase of the PVA concentration in the precursor solutions reduced the swelling degree of the hydrogel. Based on the gel fraction test, it was revealed that all PVA concentrations have approximately the same value of gel fraction at 97%. Additionally, the viscosity and the density were also measured. Both showed an increasing trend with the addition of PVA concentration, where the viscosity values from the smallest to highest concentrations were 12.4944, 34.1737, 93.8491, and 216.2979 cP while the density values were 0.9865, 0.9871, 0.9878, and 0.9885 gram.cm-3.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.