Rheological stability of carbomer in hydroalcoholic gels: Influence of alcohol type

Abstract

Objective:The main objective of this paper is to analyse and attempt to understand the nature of rheological changes observed and the dynamics of Carbopol NF 980 hydroalcoholic gels neutralized specifically by triethanol amine (TEA), both as a function of time and alcohol type to probe time stabilities and ageing effects in such carbopol gel systems. The rheological changes and dynamics of 3 carbopol gel systems were observed; the gels included a water-based, ethanolbased, and isopropyl alcohol-based gel. It is hoped that this study shall shed light on the dynamical nature and the microstructural evolution of such networked gel systems, which were maintained under closed isothermal conditions and left completely unperturbed. The experimental results can provide the information necessary to understand and proposes plausible mechanisms guiding this dynamical behaviour in hydroalcoholic carbopol gels.Methods: A TA instrument mechanical rheometer was used to measure the viscosity and storage and loss modulus, and a pH meter was utilized to determine the changes in each sample over the period.Results: Studying the differences in the gel structures upon initial preparation illustrated that the ethanol and isopropyl alcohol (IPA) gels differed from the water-based gel in terms of viscosity, G′, and G″, with the IPA gel displaying the lowest viscosity and moduli values across all shear rates. All the three gel systems exhibited strong shear thinning characteristics and were reminiscent of yield stress type found in colloidal gels. The water-based gel compared to the hydroalcoholic gels was strongly G′ dominated, with the magnitude of the difference between G′ and G″ observed to be much higher. This reflects that initial formation of the water-based gel structure possesses a much more rigid structure with a high elastic modulus component dominating. This also suggests that the water-based gel structure displayed stronger interactions between the carbopol particles when compared to those of the hydroalcoholic gels. Over the 30-day period, it was observed that the ethanol and water-based gels did not reveal any appreciable viscosity changes, with only an approximate 12% and 7% change from day 1 to 30, respectively. It was observed that the IPA systems' viscosity drastically increased over the period, with an approximately 77% change from day 1

Oxygen Nanobubbles-Embedded Hydrogel as Wound Dressing to Accelerate Healing

“…A slight increase was noted in the average amount of oxygen released from freshly prepared ONB-G compared to the stored ONB-G hydrogel, which could be attributed to the aging of the carbopol-based hydrogel. 40 There was no observable decrease in the oxygen release capacity of ONB-G noted over the 34day storage period. A picture of fresh ONB-G and ONB-G stored for different periods is provided in Figure S1.…”

“…The calculation provides an approximate indication of the amount of oxygen from ONB-G. Figure B shows the oxygen released in 12 h from ONB-G upon storage. A slight increase was noted in the average amount of oxygen released from freshly prepared ONB-G compared to the stored ONB-G hydrogel, which could be attributed to the aging of the carbopol-based hydrogel . There was no observable decrease in the oxygen release capacity of ONB-G noted over the 34-day storage period.…”

Silk Nanocarrier with Tunable Size to Improve Transdermal Capacity for Hydrophilic and Hydrophobic Drugs

“…If so, the silk nanocarriers could broaden their application from cancer treatment to skin disease and cosmetic fields, strengthening their value as functional carriers. To further study the transdermal penetration of differently sized silk nanocarriers, curcumin (CUR)-laden silk nanocarriers were applied to the dorsal skin of rats for 18 h. Carbomer was added to different silk nanocarrier solutions to tune viscosity and avoid undesirable nanocarrier losses from skin. , To evaluate the influence of SF conformation, carbomer and traditional amorphous SF were also used to load and treat the dorsal skin as controls. As expected, no significant CUR was determined inside dermal layers in the carbomer and amorphous SF groups, indicating poor transdermal capacity.…”

In situ gels: The next new frontier in ophthalmic drug delivery system

“…Carbomer is a polymer of acrylic acid crosslinked with acrylate‐based sucrose 55 . Many carboxyl groups in the molecule make it strongly hygroscopic and more easily soluble in water.…”

“…Carbomer is a polymer of acrylic acid crosslinked with acrylatebased sucrose. 55 Many carboxyl groups in the molecule make it strongly hygroscopic and more easily soluble in water. Due to this property, carbomer can be used as a good material for preparing water-soluble gel matrices.…”