Search Results (7)

A promising area of emulsion system research is biocatalysis, particularly lipase-catalyzed reactions. Recognizing the potential of emulsions stabilized by both an emulsifier and a polymer, we conducted experimental studies to evaluate the effectiveness of a dual-stabilized system. In this study, we examined the effect of an emulsion system containing an anionic emulsifier (sodium dodecyl sulfate (SDS)) and a gelling agent (carbomer (Carbopol^® Ultrez 10, cross-linked poly(acrylic acid), PAA)) on the catalytic activity of Candida antarctica lipase B (CALB), in both its free and immobilized forms. The results demonstrated that the activity of immobilized CALB in emulsions containing 5.0% SDS and 0.1% carbomer was significantly higher than in emulsions with 5.0% SDS alone (124.44 ± 5.09 vs. 104.44 ± 5.09 U/g of support). At 2.5% SDS, the addition of 0.1% carbomer also enhanced the activity of immobilized CALB (121.11 ± 1.92 vs. 93.33 ± 3.33 U/g of support, p < 0.05). Notably, in emulsions with 2.5% or 5.0% SDS and 0.1% carbomer, hyperactivation of immobilized CALB was observed, with activity exceeding that of the free form by approximately six-fold. These findings highlight the beneficial effect of combining SDS (2.5% or 5.0%) and 0.1% carbomer to enhance the catalytic activity of immobilized CALB in emulsion-based formulations. Full article

The application of lipases in biphasic oil–water emulsions offers an efficient and sustainable alternative to conventional chemical synthesis. However, the natural immiscibility of these phases is a substantial limitation. To address this issue, we proposed a dual-stabilized emulsion system combining a nonionic emulsifier (Kolliphor^® CS 20) and cross-linked polyacrylic acid (Carbopol^® Ultrez 10), exceeding conventional single-stabilized systems. The activity of Candida antarctica lipase B (CALB), both in its free form and immobilized onto an IB-D152 support, was investigated in the prepared emulsion system. The olive oil emulsion stabilized with 10.0% Kolliphor^® CS 20 and 0.1% Carbopol^® Ultrez 10 significantly enhanced the lipolytic activity of immobilized CALB (156.27 ± 3.91 U/g of support), compared to the activity obtained in the emulsion stabilized only with 10.0% Kolliphor^® CS 20 (71.11 ± 3.86 U/g of support). On the other hand, the activity of immobilized CALB in the emulsion containing 5.0% Kolliphor^® CS 20 and 0.1% Carbopol^® Ultrez 10 (62.22 ± 3.85 U/g of support) was lower than in the corresponding system without Carbopol^® Ultrez 10 (72.03 ± 4.63 U/g of support), stabilized with only 5.0% Kolliphor^® CS 20. Furthermore, immobilization onto IB-D152 led to lipase hyperactivation, with activity approximately eight-fold higher than that of free CALB. This dual emulsion stabilization strategy not only improves emulsion stability but also enhances lipase activity, offering new opportunities for scalable, high-performance biocatalysis using emulsions in industrial applications. Full article

In this work, the effect of sonication on the molecular characteristics of polyacrylic acid (Carbopol^® Ultrez 10), as well as on its rheological behavior in aqueous dispersions and microgels, was analyzed for the first time by rheometry, weight-average molecular weight (M_w) measurements via static light scattering (SLS), Fourier transform infrared (FTIR) spectroscopy and confocal microscopy. For this, the precursor dispersion and the microgels containing 0.25 wt.% of Ultrez 10 were sonicated in a commercial ultrasound bath at constant power and at different times. The main rheological properties of the microgel, namely, shear modulus, yield stress and viscosity, all decreased with increasing sonication time, while the microgel’s Herschel–Bulkley (H-B) behavior, without thixotropy, was preserved. Also, M_w of Ultrez 10 decreased up to almost one-third (109,212 g/mol) of its original value (300,860 g/mol) after 180 min of sonication. These results evidence a softening of the gel microstructure, which results from the reduction in the M_w of polyacrylic acid with sonication time. Separately, FTIR measurements show that sonication produces scission in the C-C links of the Carbopol^® backbone, which results in chains with the same chemistry but lower molecular weight. Finally, confocal microscopy observations revealed a diminution of the size of the microsponge domains and more free solvent with sonication time, which is reflected in a less compact and softer microstructure. The present results indicate that both the microstructure and the rheological behavior of Carbopol^® microgels, in particular, and complex fluids, in general, may be manipulated or tailored by systematic high-power ultrasonication. Full article

The aim of this study is to compare three different dissolution methods to assess the drug release from oral lyophilisates, based on interpolyelectrolyte complexes (IPECs). IPECs were prepared by mixing solutions of a linear polymer, Eudragit^® EPO, with a polymer with a cross-linked structure, Noveon^® AA-1 or Carbopol^® 10 Ultrez (in ratios of 1:2 and 1:1, respectively). Metformin or metronidazole were used as model drugs to achieve a systemic or local effect. A comparative assessment of the drug release kinetics was carried out using artificial saliva and three different set-ups: a paddle stirrer (USP apparatus 2), a flow cell (USP apparatus 4) and a Franz diffusion cell. The results demonstrated that oral lyophilisates disintegrated within 1 min. In the case of metformin, the drug release was completed in about 90 min independently of the set-up. The static conditions in the Franz diffusion cell and USP apparatus 2 permitted the aggregation of the IPEC; therefore, the release profiles show a significant difference compared to the USP apparatus 4. Full article

Insulin loaded to the polymer network of hydrogels may affect the speed and the quality of wound healing in diabetic patients. The aim of our research was to develop a formulation of insulin that could be applied to the skin. We chose hydrogels commonly used for pharmaceutical compounding, which can provide a form of therapy available to every patient. We prepared different gel formulations using Carbopol^® Ultrez^TM 10, Carbopol^® Ultrez^TM 30, methyl cellulose, and glycerin ointment. The hormone concentration was 1 mg/g of the hydrogel. We assessed the influence of model hydrogels on the pharmaceutical availability of insulin in vitro, and we examined the rheological and the texture parameters of the prepared formulations. Based on spectroscopic methods, we evaluated the influence of model hydrogels on secondary and tertiary structures of insulin. The analysis of rheograms showed that hydrogels are typical of shear-thinning non-Newtonian thixotropic fluids. Insulin release from the formulations occurs in a prolonged manner, providing a longer duration of action of the hormone. The stability of insulin in hydrogels was confirmed. The presence of model hydrogel carriers affects the secondary and the tertiary structures of insulin. The obtained results indicate that hydrogels are promising carriers in the treatment of diabetic foot ulcers. The most effective treatment can be achieved with a methyl cellulose-based insulin preparation. Full article

A transparent clay manufactured using Carbopol^® Ultrez^TM 10 (simplified as U10) was introduced, and its manufacturing processes were briefly described. Both relative transparency (RT) and modulation transfer function (MTF) methods were used to quantify the optical character variation via soil thickness. The transparency of this new transparent clay was analyzed and compared with four traditional transparent materials. The thixotropic properties of this synthetic transparent clay were measured in detail through the laboratory vane test. An exponential function was used to describe the thixotropy and sensitivity of the clay. The results showed that the new transparent clay has a relatively higher optical transparency than the majority of previous materials. Good-fitting results showed a similar development trend in thixotropy for the synthetic transparent clay and the natural ones. Furthermore, the sensitivity of the transparent clay was low to medium, which can simulate marine soil. With higher optical transparency than and similar thixotropy and sensitivity as natural clays, Carbopol^® Ultrez^TM 10 shows great potential as a substitute for natural clay and is expected to be widely used in model tests. Full article

When colossal gravity-driven mass flows enter a body of water, they may generate waves which can have destructive consequences on coastal areas. A number of empirical equations in the form of power functions of several dimensionless groups have been developed to predict wave characteristics. However, in some complex cases (for instance, when the mass striking the water is made up of varied slide materials), fitting an empirical equation with a fixed form to the experimental data may be problematic. In contrast to previous empirical equations that specified the mathematical operators in advance, we developed a purely data-driven approach which relies on datasets and does not need any assumptions about functional form or physical constraints. Experiments were carried out using Carbopol Ultrez 10 (a viscoplastic polymeric gel) and polymer–water balls. We selected an artificial neural network model as an example of a data-driven approach to predicting wave characteristics. We first validated the model by comparing it with best-fit empirical equations. Then, we applied the proposed model to two scenarios which run into difficulty when modeled using those empirical equations: (i) predicting wave features from subaerial landslide parameters at their initial stage (with the mass beginning to move down the slope) rather than from the parameters at impact; and (ii) predicting waves generated by different slide materials, specifically, viscoplastic slides, granular slides, and viscoplastic–granular mixtures. The method proposed here can easily be updated when new parameters or constraints are introduced into the model. Full article