Development of Bigels Based on Stearic Acid–Rice Bran Oil Oleogels and Tamarind Gum Hydrogels for Controlled Delivery Applications

In the last few decades, different types of gels have been widely studied as potential drug delivery carriers. In this paper, we propose the synthesis of an oleogel, a tamarind gum hydrogel, and bigels for applications as drug delivery matrices. The oleogel was prepared by mixing stearic acid and rice bran oil, whereas the hydrogel was prepared by mixing tamarind gum with a hydroethanolic solution. Hydrogel‐in‐oleogel and oleogel‐in‐hydrogel bigels were prepared by mixing the hydrogel and the oleogel. The suitability of the formulations for controlled drug release applications was thoroughly examined using microscopy, Fourier transform infrared (FTIR) spectroscopy, as well as mechanical, electrical, thermal, drug release, and antimicrobial studies. An alteration in the microarchitecture of the bigels is observed when the oleogel and the hydrogel are mixed in varying proportions. The associative interactions within the formulations increase with the increase in the hydrogel content. The bigels exhibit the presence of stearic acid melting endotherm (associated with the oleogel) and water evaporation endotherm (associated with the hydrogel). This study suggests that the hydrogel has lowest bulk resistance compared to the other formulations. The structural breakdown of the bigels is composition‐dependent, and the bulk electrical resistance is mainly governed by the oleogel phase. An increase in the diffusion of the moxifloxacin HCl from the formulations is observed with the increase of the hydrogel proportion, which in turn increases the rate of release of the drug. The proposed formulations also exhibit good antimicrobial efficacy. The analysis of these properties suggests that specific formulations can be tailored by need‐based applications of the drug release rate.     

Development of hydrogels,oleogels, and bigels as local drug delivery systems for periodontitis

Periodontal disease is a chronic inflammation of gum and tissues that surround and support the teeth. Nonsteroidal anti-inflammatory drugs (NSAIDs) can be used in the treatment of periodontitis to ease swelling and inflammation. One approach of treating periodontitis is loading the NSAIDs in local drug delivery systems. Therefore, the objective of this study was to investigate the local delivery of the NSAIDs model drug ibuprofen to treat periodontitis using different types of gel formulations (hydrogel, oleogel, and bigel). Gel formulations were characterized in terms of their rheological properties (flow behavior, viscoelastic, and bioadhesive properties) using a controlled-stress rheometer. The in vitro drug release of ibuprofen from gel formulations was investigated using Franz diffusion cells. Gels exhibited more solid-like (elastic) behavior. The viscosity and viscoelastic properties were in the order of oleogel?>?bigel?>?hydrogel, respectively. In bioadhesion study, mucin dispersion/plain ibuprofen-hydrogel mixture showed a frequency-dependent interaction of ΔG’?=??31 and ΔG’?=?+?53?Pa at 1 and 10?rad/s, respectively. A strong positive interaction (ΔG’?=?+?6000 and +130,667?Pa at 1 and 10?rad/s, respectively) was found in mucin dispersion/plain ibuprofen–oleogel mixture. The extent of the negative interaction increased in mucin dispersion/plain ibuprofen-bigel mixture (ΔG’?=??59,000 and ?79,375?Pa at 1 and 10?rad/s, respectively). After 6?h, ibuprofen release from hydrogel, oleogel, and bigel was 59.5?±?2.2, 80.6?±?3.9, and 94.6?±?3.2%, respectively. Results showed that the rheological and bioadhesive properties and in vitro drug release were influenced by the type of gel formulations.     

Effect of storage time on the mechanical and microstructural properties of bigels based on xanthan gum and castor oil

As biphasic systems bigels are formed by hydrogels and organogels. Given their characteristics, they have been studied in food, pharmaceutical and cosmetic applications for bioactives delivery. The rheological characteristics and amount used of the individual structured systems influence the final properties; thus, the objective of this work was to evaluate the effect of the proportion of castor oil organogel, the concentration of organogelator, and the storage time in the mechanical and microstructural properties of bigeles. Bigels were prepared from structured castor oil organogels with monoacylglycerides at concentrations of 6% (MOG) and 6.5% (HOG) wt/wt, and hydrogels with 2% wt/wt xanthan gum (HG) at three organogel/hydrogel ratios 15 of 85, 30 of 70, and 45 of 55. Bigels were characterized by optical microscopy with polarized light filter, centrifugal stability, texture, and rheology for 60 days. The increase in the proportion of organogel favors the mechanical response (k, G₀, and firmness) of bigels. The high viscosity of castor oil slows down the structuring of organogel droplets, showing an improvement in its mechanical properties after 15 days of its preparation. The increase in the organogelator concentration is significant in the bigels with 30% and 45% proportions of organogel in the rheological tests. By using HOG in the formation of bigels, higher values for G₀ and k were obtained, as well as higher centrifugal stability compared with bigels formed from MOG. The rheological and microstructural behavior of bigels can be modified according to their application by varying the proportions of organogel/hydrogel and the concentration of the organogelator.     

Development of bigel based dysphagia-oriented products,structured with collagen and carnauba wax: characterisation and rheological behaviour

The aim of the study was to design composition of the bigels with required rheological properties that responds the needs of the dysphagia patients. Bigels were prepared with carnauba wax and different collagen concentrations in the hydrogel phase (40, 60%) as well as by changing oleogel to hydrogel ratio from 40:60 to 60:40. The stability, physical and rheological properties of obtained bigels were evaluated after their preparation and after 14 days storage. All obtained bigels were stable without phase separation and had a pleasant taste and good mouth-feel, exept bigels with the higher oleogel fraction. Viscosity values at 50 s⁻¹ divided formulated bigels into two groups: honey-like and spoon thick. An increase of oleogel fraction caused an increase in the consistency index and elastic modulus. Higher firmness and cohesiveness values were obtained in the samples with the higher collagen concentration. It was also obtained that all rheological parameters increased after 14 days of storage. The present work develops a novel bigel-based product with strong shear-thinning behaviour and high protein concentration (16–36%). It is believed that such product could not only ensure the safe swallowing process but also reduce the risk of malnutrition development.