Studies on the Synthesis and Characterization of Encapsulated Organogels for Controlled Drug Delivery Applications

Over the years, biopolymeric microparticles have been associated with the leaching of the internal phase. The present work was aimed at developing a new strategy in negotiating the problem of leaching from the microparticles. We hypothesized that gelation of the internal phase as organogels (core) and their encapsulation within the alginate microparticles may prevent leaching. Organogels were prepared using natural fatty acyl sources and synthetic source. Natural sources include vegetable fats (cocoa butter, mango butter), animal fat (lanolin) and fatty acid having both plant and animal origin (stearic acid), whereas, synthetic source include the mixture of Span 80 and Tween 80. Prior to encapsulation, the physicochemical, thermal and mechanical properties of the organogels were characterized in depth. The gelation mechanism and crystallization phenomenon during the formation of vegetable fat and stearic acid based organogels were critically evaluated. The predicted gelation mechanism in vegetable fat based organogels is instantaneous nucleation coupled with one or two dimensional growth of the fat crystals. On the other hand, stearate molecules followed heterogeneous nucleation coupled with one-dimensional growth during the formation of stearate organogels. The aforementioned organogels were encapsulated within the alginate microparticles by ionotropic gelation method. Microscopic, XRD and DSC studies confirmed the successful encapsulation of organogels as the core material of the developed microparticles. The organogel encapsulated microparticles prevented the leaching of the internal phase and improved the drug encapsulation efficiency. Presence of semi-solid organogels as the core material facilitated the controlled release of the drugs (model drugs: metronidazole and ciprofloxacin in stearate formulations) from the microparticles. The developed formulations showed good antimicrobial properties against Escherichia coli. The microparticles were found to be biocompatible and mucoadhesive in nature when checked against mammalian L929 fibroblast cells and goat’s small intestine, respectively. Based on the results, it was concluded that the developed formulations (organogels and microparticles) may be used as the controlled drug delivery vehicles for in vivo applications

Oleogel-Based Nanoemulsions for Beverages: Effect of Self-Assembled Fibrillar Networks on Stability and Release Properties of Emulsions

Reducing the use of stabilizers is one of the main challenges in food emulsions, especially for beverages. This work aimed to produce oleogel-structured nanoemulsions (NEs) without additional surfactants. Lecithin-stearic acid (LSa) and lecithin-sorbitan tristearate (LSt) oleogels formed stable NEs under optimized sonication conditions. Microscopy and rheometry revealed that the presence of self-assembled fibrous networks (SAFiNs) in both dispersed and continuous phases provided steric stabilization to NEs. Lecithin acted as crystal habit modifier of SAFiNs and facilitated their phase partitioning. Notably, the short fibers of LSt showed better emulsifying efficiency than the long fibers of LSa. Curcumin release studies under simulated gastrointestinal conditions demonstrated that SAFiNs affect the release capabilities of NEs. Polydispersity index, zeta potential and oil syneresis data showed that the emulsions are stable for six months. Moreover, NEs showed thermal stability upon curcumin release at 25 and 50 °C. These results suggest that the developed oleogel-based NEs are suitable for the delivery of bioactive agents for beverages and other food applications

Radiation-Responsive Esculin-Derived Molecular Gels as Signal Enhancers for Optical Imaging

Recent interest in detecting visible photons that emanate from interactions of ionizing radiation (IR) with matter has spurred the development of multifunctional materials that amplify the optical signal from radiotracers. Tailored stimuli-responsive systems may be paired with diagnostic radionuclides to improve surgical guidance and aid in detecting therapeutic radionuclides otherwise difficult to image with conventional nuclear medicine approaches. Because light emanating from these interactions is typically low in intensity and blue-weighted (i.e., greatly scattered and absorbed in vivo), it is imperative to increase or shift the photon flux for improved detection. To address this challenge, a gel that is both scintillating and fluorescent is used to enhance the optical photon output in image mapping for cancer imaging. Tailoring biobased materials to synthesize thixotropic thermoreversible hydrogels (a minimum gelation concentration of 0.12 wt %) offers image-aiding systems which are not only functional but also potentially economical, safe, and environmentally friendly. These robust gels (0.66 wt %, ∼900 Pa) respond predictably to different types of IRs including β- and γ-emitters, resulting in a doubling of the detectable photon flux from these emitters. The synthesis and formulation of such a gel are explored with a focus on its physicochemical and mechanical properties, before being utilized to enhance the visible photon flux from a panel of radionuclides as detected. The possibility of developing a topical cream of this gel makes this system an attractive potential alternative to current techniques, and the multifunctionality of the gelator may serve to inspire future next-generation materials