Evaluation of Organogel Nanoparticles as Drug Delivery System for Lipophilic Compounds

Lecithin Organogel: A Promising Carrier for the Treatment of Skin Diseases

Skin is the largest organ of the human body, as it protects the body from the external environment. Nowadays, skin diseases and skin problems are more common, and millions of people are affected daily. Skin diseases are due to numerous infectious pathogens or inflammatory conditions. The increasing demand for theoretical research and practical applications has led to the rising prominence of gel as a semisolid material. To this end, organogels has been widely explored due to their unique composition, which includes organic solvents and mineral or vegetable oils, among others. Organogels can be described as semisolid systems wherein an organic liquid phase is confined within a three-dimensional framework consisting of self-assembled, cross-linked, or entangled gelator fibers. These gels have the ability to undergo significant expansion and retain substantial amounts of the liquid phase, reaching up to 99% swelling capacity. Furthermore, they respond to a range of physical and chemical stimuli, including temperature, light, pH, and mechanical deformation. Notably, due to their distinctive properties, they have aroused significant interest in a variety of practical applications. Organogels favor the significant encapsulation and enhanced permeation of hydrophobic molecules when compared with hydrogels. Accordingly, organogels are characterized into lecithin organogels, pluronic lecithin organogels, sorbitan monostearate-based organogels, and eudragit organogels, among others, based on the nature of their network and the solvent system. Lecithin organogels contain lecithin (natural and safe as a living cell component) as an organogelator. It acts as a good penetration enhancer. In this review, first we have summarized the fundamental concepts related to the elemental structure of organogels, including their various forms, distinctive features, methods of manufacture, and diverse applications. Nonetheless, this review also sheds light on the delivery of therapeutic molecules entrapped in the lecithin organogel system into deep tissue for the management of skin diseases and provides a synopsis of their clinical applications.

Mucoadhesive Polymeric Polyologels Designed for the Treatment of Periodontal and Related Diseases of the Oral Cavity

The study objective was to design and characterise herein unreported polyologels composed of a range of diol and triol solvents and polyvinyl methyl ether-co-maleic acid (PVM/MA) and, determine their potential suitability for the treatment of periodontal and related diseases in the oral cavity using suitable in vitro methodologies. Polyologel flow and viscoelastic properties were controlled by the choice of solvent and the concentration of polymer. At equivalent polymer concentrations, polyologels prepared with glycerol (a triol) exhibited the greatest elasticity and resistance to deformation. Within the diol solvents (PEG 400, pentane 1,5-diol, propane 1,2-diol, propane 1,3-diol, and ethylene glycol), PEG 400 polyologels possessed the greatest elasticity and resistance to deformation, suggesting the importance of distance of separation between the diol groups. Using Raman spectroscopy bond formation between the polymer carbonyl group and the diol hydroxyl groups was observed. Polyologel mucoadhesion was influenced by viscoelasticity; maximum mucoadhesion was shown by glycerol polyologels at the highest polymer concentration (20% w/w). Similarly, the choice of solvent and concentration of PVM/MA affected the release of tetracycline from the polyologels. The controlled release of tetracycline for at least 10 h was observed for several polyologels, which, in combination with their excellent mucoadhesion and flow properties, offer possibilities for the clinical use of these systems to treat diseases within the oral cavity.

Supramolecular gels - a panorama of low-molecular-weight gelators from ancient origins to next-generation technologies

Supramolecular gels, self-assembled from low-molecular-weight gelators (LMWGs), have a long history and a bright future. This review provides an overview of these materials, from their use in lubrication and personal care in the ancient world, through to next-generation technologies. In academic terms, colloid scientists in the 19th and early 20th centuries first understood such gels as being physically assembled as a result of weak interactions, combining a solid-like network having a degree of crystalline order with a highly mobile liquid-like phase. During the 20th century, industrial scientists began using these materials in new applications in the polymer, oil and food industries. The advent of supramolecular chemistry in the late 20th century, with its focus on non-covalent interactions and controlled self-assembly, saw the horizons for these materials shifted significantly beyond their historic rheological applications, expanding their potential. The ability to tune the LMWG chemical structure, manipulate hierarchical assembly, develop multi-component systems, and introduce new types of responsive and interactive behaviour, has been transformative. Furthermore, the dynamics of these materials are increasingly understood, creating metastable gels and transiently-fueled systems. New approaches to shaping and patterning gels are providing a unique opportunity for more sophisticated uses. These supramolecular advances are increasingly underpinning and informing next-generation applications - from drug delivery and regenerative medicine to environmental remediation and sustainable energy. In summary, this article presents a panorama over the field of supramolecular gels, emphasising how both academic and industrial scientists are building on the past, and engaging new fundamental insights and innovative concepts to open up exciting horizons for their future use.

Development of Gelled-Oil Nanoparticles for the Encapsulation and Release of Berberine

In this study, a new drug carrier based on gelled-oil nanoparticles (GNPs) was designed and synthesized for the encapsulation and release of the model hydrophobic drug, berberine chloride (BCl). Two compositions with different oil phases were examined, sesame oil (SO) and cinnamaldehyde (Cin), which were emulsified with water, stabilized with Tween 80 (Tw80), and gelled using an N-alkylated primary oxalamide low-molecular-weight gelator (LMWG) to give stable dispersions of GNPs between 100 and 200 nm in size. The GNP formulation with Cin was significantly favored over SO due to (1) lower gel melting temperatures, (2) higher gel mechanical strength, and (3) significantly higher solubility, encapsulation efficiency, and loading of BCl. Also, the solubility and loading of BCl in Cin were significantly increased (at least 7-fold) with the addition of cinnamic acid. In vitro release studies showed that the release of BCl from the GNPs was independent of gelator concentration and lower than that for BCl solution and the corresponding nanoemulsion (no LWMG). Also, cell internalization studies suggested that the N-alkylated primary oxalamide LMWG did not interfere with the internalization efficiency of BCl into mouse mast cells. Altogether, this work demonstrates the potential use of these new GNP formulations for biomedical studies involving the encapsulation of drugs and nutraceuticals and their controlled release.

Resveratrol-Loaded Attalea funifera Oil Organogel Nanoparticles: A Potential Nanocarrier against A375 Human Melanoma Cells

This study aimed to evaluate Attalea funifera seed oil with or without resveratrol entrapped in organogel nanoparticles in vitro against A375 human melanoma tumor cells. Organogel nanoparticles with seed oil (SON) or with resveratrol entrapped in the seed oil (RSON) formed functional organogel nanoparticles that showed a particle size <100 nm, polydispersity index <0.3, negative zeta potential, and maintenance of electrical conductivity. The resveratrol entrapment efficiency in RSON was 99 ± 1%. The seed oil and SON showed no cytotoxicity against human non-tumor cells or tumor cells. Resveratrol at 50 μg/mL was cytotoxic for non-tumor cells, and was cytotoxic for tumor cells at 25 μg/mL. Resveratrol entrapped in RSON showed a decrease in cytotoxicity against non-tumor cells and cytotoxic against tumor cells at 50 μg/mL. Thus, SON is a potential new platform for the delivery of resveratrol with selective cytotoxic activity in the treatment of melanoma.

Development of Chincho (Tagetes elliptica Sm.) Essential Oil Organogel Nanoparticles through Ionic Gelation and Process Optimization with Box-Behnken Design

The aim of this work was to obtain chitosan nanoparticles (<1000 nm) with chincho (Tagetes elliptica Sp.) essential oil (CEO-CSNPs) using the ionic gelation method. A Box−Behnken design (BBD) was applied, using chitosan solution (CS) pH (4.0, 4.4, 4.8); the mass ratio of CS/CEO (1:0.7, 1:0.85, 1:1.0) and the mass ratio of CS/CS-tripolyphosphate (1:0.46, 1:0.58, 1:0.7) as independent variables. The formulation-dependent variables, encapsulation efficiency (EE) and loading capacity (LC) of the CEO-CSNPs were evaluated. BBD determined that optimal conditions for CEO-CSNPs were pH: 4.4, CS/CEO mass ratio 1:0.7 and CS/TPP mass ratio 1:0.46. Once the optimization was defined, particle size (PS), zeta potential (ZP), polydispersity index (PDI), CEO-CSNPs morphological studies, in vitro CEO release, and antibacterial activity were determined. The CEO-CSNPs showed an EE of 52.64% and a LC of 11.56%, with a diameter of 458.5 nm, with a ZP of 23.30mV, and a PDI of 0.418. The SEM studies showed that the nanoparticles were rounded and had uniform shapes. In addition, CEO-CSNPs showed a minimum inhibitory concentration against Staphylococcus aureus, Salmonella infantis and Escherichia coli of 5.29, 10.57 and 10.57 µg/mL, respectively. These results could be very useful for the stabilization of chincho essential oil for food industry purposes. However, several studies about the release, as well as interaction with food matrices, will be necessary.

Design and evaluation of molecular organogel based on folic acid as a potential green drug carrier for oral route

OBJECTIVE

The low molecular weight organogels are interesting carriers for pharmaceutical compounds. However, their uses are limited due to the toxicity burden of the organic solvent used. Hence, this study aimed to prepare organogel using folic acid (FA) in different concentrations as a gelator for propylene glycol (PG) biocompatible solvent.

METHODS

The simple mixing method followed by incubation in a water bath at 90 °C was used to prepare organogels. Then, formulations were assessed using different methods including differential scanning calorimetry (DSC), dropping method, attenuated total reflectance - Fourier transform infrared spectroscopy (ATR-FTIR), oscillatory rheology studies, scanning electron microscopy (SEM), and in vitro dissolution study.

RESULTS

Gel formation and its consistency were highly depending on FA concentration. The results showed that increasing the concentration of FA in the organogel led to accelerating the gelation process, and the least amount of FA that could gel the PG was 0.25% w/w. However, higher concentrations were needed to create an organogel with excellent properties. The DSC and dropping studies revealed stable organogels formulations at body temperature. The ATR-FTIR showed interactions between the pteridine ring of FA and PG. The strain amplitude and frequency sweep tests demonstrated an increase in storage modulus values as the concentration of FA increased at 37 °C, which were frequency independent at high frequencies. In addition, the SEM exposed the fabrics like the structure of these organogels. Furthermore, the in vitro dissolution of organogel was pH-dependent, with a high possibility of taking place in the large intestine.

CONCLUSION

FA/PG organogel formulation is a promising carrier for drug and nutraceuticals compound for the oral delivery system.

Gel-in-water nanodispersion for potential application in intravenous delivery of anticancer drugs

Organogels are semi-solid systems that can gel organic liquids at low concentrations. The use of organogels in drug delivery has grown rapidly in the last decade owing to their fibrous microstructure and suitability for different routes of administration. The current study is characterized by nanogel dispersion (NGD) development based on emulsion technology. The efficiency of this organogel based NGD as a carrier for anticancer drugs was assessed both in vitro and in vivo. 12-Hydroxystearic acid formed an organogel with lipiodol and encapsulated the anticancer drug paclitaxel. The gel-in-water (G/W) nanodispersion was prepared via ultrasonication and stabilized by a nonionic surfactant. The results showed that the organogel enabled sustained drug release from G/W nanodispersion over time, along with enhanced cellular uptake. The prepared G/W nanodispersion was found to be biocompatible with mouse hepatocytes and fibroblast cells in vitro, whereas paclitaxel-loaded G/W nanodispersion showed cytotoxicity (p <0.05) against lung cancer (A549) cell lines. Similarly, intravenous administration of paclitaxel-loaded G/W nanodispersion exerts an anticancer effect against lung cancer in vivo, with a significant decrease in tumor volume (p <0.05). Therefore, the proposed G/W nanodispersion could be a promising carrier for chemotherapy agents with sustained drug release and better therapeutic outcomes against cancer.

A novel promising delivery system for cuminaldehyde using gelled lipid nanoparticles: Characterization and anticancer, antioxidant, and antibacterial activities

This work aimed to develop a novel nanoencapsulation system for food colloidal formulations using gelled lipid nanoparticles (GLNs) to improve the functionality, stability, and bioactivity of cuminaldehyde as a highly volatile and poor hydrophilic food additive. Cuminaldehyde-loaded GLNs with diameters of 117-138 nm were fabricated through a hot emulsification process with monoglyceride (10 and 15 g/100 g lipid phase) as a lipid gelator at two concentrations of cuminaldehyde (500 and 1000 mg/L). All samples remained stable towards macroscopic phase separation and creaming during 28 days of storage at 4 °C, which could be related to the rigid structure of dispersed particles in the gelled state and retarding droplet movement. Moreover, all samples were stable to creaming after subjecting to the environmental changes including temperature (30, 60, and 90 °C for 30 min), ionic strength (100, 200, and 300 mM NaCl), and pH (3, 5, and 7). Measurement of apparent viscosity showed non-Newtonian shear thinning nature in all samples, which was more pronounced at higher concentrations of the gelator. Interestingly, higher cytotoxic effects of cuminaldehyde against human lung and colorectal cancer cells were observed after encapsulation within GLNs. However, weak toxicity was also found against normal peripheral blood mononuclearcells.On the other hand, the antioxidant activity and lipid oxidation stability were improved by increasing cuminaldehyde concentration, while it was reduced at higher monoglyceride concentration. All samples exhibited stronger antibacterial activity against Bacillus cereus than Eschershia coli. These findings suggest the significant potential benefits of GLNs as novel nanocarriers to enrich various food and beverage formulations with essential oils, flavors, and aromas.

Nanoparticles as a Tool for Broadening Antifungal Activities

Fungal infections are diseases that are considered neglected although their infection rates have increased worldwide in the last decades. Thus, since the antifungal arsenal is restricted and many strains have shown resistance, new therapeutic alternatives are necessary. Nanoparticles are considered important alternatives to promote drug delivery. In this sense, the objective of the present study was to evaluate the contributions of newly developed nanoparticles to the treatment of fungal infections. Studies have shown that nanoparticles generally improve the biopharmaceutical and pharmacokinetic characteristics of antifungals, which is reflected in a greater pharmacodynamic potential and lower toxicity, as well as the possibility of prolonged action. It also offers the proposition of new routes of administration. Nanotechnology is known to contribute to a new drug delivery system, not only for the control of infectious diseases but for various other diseases as well. In recent years, several studies have emphasized its application in infectious diseases, presenting better alternatives for the treatment of fungal infections.

Development and characterization of gel-in-water nanoemulsion as a novel drug delivery system

The effective delivery of anti-cancer drugs with minimal side effects and better therapeutic efficacy has remained an active area of research for many decades. Organogels have gained attention in recent years as potential drug delivery systems due to their high bioavailability, no first-pass metabolism and rapid action. Considering this, in the current study an organogel based nanoemulsion was developed aiming to effectively deliver hydrophobic drugs via encapsulation within in situ gellable organogel droplets, termed as gel-in-water (G/W) nanoemulsion. G/W nanoemulsion was prepared using a combination of lipiodol and organogelator 12-hydroxystearic acid (12-HSA) as inner gel phase; dispersed in water by ultrasonication and stabilized with polyoxyethylene hydrogenated castor oil (HCO-60) as a surfactant. The prepared nanoemulsion showed high drug loading efficiency (≈97%) with a mean diameter of 206 nm. Lower polydispersity index (PdI) value (≈0.1) suggests monodispersed nature of G/W nanoemulsion in the continuous phase. G/W nanoemulsion was found stable over six months in terms of particle size, zeta potential and pH at different storage temperatures. There was no cytotoxic effect of prepared G/W nanoemulsion on primary hepatocytes in vitro. In contrast, paclitaxel-loaded G/W showed a significant decrease in melanoma cell growth (*p < 0.05) both in vitro and in vivo. Our results support the hypothesis that organogel based nanoemulsions can be a promising drug delivery system.

In vitro digestion of edible nanostructured lipid carriers: Impact of a Candelilla wax gelator on performance

In this study, food-grade nanostructured lipid carriers (NLCs) were used as delivery systems to overcome some of the limitations of solid lipid nanoparticles (SLNs) and liquid lipid nanoparticles (LLNs). Organogel NLCs were prepared using an oil phase consisting of a hydrophobic gelator (Candelilla wax) dispersed in liquid corn oil. The oil phase undergoes a gel-to-sol transition when heated, which means that oil-in-water nanoemulsions can be used as templates to form the NLCs. The impact of lipid phase composition on the gastrointestinal fate of the NLCs was determined using a simulated gastrointestinal tract (GIT). The particle size, ζ-potential, and microstructure of the LLNs, NLCs and SLNs were characterized when they were exposed to model oral, gastric, and small intestine conditions. The oil phase in the LLNs and SLNs consisted of pure corn oil and pure Candelilla wax, respectively. Initially, all samples contained small lipid particles (d₄₃ = 150-202 nm) with negative surface potentials (ζ = -26 to -47 mV). The LLNs, SLNs and NLCs behaved similarly in the simulated GIT in terms of their particle properties: there was a large increase in particle size and decrease in charge magnitude in the mouth, stomach, and intestine. The Candelilla wax in the SLNs and NLCs was not digested by lipase, but the corn oil in the LLNs and NLCs was fully digested. This phenomenon may be used to create colloidal delivery systems that can control the release of encapsulated bioactive agents within the GIT.

Organogel Nanoparticles as a New Way to Improve Oral Bioavailability of Poorly Soluble Compounds

PURPOSE

The aim of the study was to evaluate organogel nanoparticles as a lipophilic vehicle to increase the oral bioavailability of poorly soluble compounds. Efavirenz (EFV), a Biopharmaceutical Classification System (BCS) Class II, was used as drug model.

METHODS

Organogel nanoparticles loaded with EFV were formulated with sunflower oil, 12-hydroxystearic acid (HSA) and polyvinyl alcohol (PVA). Various parameters have been investigated in the current study such as (i) the release profile of organogel assessed by USP 4 cell flow dialysis, (ii) the impact of organogel on intestinal absorption, using Caco-2 cells as in vitro model and jejunum segments as ex vivo assay and (iii) the bioavailability of organogel following oral pharmacokinetic study.

RESULTS

250-300 nm spherical particles with a final concentration of 4.75 mg/mL drug loading were obtained, corresponding to a thousand fold increase in EFV solubility, combined to a very high encapsulation efficiency (>99.8%). Due to rapid diffusion, drug was immediately released from the nanoparticles. The biopharmaceutical evaluation on ex vivo jejunum segments demonstrated an increased absorption of EFV from organogel nanoparticles compare to a native EFV suspension. In vitro assays combining Caco-2 cell cultures with TEM and confocal microscopy demonstrated passive diffusion, while paracellular integrity and endocytosis activity remain expelled. Oral pharmacokinetics of EFV organogel nanoparticles improve oral bioavailability (F_r: 249%) and quick absorption compared to EFV suspension.

CONCLUSION

Organogel nanoparticles increase the bioavailability of BCS Class II drugs. The main phenomena is simply oil transfer from the gelled particles through the cell membrane.

How an organogelator can gelate water: gelation transfer from oil to water induced by a nanoemulsion

A hydrogel can be formed by an organogelator in the presence of a nanoemulsion. It is expected that this is due to a gelation transfer from oil to water. The system started with an oil-in-water nanoemulsion prepared according to a phase inversion temperature (PIT) process. Into this nanoemulsion consisting of Kolliphor® RH40 and Brij® L4 as surfactants, and Miglyol® 812 as oil and water, we introduced the organogelator 12-hydroxyoctadecanoic acid (12-HOA) in the oil phase. After cooling at room temperature, a slow reversible gelation of the water phase occurred with persistence of the nanoemulsion. This thermally reversible system was investigated using various techniques (rheology, turbidimetry, optical and electron microscopies, scattering techniques). Successive stages appeared during the cooling process after the nanoemulsion formation, corresponding to the migration and self-assembly of the organogelator from the oil nanodroplets to the water phase. According to our measurements and the known self-assembly of 12-HOA, a mechanism explaining the formation of the gelled nanoemulsion is proposed.

Basic principles of drug delivery systems - the case of paclitaxel

Cancer is the second cause of death worldwide, exceeded only by cardiovascular diseases. The prevalent treatment currently used against metastatic cancer is chemotherapy. Among the most studied drugs that inhibit neoplastic cells from acquiring unlimited replicative ability (a hallmark of cancer) are the taxanes. They operate via a unique molecular mechanism affecting mitosis. In this review, we show this mechanism for one of them, paclitaxel, and for other (non-taxanes) anti-mitotic drugs. However, the use of paclitaxel is seriously limited (its bioavailability is <10%) due to several long-standing challenges: its poor water solubility (0.3 μg/mL), its being a substrate for the efflux multidrug transporter P-gp, and, in the case of oral delivery, its first-pass metabolism by certain enzymes. Adequate delivery methods are therefore required to enhance the anti-tumor activity of paclitaxel. Thus, we have also reviewed drug delivery strategies in light of the various physical, chemical, and enzymatic obstacles facing the (especially oral) delivery of drugs in general and paclitaxel in particular. Among the powerful and versatile platforms that have been developed and achieved unprecedented opportunities as drug carriers, microemulsions might have great potential for this aim. This is due to properties such as thermodynamic stability (leading to long shelf-life), increased drug solubilization, and ease of preparation and administration. In this review, we define microemulsions and nanoemulsions, analyze their pertinent properties, and review the results of several drug delivery carriers based on these systems.

Biochemical Characterization of CYP505D6, a Self-Sufficient Cytochrome P450 from the White-Rot Fungus Phanerochaete chrysosporium

The activity of a self-sufficient cytochrome P450 enzyme, CYP505D6, from the lignin-degrading basidiomycete Phanerochaete chrysosporium was characterized. Recombinant CYP505D6 was produced in Escherichia coli and purified. In the presence of NADPH, CYP505D6 used a series of saturated fatty alcohols with C_9-18 carbon chain lengths as the substrates. Hydroxylation occurred at the ω-1 to ω-6 positions of such substrates with C_9-15 carbon chain lengths, except for 1-dodecanol, which was hydroxylated at the ω-1 to ω-7 positions. Fatty acids were also substrates of CYP505D6. Based on the sequence alignment, the corresponding amino acid of Tyr51, which is located at the entrance to the active-site pocket in CYP102A1, was Val51 in CYP505D6. To understand the diverse hydroxylation mechanism, wild-type CYP505D6 and its V51Y variant and wild-type CYP102A1 and its Y51V variant were generated, and the products of their reaction with dodecanoic acid were analyzed. Compared with wild-type CYP505D6, its V51Y variant generated few products hydroxylated at the ω-4 to ω-6 positions. The products generated by wild-type CYP102A1 were hydroxylated at the ω-1 to ω-4 positions, whereas its Y51V variant generated ω-1 to ω-7 hydroxydodecanoic acids. These observations indicated that Val51 plays an important role in determining the regiospecificity of fatty acid hydroxylation, at least that at the ω-4 to ω-6 positions. Aromatic compounds, such as naphthalene and 1-naphthol, were also hydroxylated by CYP505D6. These findings highlight a unique broad substrate spectrum of CYP505D6, rendering it an attractive candidate enzyme for the biotechnological industry.IMPORTANCE Phanerochaete chrysosporium is a white-rot fungus whose metabolism of lignin, aromatic pollutants, and lipids has been most extensively studied. This fungus harbors 154 cytochrome P450-encoding genes in the genome. As evidenced in this study, P. chrysosporium CYP505D6, a fused protein of P450 and its reductase, hydroxylates fatty alcohols (C_9-15) and fatty acids (C_9-15) at the ω-1 to ω-7 or ω-1 to ω-6 positions, respectively. Naphthalene and 1-naphthol were also hydroxylated, indicating that the substrate specificity of CYP505D6 is broader than those of the known fused proteins CYP102A1 and CYP505A1. The substrate versatility of CYP505D6 makes this enzyme an attractive candidate for biotechnological applications.

Application of Solvent Parameters for Predicting Organogel Formation

Solvents, accounting the majority of the organogel system, have a tremendous impact on the characteristics of gels. To date, there is a large variety of organogel systems; relatively few have been investigated in the field of structure-solvent correlation. Here, a series of solvent parameters were applied to explore the role of solvent effect on network forming and gel property, intending to build the connection between the precise solvent parameter and gel property. Among the solvent parameters, Kamlet-Taft Parameters and Hansen solubility parameters can distinguish specific types of intermolecular interactions, which could correlate solvent parameter with the gel property. From an analysis of the morphologies obtained from POM and SEM, the gelator structure has an impact on its self-assembly. For possible conformations, the gelators were investigated through XRD. The investigation of solvent-property relationship will provide a theoretical basis for controllable drug delivery implants.

Release of small bioactive molecules from physical gels

Pharmaceutical drugs with low water solubility have always received great attention within the scientific community. The reduced bioavailability and the need of frequent administrations have motivated the investigation of new drug delivery systems. Within this context, drug carriers that release their payload in a sustained way and hence reduce the administration rate are highly demanded. One interesting strategy to meet these requirements is the entrapment of the drugs into gels. So far, the most investigated materials for such drug-loaded gels are derived from polymers and based on covalent linkages. However, over the last decade the use of physical (or supramolecular) gels derived from low molecular weight compounds has experienced strong growth in this field, mainly due to important properties such as injectability, stimuli responsiveness and ease of synthesis. This review summarizes the use of supramolecular gels for the encapsulation and controlled release of small therapeutic molecules.

Colloidal Dispersions of Gelled Lipid Nanoparticles (GLN): Concept and Potential Applications

The interest in using colloidal dispersions of gelled lipid nanoparticles (GLN) for different fields of application has increased in recent years, notably in cosmetic, dermatology, and/or pharmaceutics due to their capacity to immobilize compounds with poor water solubility. The pharmaceutical field desires to achieve lipophilic drug formulations which are able to conserve their stability, although it is well-known that emulsions and solid lipid nanoparticles (SLN) present a lack of stability over time, leading to system destabilization. Furthermore, stable colloidal dispersions of gelled oil particles do not affect the properties of the molecule to be delivered, and they result as an alternative for the previously appointed systems. This review is an attempt to present the reader with an overview of colloidal dispersions of GLN, their concept, formulation methods, as well as the techniques used for their characterization. Moreover, various application fields of organogel dispersions have been illustrated to demonstrate the potential application range of these recent materials.