A vegetable oil-based organogel for use in pH-mediated drug delivery

Organogels: "GelVolution" in Topical Drug Delivery - Present and Beyond

Topical drug delivery holds immense significance in dermatological treatments due to its non-invasive nature and direct application to the target site. Organogels, a promising class of topical drug delivery systems, have acquired substantial attention for enhancing drug delivery efficiency. This review article aims to explore the advantages of organogels, including enhanced drug solubility, controlled release, improved skin penetration, non-greasy formulations, and ease of application. The mechanism of organogel permeation into the skin is discussed, along with formulation strategies, which encompass the selection of gelling agents, cogelling agents, and additives while considering the influence of temperature and pH on gel formation. Various types of organogelators and organogels and their properties, such as viscoelasticity, non-birefringence, thermal stability, and optical clarity, are presented. Moreover, the biomedical applications of organogels in targeting skin cancer, anti-inflammatory drug delivery, and antifungal drug delivery are discussed. Characterization parameters, biocompatibility, safety considerations, and future directions in optimizing skin permeation, ensuring long-term stability, addressing regulatory challenges, and exploring potential combination therapies are thoroughly examined. Overall, this review highlights the immense potential of organogels in redefining topical drug delivery and their significant impact on the field of dermatological treatments, thus paving the way for exciting prospects in the domain.

Bis-Pyridine-Based Organogel with AIE Effect and Sensing Performance towards Hg2

A novel gelator (1) based on a bis-pyridine derivative was designed and synthesized, which could form stable gels in methanol, ethanol, acetonitrile, ethyl acetate, DMF/H₂O (4/1, v/v) and DMSO/H₂O (4/1, v/v). The self-assembly process of gelator 1 was studied by field emission scanning electron microscopy (FESEM), UV–vis absorption spectroscopy, fluorescence emission spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction and a water contact angle experiment. Gelator 1 exhibited obvious AIE behavior. On the base of its AIE, the gel of 1 could detect Hg²⁺, which resulted in fluorescence quenching and a gel–sol transition. ¹H NMR titration experiments with Hg²⁺ revealed that the metal coordination interaction induced the fluorescence quenching and the breakdown of the noncovalent interaction in the gel system. This research provides a new molecular mode for designing a functional self-assembly gel system.

Chemoenzymatic Polymerization of l-Serine Ethyl Ester in Aqueous Media without Side-Group Protection

Poly(l-serine) (polySer) has tremendous potential as a polypeptide-based functional material due to the utility of the hydroxyl group on its side chain; however, tedious protection/deprotection of the hydroxyl groups is required for its synthesis. In this study, polySer was synthesized by the chemoenzymatic polymerization (CEP) of l-serine ethyl ester (Ser-OEt) or l-serine methyl ester (Ser-OMe) using papain as a catalyst in an aqueous medium. The CEP of Ser-OEt proceeded at basic pH ranging from 7.5 to 9.5 and resulted in the maximum precipitate yield of polySer at an optimized pH of 8.5. A series of peaks detected by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry revealed that the formed precipitate consisted of polySer with a degree of polymerization ranging from 5 to 22. Moreover, infrared spectroscopy, circular dichroism spectroscopy, and synchrotron wide-angle X-ray diffraction measurements indicated that the obtained polySer formed a β-sheet/strand structure. This is the first time the synthesis of polySer was realized by CEP in aqueous solution without protecting the hydroxyl group of the Ser monomer.

Nonionic and Water-Soluble Poly(d/l-serine) as a Promising Biomedical Polymer for Cryopreservation

Water-soluble, biodegradable, nonionic, and biocompatible polymers with multiple functional groups are highly desired for biomedical applications. Here, we report that water-soluble nonionic poly(d/l-serine) is chirality-controllable, biodegradation-controllable, and non-cytotoxic. Hence, it can be a highly sought-after alternative to the widely used poly(ethylene glycol), with an additional advantage of having multiple hydroxyl groups for further functionalization. As one example of its biomedical applications, poly(d/l-serine) demonstrated an obvious cryoprotective effect on the red blood cells. The usage of poly(d/l-serine) in the cryopreservation field would be of great promise to resolve the difficulties in separating cryoprotectants due to toxicity.

Preparation and characterization of 12-HSA-based organogels as injectable implants for the controlled delivery of hydrophilic and lipophilic therapeutic agents

Organogels prepared with low molecular weight organogelators to structure liquid oils represent excellent matrices for the controlled delivery of a wide variety of drug molecules. Although studies on organogel systems are reported in the literature, relatively few investigate their potential as gels formed in situ intended for drug delivery. This study reports the development of injectable subcutaneous 12- hydroxystearic acid (12-HSA) organogels for the delivery of both lipophilic and hydrophilic drugs. The rheological characterization (flow, dynamic temperature ramp and amplitude oscillatory measurements) and physicochemical properties (syringeability, swelling and degradation studies), as well as permeability and cytotoxicity were analyzed to gain insights into the influence of the gel composition (surfactant addition, organogelator concentration) on the gelation process and organogel properties. Sol-gel phase transition temperature (Tgel) and gel-sol phase transition temperature (Tmelt) were determined by the tube-inverting method and complementary rheology studies. An increase in 12-HSA concentration led to an augmentation in gel strength and storage (G') and loss (G″) moduli values, evidencing the self-assembly of crystalline gelator structure entrapping the oil phase into a three-dimensional (3D) network. The addition of polysorbate 80 (Tween 80, T80) surfactant molecules in the system caused a weaker gel-like structure, with lower flow rate during syringeability assays, despite its lower apparent viscosity compared to those of 12-HSA organogels. In addition, the swelling studies of 12-HSA/12-HSA T80 organogels as a function of time in phosphate buffered saline (PBS) revealed that the erosion rates were modulated by the organogel compositions. The permeability of acyclovir (ACV) and clotrimazole (CTM), hydrophilic and lipophilic model drugs, respectively, loaded in 12-HSA-based organogels, was assessed in Franz diffusion cells. Organogel-loaded drugs presented lower in vitro release rates and ex vivo drug permeabilities compared to the corresponding drug solutions. Furthermore, 12-HSA T80 organogel could slow down the release of ACV by a factor of about 2.6-fold, up to 6 h, compared to CTM-loaded 12-HSA organogels. Finally, the cytotoxicity of 12-HSA-based organogels was evaluated through in vitro cell viability assays in human foreskin fibroblasts (HFF). Increased 12-HSA concentration resulted in higher cytotoxic effect, with a higher test sensitivity observed for the 3D collagen-embedded cell layer setup matrix versus 2-D cell cultures. Our results support the hypothesis that 12-HSA-based organogels are promising systems for controlled drug delivery as in situ-forming implants.

Water-in-oil organogel based emulsions as a tool for increasing bioaccessibility and cell permeability of poorly water-soluble nutraceuticals

The use of organogels in food and pharmaceutical sciences has several technical problems related with restricted diffusion of the drugs and lack of a proper gelator molecule. These features are important into the new product design. An alternative to improve technological properties in organogels is the use of emulsions. However, there is a lack of knowledge about the behavior on bioaccessibility and permeability of bioactives loaded into organogel-based emulsions. The objective of the present experimental work was to study the physical properties of organogel-based emulsions made with vegetable oil loaded with three different bioactives (betulin, curcumin and quercetin) and the influence on their bioaccessibility. Organogels were made of canola or coconut oils and myverol as gelator (10% w/w). Water-in-oil emulsions (at 5, 10 and 12.5 wt% of water content) were prepared by mixing the melted proper organogel and water (80 °C) under high shear conditions (20,000 rpm). Micrographs, rheological tests (amplitude, frequency, temperature sweeps and creep-compliance measurements), DSC and particle size analysis were performed to samples. In vitro digestion (oral, gastric and intestinal phase), lipolysis assays, bioaccessibility and permeability tests by cell culture of Caco-2 were made. Organogels of coconut oil have shown poor emulsification properties.

Exploiting poly(α-hydroxy acids) for the acid-mediated release of doxorubicin and reversible inside-out nanoparticle self-assembly

Biodegradable poly(α-hydroxy acid) copolyesters consisting of benzyl-protected glutamic acid and carboxybenzyl-protected lysine derived blocks possess the capability to self-assemble to form stable nanoparticles in aqueous solution (pH 7.4), that are able to withhold doxorubicin, prior to its directed release in acidic solution. Such pH-responsive nanoparticles are non-toxic against a panel of human breast cancer cell lines, but demonstrated comparable toxicities to free doxorubicin when loaded with doxorubicin. Significantly, comparable efficacy to free doxorubicin was observed even against triple negative breast cancer cells, highlighting the potential of the materials generated as drug delivery vehicles for cancer treatment. Facile block copolymer deprotection resulted in a polymer that presents an altered self-assembly/disassembly profile; forming nanoparticles when stored in either acidic or alkaline solution, but undergoing self-disassembly when added to aqueous solution of pH 7.4. This second polymer highlights the considerable versatility that poly(α-hydroxy acids) inherently possess.

Synthesis, Characterization and Biocompatibility of N-palmitoyl L-alanine-based Organogels as Sustained Implants of Granisetron and Evaluation of thier Antiemetic Effect

PURPOSE

To assess the gelation power of N-palmitoyl L-alanine derivatives in injectable oils and to use the best chosen organogel as parenteral implant of granisetron for the treatment of emesis.

METHODS

Twelve N-palmitoyl L-alanine derived organogels were developed and evaluated in terms of morphology, thermal properties and in vivo performance. The ability of the selected formula to form in situ gel upon subcutaneous injection in rats and its biocompatibility were monitored over 2 weeks by histopathological examination of the injection site.

RESULTS

The acid derivative (N-palmitoyl L-alanine; PA) was superior to ester derivatives. The chosen formula (PA/safflower oil 10% w/v) was successful in forming an in situ gel of granisetron when subcutaneously injected in rats, lasting for 2 weeks and proved to be biocompatible by histopathological examination. Moreover, it exerted an extended antiemetic activity by decreasing the cisplatin-induced pica for a duration of 96 h and reduced preprotachykinin A mRNA expression and Substance P level for up to 4 days (gastric tissue) or 5 days (medulla oblongata) in rats.

CONCLUSION

Granisetron organogel could be considered as a safe, sustained-release and supportive anticancer treatment in both acute and chronic emesis as well as an accompanying treatment with chemotherapeutics in cancer cases.

Poly(amino acid)-polyester graft copolymer nanoparticles for the acid-mediated release of doxorubicin

Biodegradable polymers have emerged as highly effective drug delivery vehicles. We combine N-carboxyanhydride and O-carboxyanhydride ring opening polymerisations to synthesise a poly(amino acid)-polyester graft copolymer capable of encapsulating, and subsequently releasing doxorubicin via acid-mediated hydrolysis. Consequently, the nanoparticles detailed are extremely promising vehicles for the controlled delivery of chemotherapeutic agents.

Synthesis of Oil-Laden Poly(ethylene glycol) Diacrylate Hydrogel Nanocapsules from Double Nanoemulsions

Multiple emulsions have received great interest due to their ability to be used as templates for the production of multicompartment particles for a variety of applications. However, scaling these complex droplets to nanoscale dimensions has been a challenge due to limitations on their fabrication methods. Here, we report the development of oil-in-water-in-oil (O₁/W/O₂) double nanoemulsions via a two-step high-energy method and their use as templates for complex nanogels comprised of inner oil droplets encapsulated within a hydrogel matrix. Using a combination of characterization methods, we determine how the properties of the nanogels are controlled by the size, stability, internal morphology, and chemical composition of the nanoemulsion templates from which they are formed. This allows for identification of compositional and emulsification parameters that can be used to optimize the size and oil encapsulation efficiency of the nanogels. Our templating method produces oil-laden nanogels with high oil encapsulation efficiencies and average diameters of 200-300 nm. In addition, we demonstrate the versatility of the system by varying the types of inner oil, the hydrogel chemistry, the amount of inner oil, and the hydrogel network cross-link density. These nontoxic oil-laden nanogels have potential applications in food, pharmaceutical, and cosmetic formulations.

Glucose-bearing biodegradable poly(amino acid) and poly(amino acid)-poly(ester) conjugates for controlled payload release

The glucoseamine-initiated ring-opening polymerisation of amino acid N-carboxyanhydrides and O-carboxanhydrides to yield amphiphilic block copolymers that are capable of self-assembly in aqueous solution to form well-defined, glucose-presenting, particles is reported.