Self-Assembly and Drug Release Capacities of Organogels via Some Amide Compounds with Aromatic Substituent Headgroups

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.

Self-Assembly of a Series of Carbazole-Based Vinyl-benzoxazole Derivatives in Gel Phases

A series of carbazole-based vinyl-benzoxazole derivatives have been synthesized in order to verify whether X-ray diffraction (XRD) simulation can give more information about intermolecular stacking in the gel phase. It was found that their gelation capabilities were strongly dependent on the length of the alkyl chain. The compounds with shorter alkyl chains have lower critical gelation concentrations (CGCs) in nonpolar alkane and alcohols with longer carbon chains. On the other hand, compounds with long alkyl chains presented small CGCs in polar methanol. Powder XRD structure solution gave more information about intermolecular stacking than the traditional way of analyzing diffraction peaks to derive approximate molecular stacking patterns. The results verified that gelators had a similar head-to-tail π-stacking between aromatic groups in gel phases although different slipping angles existed. Moreover, ordered stacking between the alkyl chains was also present.

Engineering water-induced ceramide/lecithin oleogels: understanding the influence of water added upon pre- and post-nucleation

A mixture of ceramide (CER) and lecithin (LEC) at specific ratios was capable of forming oleogels in sunflower oil triggered by adding a trace amount of water. It was noted that the addition of water at different temperatures (TW) resulted in different gelation behaviors and microstructures. To better illuminate the assembly mechanism at different TW, samples with water added at different TW (20 °C, 45 °C, 70 °C and 95 °C) were prepared. The viscoelastic properties, microstructures, and the crystal packing of these samples were investigated. It was observed that all samples prepared at TW of 20 °C and 95 °C formed gels, while most samples prepared at TW of 45 °C and 70 °C were too weak to form gels. Gels prepared at 95 °C were stronger but more fragile in texture compared to gels produced at 20 °C. The crystal morphology of gels drastically changed with TW. Spindle-shaped crystals were observed in gels prepared at low TW (20 °C), while gels prepared at high TW (95 °C) exhibited a network with packed oil droplets stabilized by lamellar shells together with fibrillar crystals in the bulk phase. X-ray diffractograms showed a different reflection peak (d-spacing of 14.5 Å) in gel prepared at 20 °C, compared to the d-spacing in oleogels with a single gelator (13.14 Å and 15.33 Å, respectively, for CER and LEC). Gel prepared at 95 °C showed two long-spacing characteristic peaks, which correspond to the characteristic peaks of CER gel (∼13 Å) and LEC gel (∼12 Å). Fourier transform infrared spectroscopy results indicated that the different gelation behaviors at different TW were mainly caused by vibrational changes in the amide bond of CER. Our hypothesized assembly mechanism can be concluded as: increasing TW resulted in the conversion of CER and LEC crystallization from co-assembly (TW = 20 °C) to self-sorting by individual gelators (TW = 95 °C). In this study, novel water-induced oleogels were produced by manipulating TW, and such information further assists the rational design of lipid-based healthy fat products.

Solvent Effects on Gelation Behavior of the Organogelator Based on L-Phenylalanine Dihydrazide Derivatives

A series of organogelators based on L-phenylalanine has been synthesized and their gelation properties in various organic solvents were investigated. The results showed that these organogelators were capable of forming stable thermal and reversible organogels in various organic solvents at low concentrations, and the critical gel concentration (CGC) of certain solvents was less than 1.0 wt%. Afterward, the corresponding enthalpies (ΔH_g) were extracted by using the van ’t Hoff equation, as the gel–sol temperature (T_GS) was the function of the gelator concentration. The study of gelling behaviors suggested that L-phenylalanine dihydrazide derivatives were excellent gelators in solvents, especially BOC–Phe–OdHz (compound 4). The effects of the solvent on the self-assembly of gelators were analyzed by the Kamlet–Taft model, and the gelation ability of compound 4 in a certain organic solvent was described by Hansen solubility parameters and a Teas plot. Morphological investigation proved that the L-phenylalanine dihydrazide derivatives could assemble themselves into an ordered structure such as a fiber or sheet. Fourier-transform infrared spectroscopy (FTIR) and hydrogen nuclear magnetic resonance (¹H NMR) studies indicated that hydrogen bonding, π–π stacking, and van der Waals forces played important roles in the formation of a gel.

Nanocarrier-based systems for targeted and site specific therapeutic delivery

Systemic drug delivery methods such as oral or parenteral administration of free drugs possess relatively low treatment efficiency and marked adverse side effects. The use of nanoparticles for drug delivery in most cases substantially enhances drug efficacy, improves pharmacokinetics and drug release and limits their side effects. However, further enhancement in drug efficacy and significant limitation of adverse side effects can be achieved by specific targeting of nanocarrier-based delivery systems especially in combination with local administration. The present review describes major advantages and limitations of organic and inorganic nanocarriers or living cell-based drug and nucleic acid delivery systems. Among these, different nanoparticles, supramolecular gels, therapeutic cells as living drug carriers etc. have emerged as a new frontier in modern medicine.

Anti-inflammatory effect of active nanofibrous polymeric membrane bearing nanocontainers of atorvastatin complexes

Aim: We developed polymeric membranes for local administration of nonsoluble anti-inflammatory statin, as potential wound patch in rheumatic joint or periodontal lesions. Methods: Electrospun polycaprolactone membranes were fitted with polysaccharide-atorvastatin nanoreservoirs by using complexes with poly-aminocyclodextrin. Characterization methods are UV-Visible and X-ray photoelectron spectroscopy, molecular dynamics, scanning and transmission electron microscopy. In vitro, membranes were seeded with macrophages, and inflammatory cytokine expression were monitored. Results & conclusion: Stable inclusion complexes were formed in solution (1:1 stability constant 368 M- 1, -117.40 kJ mol- 1), with supramolecular globular organization (100 nm, substructure 30 nm). Nanoreservoir technology leads to homogeneous distribution of atorvastatin calcium trihydrate complexes in the membrane. Quantity embedded was estimated (70–90 μg in 30 μm × 6 mm membrane). Anti-inflammatory effect by cell contact-dependent release reached 60% inhibition for TNF-α and 80% for IL-6. The novelty resides in the double protection offered by the cyclodextrins as drug molecular chaperones, with further embedding into biodegradable nanoreservoirs. The strategy is versatile and can target other diseases.