Self-assembled lyotropic liquid crystal gel for osteoarthritis treatment via anti-inflammation and cartilage protection.

Osteoarthritis (OA) is a chronic joint disease with occurrence of articular inflammation and cartilage degeneration. An ideal drug delivery system for effective treatment of OA should integrate inflammation alleviation with cartilage protection. Herein, a lyotropic liquid crystal (LLC) precursor co-loading hyaluronic acid (HA) and celecoxib, formulated as the HLC precursor, was developed for the combined therapeutic efficacy. The in situ gelling property of the HLC precursor effectively prolongs drug retention in the articular cavity to achieve a long-term anti-inflammation effect. Based on the rheological tests, HLC gel with a cubic lattice structure endows it with a spring-like effect to buffer joint shock and shows great potential in providing cartilage protection by resisting mechanical destruction, lubricating joint, and decomposing intensive stress (about 50%). Meanwhile, the pharmacodynamics study on the OA-induced SD rats demonstrated that HLC gel was the most effective to reduce inflammation levels and to protect the cartilage against abrasion and degeneration. Furthermore, the in vivo degradation behavior and the intra-articular irritation results of LLC/HLC gel demonstrated that it was biodegradable and biocompatible. These results collectively demonstrated that HLC gel with anti-inflammation and cartilage protection performance provides a useful approach to treat OA.

In situ biomimetic lyotropic liquid crystal gel for full-thickness cartilage defect regeneration.

There is a great challenge in regenerating cartilage defects, which usually involve absent bearing capacity and poor adaptation to joint movement, further exacerbating subchondral bone damage. Therefore, ideal tissue-engineering cartilage scaffolds should be endowed with biomimetic and sustained-release function for promoting long-term chondrogenesis while protecting subchondral bone. Herein, in situ self-assembling gel based on glyceryl monooleate (GMO)-hyaluronic acid (HA) composite lyotropic liquid crystal (HLC) was developed as the biomimetic scaffold to deliver kartogenin for long-term cartilage regeneration. Compared to the GMO based (LLC) gel, HLC gel with modified lattice structure exhibited improved rheological properties for better joint protection by increasing mechanical strength, elasticity and lubrication. Besides, HLC gel successfully prolonged drug release and retention in the joint cavity over 4 weeks to provide combined effect of kartogenin and HA for cartilage repair. Pharmacodynamic studies demonstrated that HLC gel was the most effective to promote chondrogenesis and protect subchondral bone, making the damaged bone tissue restored to normal in divergent features as evidenced by the MRI, Micro-CT and histological results. Therefore, the HLC gel with joint protection and controlled drug release can serve as a firm scaffold for providing long-term cartilage repair.

A pirfenidone loaded spray dressing based on lyotropic liquid crystals for deep partial thickness burn treatment: healing promotion and scar prophylaxis.

A deep partial thickness (DPT) burn injury refers to burn damage involving the epidermis and major dermis, whose prognosis depends greatly on wound management. Lack of effective management can lead to an elongated healing process and aggravated scar formation, which can severely disturb patients, both physically and mentally. A dressing with good water absorption and moderate mechanical properties is crucial for healing promotion, and the prevention of scar formation is highly desirable. In this project, a hyaluronic acid combined lyotropic liquid crystal based spray dressing (HLCSD) loaded with the anti-fibrotic drug pirfenidone (PFD) has been designed. HLCSD is expected to achieve the goals of both wound healing promotion and scar prophylaxis. Its water absorption capacity, mechanical properties, drug release behavior and phase transition are fully evaluated. HLCSD possesses low viscosity for spray administration and high levels of water absorption for exudate absorption. An in situ gel composed of self-assembled lattice nanostructures provides excellent mechanical protection to promote the healing process and steady PFD release to exert a scar prophylaxis effect. The benefit of HLCSD on the wound healing rate is verified in vivo. In the DPT burn wound model we established, HLCSD also exhibits excellent healing promotion effects, and PFD-loaded HLCSD shows scar prophylaxis effects and displays an ideal prognosis, with skin as smooth as healthy skin. The healing promotion of HLCSD is considered to be related to the alleviation of inflammation, with an obviously shortened inflammation phase, with contributions from water management, mechanical protection and anti-inflammation by HLCSD. The scar prophylaxis of PFD-loaded HLCSD is proven to be related to the regulation of collagen synthesis and degradation, involving key cytokines like TGF-ß and MMP-1. Taken together, the PFD-loaded HLCSD with healing promotion and scar prophylaxis offers significant promise as a spray dressing for DPT burn injuries.

A liquid crystalline precursor incorporating chlorhexidine acetate and silver nanoparticles for root canal disinfection.

Lyotropic liquid crystals (LLC) have received increasing attention as a drug delivery system. In this study, a novel intra-canal disinfectant based on the glycerol monooleate (GMO) LLC precursor incorporation with chlorhexidine (CHX) and silver nanoparticles (Ag-NPs) was designed and evaluated. The LLC precursor with excellent fluidity was able to penetrate deeply into the complex tiny collateral branch root canals. The transformation of cubic LLC in root canals upon coming into contact with water provided long-lasting disinfection against multidrug-resistant bacteria to avoid the endodontic reinfection and follow-up visits. The GMO-ethanol-water (48% : 12% : 40%, w/w) formulation containing 0.5% CHX and 0.02% Ag-NPs was selected for further studies. The low viscosity of the precursor presented excellent injectability and flowabilities. From the in vitro release test, the release behaviours were found to be influenced by CHX and Ag-NP contents, allowing the optimized precursor to obtain a 28-day release profile. The CHX-Ag-NP containing LLC precursor exhibited an excellent and sustained sterilization effect on Enterococcus faecalis for more than one month with a bacterial inactivation rate of ≥98.5%, which was far more than the minimum clinical requirement (7 days). Furthermore, no in vitro toxicity was observed in the cytotoxicity evaluation. The CHX-Ag-NP containing LLC precursor was proved to be a promising intra-canal disinfectant in our study.

Anhydrous reverse micelle lecithin nanoparticles/PLGA composite microspheres for long-term protein delivery with reduced initial burst.

To address the issue of initial burst release from poly (lactic-co-glycolic) acid (PLGA) microspheres prepared by water-in-oil-in-water (W/O/W) double emulsion technique, PLGA composite microspheres containing anhydrous reverse micelle (ARM) lecithin nanoparticles were developed by a modified solid-in-oil-in-water (S/O/W) technique. Bovine serum albumin (BSA) loaded ARM lecithin nanoparticles, which were obtained by initial self-assembly and subsequent lipid inversion of the lecithin vesicles, were then encapsulated into PLGA matrix by the S/O/W technique to form composite microspheres. In vitro release study indicated that BSA was slowly released from the PLGA composite microspheres over 60 days with a reduced initial burst (11.42 ±â€¯2.17% within 24 h). The potential mechanism of reduced initial burst and protein protection using this drug delivery system was analyzed through observing the degradation process of carriers and fitting drug release data with various kinetic models. The secondary structure of encapsulated BSA was well maintained through the steric barrier effect of ARM lecithin nanoparticles, which avoided exposure of proteins to the organic solvent during the preparation procedure. In addition, the PLGA composite microspheres exhibited superior biocompatibility without notable cytotoxicity. These results suggested that ARM lecithin nanoparticles/PLGA composite microspheres could be a promising platform for long-term protein delivery with a reduced initial burst.

Injectable in situ forming gel based on lyotropic liquid crystal for persistent postoperative analgesia.

Local anesthetics have been widely used for postoperative analgesia. However, multiple injections or local infiltration is required due to the short half-lives of local anesthetics after single injection, which results in poor compliance and increasing medical expense. In this study, an in situ forming gel (ISFG) based on lyotropic liquid crystal was developed to deliver bupivacaine hydrochloride (BUP) for long-acting postoperative analgesia. BUP-ISFG was designed to be administrated as a precursor solution which would spontaneously transform into gel with well-defined internal nanostructures for sustained drug release at the site of administration when exposed to physiological fluid. A lamellar-hexagonal-cubic phase transition occurred during the in situ gelation. The lamellar phase of the precursor solution endows it with low viscosity for good syringeability while the unique nanostructures of hexagonal and cubic phases of the in situ gel provide sustained drug release. Persistent analgesia effect in vivo was achieved with BUP-ISFG, and the plasma BUP concentration was found to be steadier compared to commercially available BUP for injection. In addition, the ISFG displayed acceptable biocompatibility and good biodegradability. The findings are positive about ISFG as a sustained release system for persistent postoperative analgesia. STATEMENT OF SIGNIFICANCE: To address the issue of insufficient postoperative analgesia associated with short half-lives of local anesthetics after single injection, an in situ forming gel (ISFG) based on lyotropic liquid crystal was developed to deliver bupivacaine hydrochloride (BUP) for postoperative analgesia over three days. The results demonstrated that persistent analgesia effect in vivo was achieved with single injection of BUP-ISFG, and the plasma BUP concentration was found to be steadier compared to commercially available BUP injection. The BUP-ISFG possessed a lamellar-hexagonal-cubic phase transition with corresponding crystal change in 3D nanostructure during the in situ gelation. The relationship between crystal nanostructure and carrier function, might provide some insights to the design and clinical applications of the drug delivery systems based on lyotropic liquid crystal.

Expansible thermal gelling foam aerosol for vaginal drug delivery.

Vaginal delivery of antimicrobial drugs is the most effective method for the local treatment of the vaginal infections. However, current vaginal drug delivery systems (VDDS), including gel, lotion, aerosol and cream, are suffering from low penetration in the deep vaginal rugae and easy elimination by self-cleaning of vaginal canal. To address these issues, a foam aerosol based on the thermal transformation was designed to improve penetration efficiency and achieve the extended retention. The expansible thermal gelling foam aerosol (ETGFA) consisting of thermal sensitive matrix, silver nanoparticle, adhesive agent and propellant, was optimized by evaluations of precursor viscosity, foam expansion, thermal gelation, gel adhesiveness, antimicrobial effects and tissue irritation. The ETGFA would penetrate to the deep vaginal rugae to cover the infectious sites by foam expansion. Drug leakage was intended to be avoided by the thermal gelation at physiological temperature before foam collapse. The gel could be retained in the vaginal canal for extended time due to its superior adhesiveness when compared to the commercial gel Asimi®. The ETGFA provided extended drug release for over 4 h and maintained effective drug concentrations at the infectious sites. The ETGFA containing silver nanoparticles showed dose-dependent antimicrobial effects on the vaginal floras and irritation reduction to the vaginal tissues. The results demonstrated that the ETGFA could overcome the limitations of conventional dosage forms, including poor drug penetration, carrier retention and patient compliance and satisfied the requirements for vaginal drug delivery.

An injectable in situ gel with cubic and hexagonal nanostructures for local treatment of chronic periodontitis.

Periodontitis is a chronic bacterial infection, and its effective treatment is dependent on the retention of antibiotics of effective concentrations at the periodontal pockets. In this study, a solution-gel based inverse lyotropic liquid crystalline (LLC) system was explored to deliver metronidazole to the periodontal pockets for local treatment of periodontitis. It was found that the metronidazole-loaded LLC precursor spontaneously transformed into gel in the presence of water in the oral cavity. The low viscosity of the precursor would allow its penetration to the rather difficult to reach infection sites, while the adhesiveness and crystalline nanostructures (inverse bicontinuous cubic Pn3m phase and inverse hexagonal phase) of the formed gel would permit its firm adhesion to the periodontal pockets. The LLC system provided sustained drug release over one week in vitro. Results from in vivo study using a rabbit periodontitis model showed that the LLC system was able to maintain the metronidazole concentrations in the periodontal pockets above the minimum inhibition concentration for over 10 days without detectable drug concentration in the blood. Owing to the spontaneous solution-gel transition in the periodontal pockets and unique liquid crystalline nanostructures, the LLC in situ gel provided effective treatment of periodontitis for a prolonged period of time with reduced systematic side effects, compared to metronidazole suspension which was effective for 24 h with detectable metronidazole concentrations in the blood after 6 h.

A novel design for stable self-assembly cubosome precursor-microparticles enhancing dissolution of insoluble drugs.

Cubosomes have been presented to enhance dissolution of insoluble drugs, but their applications are limited by the practical hurdles associated with both preparation and storage instability, resulting in drug delivery failure. In the present study, an innovative cubosome precursor-microparticles (CPMs) spray dried from an aqua-free precursor solution was developed to improve cubosome stability during both preparation and storage as well as to enhance the dissolution of insoluble drugs. These CPMs spontaneously self-assembled in situ forming homogeneous cubosome dispersion by hydration and disintegration after exposure to the aqueous medium. The stable cubosome dispersion was obtained from self-assembly (SA) of CPMs after administration instead of fragmentation of bulk cubic phase gel into cubosomes, which settled the preparation instability due to avoidance of high energy fragmentation (e.g. ultrasonic effect, high speed shear and high pressure homogenization). Also, the subsequent storage instability issue can be excluded as the CPMs were stored in a solid stable form. The CPMs disintegration and cubosome SA were demonstrated by the notable morphology variation and the distinct microparticle size decrease from CPMs (10-20 µm) to SA-cubosomes (150-200 nm). The cumulative release of docetaxel (DTX, model insoluble drug) incorporated in CPMs increased to 96.4% within 120 minutes compared with only 75.2% for blank CPMs and DTX physical mixture, demonstrating that CPMs significantly enhanced the dissolution extent of insoluble drug. The SA-cubosomes possessed quite high drug entrapment efficiency (>95%) and an integrated drug dissolution content, which significantly increased the drug utilization rate.

Comparative studies on glycerol monooleate- and phytantriol-based cubosomes containing oridonin in vitro and in vivo.

To improve the solubility and bioavailability of oridonin (ORI), glycerol monooleate lipid (GMO)- or phytantriol (PYT)-Poloxamer 407-propylene glycol-water systems were firstly used to develop cubosomes containing ORI for oral delivery. These cubosomes prepared through the fragmentation of bulk gels under homogenization conditions of 1200 bar and nine cycles had a mean particle size of around 200 nm with narrow size distribution, and ORI encapsulation efficiency over 85%. Powder X-ray diffraction and differential scanning calorimetry indicated that ORI was in an amorphous or molecular form in the cubosomes. The internal structures of GMO- and PYT-based cubosomes were revealed by small-angle X-ray scattering as a bi-continuous cubic liquid crystalline phase with Im3m and Pn3m geometry, respectively. About 80% of ORI was released in vitro from GMO- and PYT-based cubosomes at 24 h, showing a sustained release kinetics fitted with Higuchi's equation. The pharmacokinetic study in rats showed that the PYT-based cubosomes significantly enhanced the adsorption of ORI as compared to the GMO-based cubosomes and ORI suspension, with evidence of longer half-life and greater relative bioavailability (p < 0.01). Therefore, the PYT-based cubosomes containing ORI might be proposed as a promising candidate carrier for the efficient delivery of drug with therapeutic treatment.

Phytantriol based liquid crystal provide sustained release of anticancer drug as a novel embolic agent.

Phytantriol has received increasing amount of attention in drug delivery system, however, the ability of the phytantriol based liquid crystal as a novel embolic agent to provide a sustained release delivery system is yet to be comprehensively demonstrated. The purpose of this study was to prepare a phytantriol-based cubic phase precursor solution loaded with anticancer drug hydroxycamptothecine (HCPT) and evaluate its embolization properties, in vitro drug release and cytotoxicity. Phase behavior of the phytantriol-solvent-water system was investigated by visual inspection and polarized light microscopy, and no phase transition was observed in the presence of HCPT within the studied dose range. Water uptake by the phytantriol matrices was determined gravimetrically, suggesting that the swelling complied with the second order kinetics. In vitro evaluation of embolic efficacy indicated that the isotropic solution displayed a satisfactory embolization effect. In vitro drug release results showed a sustained-release up to 30 days and the release behavior was affected by the initial composition and drug loading. Moreover, the in vitro cytotoxicity and anticancer activity were evaluated by MTT assay. No appreciable mortality was observed for NIH 3T3 cells after 48 h exposure to blank formulations, and the anticancer activity of HCPT-loaded formulations to HepG2 and SMMC7721 cells was strongly dependent on the drug loading and treatment time. Taken together, these results indicate that phytantriol-based cubic phase embolic gelling solution is a promising potential carrier for HCPT delivery to achieve a sustained drug release by vascular embolization, and this technology may be potential for clinical applications.

Comparative studies on exenatide-loaded poly (D,L-lactic-co-glycolic acid) microparticles prepared by a novel ultra-fine particle processing system and spray drying.

The purpose of this study was to compare the properties of exenatide-loaded poly (D,L-lactic-co-glycolic acid) microparticles (Ex-PLGA-MPs) prepared by a novel ultra-fine particle processing system (UPPS) and spray drying. UPPS is a proprietary technology developed by our group based on the disk rotation principle. Characteristics of the MPs including morphology, particle size distribution, drug content, encapsulation efficiency and in vitro release were comparatively studied. Cytotoxicity of the MPs was examined on A549 cells and the pharmacodynamics was investigated in vivo in type 2 diabetes Sprague-Dawley (SD) rats. Ex-PLGA-MPs prepared by UPPS showed larger particle size, denser surface, greater encapsulation efficiency, less initial burst release, and stable sustained release for more than one month in vitro as compared with the spray drying MPs. Meanwhile, the UPPS MPs effectively controlled the body growth rate and blood glucose in diabetes rats for at least three weeks after a single injection, while the spray drying MPs showed effective control period of about two weeks. UPPS technology was demonstrated to manufacture Ex-PLGA-MPs as a potential sustained release protein/polypeptide delivery system, which is an alternative method for the most commonly used spray drying. This comparative research provides a new guidance for microparticle preparation technology.

Fabrication and characterization of silk fibroin-coated liposomes for ocular drug delivery.

The unique structure and protective mechanisms of the eye result in low bioavailability of ocular drugs. Using a mucoadhesive material is an efficient solution to improve ocular drug therapeutic efficacy. This study was designed to prepare a liposomal formulation coated by a novel adhesive excipient, silk fibroin (SF), for topical ocular drug delivery. The regenerated silk fibroins (SFs) with different dissolving time were coated onto the ibuprofen-loaded liposomes. The morphology, drug encapsulation efficiency, in vitro release and in vitro corneal permeation of SF-coated liposomes (SLs) were investigated in comparison with the conventional liposome. Cellular adhesion and cytotoxicity assay of SF and SLs were tested using human corneal epithelial cells (HCEC). SLs showed sustained drug release and in vitro corneal permeation of ibuprofen as compared to drug solution and conventional liposome. The cellular fluorescence appeared after 7 min of exposure to SF, and the intensity increased sustainedly up to 12h with no detectable cytotoxicity. Higher fluorescence intensity of Nile red in SLs was observed in a short period of 15 min showing a rapid uptake. These favorable properties make SF-coated liposome be a promising ocular drug delivery system.