Bioadhesive lipid compositions: self-assembly structures, functionality, and medical applications

Swelling kinetics of mixtures of soybean phosphatidylcholine and glycerol dioleate

Lipid-based drug delivery systems offer the potential to enhance bioavailability, reduce dosing frequency, and improve patient adherence. In aqueous environment, initially dry lipid depots take up water and form liquid crystalline phases. Variation of lipid composition, depot size and hydration-induced phase transitions will plausibly affect the diffusion in and out of the depot. Lipid depots of soybean phosphatidylcholine (SPC) and glycerol dioleate (GDO) mixtures were hydrated for varying time durations in a phosphate-buffered saline (PBS) buffer and then analyzed with Karl Fischer titration, magnetic resonance imaging (MRI) and gravimetrically. Mathematical modeling of the swelling process using diffusion equations, was used to estimate the parameters of diffusion. Both composition of lipid mixture and depot size affect swelling kinetics… The diffusion parameters obtained in Karl Fischer titration and MRI (with temporal and spatial resolution respectively) are in good agreement. Remarkably, the MRI results show a gradient of water content within the depot even after the end of diffusion process. Apparently contradicting the first Fick's law in its classical form, these results find an explanation using the generalized Fick's law that considers the gradient of chemical potential rather than concentration as the driving force of diffusion.

Phase behavior of soybean phosphatidylcholine and glycerol dioleate in hydrated and dehydrated states studied by small-angle X-ray scattering

Soybean phosphatidylcholine (SPC) and glycerol dioleate (GDO) form liquid crystal nanostructures in aqueous environments, and their mixtures can effectively encapsulate active pharmaceutical ingredients (API). When used in a subcutaneous environment, the liquid crystalline matrix gradually hydrates and degrades in the tissue whilst slowly releasing the API. Hydration dependent SPC/GDO phase behavior is complex, non-trivial, and still not fully understood. A deeper understanding of this system is important for controlling its function in drug delivery applications. The phase behavior of the mixture of SPC/GDO/water was studied as a function of hydration and lipid ratio. Small-angle X-ray scattering (SAXS) was used to identify space groups in liquid crystalline phases and to get detailed structural information on the isotropic reverse micellar phase. The reported pseudo ternary phase diagram includes eight different phases and numerous multiphase regions in a thermodynamically consistent way. For mixtures with SPC as the predominant component, the system presents a reverse hexagonal, lamellar and R3m phase. For mixtures with lower SPC concentrations, reverse cubic (Fd3m and Pm3n) as well as intermediate and isotropic micellar phases were identified. By modeling the SAXS data using a core-shell approach, the properties of the isotropic micellar phase were studied in detail as a function of concentration. Moreover, SAXS analysis of other phases revealed new structural features in relation to lipid-water interactions. The new improved ternary phase diagram offers valuable insight into the complex phase behavior of the SPC/GDO system. The detailed structural information is important for understanding what APIs can be incorporated in the liquid crystal structure.

Self-Assembly of Lipid Molecules under Shear Flows: A Dissipative Particle Dynamics Simulation Study

The self-assembly of lipid molecules in aqueous solution under shear flows was investigated using the dissipative particle dynamics simulation method. Three cases were considered: zero shear flow, weak shear flow and strong shear flow. Various self-assembled structures, such as double layers, perforated double layers, hierarchical discs, micelles, and vesicles, were observed. The self-assembly behavior was investigated in equilibrium by constructing phase diagrams based on chain lengths. Results showed the remarkable influence of chain length, shear flow and solution concentration on the self-assembly process. Furthermore, the self-assembly behavior of lipid molecules was analyzed using the system energy, particle number and shape factor during the dynamic processes, where the self-assembly pathways were observed and analyzed for the typical structures. The results enhance our understanding of biomacromolecule self-assembly in a solution and hold the potential for applications in biomedicine.

Efficacy of bioadhesives in the management of oral mucositis in patients undergoing radio-chemotherapy for treatment of head and neck cancer-a systematic review and meta-analysis

BACKGROUND

Management of head and neck cancers requires a multidisciplinary approach where surgery followed by radio and chemotherapy is the mainstay of treatment. The above-mentioned treatment can cause mucositis, a severely debilitating side effect. This can have a significant impact on quality of life. A recent advancing mode of drug delivery is the bioadhesive system. This interacts with mucosa by adhering to it and thereby improving the efficacy of the therapeutic agent delivered.

AIM AND OBJECTIVE

The purpose of this systematic review is to evaluate the effectiveness of bioadhesives in reducing oral mucositis and relieving pain associated with mucositis in head and neck cancer patients receiving radio-chemotherapy.

MATERIALS AND METHOD

Studies assessing the effectiveness of bioadhesives for the treatment of radiation-induced oral mucositis were retrieved from specialized databases (PubMed/MEDLINE, Scopus, ProQuest, Google Scholar, LILACS, OpenGrey) as well as institutional repositories. Data on incidence, pain reduction, resolution, and improvement of oral mucositis using bioadhesive were compiled. A Cochrane tool was used for randomized controlled trials and a JBI tool for non-randomized controlled trials and observational studies to assess the quality of included studies. Based on the eligible study data, a meta-analysis was conducted with STATA version 16, 2019 software, and 95% confidence intervals and p values greater than 0.05.

RESULTS

A total of 15 studies were included which assessed the effectiveness of bioadhesives in managing mucositis and its associated pain. Studies included in the review described either reduction, resolution, or incidence of oral mucositis respectively. A total of three meta-analyses were conducted to assess the incidence of oral mucositis and the pain associated with it, as well as the reduction in incidence. Bioadhesives showed statistically significant differences in the incidence of severe mucositis (p = 0.04). A meta-analysis comparing bioadhesives efficacy in reducing mucositis and pain associated with it found no statistically significant differences (p = 0.36).

CONCLUSION

Bioadhesives are emerging as a novel drug delivery method for treating radio-chemotherapy-induced oral mucositis because of their rapid absorption and easy application. Regardless of its benefits, clinical trials comparing it with conventional treatment methods are necessary to assess its efficacy in treating oral mucositis.

A Bioadhesive Barrier-Forming Oral Liquid Gel Improved Oral Mucositis and Nutritional Status in Patients With Head and Neck Cancers Undergoing Radiotherapy: A Retrospective Single Center Study

Background

Episil^® is a bioadhesive barrier-forming oral liquid gel that can relieve oral mucositis (OM) caused by radiotherapy (RT) and hence relieves pain effectively. In this study, we observed the effects of Episil^® on the OM and nutritional status of patients with head and neck cancers (HNCs) undergoing RT.

Methods

A total of 50 HNC patients were divided into the Episil^® (25 patients) and control (25 patients) groups. Patients in the Episil^® group were sprayed with Episil^®. In the control group, the kangfuxin solution or Kangsu™ oral gargle was used. Medical staff assessed the OM extent and timing as well as the nutritional status during treatment and recorded adverse reactions other than OM. The nutritional status assessment included the following indicators: Patient Generated-Subjective Global Assessment (PG-SGA) score, body mass index (BMI), body weight, albumin levels, and other hematological indicators.

Results

The incidence of high-level OM (III–IV) after RT was lower in the Episil^® group than in the control group (P < 0.05). Nutritional status assessments showed that the Episil^® group had a lower percentage of weight loss than the control group at weeks 4 and 7 after RT. Similar results were also obtained for BMI and albumin levels (P < 0.05). Moreover, according to PG-SGA scores, fewer patients in the Episil^® group were malnourished and more patients were well-nourished (P < 0.05) compared with the control group.

Conclusion

Episil^® effectively improved OM and malnutrition in HNC patients who received RT and has a good clinical application value.

Fast understanding of phases and phase separation in liquid crystal drug delivery systems using deuterium solid-state NMR

Characterization of lipid based (SPC/GDO/H₂O) liquid crystal (LC) drug delivery system is non-trivial and highly complex, especially when multiple and intermediate phases are present. The phase behavior of such mixtures during hydration or delivery is still poorly understood and therefore, characterizing these systems is crucially important towards controlling their function and enhancing the understanding of their drug release behavior. Current work has established an easy way to identify liquid crystal phases and phase mixtures using deuterium (²H) solid-state nuclear magnetic (NMR) spectroscopy under static conditions without disrupting the three dimensional structure and phases, as magic-angle spinning (MAS) could lead to disruption of the phases. Small angle X-ray scattering (SAXS) technique and optical microscopy were also employed to corroborate the study.

Emerging Applications of Drug Delivery Systems in Oral Infectious Diseases Prevention and Treatment

The oral cavity is a unique complex ecosystem colonized with huge numbers of microorganism species. Oral cavities are closely associated with oral health and sequentially with systemic health. Many factors might cause the shift of composition of oral microbiota, thus leading to the dysbiosis of oral micro-environment and oral infectious diseases. Local therapies and dental hygiene procedures are the main kinds of treatment. Currently, oral drug delivery systems (DDS) have drawn great attention, and are considered as important adjuvant therapy for oral infectious diseases. DDS are devices that could transport and release the therapeutic drugs or bioactive agents to a certain site and a certain rate in vivo. They could significantly increase the therapeutic effect and reduce the side effect compared with traditional medicine. In the review, emerging recent applications of DDS in the treatment for oral infectious diseases have been summarized, including dental caries, periodontitis, peri-implantitis and oral candidiasis. Furthermore, oral stimuli-responsive DDS, also known as "smart" DDS, have been reported recently, which could react to oral environment and provide more accurate drug delivery or release. In this article, oral smart DDS have also been reviewed. The limits have been discussed, and the research potential demonstrates good prospects.

Fusion dynamics of cubosome nanocarriers with model cell membranes

Drug delivery with nanocarriers relies on the interaction of individual nanocarriers with the cell surface. For lipid-based NCs, this interaction uniquely involves a process of membrane fusion between the lipid bilayer that makes up the NC and the cell membrane. Cubosomes have emerged as promising fusogenic NCs, however their individual interactions had not yet been directly observed due to difficulties in achieving adequate resolution or disentangling multiple interactions with common characterization techniques. Moreover, many studies on these interactions have been performed under static conditions which may not mimic the actual transport of NCs. Herein we have observed fusion of lipid cubosome NCs with lipid bilayers under flow. Total internal reflection microscopy has allowed visualisation of the fusion event which was sensitive to the lipid compositions and rationalized by lipid diffusion. The fusion event in supported lipid bilayers has been compared with those in cells, revealing a distinct similarity in kinetics.

Local analgesic effect of a bioadhesive barrier-forming oral liquid in cancer patients with oral mucositis caused by chemotherapy and/or radiotherapy: a randomized multicenter, single-use, positive-controlled, open-label study

Objective

CAM2028 (Episil^®; Camurus AB, Lund, Sweden) is a liquid for use in the oral cavity to treat various pains associated with mouth injuries. Upon contact with the swollen oral mucosa, the oral liquid forms a thin protective film that acts as a mechanical barrier to relieve pain. This study was the first in China to evaluate the local analgesic effect of oral liquid in cancer patients who developed oral mucositis following chemotherapy and/or radiotherapy.

Methods

A total of 60 patients were randomized in a 1:1 ratio to the CAM2028 group (the pump device was firmly pressed three times and the fluid was distributed to the painful area of the oral cavity) or KS (a mucoadhesive oral wound rinse, Kangsu™; Luye Pharmaceutical Co. Ltd, Nanjing, China) group (5 mL of the oral rinse was poured into and kept in the oral cavity for at least 1 minute). The primary endpoint was the area under the oral mucosal pain score-time curve (AUC) within 6 hours of treatment in the trial and control groups. Medical device adverse events were assessed according to the National Cancer Institute's Common Terminology Criteria for Adverse Events, version 4.0. Statistical analyses were performed using the chi-squared test (Fisher's exact test), independent-samples t-test, and analysis of covariance.

Results

Sixty patients were included in the per-protocol set population analysis. The average (mean ± SD) 6-hour AUC of the CAM2028 group and the KS group was 14.20±10.29 and 24.46±14.15, respectively. The difference between the groups was statistically significant (P=0.0022). The incidence of adverse events in the trial group and the control group was 16.67% and 30.0%, respectively, and there was no statistical difference.

Conclusions

CAM2028 displayed an efficacious local analgesic effect in cancer patients who developed oral mucositis following chemotherapy and/or radiotherapy. The results demonstrated its potential value in clinical applications.

Characterization of a Liquid Crystal System for Sustained Release of a Peptide BMS-686117

Liquid crystal lipid-based formulations are an effective approach to prolong pharmacokinetics and reduce burst release of a drug on subcutaneous delivery. The objective of this paper was to investigate the influence of phase structures of a lipid-based liquid crystal delivery system and its associated mechanical properties on the release profile of a peptide. It was hypothesized that release of drug molecules are closely related to the mechanical properties that are controlled by phase structures. Experimentally, the relationship between phase structures of lipid liquid crystal system-soy phosphatidyl choline (SPC) and glycerol dioleate (GDO) in water were characterized by polarized light microscopy and small angle X-ray diffraction. Their rheological properties were evaluated with a rheometer and the in vitro release of the peptide as a measure drug release from the LC-depot injection. Three phases: disordered phase, lamellar phase, mixtures of cubic, lamellar, and hexagonal phases were detected by varying formulation compositions. A significant difference in rheological behavior was observed. The disordered phase displayed some attributes of typical Newtonian fluid with lowest viscosity while the lamellar phase showed a shear thinning behavior. Regarding the mechanical strength, the lamellar phase presents the highest storage modulus due to its layer structure followed by mixed phases. Comparing release profiles, the lamellar phase produced a fast release followed by the mixture of phases. In conclusion, this study demonstrates the ability to characterize LC phase structures with microscopy, small angle X-ray diffraction, and rheological measurements and their link to modulating a peptide release profile.

Essential oil-loaded lipid nanoparticles for wound healing

Chronic wounds and severe burns are diseases responsible for severe morbidity and even death. Wound repair is a crucial process and tissue regeneration enhancement and infection prevention are key factors to minimize pain, discomfort, and scar formation. The aim of this work was the development of lipid nanoparticles (solid lipid nanoparticles and nanostructured lipid carriers [NLC]), to be loaded with eucalyptus or rosemary essential oils and to be used, as medical devices, to enhance healing of skin wounds. Lipid nanoparticles were based on natural lipids: cocoa butter, as solid lipid, and olive oil or sesame oil, as liquid lipids. Lecithin was chosen as surfactant to stabilize nanoparticles and to prevent their aggregation. The systems were prepared by high shear homogenization followed by ultrasound application. Nanoparticles were characterized for physical–chemical properties, bioadhesion, cytocompatibility, in vitro proliferation enhancement, and wound healing properties toward normal human dermal fibroblasts. Antimicrobial activity of nanoparticles was evaluated against two reference microbial strains, one of Staphylococcus aureus, the other of Streptococcus pyogenes. Finally, the capability of nanoparticles to promote wound healing in vivo was evaluated on a rat burn model. NLC based on olive oil and loaded with eucalyptus oil showed appropriate physical–chemical properties, good bioadhesion, cytocompatibility, in vitro proliferation enhancement, and wound healing properties toward fibroblasts, associated to antimicrobial properties. Moreover, the in vivo results evidenced the capability of these NLC to enhance the healing process. Olive oil, which is characterized by a high content of oleic acid, proved to exert a synergic effect with eucalyptus oil with respect to antimicrobial activity and wound repair promotion.

Relationship between Structure and Fluctuations of Lipid Nonlamellar Phases Deposited at the Solid-Liquid Interface

The structure and dynamics of nanostructure films formed by mixtures of soy phosphatidylcholine and glycerol dioleate at the silicon-aqueous interface were studied by grazing incidence neutron spin echo spectroscopy (GINSES), specular and off-specular neutron reflectometry, and small-angle X-ray diffraction. Reverse hexagonal (H_II) and micellar cubic phase (Fd3m) layers at the solid-liquid interface have been identified with neutron reflectometry measurements. A preferred orientation of the liquid crystalline (LC) domains was observed only for the anisotropic H_II phase. The size of the LC domains was found to be about 1 micrometer as estimated from the width of the diffraction peaks. GINSES revealed that the cubic phase forms rather rigid films. In comparison, the H_II film was more flexible, appearing as a modified undulation spectrum of the cylinders due to the interaction with the substrate.

Temperature responsive lipid liquid crystal layers with embedded nanogels

Polymer nanogels are embedded within layers consisting of a nonlamellar liquid crystalline lipid phase to act as thermoresponsive controllers of layer compactness and hydration.

Mesoporous self-assembled nanoparticles of biotransesterified cyclodextrins and nonlamellar lipids as carriers of water-insoluble substances

Soft mesoporous hierarchically structured particles were created by the self-assembly of an amphiphilic deep cavitand cyclodextrin βCD-nC₁₀ (degree of substitution n = 7.3), with a nanocavity grafted by multiple alkyl (C₁₀) chains on the secondary face of the βCD macrocycle through enzymatic biotransesterification, and the nonlamellar lipid monoolein (MO). The effect of the non-ionic dispersing agent polysorbate 80 (P80) on the liquid crystalline organization of the nanocarriers and their stability was studied in the context of vesicle-to-cubosome transition. The coexistence of small vesicular and nanosponge membrane objects with bigger nanoparticles with inner multicompartment cubic lattice structures was established as a typical feature of the employed dispersion process. The cryogenic transmission electron microscopy (cryo-TEM) images and small-angle X-ray scattering (SAXS) structural analyses revealed the dependence of the internal organization of the self-assembled nanoparticles on the presence of embedded βCD-nC₁₀ deep cavitands in the lipid bilayers. The obtained results indicated that the incorporated amphiphilic βCD-nC₁₀ building blocks stabilize the cubic lattice packing in the lipid membrane particles, which displayed structural features beyond the traditional CD nanosponges. UV-Vis spectroscopy was employed to characterize the nanoencapsulation of a model hydrophobic dimethylphenylazo-naphthol guest compound (Oil red) in the created nanocarriers. In perspective, these dual porosity carriers should be suitable for co-encapsulation and sustained delivery of peptide, protein or siRNA biopharmaceuticals together with small molecular weight drug compounds or imaging agents.

Responsive self-assembled nanostructured lipid systems for drug delivery and diagnostics

While stimuli-responsive polymers have received a huge amount of attention in the literature, responsive lipid-based mesophase systems offer unique opportunities in biomedical applications such as drug delivery and biosensing. The different mesophase equilibrium structures enables dynamic switching between nanostructures to facilitate drug release or as a transducer for recognition events. In drug delivery, this behavior offers researchers the means to deliver a therapeutic payload at a specific rate and time i.e. 'on-demand'. This review summarizes the distinctive features of these multifaceted materials and aggregates the current state of the art research from our groups and others into the use of these materials as bulk gels and nanostructured dispersions for drug delivery, biosensing and diagnostics.

Interfacial properties of POPC/GDO liquid crystalline nanoparticles deposited on anionic and cationic silica surfaces

Reversed lipid liquid crystalline nanoparticles (LCNPs) of the cubic micellar (I₂) phase have high potential in drug delivery applications due to their ability to encapsulate both hydrophobic and hydrophilic drug molecules.

Non-lamellar lipid liquid crystalline structures at interfaces

The self-assembly of lipids leads to the formation of a rich variety of nano-structures, not only restricted to lipid bilayers, but also encompassing non-lamellar liquid crystalline structures, such as cubic, hexagonal, and sponge phases. These non-lamellar phases have been increasingly recognized as important for living systems, both in terms of providing compartmentalization and as regulators of biological activity. Consequently, they are of great interest for their potential as delivery systems in pharmaceutical, food and cosmetic applications. The compartmentalizing nature of these phases features mono- or bicontinuous networks of both hydrophilic and hydrophobic domains. To utilize these non-lamellar liquid crystalline structures in biomedical devices for analyses and drug delivery, it is crucial to understand how they interact with and respond to different types of interfaces. Such non-lamellar interfacial layers can be used to entrap functional biomolecules that respond to lipid curvature as well as the confinement. It is also important to understand the structural changes of deposited lipid in relation to the corresponding bulk dispersions. They can be controlled by changing the lipid composition or by introducing components that can alter the curvature or by deposition on nano-structured surface, e.g. vertical nano-wire arrays. Progress in the area of liquid crystalline lipid based nanoparticles opens up new possibilities for the preparation of well-defined surface films with well-defined nano-structures. This review will focus on recent progress in the formation of non-lamellar dispersions and their interfacial properties at the solid/liquid and biologically relevant interfaces.

Effects of rigid cores and flexible tails on the phase behaviors of polynorbornene-based mesogen-jacketed liquid crystalline polymers

MJLCPs with a polynorbornene main chain and different side groups have been precisely synthesized for investigating the effect of side-chain structures on the liquid crystalline phase behaviors.

Sterically stabilized spongosomes for multidrug delivery of anticancer nanomedicines

SAXS patterns of drug-loaded lipid nanocarriers stabilized by polysorbate P80 (left); cryo-TEM image of BAI-BJO-spongosomes-2 (right).

Treatment of oral mucositis pain following radiation therapy for head-and-neck cancer using a bioadhesive barrier-forming lipid solution

PURPOSE

CAM2028, a vehicle that forms a bioadhesive lipid barrier when applied to the oral mucosa, was developed as a carrier system for local delivery of benzydamine, an NSAID used for pain relief in oral mucositis. This trial compared the analgesic effect of CAM2028 plus benzydamine (CAM2028-benzydamine) with unmedicated CAM2028 (CAM2028-control) for the treatment of oral mucositis in patients with head-and-neck cancer.

METHODS

Thirty-eight study participants were enrolled during their 3rd to 4th week of radiation therapy. Participants were required to have symptomatic oral mucositis (WHO Grade 2 or above) at screening and pain scores of at least 6 on an 11-point Likert scale at screening and on each day before treatment with study medication. After undergoing radiation, patients were administered a single dose of CAM2028-control or CAM2028-benzydamine 2 days apart, in a randomized crossover fashion. Pain was assessed over the following 8 h.

RESULTS

With both treatments, patients experienced a mean 40 % decrease in pain intensity at 6 h (the primary study endpoint). Both treatments resulted in significant pain relief within 5 min of application that was evident during the entire 8-h assessment period. There was no difference in pain relief between the two interventions at any time point. Both treatments were safe and well tolerated.

CONCLUSIONS

CAM2028-benzydamine and CAM2028-control were both efficacious in reducing pain in patients with oral mucositis related to radiation therapy for head-and-neck cancer. Analgesic effects of both medications were immediate, clinically significant, and persistent for up to 8 h.