Immobilization of cationic rifampicin-loaded liposomes on polystyrene for drug-delivery applications

Liposome-polymer complex for drug delivery system and vaccine stabilization

Liposomes have been used extensively as micro- and nanocarriers for hydrophobic or hydrophilic molecules. However, conventional liposomes are biodegradable and quickly eliminated, making it difficult to be used for delivery in specific routes, such as the oral and systemic routes. One way to overcome this problem is through complexation with polymers, which is referred to as a liposome complex. The use of polymers can increase the stability of liposome with regard to pH, chemicals, enzymes, and the immune system. In some cases, specific polymers can condition the properties of liposomes to be explicitly used in drug delivery, such as targeted delivery and controlled release. These properties are influenced by the type of polymer, crosslinker, interaction, and bond in the complexation process. Therefore, it is crucial to study and review these parameters for the development of more optimal forms and properties of the liposome complex. This article discusses the use of natural and synthetic polymers, ways of interaction between polymers and liposomes (on the surface, incorporation in lamellar chains, and within liposomes), types of bonds, evaluation standards, and their effects on the stability and pharmacokinetic profile of the liposome complex, drugs, and vaccines. This article concludes that both natural and synthetic polymers can be used in modifying the structure and physicochemical properties of liposomes to specify their use in targeted delivery, controlled release, and stabilizing drugs and vaccines.

Cell membrane-biomimetic coating via click-mediated liposome fusion for mitigating the foreign-body reaction

The foreign-body reaction (FBR) caused by the implantation of synthetic polymer scaffolds seriously affects tissue-biomaterial integration and tissue repair. To address this issue, we developed a cell membrane-biomimetic coating formed by "click"-mediated liposome immobilization and fusion on the surface of electrospun fibers to mitigate the FBR. Utilization of electrospun polystyrene microfibrous scaffold as a model matrix, we deposited azide-incorporated silk fibroin on the surface of the fibers by the layer-by-layer assembly, finally, covalently modified with clickable liposomes via copper-free SPAAC click reaction. Compared with physical adsorption, liposomes click covalently binding can quickly fuse to form lipid film and maintain fluidity, which also improved liposome stability in vitro and in vivo. Molecular dynamics simulation proved that "click" improves the binding rate and strength of liposome to silk substrate. Importantly, histological observation and in vivo fluorescent probes imaging showed that liposome-functionalized electrospun fibers had negligible characteristics of the FBR and were accompanied by many infiltrated host cells and new blood vessels. We believe that the promotion of macrophage polarization toward a pro-regenerative phenotype plays an important role in vascularization. This bioinspired strategy paves the way for utilizing cell membrane biomimetic coating to resist the FBR and promote tissue-scaffold integration.

Design of an Antifungal Surface Embedding Liposomal Amphotericin B Through a Mussel Adhesive-Inspired Coating Strategy

Microbial colonization of urinary catheters remains a serious problem for medicine as it often leads to biofilm formation and infection. Among the approaches reported to deal with this problem, surfaces functionalization to render them with antimicrobial characteristics, comprises the most promising one. Most of these strategies, however, are designed to target bacterial biofilms, while fungal biofilms are much less taken into account. In real-life settings, fungi will be inevitably found in consortium with bacteria, especially in the field of biomaterials. The development of antifungal coating strategies to be combined with antibacterial approaches will be pivotal for the fight of biomaterial-associated infections. The main goal of the present study was, therefore, to engineer an effective strategy for the immobilization of liposomal amphotericin B (LAmB) on polydimethylsiloxane (PDMS) surfaces to prevent Candida albicans colonization. Immobilization was performed using a two-step mussel-inspired coating strategy, in which PDMS is first immersed in dopamine solution. Its polymerization results in the deposition of a thin adherent film, called polydopamine (pDA), which allowed the incorporation of LAmB, afterwards. Different concentrations of LAmB were screened in order to obtain a contact-killing surface with no release of LAmB. Surface characterization confirmed the polymerization of dopamine and further functionalization with LAmB yielded surfaces with less roughness and more hydrophilic features. The proposed coating strategy rendered the surfaces of PDMS with the ability to prevent the attachment of C. albicans and kill the adherent cells, without toxicity toward mammalian cells. Overall results showed that LAmB immobilization on a surface retained its antifungal activity and reduced toxicity, holding therefore a great potential to be applied for the design of urinary catheters. Since the sessile communities commonly found associated to these devices exhibit a polymicrobial nature, the next challenge will be to co-immobilize LAmB with antibacterial agents to prevent the establishment of catheter-associated urinary tract infections (CAUTI).

One-Step Fabrication of Three-Dimensional Fibrous Collagen-Based Macrostructure with High Water Uptake Capability by Coaxial Electrospinning

One step fabrication of the three dimension (3D) fibrous structure of Collagen-g-poly(MMA-co-EA)/Nylon6 was investigated by controlling the experimental conditions during coaxial electrospinning. This 3D fibrous structure is the result of interactions of two polymeric systems with a varied capability to be electrostatically polarized under the influence of the external electric field; the solution with the higher conductivity into the inner spinneret and the solution with the lesser conductivity into the outer capillary of the coaxial needle. This set-up was to obtain bimodal fiber fabrication in micro and nanoscale developing a spatial structure; the branches growing off a trunk. The resultant 3D collagen-based fibrous structure has two distinguished configurations: microfibers of 6.9 ± 2.2 µm diameter gap-filled with nanofibers of 216 ± 49 nm diameter. The 3D fibrous structure can be accumulated at an approximate height of 4 cm within 20 min. The mechanism of the 3D fibrous structure and the effect of experimental conditions, the associated hydration degree, water uptake and degradation rate were also investigated. This highly stable 3D fibrous structure has great potential end-uses benefitting from its large surface area and high water uptake which is caused by the high polarity and spatial orientation of collagen-based macrostructure.

A mannose-conjugated multi-layered polymeric nanocarrier system for controlled and targeted release on alveolar macrophages

To improve the performance of drug delivery systems in macrophages, targeted ligand-conjugated polymeric carriers have been realized to be vital for targeted, sustainable and controlled drug release with remarkable biocompatibility and bioavailability.

Facile and Versatile Strategy for Construction of Anti-Inflammatory and Antibacterial Surfaces with Polydopamine-Mediated Liposomes Releasing Dexamethasone and Minocycline for Potential Implant Applications

Reducing early nonbacterial inflammation induced by implanted materials and infection resulting from bacterial contamination around the implant-abutment interface could greatly decrease implant failure rates, which would be of clinical significance. In this work, we presented a facile and versatile strategy for the construction of anti-inflammatory and antibacterial surfaces. Briefly, the surfaces of polystyrene culture plates were first coated with polydopamine and then decorated with dexamethasone plus minocycline-loaded liposomes (Dex/Mino liposomes), which was validated by contact angle goniometry, quartz crystal microbalance, and fluorescence microscopy. Dex/Mino liposomes were dispersed on functional surfaces and the drug release kinetics exhibited the sustained release of dexamethasone and minocycline. Our results demonstrated that the Dex/Mino liposome-modified surfaces had good biocompatibility. Additionally, liposomal dexamethasone reduced proinflammatory mediator expression (particularly IL-6 and TNF-α) in lipopolysaccharide-stimulated human gingival fibroblasts and human mesenchymal stem cells. Moreover, liposomal minocycline prevented the adhesion and proliferation of Porphyromonas gingivalis (Gram-negative bacteria) and Streptococcus mutans (Gram-positive bacteria). These findings demonstrate that an anti-inflammatory and antibacterial surface was developed, using dopamine as a medium and combining a liposomal delivery device, which has potential for use to reduce implant failure rates. Accordingly, the surface modification strategy presented could be useful in biofunctionalization of implant materials.

Immobilization of nattokinase-loaded red blood cells on the surface of superhydrophobic polypropylene targeting fibrinolytic performance

A superhydrophobic polypropylene (PP) platform with fibrinolytic ability was fabricated by capturing and releasing nattokinase (NK)-encapsulating red blood cells (RBCs).

Nanoengineered drug delivery systems for enhancing antibiotic therapy

Formulation scientists are recognizing nanoengineered drug delivery systems as an effective strategy to overcome limitations associated with antibiotic drug therapy. Antibiotics encapsulated into nanodelivery systems will contribute to improved management of patients with various infectious diseases and to overcoming the serious global burden of antibiotic resistance. An extensive review of several antibiotic-loaded nanocarriers that have been formulated to target drugs to infectious sites, achieve controlled drug release profiles, and address formulation challenges, such as low-drug entrapment efficiencies, poor solubility and stability is presented in this paper. The physicochemical properties and the in vitro/in vivo performances of various antibiotic-loaded delivery systems, such as polymeric nanoparticles, micelles, dendrimers, liposomes, solid lipid nanoparticles, lipid-polymer hybrid nanoparticles, nanohybirds, nanofibers/scaffolds, nanosheets, nanoplexes, and nanotubes/horn/rods and nanoemulsions, are highlighted and evaluated. Future studies that will be essential to optimize formulation and commercialization of these antibiotic-loaded nanosystems are also identified. The review presented emphasizes the significant formulation progress achieved and potential that novel nanoengineered antibiotic drug delivery systems have for enhancing the treatment of patients with a range of infections.

Antibacterial activities effectuated by co-continuous epoxy-based polymer materials

We report antibacterial activities of the epoxy-resin-based monolithic media (epoxy monoliths) having macroporous co-continuous structure as well as hydrophobic and/or hydrophilic surface. Utilizing epoxy monoliths containing ammonium groups, the antibacterial experiments were examined using Escherichia coli. As the results, the monolithic media prepared with an epoxy monomer having nitrogen atoms clearly showed antibacterial activities, while those prepared using the monomer without nitrogen atom showed less antibacterial activities. Additionally, the quaternization of the epoxy polymers were expressed significant antibacterial activities. Further studies elucidated that the observed antibacterial activities involved the steep effect based on pH changing of solution and hydrophobic interactions by the quaternary ammonium.

Using 96-well tissue culture polystyrene plates and a fluorescence plate reader as tools to study the survival and inactivation of viruses on surfaces

A method for studying the behavior of viruses on surfaces has been developed and is illustrated by determining the temperatures that inactivate adsorbed viral hemorrhagic septicemia virus (VHSV) and the concentration of 1-propanol that disinfected surfaces with adsorbed VHSV and chum salmon virus (CSV). VHSV is a rhabdovirus; CSV, a reovirus, and they were detected with two fish cell lines, EPC and CHSE-214, respectively. When polystyrene tissue culture surfaces were incubated with virus, rinsed, and left to dry, they still supported the attachment and spreading of cell lines and after 7 days these cells showed the characteristic CPE of the viruses. Thus cells appeared to be infected directly from surfaces on which viruses had been adsorbed. Applying this property to 96-well plates allowed duplicate surfaces to be examined for their infectiousness or support of CPE. For each treatment 80 replicate surfaces in a 96-well plate were tested at one time and the results expressed as the number of wells showing CPE. VHSV adsorbed to polystyrene was inactivated by drying in the dark at temperatures above 14 °C, but remained infectious for at least 15 days of drying at 4 °C. For chemical sterilization of polystyrene surfaces with adsorbed virus, disinfection was achieved with 1-propanol at 40% for VHSV and at 60% for CSV. As CPE can be conveniently monitored in 96-well plates with a fluorescence plate reader, this method can be used to rapidly evaluate a variety of treatments for their ability to inactivate surface-bound viruses.

In vitro skin permeation of hinokitiol loaded in vesicles composed of behenyltrimethylammonium chloride and stearic acid

INTRODUCTION

Behenyltrimethylammonium chloride (BTAC) and stearic acid (SA) could be associated with each other through salt bridges, and the associated BTAC/SA could build bilayer vesicles with the aid of hinokitiol (HKL).

METHOD

The vesicles were prepared by a precipitation method and used to enhance the skin permeation of HKL.

RESULTS

In case the molar ratio of BTAC/SA/HKL was 1/1/0, no vesicle was observed on transmission electron microscope photos. When the molar ratio of BTAC/SA/HKL was 1/1/0.4, vesicle was observed together with some agglomerates. When the content of HKL increased to the ratios of 1/1/0.8 and 1/1/1.2, vesicles were exclusively observed. In vitro fluxes for 18 hours through hairless mouse skin of HKL dissolved in alcoholic solutions were less than 1 mg/cm2/h. Whereas the fluxes of HKL encapsulated in the vesicles were about three times higher than that of HKL in the alcoholic solutions.

CONCLUSION

The vesicles could be used for the hair growth promotion.