Ali Demir Sezer

Chitosan film containing fucoidan as a wound dressing for dermal burn healing: preparation and in vitro/in vivo evaluation.

The aim of this study was to develop chitosan film containing fucoidan and to investigate its suitability for the treatment of dermal burns on rabbits. Porous films, thickness between 29.7 and 269.0 μm, were obtained by the solvent dropping method. Water vapor permeability (3.3–16.6/0.1 g), the swelling (0.67–1.77 g/g), tensile strength (7.1–45.8 N), and bioadhesion (0.076–1.771 mJ/cm2) of the films were determined. The thinnest films were obtained with the lowest chitosan concentration (P<.05). The water absorption capacity of the films sharply increased with the freeze-drying technique. The film having the thickness of 29.7 μm showed the highest amount of moisture permeability (16.6 g/0.1 g). Higher chitosan concentration significantly increased tensile strength of the films (P<.05). Using higher concentration of lactic acid made films more elastic and applicable, and these films were selected for in vivo studies. Seven adult male New Zealand white rabbits were used for the evaluation of the films on superficial dermal burns. Biopsy samples were taken at 7, 14, and 21 days after wounding, and each wound site was examined macroscopically and histopathologically. After 7 days treatment, fibroplasia and scar were observed on wounds treated with fucoidan-chitosan film. The best regenerated dermal papillary formation, best reepithelization, and the fastest closure of wounds were found in the fucoidan-chitosan film treatment group after 14 days compared with other treatment and control groups. It can be concluded that fucoidan-chitosan films might be a potential treatment system for dermal burns and that changing formulation variables can modulate the characterizations of the films.

Topical drug delivery using chitosan nano- and microparticles

Introduction: Topical drug delivery offers important benefits for improving the therapeutic effect and reducing systemic side effects of the administered compounds. In addition, utilization of biopolymeric material-based systems can play a key role in developing new topical dosage forms and their applications. This review describes the advances that have been made, new strategies and as well as possible challenges of particular systems of chitosan used in topical drug delivery, including challenging innovations in topical usage of these systems that can make significant impact on clinical practice. Areas covered: The main area covered is hypothesis that particulate carriers based on chitosan and its derivatives can penetrate the topical barriers from the body. For this reason, the novel studies described emphasize the fact that chitosan-based particular systems are popular that can be tailor-made according to in vitro and in vivo characterization. Such parameters, which are known to influence their in vivo performance, can be modulated by adjusting the formulation conditions of the chitosan-based particular systems for topical application. Expert opinion: The topical application of drugs with particulate systems comprising a natural polymer, chitosan, is one of the most popular drug delivery routes. The aim of topical use of chitosan particles is to improve the drug bioavailability by prolonging the residence time of drugs applied topically or by enhancing the passing of drugs through the epithelial cells by opening the tight junctions between epithelial cells and also to reduce the side effects of the drugs.

Encapsulation of enrofloxacin in liposomes I: preparation and in vitro characterization of LUV.

Liposomes are effectively used in the treatment of microbial infections. Higher cellular uptake has been reported when antibiotics are encapsulated in liposomes. In this study, enrofloxacin (ENF) was encapsulated in large unilamellar vesicles (LUVs) and the effects of formulation variables on the liposome characteristics were investigated. Liposomes were prepared using dry lipid film method. A number of variables such as molar ratios of phospholipid (DPPC; DL‐α‐phosphatidylcholine dipalmitoyl), cholesterol, ENF and amount of α‐tocopherol and the volumes of internal (chloroform) and external phases [phosphate buffered saline PBS (pH 7.4)] were studied. In vitro characterization of the liposomes including the encapsulation capacity, size and drug release properties were carried out. Using of this method, spherical LUV liposomes with high drug content could be produced. Particle size of liposomes changed between 3.12 and 4.95 µm. The molar ratios of DPPC, cholesterol and ENF affected the size of the liposome (p < 0.05). The drug encapsulation capacities were high and changed between 37.1% and 79.5%. The highest ENF encapsulation was obtained with the highest cholesterol content. An increase in the drug encapsulation capacity of the liposome was found with increasing molar ratios of DPPC, cholesterol and ENF (p < 0.05). Furthermore, the release of ENF from the liposomes decreased as the molar ratios of DPPC, cholesterol and ENF increased (p < 0.05). In conclusion, a convenient colloidal carrier for the controlled release of ENF can be prepared by changing the formulation parameters of LUVs.

Gene Delivery Systems: Recent Progress in Viral and Non-Viral Therapy

Thanks to the changes in medicine, pharmacological treatment rapidly progresses into new fields. There is an emphasis on the development of treatment methods to eliminate underlying factors rather than to treat the symptoms of a disease. Therefore, research is increasingly utilizing knowledge from the field of genetics. Genetic mutation and deletion lead to many genetic disorders. Genetic disorders in metabolic pathways, regulation of cell cycle, ligand/receptor function, cell skeleton and extracellular proteins cause serious diseases (Yaron et al., 1997).

Development and characterization of vancomycin-loaded levan-based microparticular system for drug delivery

Abstract Encapsulation of vancomycin (VANCO) into biodegradable levan microparticles was achieved using a simple preparation technique. Microparticles were prepared by using levan polysaccharide produced by a halophilic bacterium Halomonas smyrnensis AAD6T. To optimize efficiency of encapsulation process by precipitation method, three parameters were studied: drug and polymer concentrations and preparation rotating speed. The particles were characterized in vitro. The size of levan microparticles was changed between 0.404 μm and 1.276 μm. The surface charge was detected between +4.1 mV and +6.5 mV. The highest drug encapsulation capacity of the system was 74.7% and was depending on the polymer concentration. In dissolution studies, initial burst effect around 10–20% from all the formulations was observed and then the release was slowed down and continued at a constant level. In vitro antibiotic release from the microparticles was controlled with the drug carrier system and release fit to Higuchi kinetic model. All the released samples collected at different time intervals during dissolution studies have exhibited intrinsic bactericidal activity against Bacillus subtilis ATCC 6633. WST-1 cell proliferation and viability studies showed that VANCO-loaded levan microparticles at concentrations between 100 μg/mL and 1000 μg/mL were nontoxic to L929 cells. As conclusion, levan microparticulate system could be a potential carrier of antibiotic drugs such as VANCO.

Biopolymers as Wound Healing Materials: Challenges and New Strategies

Wound healing is a multi-factorial physiological process. The complexity of this phenomenon makes it prone to several abnormalities. Apart from cellular and biochemical components, several enzymatic pathways also become active during repair and help the tissue to heal. The goal of this chapter is to introduce the biomaterials community to the emerging field of self-healing materials, and also to suggest how one could utilize and modify self-healing approaches to develop new classes of biomaterials. On the other hand, natural and synthetic gel-like materials, films/membranes, composites, micro/nanoparticulate systems have featured heavily in the development of biomaterials for wound healing and other tissue-engineering purposes. Nanofibrous membranes are highly soft materials with high surface-to-volume ratios, and therefore can serve as excellent carriers for therapeutic agents or accelerate wound healing. Biocompatible and biodegradable polymer scaffolds combined with cells or biological signals are being investigated as alternatives to traditional options for tissue reconstruction and transplantation. These approaches are already in clinical use as engineered tissues that enhance wound healing and skin regeneration. This chapter covers the recent reports on the preparation and biomedical applications of biopolymers and biomaterials based on pharmaceutical dosage forms and wound dressing.

In Vitro Evaluation of Enrofloxacin-Loaded MLV Liposomes

Fluoroquinolones are broad-spectrum antimicrobial agents that seem to reach their intracellular target site (DNA gyrase) in Escherichia coli by means of an uptake process through the outer and inner membranes. Delivery of quinolones with liposomes has many advantages than the free form of the drug. Liposomes may represent an excellent device for improving the selective transport of antibiotics in these respects. In this study, enrofloxacin-loaded multilamellar vesicles (MLVs) were prepared and the effects of formulation variables on the liposome characteristics were investigated. Liposomes were prepared by using the dry lipid film method. A number of variables, such as phospholipid (DL-α -phosphatidylcholine dipalmitoyl), cholesterol, enrofloxacin (ENF), stearylamine, and dicetyl phosphate molar ratios and α -tocopherol amounts, were studied. The liposome size, encapsulation capacity, drug release, stability, and electrophoretic mobility of ENF-loaded liposomes were determined. Using this method, spherical MLVs with high drug content could be produced. Particle size of liposomes changed between 1.63 and 3.31 μ m and liposome size was affected by all formulation variables (p < 0.05) except molar ratio of ENF. MLVs can be used as a carrier system for the controlled release of ENF. The highest encapsulation of ENF amount can be obtained using positively charged SA in the formulation and changing the formulation parameters can vary drug release patterns.

The design of biodegradable ofloxacin-based core-shell microspheres: Influence of the formulation parameters on in vitro characterization

Ofloxacin (OFL), second-generation fluoroquinolone, is a broad-spectrum antibiotic which is active against both Gram-positive and Gram-negative bacteria. However, OFL has a short biological half life (8–9 h) and poor stability in serum and needs frequently repeated doses during the treatment. The objective of this study was to fabricate the fucospheres and chitosan microspheres containing a poorly soluble drug, OFL, and to compare the formulation parameters influencing the in vitro properties of microparticles such as size, zeta potential, encapsulation efficiency and drug release characteristics. Particle size of fucospheres and chitosan microspheres has been found to be 0.61–1.48 µm and 1.05–2.08 µm, respectively. The zeta potentials have changed between 5.6 mV and 28.0 mV for fucospheres; 22.3 mV and 42.4 mV for chitosan microspheres. The fucospheres have had higher drug encapsulation efficiency than those of chitosan microspheres. The particle size, surface charge, encapsulation efficiency and in vitro drug release from both fucospheres and chitosan microspheres have been affected by type and concentration of the polymers used. The release mechanism from most of the microsphere formulations has been fitted to Higuchi kinetic model. It can be concluded that OFL-encapsulated fucospheres can be a potential delivery system for antibiotics.

Fucoidan: A Versatile Biopolymer for Biomedical Applications

Fucoidan is a natural, anionic sulfated polysaccharide extracted from brown marine algae with a wide variety of pharmacological features like anti-inflammatory, anti-oxidative, anticoagulant and antithrombotic effects. Fucoidan has been extensively studied for last decade due to its numerous interesting biological activities. In recent years, the research on drug and gene delivery systems, diagnostic microparticles and wound and burn healing formulations of fucoidan has been increasing in course of time. This review gives an overview about the research of concerning structural characterization and biological activity of fucoidan; application of fucoidan-based systems in pharmaceutical field for drug and DNA delivery and in biomedical area for wound and burn treatment.

Future prospects for gene delivery systems

ABSTRACT Introduction: Gene therapy is the challenging area of biotechnology. Despite its promise for critical diseases, it has serious safety and efficiency issues, particularly with regards to gene transfer systems. Areas covered: We examined the current situation with gene transfer systems and addressed problems this technology. We then searched patent applications about in the area from the Patentscope online system, the international patent database. We analyzed the data obtained to get a general idea about gene delivery systems designed for future use and assessed approaches for more efficient, safer and valid delivery systems. Expert opinion: When quality assurance terms are fulfilled, some of these issues (genetic changes, mutations) could be minimized during the production process. Modification of vectors for improving their efficiency and safety or development of alternative transfer systems could be the solutions for these problems. Gene transfer technologies are important for gene therapy and should demonstrate effective, target-specific and acceptable safety profiles. For this reason, searching for alternatives to current systems is a necessity.