Evaluation of nystatin containing chitosan hydrogels as potential dual action bio-active restorative materials: in vitro approach.

Healing is a specific biological process related to the general phenomenon of growth and tissue regeneration and is a process generally affected by several systemic conditions or as detrimental side-effects of chemotherapy- and radiotherapy-induced inflammation of the oral mucosa. The objectives of this study is to evaluate the novel chitosan based functional drug delivery systems, which can be successfully incorporated into "dual action bioactive restorative materials", capable of inducing in vitro improved wound healing prototype and containing an antibiotic, such as nystatin, krill oil as an antioxidant and hydroxyapatite as a molecular bone scaffold, which is naturally present in bone and is reported to be successfully used in promoting bone integration when implanted as well as promoting healing. The hydrogels were prepared using a protocol as previously reported by us. The physico-chemical features, including surface morphology (SEM), release behaviors, stability of the therapeutic agent-antioxidant-chitosan, were measured and compared to the earlier reported chitosan-antioxidant containing hydrogels. Structural investigations of the reactive surface of the hydrogel are reported. Release of nystatin was investigated for all newly prepared hydrogels. Bio-adhesive studies were performed in order to assess the suitability of these designer materials. Free radical defense capacity of the biomaterials was evaluated using established in vitro model. The bio-adhesive capacity of the materials in the in vitro system was tested and quantified. It was found that the favorable synergistic effect of free radical built-in defense mechanism of the new functional materials increased sustainable bio-adhesion and therefore acted as a functional multi-dimensional restorative material with potential application in wound healing in vitro.

IPNs from Cyclodextrin:Chitosan Antioxidants: Bonding, Bio-Adhesion, Antioxidant Capacity and Drug Release.

IPNs are unique "alloys" of cross-linked polymers in which at least one network is synthesized and/or cross-linked in the presence of the other. IPNs are also known as entanglements of polymer networks that are ideally held together only by permanent topological interactions. The objectives of this study are to evaluate novel chitosan-based functional drug delivery systems that can be successfully incorporated into "dual action bioactive tooth restorative materials". These materials should be capable of inducing an improved wound healing prototype. The novel hydrogels will be investigated with respect to the antioxidant capacity of conventional antioxidants, such as resveratrol, b-carotene and propolis, as a designer drug delivery system, with the use of SEM imaging for the characterization of the surfaces, bio-adhesive property, antioxidant capacity, free radical defence, antioxidant, active ingredient stability and reactive features of novel materials. The additional benefit of the site-specific "functional restorative material" for use in dressings to deliver antibiotics to wound sites can provide tissue compatibility and reduced interference with wound healing. The materials were tested using an effective in vitro free radical generation model as functional additive prototypes for further development of "dual function restorative wound healing materials". We quantified the effects of functional designer biomaterials on the dentin bond strength of a composite and evaluated the bio-adhesive capacity of the materials in the two separate "in vitro" systems. The added benefits of the chitosan/vitamin C/cyclodextrin (CD) host:guest complex-treated hydrogels involved a positive influence on the tetracycline release, increased dentin bond strength, as well as a demonstrated in vitro "built-in" free radical defence mechanism and, therefore, acting as a "proof of concept" for functional multi-dimensional restorative wound healing materials with a built-in free radical defence mechanism. Based on our results, we can conclude that the CD:chitosan-antioxidant-containing hydrogels are a suitable carrier for tetracycline to be slow-released. Within the limitations of the study design, chitosan-based hydrogels are suitable materials for functional restorative and wound healing applications in vitro. Cytotoxicity data are currently being evaluated in our laboratory.

Chitosan and gelatin based prototype delivery systems for the treatment of oral mucositis: from material to performance in vitro.

In this study we developed and evaluated a prototype of an effective occlusive mucoadhesive system for prophylaxis and/or treatment of oral mucositis based on chitosan and gelatine models together with nystatin as a prophylactic agent incorporated into the formulation and investigated drug release in-vitro. Results of in vitro studies showed that chitosan and gelatine based gels posses properties that makes them excellent candidates for treatment of oral mucositis. These properties include not only the palliative effects of an occlusive dressing but also the potential for delivering therapeutic compounds with chitosan gels providing drug concentrations above their minimum inhibition concentration and extending the retention time in the oral cavity due to their bioadhesive properties. Chitosan also offers an advantage over suspensions because of its inherent antimicrobial properties. The performance of gelatin-based gels highlights the novel, non-toxic, in situ forming gelatine based hydrogel. The results of in vitro drug release experiments demonstrated that all the hydrogel showed sustained release properties.

On the modeling of arginine-bound carboxylates: a case study with Pyruvate Formate-Lyase.

High level ab initio and density functional calculations have been employed to determine the most appropriate manner in which to truncate an arginine-bound carboxylate motif, using the substrate mechanism of Pyruvate Formate-Lyase as a case study. The results show that, both qualitatively and quantitatively, a neutral carboxylic acid provides a more realistic approximation to the salt bridge arrangement than does a bare anionic carboxylate substituent.