Zirconium-based metal-organic framework composite synthesis and use in drug release systems

Controlled drug release systems are constructed by combining an organic or inorganic material and a drug active ingredient in such a way that it is released from its designed matrix in the expected profile. In order to delay the release kinetics, the drug loaded carrier system can be improved by using coating materials. Tetracycline (TC) is classified as a protein synthesis inhibitor and broad spectrum antibiotic used to treat various bacterial infections. Controlled release by utilizing biocompatible materials to prevent toxic levels in the blood caused by frequent intake is a frequently studied area. Hydroxyapatite (HAp) is a bioceramic material that is also found in the tooth structure, which is widely used for medical purposes. HAp, which is the hydroxyl form of calcium phosphate, is involved in adsorption processes due to its ability to contain many functional structures. By being modified with various advanced material derivatives, it is evaluated as a sorbent material in the drug loading stage and plays a role in drug release as a drug carrier component. Metal-organic frameworks (MOFs) are a material class preferred in many fields today due to their large surface area, superior porous form and functional structure due to many components. MOFs containing biocompatible metals are frequently used in drug delivery systems. Zirconium-based metal-organic cages (Zr-MOFs) are preferred in drug delivery systems due to their low toxicity and excellent biocompatibility. These structures can be coated with hydrogel systems and can deliver the drug they carry to the target shadow in a controlled manner with a much slower kinetics. The gel-forming property of alginates has been widely utilised to develop many useful hydrogel systems for different biomedical applications, including drug delivery. Sodium alginate (SA) particles swell to form a diffusion barrier that slows the passage of drug molecules. In this thesis, four different composites were prepared for TC adsorption by doping Zr-MOF structures at different mass ratios (10%, 30% and 50%) on the HAp surface. The 30Zr-MOF/HAp composite showed the most superior adsorption performance and the maximum monolayer adsorption capacity was 188.68 mg g-1. The equilibrium experimental results of the adsorbents were in accordance with the Langmuir isotherm model. In the next steps, time effect, pH effect and temperature effect on TC adsorption of 30Zr-MOF/HAp composite adsorbent were investigated. The time to equilibrium was 300 min and the fitting model was determined as a pseudo-second order kinetic model. The TC adsorption performance, which showed a significant decrease below pH: 3.0, was attributed to the electrostatic repulsion of the surface and TC molecules. In terms of adsorption thermodynamics, it is concluded that it is an endothermic and spontaneous process. In accordance with the optimised TC loading procedure, 30Zr-MOF/HAp composites were bulk loaded. Then, they were coated with SA at 10%, 30% and 50% by mass and formed into tablets. The release performance of the prepared tablets was analysed in artificial gastric and intestinal media solutions. 30SA-TC@30Zr-MOF/HAp exhibited the longest release profile with 78 and 63 hours in gastric and intestinal media, respectively. While the Korsmayer-Peppas kinetic model was consistent in the gastric environment, the zeroth order kinetic model was consistent in the intestinal environment. The structures of the prepared adsorbents and tablets were investigated by various characterisation analyses and the results were supported by physicochemical data.