Preparation of pH-responsive dendrimer connected polymeric materials and use in biomedical field

In this thesis, for use in controlled drug release studies, polyamidoamine (PAMAM) and polyester (PEs) dendrimers which are bound to microcrystalline cellulose (MKS) and polyvinyl alcohol (PVA) main chain have been synthesized and the release of 5- aminosalicylic acid (5–ASA) used as active ingredient in the treatment of ulcerative colitis has been investigated at different pH. Medicines with the active ingredient 5–ASA are among the drugs in the treatment of active ulcerative colitis that need to be taken 6 times a day and total 3-4 grams daily dose for lifetime. In the present study was to provide long-term controlled release of 5–ASA in the intestinal tract and to decrease the daily dose and to provide patient comfort by prolonging the intake period. For this purpose, –NH2 functional PAMAM and –OH functional polyester dendrimers were synthesized by convergent and divergent methods on MKS and PVA main backbone in different generations. The release of 5–ASA in the cavitations of each generation of dendrimers was investigated conditions of in-vitro which the digestive system was in accordance with the physiological pH (3.5; 7.4 and 8.5) of the stomach, small intestine, and large intestine. While 5–ASA release from both PAMAM and ester dendrimers was below 50% at pH 3.5, it was seen that 5–ASA release was increased by shifting the pH to the basic region. As the number of generation of dendrimers increased, the amount of 5– ASA released was also found to be increased. This is due to the increase in the amount of 5– ASA in cavitations due to the increased dendrimer generation number.The increase of the release with the increase of the pH is stem from the weakening of the hydrogen bonds between guest and host due to the deprotonation of the 5–ASA acid group. Characterization of the synthesized compounds within this study was carried out with FT-IR, 1H NMR, TGA–DSC, SEM, XRD techniques and 5–ASA release studies were performed with UV-vis.