ENHANCEMENT OF AMYLOSE ESTERS DEGRADATION RATE BY INCORPORATION OF CATALYTIC GROUPS

• Main Author: Herlianty Stefanus, Devi
• Format: Theses
• Language: Indonesia
• Subjects: Kimia
• Online Access: https://digilib.itb.ac.id/gdl/view/35403
• Institution: Institut Teknologi Bandung

Metallic bone plates have been used to repair bone fractures in humans for many years. This material was very successful, but they have some disadvantages. A major drawback is the fact that a second operation is required to remove the plates after healing. Therefore, metallic bone plate has to be replaced by biodegradable materials. Some of these materials have been investigated for temporary bone plates. Commercially available degradable bone plates and screws are made mostly of poly lactic acid. This material, however, has the problem of crystallization of segments, leading to non-degradable remnants, and in case of non-crystallizable co-polyesters of D- and L-lactic acid, a lack of suitable mechanical properties is observed. In this study, we look for other alternative materials that can be used as bioresorbable bone plates. The materials that hopefully can fulfill all the requirements are based on amylose derivatives. Amylose, a linear poly (1,4-?-glucoside) from natural sources, is a hydrophilic, non-processable polymer, similar to cellulose. In contradiction to cellulose, however, it is readily degraded in the human body due to the presence of compatible enzymes producing glucose, which later can be metabolized easily. One of the derivates is Amylose triacetate, a processable but almost non degradable polymer with excellent mechanical properties. Lowering the degree of substitution of the amylose, results in more hydrophilic polymers with, hopefully gives the optimal properties for biodegradable bone plates. Here, amylose was reacted with monochloroacetic acid to produce carboxymethylamylose (CMA). This carboxylic acid is meant to catalyze the degradation process. From 1H-NMR results, it appeared that this polymer has a carboxylic acid group attached to C-2 in the amylose ring and a degree of substitution of around 0.38. Then, CMA was reacted with acetic anhydride with different concentrations to produce carboxymethylamylose-acetate (CMA-Ac) with varying degrees of substitution of acetate (DSac) between 1.91 to 2.64. Besides using carboxylic acid as internal catalytic group, we also try to use bases that hopefully can catalyze the degradation process. Amylose was reacted with chloropropylamine that protected using di-tert-butyl dicarbonate (Boc¬2O) to produce aminopropylamylose-Boc (APA-Boc). The next process was acetylation of APA-Boc to gain aminopropylamylose-Boc acetate (APA-Boc-Ac). The last step was deprotecting Boc group so the last result that reached is aminopropylamylose acetate (APA-Ac). The synthesized polymers were characterized by ATR-FTIR, 1H Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimetry (DSC), and Thermal Gravimetric Analysis (TGA). It appeared that these materials were processable with glass transition temperatures around 163°C and showed no sign of crystallization. Compression molding at 180°C of these materials gave excellent plastic test bars. The test bars were placed in phosphate buffered saline (PBS) and NaN3 at 37°C for degradation tests. The degradation process is monitored by the weight loss, degree of swelling, and ATR-FTIR every week in 2 months. From the degradation test it appeared that CMA-Ac with low DSac has a higher degree of swelling and weight loss than CMA with high DSac. Besides that, the value of weight loss from CMA-Ac is higher than APA-Ac. The carboxylic acid group that attached to the glucopyranose ring of amylose was definitely enhanced the polymer degradation process as shown by the higher degree of swelling and weight loss of CMA-Ac than the amylose acetate itself.