Şükran Melda ESKİTOROS TOĞAY, Ulya TOKGOZ

SURFACE MODIFIED TITANIUM DIOXIDE/POLY (LACTIC ACID) NANOCOMPOSITE FILMS FOR TISSUE ENGINEERING

Objective This study aims to synthesize and characterize the nanocomposite films incorporating unmodified and modified nanoparticles within the poly(lactic acid) matrix, and to investigate their usage as an alternative scaffold for tissue engineering. Materials and Methods Titanium dioxide (TiO2) nanoparticles were firstly grafted by L-lactic acid oligomer (LA-g-TiO2) and the mixture of propionic acid/hexylamine (AA-g-TiO2), respectively. Then the unmodified and modified nanoparticles were incorporated within the poly(lactic acid) matrix via the solvent casting method to produce the PLA/TiO2, PLA/LA-g-TiO2, and PLA/AA-g-TiO2 nanocomposite films. The chemical, thermal and mechanical structures of these synthesized films were subsequently characterized. Results The attenuated total reflectance (ATR) results demonstrated that the surface modification of the nanoparticles was accomplished. The results of differential scanning calorimeter (DSC) analysis showed that the crystallization of the PLA was partly increased by the incorporation of modified nanoparticles. The results of thermogravimetric analysis (TGA) showed that the addition of LA-g-TiO2 into the polymer matrix improved the thermal stability of PLA/LA-g-TiO2 nanocomposite film more than the addition of AA-g-TiO2 into the polymer matrix. The first and second decomposition temperatures of the nanocomposites containing LA-g-TiO2 were 348.3 oC and 392 oC, respectively, which were 6% greater than those of the neat PLA. The micrograph of atomic force microscopy (AFM) of the nanocomposites indicated that LA-g-TiO2 and AA-g-TiO2 were homogeneously dispersed in polymer matrices. The results of dynamic mechanical analysis (DMA) demonstrated that the most efficient bonding and compatibility were obtained in PLA/LA-g-TiO2 nanocomposite compared to the other nanocomposites. Conclusion These grafted nanoparticles, LA-g-TiO2 and AA-g- TiO2, enhanced the thermal and mechanical properties of the nanocomposites owing to their uniform distribution in the matrix and good interactions with the polymeric matrix. Therefore, these nanocomposites can be utilized as alternative scaffolds in bone tissue engineering.

DOKU MÜHENDİSLİĞİ İÇİN YÜZEYİ MODİFİYE EDİLMİŞ TİTANYUM DİOKSİT/POLİ (LAKTİK ASİT) NANOKOMPOZİT FİLMLER

Amaç Bu çalışmanın amacı, poli(laktik asit) matrisi içerisinde modifiye edilmemiş ve modifiye edilmiş nanopartiküller içeren nanokompozit filmleri sentezlemek, karakterize etmek ve doku mühendisliğinde alternatif bir yapı iskelesi olarak kullanımlarını araştırmaktır. Gereç ve Yöntem İlk olarak, titanyum dioksit (TiO2) nanopartikülleri sırasıyla L-laktik asit oligomeri (LA-g-TiO2) ve propiyonik asit/heksilamin (AA-g-TiO2) karışımı ile aşılanmıştır. Daha sonra, PLA/TiO2, PLA/LA-g-TiO2 ve PLA/AAg- TiO2 nanokompozit filmleri üretmek için modifiye edilmemiş ve modifiye edilmiş nanopartiküller solvent döküm yöntemi ile poli (laktik asit) matrisi içine eklenmiştir. Sentezlenen bu filmlerin kimyasal, termal ve mekanik yapıları daha sonra karakterize edilmiştir. Bulgular Azaltılmış toplam yansıma (ATR) sonuçları, nanopartiküllerin yüzey modifikasyonunun başarılı olduğunu göstermiştir. Diferansiyel tarama kalorimetresi (DSC) analizinin sonuçları, modifiye edilmiş nanopartiküllerin dahil edilmesiyle PLA’nın kristalleşmesinin kısmen arttığını göstermiştir. Termogravimetrik analizin (TGA) sonuçları, polimer matrisine LA-g-TiO2 eklenmesinin, PLA/LA-g-TiO2 nanokompozit filmin termal stabilitesini, polimer matrisine AA-g-TiO2 ilavesinden daha fazla geliştirdiğini göstermiştir. LA-g-TiO2 içeren nanokompozitlerin birinci ve ikinci bozunma sıcaklıkları sırasıyla 348.3 oC ve 392 oC, saf PLA’nınkinden %6 daha yüksektir. Nanokompozitlerin atomik kuvvet mikroskobu (AFM) mikrografı, LA-g-TiO2 ve AAg- TiO2 nanopartiküllerin polimer matrislerde homojen olarak dağıldığını göstermiştir. Dinamik mekanik analiz (DMA) sonuçları, diğer nanokompozitlere kıyasla PLA/LA-g-TiO2 nanokompozitinde en verimli bağlanma ve uyumluluğun elde edildiğini göstermiştir. Sonuç Aşılanmış nanopartiküller, LA-g-TiO2 ve AA-g-TiO2, matris içindeki homojen dağılımları ve polimerik matris ile iyi etkileşimleri sayesinde nanokompozitlerin termal ve mekanik özelliklerini iyileştirmiştir. Bu nedenle, bu nanokompozitler kemik doku mühendisliğinde alternatif doku iskeleleri olarak kullanılabilir.

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