This study was performed to identify the calcium phosphate minerals, chemical element and Ca/P ratio and to examine the surface structure of autogenous tooth bone grafting material (AutoBT) which recently developed and applied clinically as a bone graft materials. The analytical results showed that AutoBT is composed of low-crystalline hydroxyapatite (HA) and possibly other calcium phosphate minerals, which is similar to the minerals of human bone tissues. And the dental crown portion was composed of high-crystalline calcium phosphate minerals (mainly HA) with higher Ca/P ratio while the root portion was mainly composed of low-crystalline calcium phosphates with relatively low Ca/P ratio.

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Piston and screw type extruders were used to prepare calcium phosphate blocks comprising macro-pores interconnected with micro-pores for bone substitutes and scaffolds. First, dicalcium phosphate dehydrate (DCPD, CaHPO 4 ·2H 2 O), calcium nitrate tetrahydrate (CN, Ca(NO 3 ) 2 ·4H 2 O), hydroxyapatite (HAp, Ca 10 (PO 4 ) 6 (OH) 2 ), and polymer (poly-methyl methactrylate PMMA, (C 5 O 2 H 8 ) n ) beads were mixed with lubricants and a plasticizer to make a paste using a table mixer. The paste prepared for the screw extruder was thicker than that prepared for the piston extruder. The pastes were kneaded more than three times and then extruded. The extruded rods were dried at 100 o C for 24hrs and sintered at 1250 o C for 5hrs in the air. The porosity increased with increasing amount of DCPD and CN in both systems. The porosity of the piston extruded rod was higher than that of the screw extruder rod for the same raw material composition, except for the pure HAp porous bodies. In contrast to the porosity, the compressive strength was decreased upon the addition of DCPD and CN. The screw extruded specimens showed higher compressive strength than piston extruded ones. The macro-pores generated from the PMMA polymer beads were interconnected by micro-pores generated by the reaction of DCPD and CN, which existed in the strut. The SEM images clearly showed that the piston extruder generated more micro-pores than the screw extruder. The reaction of DCPD and CN affects the porosity, compressive strength and pore structure of the porous blocks. Also, the extruding method affects the pore characteristics.

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Chemo-biological upcycling of poly(ethylene terephthalate) (PET) developed in this study includes the following key steps: chemo-enzymatic PET depolymerization, biotransformation of terephthalic acid (TPA) into catechol, and its application as a coating agent. Monomeric units were first produced through PET glycolysis into bis(2-hydroxyethyl) terephthalate (BHET), mono(2-hydroxyethyl) terephthalate (MHET), and PET oligomers, and enzymatic hydrolysis of these glycolyzed products using Bacillus subtilis esterase (Bs2Est). Bs2Est efficiently hydro-lyzed glycolyzed products into TPA as a key enzyme for chemoenzymatic depolymerization. Furthermore, catechol solution produced from TPA via a whole-cell biotransformation (Escherichia coli) could be directly used for functional coating on various substrates after simple cell removal from the culture medium without further purification and water-evaporation. This work demonstrates a proof-of-concept of a PET upcycling strategy via a combination of chemo-biological conversion of PET waste into multifunctional coating materials.