Polyethylene Glycol-Poly D,L-Lactide

3 Poly(D,L-lactide)-Polyethylene Glycol-Poly(D,L-lactide) 

Bone is a natural composite comprised of type I collagen and calcium phosphate minerals, of which nanocrystalline apatite is the main component [39, 40]. Certain osteoconductive bioceramics exert an effect on bone cell attachment and growth factor binding or release, and can accelerate the treatment of bone defects [41-43]. Polymer composite scaffolds can be produced, via electrospinning, which contain a specific amount of electrical charge in order to form non-woven fibrous meshes with fibre dimensions in the nano- to microscale [44-46]. 

HMS have been chemically modified using (3-aminopropyl)triethoxysilane (APTES). A solution (30 ml) of HMS (0.1 g) and APTES (2 ml) was prepared in toluene. In fact, APTES, an aminosilane, can be used in the silanisation process to functionalise the HMS surfaces with alkoxysilane molecules. APTES can also be used to covalently bond thermoplastics to polydimethylsiloxane (PDMS). APTES-functionalised HMS surfaces have been shown to be non-toxic to embryonic rat cardiomyocytes in vitro. In this study, the resulting magnetite/silicon particles were washed with ethanol and then dried under vacuum at 60 C for 24 h [57]. The obtained amine-functionalised HMS (HMS-NHi) were dispersed by ultrasound in toluene (30 ml). Another modification involved D,L-lactide (0.4 g) and PEG (0.1 g), which were placed into a three-neck round-bottom flask containing a magnetic stirrer. The catalyst, Sn(Oct)2, was added to the flask at a concentration of 0.1% of the solution the flask was put into an oil bath to react for 24 h at 110 C in nitrogen under ambient conditions [58]. 

To remove PLA-PEG, the resulting product was first dissolved in dichloromethane and petroleum ether was then used to rinse off the catalyst. The final product was then placed under vacuum at room temperature (RT) and dried for 48 h. However, a little cytotoxicity was observed for HMS at a concentration higher than 800 pg/ml and HMS PEG-PLA at a concentration higher than 400 pg/ml. In addition, the cell viability decreased due to the reduced survival capacity of the cells. 

Overall, HMS PEG-PLA displayed no obvious cytotoxicity which could adversely affect humans and should be considered as a candidate for biological applications 

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Yamamoto, Y, Y. Nagasaki, Y. Kato, Y. Sugiyama, and K. Kataoka (2001). Long-circulating polyethylene glycol)-poly(D-L-lactide) block copolymer micelles with modulated surface chacfcjdSontrolled Release, 77 27-38. 

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