1. a Faculty of Science, Department of Chemistry, Biomedical Polymers Technology Unit , Chiang Mai University , Chiang Mai , 50200 , Thailand
2. b Faculty of Science , Materials Science Research Center, Chiang Mai University , Chiang Mai , 50200 , Thailand
3. c Department of Chemical Engineering and Applied Chemistry, Biomaterials Research Unit , School of Engineering and Applied Science, Aston University , Birmingham , B4 7ET , UK