1. State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics & Center for Molecular Imaging and Translational MedicineSchool of Public HealthXiamen University Xiamen 361102 China
2. College of MaterialsXiamen University Xiamen 361005 China
3. Laboratory of Molecular Imaging and NanomedicineNational Institute of Biomedical Imaging and Bioengineering (NIBIB)National Institutes of Health (NIH) Bethesda MD 20892 USA