Universal and facile synthesis of multicolored upconversion hollow nanospheres using novel poly(acrylic acid sodium salt) microspheres as templates

A novel, fast and simple method was developed to fabricate poly(acrylic acid sodium salt) microspheres (PAAS MSs). The resulting PAAS MSs were utilized as active templates to universally synthesize the mesoporous lanthanide-doped gadolinium oxide hollow nanospheres with multicolored upconversion emissions under mild conditions.