DOTA-GA-maleimide Acetate is a bifunctional chelator with protein conjugation and radiometal chelation capabilities. DOTA-GA-maleimide Acetate forms stable complexes with 111In and conjugates with proteins via maleimide chemistry. DOTA-GA-maleimide Acetate conjugates with LFn, enabling 111In radiolabeling of LFn through direct or pre-labeling strategies. Radiolabeled LFn is applicable to MMP activity imaging studies. DOTA-GA-maleimide Acetate is used in cancer research.