NOTA-NHS ester is a chelating agent. NOTA-NHS ester can be coupled with T140 (HY-P4810) to produce NOTA-T140. NOTA-T140 can be radiolabeled with Al[18F]. The uptake of Al[18F]NOTA-T140 in tumors is correlated with the expression level of CXCR4. Al[18F]NOTA-T140 can be used in tumor PET imaging studies. NOTA-NHS ester can be used for fluorescent labeling[1][2][3].