Aptamer-mediated active targeted molecularimaging probe is vital for cancer diagnosis and therapy.However,there are several drawbacks of aptamershould be considered in vivo application,such as susceptibility to biodegradation,short blood residence time.Our previous studies found D-/L-isonucleotideendowedwith the ability of modulating localconformation of nucleotides,which isa type ofnucleoside isomer in which the base is shifted to 2-positions of theglycosyl group,can alleviate these problems.