A polymeric prodrug for non-invasive, real-time reporting drug release based on “turn-on” fluorescent probes

Non-invasive monitoring of the in situ drug release in a real-time manner is crucial for the clinical cancer treatment. In this work, a polymeric prodrug, P(HPMA-co-(CPT-SS-CyN)), composed of N-(2-hydroxypropyl) methacrylamide (HPMA) and a functional monomer (a near-infrared fluorescent cyanine-amine dye (CyN) and camptothecin (CPT) linked by disulfide bond) was reported for the non-invasive and real-time reporting drug release. The cleavage of the disulfide bond intracellularly could lead to the release of free CPT as well as the blue shift of the dye (CyN conjugated polymer), enabling facile monitoring of the drug release. Moreover, the percentage of the released drug showed a linear correlation with the normalized increase in the fluorescence intensity, which can be further used for the quantification of the local drug concentration. In vitro cell study showed that the fluorescence intensity gradually increased with the prolongation of incubation time, and P(HPMA-co-(CPT-SS-CyN)) exhibited the same inhibition efficiency of tumor cell proliferation as CPT. This work may guide researchers for the precise design and development of various pharmaceutical formulations. [Display omitted] •A functional polymeric prodrug, P(HPMA-co-(CPT-SS-CyN)), featuring in situ monitoring and quantification of drug release and inhibition of tumor cell proliferation was designed and prepared.•Introduction of reducing agent into P(HPMA-co-(CPT-SS-CyN) could induce the simultaneous release of CPT and NIR dye as well as over 30 times increasement in the fluorescence intensity.•The percentage of the released drug showed a linear correlation with the normalized increase in the fluorescence intensity.•P(HPMA-co-(CPT-SS-CyN) exhibited the same inhibition efficiency of tumor cell proliferation as CPT.