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Clinical and Translational Medicine
Fig. 3 | Clinical and Translational Medicine

Fig. 3

From: Analyses of repeated failures in cancer therapy for solid tumors: poor tumor-selective drug delivery, low therapeutic efficacy and unsustainable costs

Fig. 3

(Figures were adapted from Refs. [99, 122] with permission)

Superiority of macromolecular photosensitizer: a polymer (HPMA)-conjugated zinc protoporphyrin (ZnPP) and b bovine serum albumin (BSA)-conjugated rhodamine. Fluorescence shows as visible only in tumors (a) and (b) (T marks). However, when both low MW photosensitizer, free ZnPP (aʹ), and free tetramethylrhodamine (bʹ) in tumor-bearing mice are injected iv, no tumor selective fluorescence image was visible. Macromolecules, namely polymer-(HPMA) ZnPP and BSA-rhodamine with apparent MWs about 50–70 kDa, respectively, selectively accumulated in tumors, because of the EPR effect, as shown by in vivo fluorescent imaging system; Contrary to above, free ZnPP and free rhodamine, with MWs less than 1000 Da, showed little tumor uptake (aʹ, bʹ). c Demonstrates therapeutic effect of PDT-treatment using polymeric ZnPP and endoscopic xenon light irradiation. Tumors used were chemically (diaminobenzene[α]anthracene) induced breast cancer in rats. Polymer-ZnPP alone or light irradiation alone respectively has no therapeutic effect [99, 122]

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