Drug-delivery and multifunction possibilities of hypocrellin photosensitizers

Abstract

Photodynamic therapy (PDT) has been a routine treatment of tumors and some microvascular diseases, but clinically available photosensitizers are still scarce. Among all kinds of photosensitizers, hypocrellins possess the most characteristics of ideal photosensitizers, such as, high photo-activity but low dark toxicity, fast clearance from tissues. This review is focused on two main topics, drug-delivery problem of hypocrellins and how the environment-sensitive°uorescence of hypocrellins was used for recognition of various biomolecules. Drug-delivery of hypocrellins was mainly achieved in two strategies -preparing the drug-delivery vehicles and¯nding quantitatively amphiphilic derivatives. Hypocrellin°uorescence originated from the intramolecular proton transfer is very distinct from other kinds of photosensitizers. Recently, it was proved that quantitative hypocrellin°uorescence could not only recognize various biomolecules, including proteins, polysaccharides and lipids, but also distinguish the speci¯c binding from nonspeci¯c binding with some kind of biomolecules. Meantime, hypocrellin°uorescence was pH-sensitive. It is known that tumor cells or tissues have the features of a large amount of lipid, neonatal collagen, over-expression of polysaccharides, and lower pH values compared to normal tissues. According to the relative but not absolute speci¯city, further studies on quantitative recognition of various biomolecules at a cellular level, may¯nd a new clue to treat tumors by joint usage of photodynamic diagnosis (PDD) and PDT.

Editorial

“…3 As a promising PS for PDT, Deng et al summarize the available drug delivery systems for hypocrellins A and B and discuss how the environment-sensitive°uorescence of this class of PS can be used for the recognition of various biomolecules in photodynamic diagnosis. 4 In a study of PDT dosimetry, the Guest Editors and their colleagues report on the correlation between in vivo tumor response and near-infrared luminescence measurements of singlet oxygen ( 1 O 2 ) generated during meso-tetrahydroxyphenylchlorin (mTHPC)-mediated PDT in an animal model comprising luciferase-and green°uorescent protein-transduced gliosarcoma grown in a dorsal window chamber. The results clearly show the correlation between the bioluminescence-based PDT response and the volume-averaged Since PDT is inevitably subject to intrinsic cancer resistance at the cellular and molecular levels via drug e®lux, hypoxia, levels of pigmentation and repair mechanisms, Huang et al in Fuzhou, China review the recent progress in understanding the interaction between multidrug resistance (MDR) transporters and PS uptake.…”