LAUSR

Photodynamic antifungal therapy is a promising treatment for increasing drug-resistant fungi. However, low physiological solubility and low fungi-affinity of most potential photosensitizers limits their therapeutic efficacy. To improve the water-solubility and photodynamic antifungal activity of zinc(II) phthalocyanine, two molecular-weight carboxymethyl chitosans (CMC1,50 kDa; CMC2,170 kDa) were herein respectively conjugated with 1-[4-(2-aminoethyl)phenoxy] zinc(II) phthalocyanine (ZnPcN) and further quaternized, and eight novel conjugates were obtained and characterized. Their photophysical and photochemical properties, cellular uptakes and in vitro photodynamic antifungal activities against Candida albicans have also been investigated. All the conjugates are less aggregated in water than ZnPcN. The low-molecular-weight CMC1-conjugated ZnPcN is more readily ingested and highly photoactive. Mainly due to its highest uptake by Candida cells, a conjugate of CMC1 and ZnPcN shows the highest photocytotoxicity with an IC90 value down to 0.72 μM. Further quaternization decreases the photocytotoxicity. Additionally, the conjugates show special affinity to the mitochondria of C. albicans.