Conductive Polymer-Chloroplast Living Material with Enhanced ROS Generation for Tumor Treatment

A new antitumor treatment based on conjugated polymer/chloroplast biological hybrid material was proposed in this study, in which the conjugated polymer PBF (poly(boron-dipyrromethene-co-fluorene)) with a positive side chain charge could be electrostatically combined with negatively charged chloroplast. The successful combination of conjugated polymer PBF and chloroplast was demonstrated by the UV-Vis absorption spectra, the zeta potentials, and isothermal titration microcalorimetry (ITC) in sequence. In addition, the confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) were utilized to visualize the structure of the PBF/chloroplast biological hybrid. The CLSM results demonstrated that the conjugated polymer PBF was closely surrounded by the chloroplast. The SEM image showed the PBF/chloroplast biological hybrid material was much rougher than that of the pristine chloroplast on account of the coating behavior of conjugated polymer PBF. As an abiotic component, the conjugated polymer PBF possessed excellent light-harvesting and light conversion capability, which not only improved the utilization efficiency of sunlight in chloroplasts but also accelerated the electron transfer rate of the light reaction center in chloroplasts. The estimation was studied by the NADPH level of the live chloroplast. Under white light illumination, the NADPH in PBF/chloroplast was significantly increased compared to that of the pristine chloroplast. This increase in NADPH indicates that the photoinduced electron transfer by conjugated polymer PBF could improve the efficiency of NADPH-related intracellular reactions. The acceleration of the photosynthetic rate was also investigated through detecting the reduction rate of 2,6-dichlorophenolindophenol (DCPIP), an artificial electron acceptor, which would capture the transported electrons of the chloroplast during the light reaction. Moreover, it further mediated the directional enhancement of reactive oxygen species (ROS) in photosynthesis to realize the efficient clearance of tumor cells. Overall, this work provided another new biological strategy based on conjugated polymer/chloroplast hybrid material for the development of treatments for malignant tumors. [GRAPHICS]