Nano-photosensitizer Based On Covalent Organic Framework Nanosheets With High Loading And Therapeutic Efficacy

Photooxidation provides a promising strategy for photocatalysis,photodynamic therapy,and environmental protection.Unfortunately,most organic photosensitizers possess weak hydrophilicity and ?-? conjugated structure,leading to singlet oxygen self-quenching,poor loadability and therefore unsatisfactory photooxidation efficiency.Thus,dispersion of these photosensitizers with two-dimensional porous covalent organic framework has become a feasible strategy to hinder their self-aggregation and augment loading capacity of dyes.Here,we report a covalent organic framework nanosheets based nano-photosensitizer to highly disperse organic fluorescent phthalocyanines with high loading capacity.The fabricated nanosheets restrict selfaggregation of and potentiate their photooxidation activity,which may offer a new paradigm for photooxidation and its multiple applications.The paper will discuss from following four aspects.The first part was about the preparation and characterization of PcS@COF-1 nanosheets.Phthalocyanine was adsorbed onto amine-functioned COF-1.Then,PcS@COF-1 nanosheets were obtained via facile ultrasonic exfoliation method.Dynamic light scattering,Transmission electron microscope,Atomic force microscope,were employed to observe the morphology and size of the nanosheets.UV-Vis spectra and powder X-ray Diffraction were used to characterize physicochemical property of PcS@COF-1 nanosheets.Phthalocyanine was completely adsorbed on the COF-1 even at the PcS/COF-1 mass ratio of 30%.The fabricated PcS@COF-1 nanosheets were stable under simulated physiological conditions.The second part was about the siglet oxygen gerneration ability of PcS@COF-1 nanosheets.After laser ilumination,Singelt Oxygen Sensor Green(SOSG)was employed to detect the singlet oxygen generation of PcS@COF-1 nanosheets with different concentrations and different phthalocyanine loading.In additon,dopamine was used as substrates to indicated the photooxidation performance of PcS@COF-1 nanosheets.PcS@COF-1 exhibited durable and efficient singlet oxygen generation and had excellent photooxidation performance.In addition,integration phthalocyanine into COF-1 slowed photo-degaradation of the dyes.The third part was about in vitro photodynamic therapy efficacy of PcS@COF-1 nanosheets.We investigated the uptake behaviour of CT25 colorectal cancer cells to the nanosheets.Then,we found PcS@COF-1 nanosheets produced abundant intracellualr singlet oxygen after laser ilumination.Moreover,PcS@COF-1 mediated photodynamic therapy induced dose-dependent CT26 tumor cells death.The fourth part was about in vivo photodynamic therapy efficacy of PcS@COF-1 nanosheets.CT26 colorectal tumor bearing-mice were constructed.PcS@COF-1 nanosheets gradually accumulated in the tumor after intraveneously injected and reached the maximum 24 h post injection.Thus,laser illumination was performed 24 h after injection and PcS@COF-1 nanosheets mediated photodynamic therapy significantly stunted tumour growth.Overall,in order to conquer the strong propensity to aggregation and low solubility of photosensitizers,two-dimensional covalent organic framework was employed to highly disperse phthalocyanine,which simultaneously realize high photosensitizer loading capacity and singlet oxygen yield.PcS@COF-1 nanosheets exhibited excellent photodynamic therapy efficacy and provided a novel strategy for delivery of photosensitizers.