Water-Soluble Phthalocyanine-Based Covalent Organic Frameworks For Photoinitiated Antibacterial Application

Bacterial infections can lead to various diseases and seriously impact human health.Antibiotics can effectively suppress bacterial infections and reduce mortality rates.However,the overuse of antibiotics has led to the appearance of bacterial resistance.Phototherapy is a therapeutic method that uses light-responsive materials to generate heat or harmful substances to kill microorganisms or cells,and widely used in the antibacterial field and without the bacterial resistance.The key to phototherapy is light-responsive materials,such as the carbon nanomaterials,noble metal materials,semiconductor materials,and organic dyes.Phthalocyanine is a synthetically macrocyclic aromatic dye with extensive applications in corrosion inhibition,solar cells,hydrogen production,nonlinear optics,and particularly exhibits excellent photodynamic antibacterial activity in the biomedical field.However,its high conjugated planar structure is prone to molecular aggregation,resulting in poor water solubility.Covalent organic frameworks(COFs)as a new class of organic crystalline porous materials have highly orderedπ-πstacking structures,large pore sizes,abundant free active end groups,and single-layer or multilayer structures that are easily dispersed in water,making them ideal nanocarrier materials.Based on this,this article aims to address the poor water solubility of phthalocyanine by preparing novel COFs with both photodynamic and photothermal properties for use in the antibacterial field.The detail works are as follows:(1)The sp~2carbon conjugated skeletons can provideπconjugation along the x and y directions,which enhances electron delocalization and effectively improves the material’s performance by transmittingπconjugation more efficiently in the two-dimensional lattice.A novel covalent organic framework Pc-sp2-COF containing phthalocyanine units was prepared using amino phthalocyanine ligands,which not only exhibits photodynamic properties but also possesses photothermal properties due to its highly conjugated structure.After modification with carboxymethyl chitosan,the water solubility of the material was effectively improved.The material exhibits good photodynamic and photothermal properties under light irradiation and further enhances antibacterial activity by effectively inhibiting bacterial growth.(2)Loading functional small molecules onto covalent organic frameworks through non-covalent interactions is a common method for obtaining multifunctional nanocomposite materials,and non-covalent interactions do not destroy the lattice structure of the carrier material.A covalent organic framework material COF-LZU was synthesized using a room temperature liquid phase method,and tetraamino phthalocyanine was loaded onto COF-LZU through intermolecular forces,making it easy to disperse in an aqueous solution.Under light irradiation,the composite material exhibits good photodynamic and photothermal properties and shows excellent antibacterial activity.(3)Copper sulfide nanoparticles are semiconductor materials that possess both photodynamic and photothermal properties.By modifying coppersulfidenanoparticlesontoCOF-LZU,anovel photodynamic/photothermal synergistic antibacterial composite material was prepared.The addition of copper sulfide nanoparticles strengthens the photothermal activity of the covalent organic framework material while also endowing the composite material with photodynamic properties.This dual synergistic light-controlled antibacterial effect is more conducive to antibacterial applications.