A Highly Effective Antibacterial System Based On Prussian Blue And Its Research

The treatment of bacterial infection triggered by light has obvious advantages,such as high selectivity based on local light technology and avoidance of drug resistance.Photothermal Therapy?PTT?and Photodynamic Therapy?PDT?are two representative phototriggered bacteriostatic therapies.The principle of PTT is that the light source of a specific wavelength irradiates the photothermal drugs concentrated around the bacteria.The photothermal drugs absorb the energy of the light and convert it into heat energy,generating local high temperature and killing the bacteria.The principle of PDT is based on photosensitizers that produce reactive oxygen species under light conditions and cause oxidative damage to bacteria.However,in the practical application of PTT,the activity of PTT is still restricted by many factors,such as the low photothermal conversion efficiency of traditional photothermal agents.The synthesis and extraction of some high performance photothermal agents are complex.The power requirement of light source is higher.Therefore,it is of great significance to design and synthesize highly active photothermic drugs or to improve the performance of existing photothermic agents,which can lay a solid foundation for the construction of PDT and PTT combined therapy.Based on this,the photothermal materials and photosensitive drugs with high activity were synthesized respectively in this paper.In addition,polycyclodextrin was coated on the surface of the photothermal materials to realize the load on the photosensitizer phthalocyanine,and a combined photothermal-photodynamic system was obtained.The main research contents and results of this project are as follows:1.Prussian Blue?PB?is a drug approved by the United States and the food safety administration?FDA?,which has the ability of photothermal conversion and PTT bacteriostasis.The photothermal properties of PB are derived from the good response of the conjugated structure between metal ions(Fe²⁺and Fe³⁺)and-C?N-in its structure to near-infrared light,and can convert part of the received light energy into heat energy.The interference of metal on the relative electron density of conjugated structure has great influence on the photothermal conversion effect.Based on this,this chapter doped lanthanide metal ions into PB,and successfully prepared a series of lanthanide ions,including Erbium(Er³⁺),Dysprosium(Dy³⁺),Thulium(Tm³⁺),and Ytterbium(Yb³⁺)doped Prussian blue nano-cubes.The results show that the type and doping ratio of lanthanide metal ions have different influences on the photothermal properties of nanoparticles,among which 9%Yb³⁺doped Prussian blue?PB-Yb?has the best PTT properties,which is due to the change of the relative electron density of conjugated structures after metal doping.2.PDT is also a promising bacteriostatic therapy,and the performance of photosensitizer is crucial to the bacteriostatic effect.Synthesized in this chapter three zinc phthalocyanine derivatives with different substituents and the ends of two metal iridium complexes containing carboxyl,via nuclear magnetic,infrared and mass spectrometry to validate its structure,the singlet oxygen capture agent?ADPA?were used to detect the photosensitizer ability of reactive oxygen species,verified the good photodynamic activity,both photosensitizer could be used as the income light of field dynamic combination of optional photosensitizer,provide reference for later photosensitizer screening.3.The combined use of PDT and PTT can improve the efficacy of bacteriostatic therapy.On the premise of not affecting the activity of photothermal materials and photosensitive drugs,the rational stable combination of the two is the basis of combination therapy.Cyclodextrin is a drug carrier widely used in clinical and basic research.It has the advantages of low price,good water solubility and strong drug loading capacity.In this chapter,PB-Yb,which has good photothermal effect,is used as photothermal medicine,and its surface is coated with a layer of cyclodextrin polymer.The coating not only ensures that the photothermal effect of PB-Yb is not affected,but also provides a large number of drug loading sites for the later loading of photosensitizer.In addition,the coating can also improve the water-solubility of PB-Yb and enhance its ability of stable dispersion in aqueous solution.The experimental results showed that the cyclodextrin-coated PB-Yb had good stability and water solubility.After loading the amantadine phthalocyanine,the combined action system of PDT and PTT was successfully constructed.