Controllable Self-assembly Of Porphyrin/Phthalocyanine Macrocyclic Complexes For Biological Diagnosis And Treatment Research

Modern nanotechnology and biomedicine have provided a new perspective on the diagnosis and treatment of malignant tumors,and what has emerged accordingly is the necessity for more efficient,precise,and minimally invasive diagnosis and treatment methods.The fundamental of nanomaterials in diagnosis and treatment is their response to special tumor microenvironment or external stimulation（e.g.,near-infrared laser）,so a good type of nanomaterial is considered to have a high level of biocompatibility and water dispersibility,more effective accumulation at tumor locations,and more rapid response to external stimulations.Porphyrin/phthalocyanine macrocyclic complexes are characterized by their largeπ-conjugated structures and tunable substituents,and their central macrocyclic cavity structure serves as an excellent host to coordinate with various metal ions,leading to their wide applications in bionic catalysis,phototherapy,imaging,and other fields.However,most porphyrin/phthalocyanine macrocyclic complexes are insoluble in water,and their application in biological diagnosis and treatment is currently constrained by their narrow absorption wavelength and light absorption range.To tackle the aforementioned limitations,this dissertation uses the strategy of supramolecular self-assembly and selects the porphyrin/phthalocyanine macrocyclic complex molecules with excellent photophysical properties as the assembly unit.Utilizing their properties in catalysis and light absorption and intermolecular synergy,this dissertation aims to breaking through the limitations on water dispersibility,near-infrared absorption and emission of porphyrin/phthalocyanine single-molecule materials,and develop novel porphyrin/phthalocyanine nanomaterials for tumor-like enzyme-catalyzed therapy,near-infrared light-mediated photothermal therapy,and near-infrared second-region fluorescence imaging technology.The main research contents of this dissertation are as follows:1.Preparation of manganese phthalocyanine assemblies with enhanced peroxidase-like catalytic properties and their application in tumor microenvironment response-antitumor therapy.To solve the problems of poor water dispersibility and less exposure of active sites in the aggregated structure of macrocyclic complexes in enzyme-like catalyzed therapy,we chose manganese phthalocyanine（Mn Pc）with a larger conjugated structure and metal-N-C catalytic active sites as the basic unit,and used a microemulsion-assisted non-covalent self-assembly method to prepared Mn Pc assemblies.The shortened assembly cycle promotes the formation of a blended assembly structure between Mn Pc and emulsifier molecules,which is beneficial to reduce the order degree of the aggregated structure and further promote the exposure of catalytic active sites.By adjusting the type of emulsifier,the crystal structure and morphology of the Mn Pc assembly were adjusted,and two kinds of Mn Pc assemblies with different morphologies were prepared:the regularly-sized spherical Mn Pc NPs and the long-thready Mn Pc NWs.In an in vitro catalytic performance test,the Mn Pc assembly exhibited a morphology-dependent peroxidase-like（POD-like）catalytic activity.When TMB was used as the substrate,the catalytic activity of Mn Pc NPs was 2.5 times that of Mn Pc NWs.In addition,the prepared Mn Pc NPs has a good water dispersibility,and the particle size distribution of 60-80 nm enables its accumulation in the tumor area through the tumor tissue-specific EPR effect,which leads to its further biological applications.Mn Pc NPs shows efficient catalytic therapeutic properties in response to the slightly acidic tumor microenvironment,converting excess H₂O₂ in the tumor area into hydroxyl radicals（·OH）leading to apoptosis,and such response to the slightly acidic tumor microenvironment can greatly avoid the damage to normal tissues.Mn Pc NPs showed promising antitumor effects in both in vitro and in vivo catalytic therapeutic tests,promoting tumor ablation while greatly reducing side effects on normal tissues/organs.This work also lays a new foundation for further applications of metal-organic macromolecules as nanozymes in tumor catalysis therapy.2.Efficient near-infrared absorbing nanomaterials constructed by controllable self-assembly of porphyrins and their application in photothermal therapy.Photothermal therapy（PTT）,as a promising tumor thermal ablation therapy,has the advantages of short treatment period,less trauma,and large penetration depth.In order to achieve a deep treatment,a laser in the near-infrared region is usually used to excite a photothermal conversion reagent to generate heat.Porphyrin single molecules and traditional porphyrin assemblies generally suffer from weak light absorption in the near-infrared region.In order to solve the problem of weak light absorption of porphyrin assemblies in the near-infrared region,we proposed a protonation based-method of enhancing the electronic conjugation effect of porphyrin molecules in the assembled structure to achieve a strong light absorption of porphyrin assemblies in the near-infrared region.Through a co-solvent method which involves acid in the assembly process,this research used the easily protonated-photoactive precursor 5,10,15,20-tetrakis（4-aminophenyl）porphyrin（TAPP）with attached electronic substituents as the assembly unit for the preparation of the TAPP assembly with protonation-enhanced near-infrared absorption.The morphology,structure and optical properties of TAPP assemblies can be adjusted by changing the type and concentration of the emulsifier and the p H of the preparation system.It is found that in an acidic system,the protonation of the pyrrole N at the center of TAPP results in the formation of a quinoid-like resonance form,which can further expand the conjugated system of the porphine ring.More specifically,theπelectron filled on the aniline substituent transitions to theπ*orbital of the porphyrin ring,and the electron cloud moves to the central macrocyclic ring,which strengthens the electron conjugation effect with the central ring of the porphyrin.Taking the emulsifier micelle as the confined space,the centrally protonated TAPP forms aggregates through weak intermolecular interactions,and this enhancedπ-π*conjugation effect extends to adjacent porphyrin molecules,which leads to an abnormal red-shifted absorption peak.Amongst the prepared TAPP assemblies,NIR-NPs separated from a acidic system assisted by the anionic emulsifier SDBS has a red-shifted Q-band absorption peak at 790 nm,which is 100 nm larger than that of the assemblies obtained in a neutral system.In addition,the planar configuration of the TAPP molecule is bent due to the central protonation,which makes the molecular packing of the formed NIR-NPs more compact.This compact-packed form is favorable for the release of energy after photoexcitation in the form of non-radiative transition heat generation,and NIR-NPs can achieve a photothermal conversion efficiency of 83.14%under 808 nm laser irradiation.NIR-NPs modified with c RGD targeting molecules can be efficiently accumulated at tumor areas,and exhibit good biocompatibility and excellent therapeutic effects in in vitro and in vivo photothermal tests.In this work,porphyrin assemblies with strong light absorption in the near-infrared region were successfully prepared by adjusting the conjugation effect between the assembly elements,which expanded the application of porphyrins in near-infrared-mediated photothermal therapy,and provided a new strategy for manipulating absorption spectra and structure-activity relationships via adjusting porphyrin assembly structure.3.High-efficiency near-infrared second-region fluorescence imaging nanomaterials constructed by controllable self-assembly of porphyrins and their applications in the detection of tiny tumors.Near-infrared second region（NIR-Ⅱ）fluorescence imaging technology can offer superior signal-to-noise ratio and biological tissue penetration,thus has great application prospects in the fields of early diagnosis of diseases and imaging-guided tumor removal and treatment.To solve the issue that Porphyrin single molecules and traditional assemblies have no near-infrared absorption and fluorescence emission,which hinders deep,high-definition tissue imaging,we chose 5,10,15,20-tetrakis（N,N-diethyl-4-phenylamino）porphyrin（TNPP）as the assembly element,and adjusted the protonation degree of TNPP by changing the p H of the assembly environment.It is found that different degrees of protonation result in different degrees of deformation of the molecular configuration of TNPP,and the large steric hindrance of the substituents also plays a role in regulating the aggregation structure,and the synergy of the two ultimately affects the morphology of the assembly.More importantly,the aggregation structure of an assembly can tune the aggregation state ofπ-conjugated components in electron delocalization after photoexcitation,which plays a role in regulating the photophysical and chemical properties of the assembly.In addition,the pattern of molecular packing in assemblies constrains the rotation of the porphyrin molecular substituents,which is beneficial to the aggregation structure to absorb energy and release energy in the form of radiative decay and luminescence.For instance,AIL-HNPs,a TNPP assembly obtained after adding 5μL HCl（1 N,10 m L system）in a system assisted by the anionic emulsifier SDS（0.005 M）,exhibited stronger near-infrared fluorescence emission than those obtained under neutral conditions.Apart from its suitable size for the function in an organism and excellent ability of near-infrared second-region fluorescence imaging,AIL-HNPs shows its fine biocompatibility in both in vitro and in vivo biosafety tests.Therefore,AIL-HNPs,with its excellent accurate positioning and fluorescence imaging ability,can be applied in near-infrared fluorescence-guided peritoneal metastases and surgical excision.In this work,the strategy of using controllable self-assembly of porphyrin is adopted,NIR-Ⅱ fluorescence imaging,precise localization and navigation for tiny-tumor surgery are achieved by controlling the structure of porphyrin aggregates via protonation and the incorporation of electron-donating and large sterically hindered substituents,which provides a new strategy to achieve a red-shift of fluorescence emission of non-NIR absorbing organic conjugated macromolecules by adjusting their aggregate structures.