Synthesis,CO Release,Anti-Inflammatory And Anti-Tumor Properties Of Light-Activated Mn,Rare-Earth-Mn And UCNPs@mSiO₂-Mn Carbonyl Corms

In recent years,many studies have recently shown that low and safe dose of CO as a signaling molecule displays various physiological effects,such as anti-inflammatory,promoting aortic vasodilation,inhibiting coronary vasoconstriction,reducing blood pressure,anti-apoptosis of endothelial cells,inhibiting the rejection reaction after heart transplantation,killing tumor cells and so on.Additionally,CO has been demonstrated to has efficient function on the treatment of cardiovascular,respiratory and digestive system diseases,organ transplantation protection and anti-tumor treatment.However,the use of inhaled CO for therapeutic applications is limited,because of the difficulty in controlling dosage and the challenging delivery to the target sites.Therefore,the development of safe CO delivery method has become an urgent problem to be solved in the research of such drugs.In order to overcome these problems,CO-releasing molecules（CORMs）have been designed and developed.The most desirable characteristics of CORMs are the capability to release controlled amounts of CO into cells and tissues in order to induce direct biological activity.The perfect CORMs should be low toxicity,high solubility and stability in aqueous solution,specific-targeting,controlled release,and fluorescent tags.At present,transition metal carbonyl compounds have broad application prospects as CO release drugs,due to their multiple CO groups,certain stability,providing CO by local medication,and the advantages of easy control of medication timing,dosage,release rate,and realization of water solubility,low toxic side effects and targeted drug delivery through ligand regulation.Based on above,in this paper,the simple carbonyl complex of Mn,which is an essential element for life,was used as the substrate to design and synthesize a series of CORMs with photo responsiveness,water solubility,low toxicity,targeted controlled release of CO and fluorescent labeling function,and their biological activities were also studied.The main work finished is as follows:（1）Benzimidazole and derivatives have been shown to possess prospect applications in the field of medicine for antibacterial,antihistamine,ulcer treatment,anticancer.Five photo-CORMs derived from Mn（I）and benzimidazole coligands,namely,[Mn Br（CO）₃L1]（1,L1=2-（2-pyridyl）benzimidazole）,[Mn（CO）₂L1（PPh₃）₂]（Cl O₄）（2）,[Mn Br（CO）₃L₂]（3,L2=2,2′-bisbenzimidazole）,[Mn Br（CO）₃L3]·CH₃OH（4,L3=2,6-bis（benzimidazole-2′-yl）pyridine）and fac-[Mn Br（CO）₃L4]（5,L4=2,4-bis（benzimidazole-2′-yl）pyridine）were synthesized and characterized.The molecular structures for complexes 1–4 have been authenticated by single-crystal X-ray crystallography.These complexes have a good stability in the dark and exhibit moderate CO release upon illumination with 365 nm UV light.The release rate of CO gradually decreases with the increase of degree of ligands conjugation.Therefore,the rate of CO-release can be adjusted by extending the degree of unsaturation and conjugation of the ligand frame.The luminescence intensity of complexes 1–5 gradually enhance with the increasing of the rigidity and conjugate degree of ligands.Fluorescence imaging tests show that complexes 1–5display efficient cellular uptake in HL-7702 cells and SK-Hep1 cells and verify the fuorescence imaging capability in living cell systems.The viability cell assay shows that complex 3 possesses excellent anticancer activity.（2）Because of good coordination ability and variable coordination modes,the apparent electronegativity of the carboxylic group after losing protons,which could balance the charge of the central metal and enhance the solubility of the complex in water at the same time,2,2′-bipyridyl-4,4′-dicarboxylic acid（H₂BPDC L5）,2,5-pyridinedicarboxylic acid and 2,4-pyridinedicarboxylic acid（H₂PYDC L6）as ligand to react with Mn Br（CO）₅ and Eu Cl₃ respectively,seven new complexes[Mn（CO）₃（H₂O）（HBPDC）]（6）,{[Mn₃（CO）₆（H₂O）₄（BPDC）₂]·2H₂O}_n（7）,[Mn（CO）₃（H₂O）（BPDC）]₃·[Eu（H₂O）₈]（8）,{[Mn（BPDC）]}_n（9）,[Mn（CO）₃（CH₃CN）（HPYDC）]·CH₃CN（10）,[Mn（H₂O）₂（HPYDC）₂]（11）,[Mn₃（μ₃-OH）₂（PYDC）₂]_n（12）were synthesized.Complexes 6-8 and 10 can release CO upon exposure to UV and visible light.Complex 7 was the first example of CORMs with1D ladder-liked chain and Mn（I）/Mn（II）mixed valence state.Complexes 9 and 12show novel three-dimensional Mn-MOF structure.Complexes 6 and 10 exhibit highly water-soluble and air-stable,good CO release ability upon exposure to UV and visible light,and the CO releasing rate depending on the wavelength of irradiation light,therefore complexes 6 and 10 are ideal CORMs.Complexes 6 and 10 can inhibit the secretion of NO and TNF-αin LPS-stimulated RAW264.7 macrophages without obvious cytotoxicity,which may have potential application in CO based anti-inflammatory therapy.（3）Based on the unique luminescence,low toxicity,anti-tumor properties of rare earth elements,and the wide application of organic-inorganic hybrid materials in medical diagnosis and cell imaging,2 2’-bipyrimidine（bpym L7）and Schiff base 1,2-bis（pyridine-2-methylene）hydrazine（L8）as ligand to react with Mn Br（CO）₅,Ln（hfac）₃·2H₂O,Ln（tta）₃·2H₂O respectively,new Mn-CORMs:[Mn（CO）₃Br（bpym）]（13）,[Mn₂（CO）₆Br₂（bpym）]（14）,[Mn（CO）₃Br（L）]（15）,[Mn₂（CO）₆Br₂（L）]（16）and Ln-Mn CORMs:[Mn（CO）₃Br（bpym）Ln（hfac）₃]{Ln=Sm（17）,Eu（18）,Tb（19）and Dy（20）},[Mn（CO）₃Br（L）Ln（tta）₃]{Ln=Sm（21）,Eu（22）,Tb（23）和Dy（24）}were systhsized.The study showed the Ln-Mn CORMs combining the characteristics of metal CORMs and Ln elements have fluorescent tags,CO release and anti-tumor activity.The Ln-Mn CORMs have better anti-tumor activity than the mononuclear Mn-CORMs.The study of cell apoptosis and cycle detection experiments have shown that complexes 18-19,22-23 can inhibit the cell proliferation of 786-O cells at S phase arrest.The results of western blotting analysis show that complexes 13,15,17-24 could reduce the levels of anti-apoptotic protein Bcl-2,and increase the levels of pro-apoptotic protein Bax.The ratio of Bax/Bcl-2 was significantly increased,then Caspase-9 was activated to induce apoptosis of 786-O cells.（4）The core-shell structure of UCNPs@mSiO₂-COOH synthesized as the drug carrier for CORMs 10 with highly water-soluble and good CO release ability upon exposure to UV and visible light get UCNPs/CORMs@mSiO₂-COOH CORMs.The composite system constructed 980 nm NIR-active system for CO-release by UCNPs.Furthermore,in view of the weak acidity in the tumor microenvironment and the high expression of FA receptors,PEI was designed as a responsive gating molecule,FA as a targeting group,Rh B as fluorescent tags coated on the surface of mSiO₂ to design UCNPs/CORMs@mSiO₂-COOH/FA-PEI-Rh B.The composite system shown the rapid CO release at low p H and slow release at physiological p H,which can achieve the weak acid target recognition of the tumor microenvironment.In addition,the researches on biological activity,fluorescence imaging tests and mouse organ tissue distribution test have shown that the composite system have good biocompatibility and the advantages of fluorescence tracing.This study provided a new prospect for the design and synthesis of CORMs@Nano particles with targeted recognition,fluorescence imaging,p H-response and NIR-responded system for CO-release.