Fluorescent Nano-micelles For Imaging Intracellular Metal Ions And Cancer Threapy

Many trace metal elements in organisms play a vital role in many biological processes such as enzyme regulation,neural signaling,gene expression,cell metabolism and immune function.The dyshomeostasis of metal ions(such as aluminum)in the human body will disrupt the functioning of organisms,leading to many serious diseases.The development,progression and metastasis of cancers are also strongly associated with metals,especially iron,copper and zinc.Therefore,it is significant to develop analytical methods for the detection of metal ions in the organisms especially for live-cell imaging of metal ions.Most of reported probes for metal ions sensing worked well in organic solvents or a mixture of organic solvent and water,which limits practical applicability in aqueous solutions and blocks the application in biological realms,especially for intracellular imaging of metal ions.Previous efforts mainly focused on the design of small molecules for detecting metal ions,but the disadvantages of small molecular probes include complex preparation,low cellular uptake and cytotoxicity,which limits biological applications.Compared to small-molecule materials,fluorescent nanomicelles have attracted much attention due to their superior stability,good water dispersibility,and biocompatibility.In particular,fluorescent polymer micelles are very popular,since it is easier and more feasible to optimize the polymer structure,morphology,and size by covalent or non-covalent methods to meet the needs of the application.Fluorescent polymer micelles exhibit usually good cell uptake,which is promising in cell imaging applications.Furthermore,the parameters of fluorescent polymer micelles,including composition,particle size,surface properties,and particle shape,can significantly influence their blood circulation,biodistribution,cellular internalization,cell imaging and trafficking in biological systems.So in order to make better use of fluorescence probes in biomedical application,the modulation of these parameters still needs to be considered in the process of designing and preparing polymeric micelles.The transition metal chelators(iron,copper,zinc)can inhibit tumor growth by controlling the level of these metal ions in the tumor.Since fluorescent polymer micelles can show good long circulation and tumor accumulation,they would be effective as a chelating agent for these metals to be used as an anti-cancer treatment.In order to solve the above problems,a series of highly selective fluorescence probes were developed to detect metal ions in water and were used for intracellular metal ion imaging.At the same time,we have studied the roles of sizes and shapes of polymeric micelles with aggregation-induced emission(AIE)characteristics in cellular uptake,cell imaging,blood circulation lifetime and anti-cancer efficiency.The main contents of this paper are as follows:1.The characteristics of traditional fluorescent probes and aggregation-induced luminescence probes,the mechanism of interaction with metal ions,and applications are described.The effects of the physicochemical properties of nanoparticles on cellular uptake,blood circulation and in vivo distribution were also described.In addition,it also includes the role of metal chelators in the treatment of cancer.2.The hydrophobic fluorescent schiff base(Dye)was successfully encapsulated in DSPE-PEG micelles to prepare the nanochemosensor(DSPE-PEG-Dye)by the solvent evaporation method,which displayed high selectivity and sensitivity towards Al3+ ions even in the presence of other commonly coexisting metal ions in aqueous solution.Moreover,DSPE-PEG-Dye is colloidally stable in water,PBS buffer(pH 7.4)and cell culture medium even after storage for one month.Interestingly,the nano-chemosensor exerted superior cell internalization and could be used as a nontoxic bioimaging reagent for detection of Al3+ in living cells.3.An amphiphilic fluorescent schiff base poIymer(mPEG-Dye)was synthesized and could self-assemble into micelles in aqueous solution.The fluorescent emission spectra suggest that it showed excellent sensitivity for detecting Al3+ in H2O.At the same time,mPEG-Dye polymer and DSPE-PEG2000-biontin polymer were used to prepared the biotin targeted micelles(mPEG-Dye-Biotin)through film hydration method.The absorption and fluorescent emission spectra showed that it displayed also high selectivity and sensitivity towards Al3+ ions even in the presence of other commonly coexisting metal ions in aqueous solution.Both mPEG-Dye and DSPE-PEG2000-biontin showed no toxicity to HeLa cells and could be used for fluorescent imaging of Al3+ in living cells.But compared to mPEG-Dye,the cellular uptake of mPEG-Dye-Biotin was improved due to the targeting ability of the biotin moiety of IPEG-Dye-Biotin,thereby increasing responsiveness to Al3+ in cells.4.An amphiphilic polymer(mPEG2K-AIE)with aggregation-induced luminescence properties was synthesized,and AIE2KS26 micelles were prepared by vortex dispersion self-assembly method.The fluorescent emission spectra showed it exhibit good selectivity and sensitivity towards Zn2+ without interruption from other metal ions in H2O.On this basis,mPEG2K-AIE polymer and DSPE-PEG2000-biontin polymer were used for preparing the biotin targeted micelles(AIE2KS26-Biotin)through film hydration method.The absorption and fluorescent emission spectra showed that it could also detect Zn2+ in aqueous solution.Cell experiments showed that AIE2KS26 micelles and AIE2KS26-Biotin micelles displayed low cytotoxicity.Both AIE2KS26 and AIE2KS26-Biotin could image Zn2+ in livingcells.In contrast to AIE2KS26,the enhanced uptake of AIE2iKS26-Biotin was observed in cells compared with AIE2KS26 due to the targeting ability of the biotin moiety of AIE2KS26-Biotin,thereby increasing responsiveness to Al3+ in cells.Therefore,AIE2KS26-Biotin was more suitable for imaging of Zn2+ in HeLa cells than AIE2KS26.5.Three salicylaldazine-based amphiphilic polymers with aggregation-induced emission(AIE)characteristics that varied by the molecular weight of mPEG were synthesized.Subsequently,three different preparation methods were used for each polymer to form eight micelles with different sizes and morphologies.Eight AIE polymeric micelles with low critical micelle concentration(CMC),high stability in physiological environment and good biocompatibility were suitable to research the influences of size and shape on imaging in non-phagocytic cells(HepG2 cells)and phagocytic cells(RAW264.7 cells)and blood circulation.AIE2iKS 19 and AIE2KS26 were screened for better long blood circulation.Potential anti-tumor capacities of AIE2KS19 and AIE2KS26 in vivo were studied,due to their ability to chelate with Cu2+,Fe3+,and Zn2+ ions and better blood circulation.The results showed that the two micelles showed good anti-tumor efficacy and AIE2KS19 had a slightly stronger ability to inhibit tumor growth.