Construction And Application Of High Biocompatible Polymer Nanometer Controlled Release System

Polymer controlled release system not only has good stability,membrane permeability,easy functionalization and other characteristics,but also can be functionalized with recognition sites to control its recognition performance and release effect.Those advantages show broad development prospects in cells imaging,drug delivery,sensor detection and other aspects.Howe ver,in traditional polymer nanometer release system,the polymer backbone is composed of organic macromolecules,which makes the backbone polymer difficult to biodegrade in vivo,and there are huge hidden dangers in biological application safety.In order to solve the existed scientific problem,this paper intends to use degradable polymers,such as poly(amino acids),polysaccharides,and polycarbonates,which could be enzymatically digested by microorganisms or hydrolyzed in organism under natural conditions,as the hydrophobic end of controlled release system.Meanwhile,the hydrophilic end is composed by polyethylene glycol and its derivatives.Through decorating the disease biomarkers in hydrophobic end,our controlled release systems are formed.The designed strategies could be applied to hypoxia,reactive oxygen species,and reducing substances induced release.The main research contents are summarized in below:1)Construction and application of testosterone-induced hypoxia-response polycarbonate micelle near-infrared fluorescent probeCurrently,hypoxia recognition probes only detect hypoxia in artificially induced hypoxic phenomena while ignoring latent stimuli in the organism.Testosterone,as a major stimulus of androgen,can stimulate the proliferation of lymph node carcinoma of prostate(LNCa P)and produce hypoxia and hypoxia-inducible factor 1?in the process of cell proliferation.Therefore,we have prepared a polycarbonate amphiphilic block polymer PEG-b-poly(MPC)by ring-opening polymerization,and fluorescent squarylium(SQ)dye and black hole quencher 2(BHQ2)can be enwrapped in the micelles through self-assembly to constructe a near-infrared fluorescent probe based on PMPC@BHQ2/SQ micelles.At this time,the fluorescence of the fluorescent dye SQ is quenched by the BHQ2.When the tumor site is stimulated by testosterone to produce hypoxia,the BHQ2 can be destroyed with the reduction of azo-reductase,thereby reducing its quenching effect,so that the fluorescence of the SQ dye wrapped in the micelles can be recovered.Because the reduction process depends on the oxygen content,the degree of hypoxia can be determined based on the fluorescence intensity change.Through the construction of the system,the recognition of the hyp oxia degree in cells and small animal in vivo tumors induced by testosterone has been realized.2)Construction and application research of H₂O₂ responsive polypeptide micellar release systemBiopsy is widely concerned by surgeons for its simplicity and practicality.However,due to the lack of sufficient information of disease markers in this detection technology based on morphology,it is difficult to achieve accurate disease diagnosis.Therefore,we have designed a universal quantitative biopsy technology platform,viz.PEG-b-(PPRLT-g-BPmoc)@Amylose/Glu-PGM,which can cost-effectively and quantitatively detect disease markers.We have synthesized the amphiphilic polypeptide PEG-b-(PPRLT-g-BPmoc)with phenylborate recognition sites by the click reaction.The amylose is wrapped in the hydrophobic core through polymer self-assembly.In the presence of H₂O₂,it can react with the recognition site of micelles and generate hydrophilic amino groups at the hydrophobic end of the polymer through rearrangement,which can lead to the destruction of micelles and release of amylose.The released amylose can produce glucose when it encounters glucoamylase,and then the H₂O₂ concentration is quantitatively detected by the personal glucose meter(PGM).Finally,the release system could be used for the detection of hydrogen peroxide in different tumor tissues and different stages of tumor development.3)Construction and application research of Cys selective response polypeptide micellar drug delivery systemAbnormal levels of Cys in the human body can cause a variety of diseases,so qualitative and quantitative detection research on it is of great significance for early clinical diagnosis and disease progression assessment.However,most of the biological thiol probes developed in the earl y stage are small-molecule fluorescent probes.When they are dissolved in organic solvents,they can emit strong fluorescence,while in physiological solutions they are quenched by aggregation due to their poor solubility in water.Therefore,based on the reaction of aldehyde with the N-terminal group of Cys to form a thiazolidine,we have designed an amphiphilic polypeptide PEG-PBALG with aldehyde recognition sites,in which the"click"reaction is used to modify the aldehyde recognition sites.By self-assembly,the hydrophobic drug doxorubicin(Dox)can be encapsulated in micelles to obtain the controlled release system PEG-PBALG@Dox.The hydrophobic end of the micelle s is composed of peptides with good biocompatibility,w hich can further enhance the possibility of practical application in organisms.Due to the existence of specific recognition sites,PEG-PBALG@Dox can quickly form a 6-membered or5-membered ring with 1,3-or 1,2-aminothiol,while other biological thiols(such as glutathione,GSH)cannot form a ring.Therefore,it can specifically recognize Cys.Due to the destruction of the specific gravity and hydrophilicity and hydrophobicity of the micelles after ring formation,the micelles rupture and release the active drug Dox.Subsequently,the system could been applied to cancer cell imaging and in situ tumor suppression in small animals.4)Preparation of hypoxia-responsive polycyclodextrin nanogel and detection of tumor hypoxia in situHypoxia,as a potential disease diagnostic index,is of great significance to the diagnosis of tumors and related diseases.Identifying the degree of hypoxia in tumor tissues at different periods can provide optimal treatment time points and enhance curative effects for diseases.Therefore,based on t he inclusion of?-cyclodextrin(?-CD)and the reducibility of azobenzene,we have synthesized a hypoxia-responsive cyclodextrin nanogel PAAAB/?-CDP in this chapter.After amylose is encapsulated by PAAAB/?-CDP,a controlled release system of hypoxia-induced signal amplification PAAAB/?-CDP@amylose is formed,and it can be used for in situ hypoxia recognition of tumor tissues.When the probe s are injected into the hypoxic tumor site in situ,the grid structure s are destroyed due to hypoxia and the entrapped amylose can be released.Then,the amylose on the tumor slice can react with the KI/I₂ added later to form an amylose-KI/I₂ complex,and it can show a clear blue at 574 nm of visible light.We can use the degree of blueness to directly indicate the degree of hypoxia,so a s to realize the visual recognition of the degree of hypoxia in different periods of tumor tissue.