| Supramolecular chemistry focuses on the linking of multiple chemical components through non-covalent interactions(hydrogen bonding,?-? stacking,electrostatic interaction,hydrophobic interaction,metal coordination interaction and host-guest interaction)to develop functional complex architectures.These highly selective,strong and dynamic interactions can give supramolecular materials interesting kinetic properties through the reversible binding between complementary components,which can be used to construct reversible stimulation-responsive materials for a variety of applications.Macrocyclic compounds are a series of cyclic oligomers containing repeating units,including crown ethers,cyclodextrins,calixarenes,cucurbiturils,and pillararenes.They are the cornerstones of host-guest chemistry and an important part of supramolecular chemistry.Cucurbit[n]uril is a cage compound formed by 2n methylene bridged with n glycoluril units.Cucurbit[7]uril has been widely used in biomedical fields due to its good water solubility and cavity size,such as drug delivery and molecular recognition.Cucurbit[8]uril can bond two guest molecules at the same time to form a charge transfer(CT)complex,which is mostly used to construct functional materials.In this thesis,on the basis of in-depth investigation of the effects of CB[7]on the fluorescence intensity and biocompatibility of guest molecules,we constructed thermosensitive fluorescent hydrogels and multiple stimulus-responsive pseudorotaxane polymer based on the host-guest interaction of CB[7]and CB[8].At the same time,we first synthesized the side chain functionalized CB[7]parental double hydrophilic block copolymer,which laid a good foundation for CB in drug delivery,diagnosis and treatment integration.The main content includes the following four parts.1.The effect of cucurbit[7]uril(CB[7])on fluorescence properties and biocompatibility of the bis-viologen biphenyl molecule(BPV22+)was studied.CB[7]can be combined with BPV22+in a stoichiometric ratio of 1:1 and 2:1.After the formation of host-guest complex,the fluorescence emission intensity of BPV22+increased significantly,and the emission spectrum blue shifted.Meanwhile,the host-guest complexes showed better biocompatibility than BPV22+ in cell cytotoxicity studies.The main purpose of this chapter is to reveal how host-guest interaction affects the fluorescent properties and the cytotoxicity of BPV22+,expand the biological application value of fluorescent molecules,and make more molecules used for biological imaging and labeling.2.A thermosensitive polymer PNIPA-BON containing naphthol group was synthesized and self-assembled to form supramolecular hydrogels PCBs by the enhanced charge transfer interaction of naphthol/viologen/CB[8].The gel has luminescent properties due to the introduction of fluorescent molecules.The effect of crosslinking degree on polymer and hydrogel was investigated by UV-Vis spectra and rheological test.With the increase of crosslinking degree,the cloud point of the polymer increases and the light transmittance decreases.With the increase of crosslinking degree,the elastic modulus and viscosity modulus of the PCBs increase.SEM observation showed that the gel formed an ordered pore structure,and the pore size of the gel decreased with increasing crosslinking degree.The fluorescence of the gel is produced with the formation of ternary complexes.The fluorescence properties of the gel were affected by both temperature and degree of crosslinking,and the gel was redox responsive due to the presence of viologen units.This supramolecular fluorescent thermosensitive hydrogel is expected to be developed as a fluorescent thermometer.3.A stimulus responsive pseudorotaxane polymer was synthesized,which can not only respond to a variety of endogenous stimuli,but also realize the fluorescence detection of Fe3+ in aqueous solution.A triply responsive amphiphilic polymer containing poly(ethylene glycol)(PEG)and pyrene linked by a disulfide bond(PEO-SS-PY)was synthesized.PEO-SS-PY with CB[7]forms a 1:1 pseudorotaxane polymer(PEO-SS-Py@CB[7])in aqueous solution.PEO-SS-PY could self-assemble into 126 nm micelles in water.After the formation of host-guest complex,the micelles size increased to 136 nm and the fluorescence emission intensity increased.Glutathione would break the disulfde bond,leading to the dissociation of the micelles.Spermine and adamantanamine hydrochloride would dissociate the host-guest complex,leading to change of micelle size and decrease of fluorescence intensity.More interestingly,this self-assembly micelle displayed highly sensitive fluorescence quenching to Fe3+.Results of this pseudorotaxane polymer provide a new idea for the combination of metal ion detection and controlled release.4.A series of side chain functionalized CB[7]parental double hydrophilic block copolymer were synthesized by RAFT polymerization using side chain functionalized CB[7](AA1CB[7]),acryloyl morpholine and hydroxyethyl acrylate with good biocompatibility.Whether the polymer can be assembled into nanoscale micelles depends on the ratio of CB[7]to acryloyl morpholine.Only when the block copolymer contains CB[7]can micelles form,and with the increase of the proportion of CB[7],the size of micelles increase.The concentration of block copolymer solution also has an effect on the size of micelles,and the size of micelles decreases with the increase of concentration.Meanwhile,in vitro toxicity test showed that the block copolymer had good biocompatibility,which laid a good foundation for the application of functionalized CB[7]in the fields of biological imaging,drug delivery,and diagnosis and treatment integration. |
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