Research Of Supramolecular Cyclodextrin-based Materials On Biological Detection And Gene Therapy

Cyclodextrins?CDs?are synthetic substances obtained from enzymatic degradation of starch and composed of?-1,4-coupled D-glucose units.The most commonly used CD subtypes are?-,?-and?-CD,which consist of 6,7,8 D-glucose units,respectively.Structurally,CD possesses a bucket-shaped topology with an inner hydrophobic cavity and an outer shell of hydrophilic groups.Plenty of hydroxyls with various reactivities located on the hydrophilic exterior of CD make it possible to obtain CD derivatives with different functional groups.Because of its unique structure,CD belongs to the family of cage molecules.The hydrophobic cavity of CD is dimensionally stable and can encapsulate various guest molecules,like drug,inert gas,metal ion to form inclusion complexes.The significant encapsulation properties of CD lead to a“host-guest”relationship that can modify and/or improve the physical,chemical,and/or biological properties of the guest molecules.So CD-based materials usually have good mechanical properties,stimuli-responsiveness,availability,and so on,facilitating their extensive application prospect in almost all industry fields like pharmacy,food,chemistry,chromatography,catalysis,bio-technology,agriculture,cosmetics,hygiene,medicine,textiles,and the environment.In this dissertation,we designed and constructed several supramolecular CD-based systems through host-guest interaction.The chemical structures and properties of these systems were thoroughly characterized,and the applications in hydrogen peroxide detection and gene delivery of these systems were also estimated.The details and key conclusions are described as below:1.Supramolecular fluorescent nanoparticles constructed via multiple non-covalent interactions for the detection of hydrogen peroxide in cancer cellsOverabundance of hydrogen peroxide originating from environmental stress and/or genetic mutation can lead to pathological conditions.Thus,the highly sensitive detection of H₂O₂ is important.Herein,supramolecular fluorescent nanoparticles self-assembled from fluorescein isothiocyanate modified?-cyclodextrin?FITC-?-CD?/rhodamine B modified ferrocene?Fc-RB?amphiphile were prepared through host-guest interaction between FITC-?-CD host and Fc-RB guest for H₂O₂ detection in cancer cells.The self-assembled nanoparticles based on a combination of multiple non-covalent interactions in aqueous medium showed high sensitivity to H₂O₂ while maintaining stability under physiological condition.Owing to the fluorescence resonance energy transfer?FRET?effect,addition of H₂O₂ led to obvious fluorescence change of nanoparticles from red?RB?to green?FITC?in fluorescent experiments.In vitro study showed the fluorescent nanoparticles could be efficiently internalized by cancer cells and then disrupted by endogenous H₂O₂,accompanying with FRET from“on”to“off”.These supramolecular fluorescent nanoparticles constructed via multiple non-covalent interactions are expected to have potential applications in diagnosis and imaging of diseases caused by oxidative stresses.2.Cyclodextrin-highly branched poly??-amino esters?conjugates for targeted in vitro gene deliveryAfter successfully applying CD to cell imaging,we anticipated further introducing it into gene therapy.In this work,multifunctional highly branched poly??-amino esters??HPAEs?were developed via a facile and controllable“A₂+B₃/B₂”strategy as nonviral gene delivery vectors.The highly branched structure was critical to achieve high safety and efficiency in gene transfection.Moreover,by functioning as linking agents,?-CD was used to covalently link HPAE and the HPAE-?-CD conjugates could encapsulate disulfiram?DSF,a hydrophpbic drug for breast cancer?to form inclusion complex HPAE-?-CD/DSF.In vitro studies showed that compared to linear poly??-amino esters?,HPAE-?-CD induced remarkable higher luciferase expression.After encapsulating DSF,the transfection efficiency obtained could even be over an order of magnitude higher than that provided by linear poly??-amino esters?.Notablely,HPAEs were degradable and the degraded products were nontoxic.Therefore,HPAE-?-CD was basically nontoxic to MCF-7 cells.After encapsulating DSF and controlling the size of the complex?<100 nm?,HPAE-?-CD/DSF could go into cancer cells and release the drug,which makes it possible to achieve the goal of combination therapy of drug and gene.