Construction Of Intelligent Response Drug Delivery Systems Based On Mesoporous Silica Nanoparticles And Their Antitumor Study

Malignant tumor is one of the most serious lethal diseases.At present the clinical treatment of malignant tumors still faces enormous challenges.The development of nanotechnology provides an opportunity for tumor therapy.Nanoparticle-based antitumor drug delivery systems have obvious advantages,including increased stability and bioavailability of drugs,as well as lower side effects on normal tissue.More importantly,nanoparticles have been extensively developed as drug delivery carriers based on the inherent enhanced permeability and retention(EPR)effect.With the in-depth understanding for tumor microenvironment,the intelligent responsive drug delivery systems based on the endogenous characteristics of tumor microenvironment(pH,GSH,ATP,enzyme,etc.)or the exogenetic stimulus signal(light,magnetic field,ultrasound,etc.)have been developed.These intelligent drug delivery systems can exhibit "zero premature release" during blood circulation,while under the action of the stimulus signal,they could release drug into the tumor sites and release drug in situ,which reduces the systemic toxicity of free drug.Among the numerous nanomaterials,mesoporous silica nanomaterials(MSNs)have attracted great attention because of their good biosecurity,high drug load efficiency,size tunability,easy surface functionality,etc.Nevertheless,nanoparticle-based systems still face the problem of inferior drug delivery efficiency in vivo.The reason is that upon systemic administration,nanopreparation will encounter a series of biological barriers during transport process in vivo.They mainly contain three level barriers of blood,tumor tissue and tumor cells,which will greatly blocking drugs to reach the target site.These delivery barriers are renal clearance,nonspecific protein adsorption and mononuclear phagocytes system clearance,dense extracellular matrix and high intratumoral pressure,cell membrane traversal,lysosome package and drug resistance in turn.Therefore,it is urgent need to develop new multifunctional nanocarriers with the ability to overcome drug delivery obstacles for the improvement of tumor therapeutic effect.Based on the above background,in this article,the mesoporous silica particles were chosen as the primary materials,we designed and prepared several drug delivery systems for the purpose of overcoming the nanomedicine delivery obstacle and improving the tumor treatment effect.Meanwhile,biological evaluation based on nanosystems was also give consideration.The main research contents and conclusions of this study are listed as follows:(1)Construction of cascade pH-responsive controlled drug release system based on hollow mesoporous silica nanoparticles and its antitumor studyIn order to overcome blood-level barrier and cell membrane barrier in drug delivery,a cascade pH-responsive controlled drug release system was constructed.Hollow mesoporous silica particle was chosen as the carrier in this chapter.Then ?-cyclodextrin and PEG were sequentially introduced into the particle surface through two acid-cleavable chemical bonds(boric acid ester and benzene imine bonds),wherein ?-cyclodextrin as mesoporous blocking agent to prevent drug leakage,PEG endow with nanoparticle stealth characteristics.First,a series of experimental characterizations confirmed the successful preparation of the cascade pH responsive nanodrug controlled release system(HMSNs-?-CD/Ada-PEG).Then the drug release experiments demonstrated that the system had pH controlled release properties.The results of protein adsorption and macrophage phagocytosis studies showed that HMSNs-?-CD/Ada-PEG system could significantly inhibit nonspecific protein adsorption and cell uptake,confirming its potential blood stability.Subsequently,we examined the cell uptake and apoptosis of nanocomposites at the cellular level in vitro.Experiments showed that the HMSNs-?-CD/Ada-PEG system had high internalization efficiency under weak acid conditions,which confirmed that the first pH response could mediate the detachment of PEG and promote tumor cell endocytosis.The results of laser confocal,DNA ladder and flow analysis showed that the intracellular lysosomal acidity could initiate the second pH response,leading to the dissociation of ?-cyclodextrin and intracellular drug release,thereby inducing cell apoptosis.Finally,in vivo experiments results showed that HMSNs-?-CD/Ada-PEG@DOX has a good biosafety,and it can significantly inhibit the growth of tumor.This study affords an alternative for the development of new tumor microenvironment responsive drug delivery system.(2)Hierarchically stimuli-responsive nanovectors based on hollow mesoporous silica nanoparticles for improved tumor penetration and programed antitumor studyTo overcome the tissue penetration barriers in drug delivery and improve the overall efficacy,we have prepared multistage stimuli-responsive charge/size dual switchable multifunctional nanovectors.Hollow mesoporous silica particle was chosen as the carrier in this chapter,followed by the introduction of hydrophilic chitooligosaccharides(CS),dimethylmaleic anhydride(DMA).Meanwhile,electronegative DMA can endow the particles(HMSN-CS(DMA))with a charge-reversal property.After loading of anticancer drug Gemcitabine(GEM),small-sized cisplatin prodrug dendrimer(PAMAM-Pt)was integrated into the particle surface through electrostatic complexation to prepare nanosystem(HMSN@GEM-CS(DMA)/PAMAM-Pt).As-prepared nanosystem has a stable structure with suitable size at pH 7.4,which is benefited for tumor accumulation of nanovehicle.Once arrived to tumor tissue,the nanosystem could be dissociated into HMSN@GEM-CS(?120 nm)and PAMAM-Pt dendrimer nanocarriers(?5 nm)in respond to acidic tumor microenvironment.Then the HMSN@GEM exert the antitumor role in surface tumor tissue,while PAMAM-Pt penetrates into deep tumor by right of its small size,and then achieve positive charge-mediated endocytosis and lysosomal escape.Finally,the active cisplatin released from PAMAM-Pt dendrimer under intracellular reducing environment for further kill tumor cells in deep tumor tissue.First,the successful preparation of HMSN@GEM-CS(DMA)/PAMAM-Pt nanosystem was confirmed by a series of characterization experiments.Then the results of zeta potential and hydrodynamic diameter distributions detection confirmed that the HMSN-CS(DMA)/PAMAM-Pt system had properties of pH-dependent size/charge double conversion.The drug release experiments demonstrated that the system could achieve the release of PAMAM and cisplatin in response to weak acid and reducing stimulus,respectively.The results of studies in three-dimensional multicellular spheroids model in vitro proved that the HMSN-CS(DMA)/PAMAM-Pt system obtained effective multicellular spheroid penetration and cell uptake under weak acid conditions,thereby inducing apoptosis.Finally,in vivo experiments results showed that HMSN@GEM-CS(DMA)/PAMAM-Pt significantly inhibited the growth of tumor and without damage to normal tissue.(3)Preparation of near-infrared photo-responsive controlled drug release system based on mesoporous silica nanoparticles and its biological evaluationIn order to overcome the lysosomal barrier in intracellular drug delivery and increase the clinical availability of nano-pharmaceutical system,a photo responsive MSN-ZOL@tLB-IR780 drug release system was constructed.Mesoporous silica particle was chosen as the substrate in this study,the lipid bilayer was stably coupled to the surface of particles through hyperbranched polyethyleneimine(PEI)buffer layer.During the preparation of system,the anticancer drug ZOL and the photosensitizer IR780 were loaded into mesoporous silica and lipid bilayer respectively.Firstly,a series of characterization experiments demonstrated the successful preparation of MSN-PEI@t LB system.Then the drug release experiments demonstrated that MSN-calcein@t LB-IR780 system had near infrared dependent controlled release characteristics.Subsequently,test results of laser confocal and flow cytometry analysis at the cellular level demonstrated that MSN-calcein@tLB-IR780 system could be efficiently endocytosed by tumor cells,and it could produce reactive oxygen species within cells under near-infrared irradiation,leading to drug release and lysosomal escape via photochemical internalization manner.Finally,the results of cell viability detection,nuclear morphological observation and apoptotic double staining test showed that MSN-ZOL@t LB-IR780 system mediated combination of chemotherapy and photodynamic therapy has a more significant effect in tumor cell growth inhibition and induction of apoptosis when compare to single therapy.This versatile nanosystem with good biocompatibility has potential clinical application prospects.(4)Fabrication of tumor acidity activated multifunctional nanoplatform based on mesoporous silica coated gold nanorods and its antitumor studyTo overcome or avoid the blood obstacles,cell membrane barrier and drug resistance in drug delivery,a multifunctional nano-platform with charge reversal properties,mitochondrial targeting,multiple enhanced photodynamic and photothermal combined therapy was prepared.Mesoporous silica particle coated gold nanorods(AuNR@MSN)was used to load photosensitizer ICG,?-cyclodextrin,RLA peptide and PEG polymers were sequentially introduced into the particle surface to construct composite nanoplatform(AuNR@MSN-ICG-RLA/CS(DMA)-PEG).First,the successful preparation of AuNR@MSN-ICG-RLA/CS(DMA)-PEG composite nanosystem was confirmed by a series of characterization experiments.Then reactive oxygen species detection confirmed that the composite system has multiple production mechanisms of reactive oxygen species.Subsequently,cell experiments demonstrated that the AuNR@MSN-ICG-RLA/CS(DMA)-PEG system had the characteristics of pH dependent endocytosis,mitochondrial targeting,as well as the ability to induce apoptosis under near infrared radiation.Finally,in vivo experiments demonstrated that AuNR@MSN-ICG-RLA/CS(DMA)-PEG system could achieve target enrichment in tumor by virtue of its surface CS(DMA)-PEG polymer,more importantly,it can significantly inhibited the growth of tumor in vivo under near infrared radiation while without damage to normal tissue.The system provided a new idea for the development of new multifunctional nanosystem based on phototherapy.