Biomimetic Protein Nanoparticle For Cancer Diagnosis And Therapy

Malignant tumor is one of the major diseases that seriously threaten human lives and health.Therefore,it is still a great challenge to achieve efficient tumor diagnosis and therapy.In recent years,the rapid development of nanomaterials has brought new opportunities for cancer diagnosis and treatment.Protein-based nanoparticles have been extensively explored as nanomedicine for cancer theranostics.Imaging agents or therapeutic drugs can be incorporated within proteins via electrostatic adsorption,hydrophobic interaction or specific site binding to fabricate nanoparticles with higher drug payload,enhanced drug stability and prolonged blood circulation time,leading to improved cancer diagnostic and therapeutic efficacy.However,these protein-based nanoparticles often exhibited poor tumor target capacity due to lack of size control,thereby leading to insufficient tumor accumulation without satisfied efficacy.Therefore,it's highly desired to explore and develop facile construction of protein-based nanoparticles under mild conditions with controlled and uniform size for enhanced tumor accumulation,in order to achieve highly efficient tumor diagnosis and therapy.Protein nanoreactor has been exploited as an emerging strategy for inorganic nanomaterials synthesis.In this method,protein molecules are used as hollow nanocages,in which metal ions are interacted with amino acid residues(via electrostatic adsorption,coordination,etc.)to act as nucleation center to facilitate the nanocrystal growth through precipitation or reduction reaction.The biomimetic mineralization process within protein nanoreactor could result in inorganic nanoparticles with protein corona in a facile,mild and controlled manner.The synthesized protein nanoparticles with controlled size exhibit multiple advantages including great biocompatibility,effective cellular uptake as well as tumor accumulation,suggesting potential application in tumor theranostics.Herein,we demonstrate the size-dependent Ag2S@HSA nanoparticles precisely synthesized through carefully controlled growth of Ag2S nanocrystals in hollow human serum albumin(HSA)nanocages,generating sufficient in vivo second near-infrared(NIR-?)fluorescence and photoacoustic signals as well as potent hyperthermia at tumors for cancer theranostics.Moreover,tumor targeting ligand transferrin(Trf)is further employed as nanoreactor to synthesize Mn3O4@Trf with tumor microenvironment triggered magnetic resonance(MR)signal amplification for contrast-enhanced tumor imaging with high spatial resolution.These investigations are shown as follows:Chapter 1.This chapter is an overall introduction of protein-based nanoparticles for nanomedicine.Chapter 2.We have successfully synthesized size-dependent Ag2S@HSA with well-defined nanostructure as a theranostic agent for multimodal imaging and simultaneous photothermal therapy.The nucleation and growth of Ag2S nanocrystals in expansive hollow albumin nanocages was triggered by precipitation reaction between Ag+ and S2-in mild conditions.And the size of Ag2S@HSA could be precisely controlled through initial reactant ratio and reaction time.The growth mechanism of Ag2S@HSA was determined to be diffusion-controlled growth progress based on the analysis of reaction kinetics via monitoring the absorbance of Ag2S@HSA after different reaction time.Ag2S@HSA with the hydrodynamic diameter of 36.2 nm produced effective fluorescence in NIR-? region,distinct photoacoustic intensity,and potent photothermal conversion in a size-dependent manner under NIR irradiation.Ag2S@HSA were efficiently internalized by 4T1 cells via clathrin-mediated endocytosis and mainly distributed into the lysosomes.Upon NIR irradiation,Ag2S@HSA exhibited intense photo-induced cytotoxicity on 4T1 cells with IC50 of 0.17 mM.Moreover,Ag2S@HSA possessed prolonged blood circulation time with t1/2?of 5.7 h,preferable tumor accumulation and long-term retention in tumor site.Under NIR light exposure,Ag2S@HSA were able to totally ablate the tumors through the photothermal injury without damaging surrounding normal tissues after a single injection at the dose of 50 ?mol kg-1.In addition,Ag2S@HSA could be effectively eliminated from the mice after 30 days post-injection,indicating that they can avoid the long-term in vivo retention and thus have no significant safety concern.Chapter 3.Tumor targeting ligand transferrin is further employed to synthesize Mn304@Trf with tumor microenvironment triggered MR signal amplification for tumor detection with high spatial resolution.The nucleation and growth of Mn304 within Trf molecules was triggered through redox reaction between KMnO4 and Trf inside expansive nanocages in mild condition,resulting in Mn3O4@Trf with precisely regulable size through reaction time control.Owing to lattice defect,Mn304@Trf exhibited enhanced Mn2+release behavior in acidic environment,generating higher longitudinal relaxivity(r1)of 3.2 mM"1 s-1 for enhanced MR imaging.The r1 can be further increased to 7.2 mM-1 s-1 with co-incubation of GSH and acidic PBS,exhibiting dually pH/reduction-responsive MR enhancement.Moreover,Mn3O4@Trf showed prolonged blood circulation time with t1/2?of 4.5 h,specific accumulation in TfRl receptor over-expressed tumor(HT-29)in a size-dependent manner as well as deep tumor penetration,leading to enhanced MR imaging capacity with the signal-to-noise(S/N)contrast increased to 200?240%in both subcutaneous and orthotopic tumor model.With additional injection of acidic PBS and GSH directly into tumors,the S/N contrast could be further improved to 400%,thereby generating precise tumor diagnosis with high spatial resolution.Therefore,Mn3O4@Trf with dually pH/reduction-responsive MR signals can be applied for tumor spatial imaging with enhanced MR contrast.In summary,multifunctional nanoparticles synthesized through an optimized biomineralization process in protein nanoreactors are developed for applications in multimodal imaging and photothermal tumor ablation.The biomimetic synthesized nanoparticles via the facile and universal protein nanoreactor method would have promising potentials in the field of cancer theranostics.