Interactions Of Several Nanoscale Substances With Mitochondria And The Mechanism Study

As the development of material science,there are more and more metal-associated nanomaterials being applied in biological fields,such as imaging,tracing,diagnose and treatment.However,compared to the exploration of properties and functions of the materials,their biological safety especially the subcellular safety is relatively less studied.Mitochondria are energy-producing organelles in eukaryotes and usually used as a model at subcellular level.This study investigated the effects of two quantum dots on mitochondrial structure and function.Metal ions release is a very important factor when studying the mechanisms of materials or drugs on cells or subcells.In spite of the very fundamental study of the metal ions,it provides the theoretical basis for material toxicology and pharmacology in the future.Moreover,as the prolongation of the average human lifespans and the more serious aging tendency of population,a series of problems come out.For example,the morbidity rate of age-dependent Alzheimer's Disease and Parkinson Disease gets higher and higher.As reported,heavy metals accumulation and the degradation of mitochondrial functioning are both factors triggering these diseases.Therefore,this work also studied the association between mitochondria and an important protein in Alzheimer's Disease.This work consists of 5 chapters:Chapter 1:We introduced mitochondrial structure and function,the involvement of mitochondria in many disease and the mitochondria-targeting drugs.In addition,we demonstrated the biological compatibility of quantum dots as well as the application and development of microcalorimetric methods.Chapter 2:We selected isolated rat liver mitochondria as the model,characterized their structure and activity,and investigated their energetic metabolisms in the presence of different tool drugs.It is found out that isolated mitochondria keep their structure and activity in 4 h,proving the feasibility of in vitro experiments.Different tool drugs perform different influences on mitochondrial energetic metabolisms,corresponding to their effects on humans.Chapter 3:Two kinds of quantum dots,Ag2S and CuInS2,were studied on isolated rat liver mitochondria.Ag2S are small-size near-infrared quantum dots,with special advantages in biological fields compared to normal quantum dots.CuInS2 are ternary core-shell quantum dots that have been reported eminent in bioimaging,biotracing as well as photothermal effect.This chapter finds that Ag2S has no toxicity on isolated mitochondrial swelling,membrane potential,membrane fluidity,lipid peroxidation,membrane penetration and energetic metabolism.While the effects of CuInS2 quantum dots are complicated,showing as the induction on mitochondrial swelling,membrane potential and membrane penetration but the inhibition on ROS generation and lipid peroxidation.Due to the mitochondrial attraction to positive-charged substance,the-COOH terminated Ag2S are not likely to attack mitochondria,which explains their low toxicity.CuInS2,attributed to their complicated components,shows a combined action on isolated mitochondria.Chapter 4:We investigated three metal ions,Ag+,Cu2+ and In3+ acting on isolated mitochondria,based on the quantum dots in Chapter 3.These three ions all have toxicity to isolated mitochondria,except the different toxic doses and mechanisms.The damage of Ag+ on mitochondria is nonspecific,and only 5 ?M of Ag+ causes a serious mitochondrial injury.Cu2+ induces mitochondrial permeability transition pores opening and promotes protons penetrating into matrix,whose toxic dose is about 50 ?M.In3+ shows the lowest toxicity in these three ions,whose toxic dose is about 1 mM.In3+ induces mitochondrial oxidative stress and inhibits ion channels,which needs a long inductive time.Chapter 5:This chapter studied the effects of the key protein in Alzheimer's Disease,A?,on isolated rat liver mitochondria.Before that,the molar enthalpy of A?aggregation at 37 ? was measured by isothermal titration calorimetry.It is calculated that the ?Hm of A? aggregation at 37 ? is about-2200 kJ/mol.The A? aggregation is a reversible process and it cannot aggregate over 40 ?.The effects of A?1-42 differ from the states of A?,demonstrating that the aggregation state is the key factor of its toxicity.Moreover,we studied the truncated A?,A?1-16,on mitochondria and find out that A?1-16 is able to protect Ca2+-induced mitochondrial damage.