Study On Degradation Behavior And Hemolysis Toxicity Of Magnetic Mesoporous Silica Nanoparticles

Super magnetic mesoporous silica nanoparticles (M-MSNs) havebeen proposed for use as potential vehicles for biomedical imaging,real-time diagnosis and controlled delivery of multiple therapeutic agents.On one hand, the magnetic core provides contrast enhancement formagnetic resonance imaging (MRI) and can furthermore be magneticallytargeted by applying a suitable magnetic field. The large surface areas andpore volumes of the mesoporous silica shell, on the other hand, allow theefficient adsorption of a wide range of molecules, such aschemotherapeutical drugs and larger biological molecules. However, withthe accumulated evaluations of M-MSNs as theranostic carriers, morerequirements have been proposed to biosafety issues such as hemolysis,degradation behavior and so on, regarding the application of M-MSNs forbiological carriers involving intravenous administration and transport. Based on these, in this thesis we are mainly focus on the degradationbehavior and hemolysis toxicity research in physiological environment.Through template, we synthesized the M-MSNs and modified its surfacewith polyethyleneimine (PEI) or PEGylation PEI (PEI-PEG), which wasdenoted as M-MSN@PEI and M-MSN@PEI-PEG respectively. Firstly,we adopted inductively coupled plasma atomic emission spectroscopy(ICP-AES) and transmission electron microscopy (TEM) to investigatethe biodegradation behaviours of M-MSNs in phosphate buffer solution(PBS). It is evident that M-MSN-based materials experienced thedegradation process starting from inner mesoporous shell to generate arattle-type structure. Additionally, we then tried to put forward a possibledegradation mechanism for this type of core–shell M-MSNs by studyingand comparing with the dissolution behaviour of pristine mesoporoussilica nanoparticles. Then, we would like to explore the hemolysis of bareM-MSNs as well as its functionalized nanoparticles with PEI andPEI-PEG through the ultraviolet-visible spectroscopy (UV-vis) andscanning electron microscope (SEM). We then explored the influence offactors, such as concentrations, surface modifications, aggregation, anddegradation, on the hemolytic activity of nanoparticles.