Surface modifications of iron oxide nanoparticles for biological applications

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2011.Page 192 blank. Vita. Cataloged from PDF version of thesis, 2011.Includes bibliographical references.Iron oxides magnetic nanoparticles (MPs) of high crystallinity, high magnetization, and size-monodispersity were synthesized with oleic acid as their native ligands. These hydrophobic and non-functionalized MPs have magnetic properties that are suitable for various biological applications. Surface modifications were studied for transferring these MPs into biological environments as well as transforming them into functional nanoparticles. Certain surface modifications of MPs, such as attaching silane groups and silica coating, lead to formation of more complex structures of superparamagnetic and fluorescent silica microspheres and nanostructures. These microspheres and nanostructures comprising MPs and semiconductor quantum dots (QDs) are useful tools for biological applications such as for magnetically controlling with fluorescent tracking of particles and for bimodal imaging. Surface modifications of MPs with hydrophobically-modified polyacrylic acid (mPAA) amphiphilic polymer and catechol-derivative surfactants resulted in hydrophilic MPs that are stable in physiological environment and small in their hydrodynamic size. These MPs are also designed to possess active functional groups that are necessary for further conjugations with proteins and molecules of interest. These hydrophilic and functional MPs are useful in biological applications such as magnetic resonance imaging and sensing applications.by Numpon Insin.Ph.D

Green Synthesis of Gold Nanoparticles using Peronema canescens Leaves Extract and Their Catalytic Performance for Dyes and Nitro Compounds

The most interesting and well-known research in the field of gold nanomaterials synthesis is the use of "green chemistry" to prepare gold nanoparticles (AuNPs). In this study, Peronema canescens leaf extract was used as the synthesis medium to successfully produce AuNPs in a way that was cheap, quick, and good for the environment. A UV-visible spectrophotometer, particle size analysis (PSA), and transmission electron microscopy (TEM) were used to find out more about the AuNPs that were prepared. The UV-visible spectrophotometer showed a surface plasmon resonance peak at 532 nm, which proves that AuNPs exist in the solution. TEM and PSA both showed that the AuNPs were mostly spherical and had an average diameter of 14.9 nm, respectively. In the presence of NaBH4, the AuNPs were found to speed up the reduction of rhodamine B (RhB), metanil yellow (MY), and 4-nitrophenol (4-NP). The results show that the AuNPs that were prepared in a new way worked very well and could be used in catalysis

Sr3CrN3: a new electride with partially filled d-shells

Electrides are ionic crystals in which the electrons prefer to occupy free space, serving as anions. Because the electrons prefer to be in the pockets, channels, or layers to the atomic orbitals around the nuclei, it has been challenging to find electrides with partially filled d-shells, since an unoccupied d-shell provides an energetically favourable location for the electrons to occupy. We recently predicted the existence of electrides with partially filled d-shells using high-throughput computational screening. Here, we provide an experimental support using X-ray absorption spectroscopy and X-ray and neutron diffraction to show that Sr3CrN3 is indeed an electride despite its partial d-shell configuration. Our findings indicate that Sr3CrN3 is the first known electride with a partially filled d-shell, in agreement with theory, which significantly broadens the criteria for the search for new electride materials

Incorporation of Iron Oxide Nanoparticles and Quantum Dots into Silica Microspheres

We describe the synthesis of magnetic and fluorescent silica microspheres fabricated by incorporating maghemite (γ-Fe2O3) nanoparticles (MPs) and CdSe/CdZnS core/shell quantum dots (QDs) into a silica shell around preformed silica microspheres. The resultant 500 nm microspheres have a narrow size distribution and show uniform incorporation of QDs and MPs into the shell. We have demonstrated manipulation of these microspheres using an external magnetic field with real-time fluorescence microscopy imaging.Engineering and Applied Science

A Nanoparticle Size Series for In Vivo Fluorescence Imaging

Chemistry and Chemical Biolog

Rapid translocation of nanoparticles from the lung airspaces to the body

Nano-size particles show promise for pulmonary drug delivery, yet their behavior after deposition in the lung remains poorly understood. In this study, a series of near-infrared (NIR) fluorescent nanoparticles were systematically varied in chemical composition, shape, size and surface charge, and their biodistribution and elimination were quantified in rat models after lung instillation. We demonstrate that nanoparticles with hydrodynamic diameter (HD) less than ≈34 nm and a noncationic surface charge translocate rapidly from the lung to mediastinal lymph nodes. Nanoparticles of HD < 6 nm can traffic rapidly from the lungs to lymph nodes and the bloodstream, and then be subsequently cleared by the kidneys. We discuss the importance of these findings for drug delivery, air pollution and carcinogenesis

Removal of Propylparaben in an Aqueous System using Magnetite-Silica Ferrofluids of Hydrophobic Deep Eutectic Solvent

A novel sorbent based on ferrofluid hydrophobic deep eutectic solvent magnetite silica (Fe3O4@SiO2@mSiO2- HDES) was successfully synthesized by adding menthol-fatty acid as carrier liquid onto Fe3O4@SiO2@mSiO2 composite. The crystallinity, morphological, functional group and magnetic properties of the materials were characterized by x-ray diffraction, scanning electron microscopy-EDX, Brunauer–Emmett–Teller, vibrating sample magnetometer, thermogravimetric analysis and Fourier Transform-infrared spectroscopy. The adsorption performance of parabens was evaluated as model water pollutants. The Fe3O4@SiO2@mSiO2-HDES ferrofluid was used as a ferrofluid sorbent of parabens prior to spectrophotometry UV-Vis. The effect of several contribution parameters was optimized including ferrofluid volume, pH, stirring time and ionic strength. Under the optimum conditions, a combination of Fe3O4@SiO2@mSiO2-menthol/palmitic acid was achieved as the best ferrofluid with % removal values ranging from 81.00% to 98.62%. The ferrofluid Fe3O4@SiO2@mSiO2-HDES demonstrated high efficiency for the adsorption paraben in the water system which suggests a great potential alternative method for the adsorption of water contaminants in the aquatic system

3D-printed TCP-HA scaffolds delivering MicroRNA-302a-3p improve bone regeneration in a mouse calvarial model

Objective To demonstrate hydroxyapatite nanoparticles modified with cationic functional molecules. 3-aminopropyltriethoxysilane (HA-NPs-APTES) carrying microRNA-302a-3p (miR) in the 3D-printed tricalcium phosphate/Hydroxyapatite (TCP/HA) scaffold can increase healing of the critical-sized bone defect. Materials and methods 3D-printed TCP/HA were modified with HA-NPs-APTES by two methods (M1, M2). The dispersion of particles was visualized by fluorescent microscopy. Biocompatibility of the scaffolds was tested by alizarin assay. Delivery of miR to the cells and osteogenic gene expression were evaluated by qPCR. After selecting best method (M2), scaffolds, scaffolds+HA-NPs-APTES with or without miR were implanted in 4 mm mouse calvarium defect ( n = 4 per group). After 2,4 and 6 weeks, bone regeneration were evaluated by microCT and histology sections. Results Both M1 and M2 scaffolds were biocompatible with cell adhesion on its surface. M2 scaffold showed significant increase of miR, suggesting successful delivery, resulted in downregulation of its target mRNA COUP-TFII, and upregulation of RUNX2 mRNA. Calvarium defect with M2 scaffold also showed significantly higher BV/TV and higher number of filled spaces at all time points. Histomorphometry demonstrated new bone formed at the center of the HA-NPs-APTES-miR scaffold earlier than controls. Conclusion TCP/HA scaffold modified with HA-NPs-APTES facilitated delivery of miR and enhanced bone regeneration.</p