Nanoparticles: Synthesis, Surface Modification and Functionalization for Biological and Environmental Applications
In addition to the type or nature of the nanoparticles (NPs) core, the surface of the obtained nanoparticles plays a crucial role and has great impact on the physicochemical properties of the nanoparticles which reflect in turn on the nanomaterials interactions (with the surrounding medium, biolo...
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|In addition to the type or nature of the nanoparticles (NPs) core, the surface of the obtained
nanoparticles plays a crucial role and has great impact on the physicochemical properties of
the nanoparticles which reflect in turn on the nanomaterials interactions (with the
surrounding medium, biological systems and environment), functionalities and their possible
The general focus of this doctoral dissertation has been paid to the synthesis, controlled
surface modification, functionalization, purification and characterization of different types of
(plasmonic, semiconductor and magnetic) nanoparticles providing water soluble and highly
colloidally stable nanoparticles proper for environmental and biological applications.
Most of the as synthesized nanoparticles are inorganic particles (e.g. 5 nm Au NPs, 12 nm
magnetic iron oxide NPs, 3 nm iron platinum NPs, 8 nm cobalt platinum NPs, CdSe/ZnS
core/shell QDs of different sizes from 3-5 nm to 7 nm ZnO QDs) stabilized by hydrophobic
organic molecules known as the surfactant or ligand which play an important role to control
the shape and growth of the during the nanoparticles synthesis in addition to its role as
stabilizing agents preventing the nanoparticles to be agglomerated.
In case of water insoluble (hydrophobically capped) nanoparticles (not suitable for the
biological applications), they were transformed from organic phase to aqueous environment
using a very general protocol known as amphiphilic polymer coating which is based on the
hydrophobic interaction between the hydrophobic ligands on the surface of the nanoparticles
and the hydrophobic side chains of the used polymer. The polymer coating of originally
organic-solvent soluble nanoparticles converts them to water soluble ones (thanks to the free
carboxylate groups on surface) which have the ability to be further functionalized with extra
functional and/or biologically active molecules of interest.
The obtained polymer coated nanoparticles were purified and characterized using different
techniques, such as agarose gel electrophoresis, size exclusion chromatography, UV-Vis
spectroscopy, fluorescence spectroscopy (in case of fluorescent materials), transmission
electron microscopy (TEM) and dynamic light scattering (DLS). Monodisperse different types
of polymer coated nanoparticles were obtained with a high quality and colloidal stability as
inferred from their physicochemical properties such as narrow hydrodynamic diameter
distribution and the negative surface charges expressed as zeta potential.
Furthermore, the surface of some water soluble polymer coated nanoparticles was modified
with different functionalities such as some fluorophores (e.g. Dy-495, DY-647 and rhodamine),
polyethylene glycol, folic acid and methotrexate to obtain multifunctional nanoparticles that
could be useful for a wide range of biological applications such as tracking, labeling and
multimodal imaging and targeting drug delivery.