Tailoring the nanostructure of sol-gel derived bioactive glasses and investigating their interactions with proteins
Author(s)
Lin, Sen
Type
Thesis
Abstract
Sol-gel derived bioactive glasses with the 70S30C composition (70 mol% SiO2 and 30
mol% CaO) have high potential as materials for bone regeneration and devices for
sustained drug delivery. They bond to bone and have a unique tailorable nanoporosity,
which affects protein adsorption and cellular response. The first aim of this thesis is to
fully characterise the evolution of the nanoporous structure of sol-gel derived
bioactive glass for the first time, to fully understand its nanostructure evolution and
control. Nanoparticles that were produced early in the sol-gel process, agglomerated
into larger particles during gelation and during thermal stabilisation. Calcium was
found to not enter the silica network until the material was heated to 400 °C. This has
implications for the homogeneity of the calcium distribution in sol-gel derived
bioactive glasses.
Region separation was found within sol-gel derived bioactive glass monoliths
produced by the standard procedure. The calcium concentration and nanoporosity
were found to be higher near the edge of the monoliths. This is believed to be caused
by calcium accumulation on the outer surface of the monoliths during the drying stage
of the sol-gel process. The homogeneity of monoliths was successfully improved by
using Teflon moulds. To provide further control of the nanostructure of 70S30C, a
method for increasing the nanopore diameter from 12 nm to 30 nm was devised by
adding specific amount of trimethylethoxysilane (TMES) during the sol-gel process.
A series of amounts of TMES were added at different time points during the sol-gel
process. Solid state nuclear magnetic resonance (NMR) and electron microscopy were
used to explore the mechanisms behind the changes in nanostructure.
Protein adsorption to sol-gel glass was investigated using in situ studies by
monitoring the adsorption of fluorescent-labelled proteins onto various types of solgel
derived bioactive glasses under confocal microscope with fibrinogen as model
protein. Fibrinogen molecules were found to penetrate into inner nanopores of
TheraGlass® (a commercial glass with 17 nm nanopores) whereas no penetration was
found into sol-gel derived silica (with 3 nm nanopores). Protein interactions were
further studied by conducting bioactivity tests with SBF supplemented with 10%
serum. Apatite deposition was found inhibited by the interference of serum proteins.
mol% CaO) have high potential as materials for bone regeneration and devices for
sustained drug delivery. They bond to bone and have a unique tailorable nanoporosity,
which affects protein adsorption and cellular response. The first aim of this thesis is to
fully characterise the evolution of the nanoporous structure of sol-gel derived
bioactive glass for the first time, to fully understand its nanostructure evolution and
control. Nanoparticles that were produced early in the sol-gel process, agglomerated
into larger particles during gelation and during thermal stabilisation. Calcium was
found to not enter the silica network until the material was heated to 400 °C. This has
implications for the homogeneity of the calcium distribution in sol-gel derived
bioactive glasses.
Region separation was found within sol-gel derived bioactive glass monoliths
produced by the standard procedure. The calcium concentration and nanoporosity
were found to be higher near the edge of the monoliths. This is believed to be caused
by calcium accumulation on the outer surface of the monoliths during the drying stage
of the sol-gel process. The homogeneity of monoliths was successfully improved by
using Teflon moulds. To provide further control of the nanostructure of 70S30C, a
method for increasing the nanopore diameter from 12 nm to 30 nm was devised by
adding specific amount of trimethylethoxysilane (TMES) during the sol-gel process.
A series of amounts of TMES were added at different time points during the sol-gel
process. Solid state nuclear magnetic resonance (NMR) and electron microscopy were
used to explore the mechanisms behind the changes in nanostructure.
Protein adsorption to sol-gel glass was investigated using in situ studies by
monitoring the adsorption of fluorescent-labelled proteins onto various types of solgel
derived bioactive glasses under confocal microscope with fibrinogen as model
protein. Fibrinogen molecules were found to penetrate into inner nanopores of
TheraGlass® (a commercial glass with 17 nm nanopores) whereas no penetration was
found into sol-gel derived silica (with 3 nm nanopores). Protein interactions were
further studied by conducting bioactivity tests with SBF supplemented with 10%
serum. Apatite deposition was found inhibited by the interference of serum proteins.
Date Issued
2010-01
Date Awarded
2010-03
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Jones, Julian
Sponsor
NovaThera Ltd. ; Society of Chemical Engineering (Messel scholarship) ; EPSRC ; Royal Academy of Engineering ; Royal Society ; Philip Leverhulme Prize
Creator
Lin, Sen
Publisher Department
Materials
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)