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Abstract
<p class="first" id="P1">Over the last twenty years, many strategies utilizing sol-gel
chemistry to integrate
biological cells into silica-based materials have been reported. One such strategy,
Sol-Generating Chemical Vapor into Liquid (SG-CViL) deposition, shows promise as an
efficient encapsulation technique due to the ability to vary the silica encapsulation
morphology obtained by this process through variation of SG-CViL reaction conditions.
In this report, we develop SG-CViL as a tunable, multi-purpose silica encapsulation
strategy by investigating the mechanisms governing both silica particle generation
and subsequent interaction with phospholipid assemblies (liposomes and living cells).
Using Dynamic Light Scattering (DLS) measurements, linear and exponential silica particle
growth dynamics were observed which were dependent on deposition buffer ion constituents
and ion concentration. Silica particle growth followed a cluster-cluster growth mechanism
at acidic pH, and a monomer-cluster growth mechanism at neutral to basic pH. Increasing
silica sol aging temperature resulted in higher rates of particle growth and larger
particles. DLS measurements employing PEG coated liposomes and cationic liposomes,
serving as model phospholipid assemblies, revealed electrostatic interactions promote
more stable liposome-silica interactions than hydrogen bonding and facilitate silica
coating on suspension cells. However, continued silica reactivity leads to aggregation
of silica coated suspensions cells, revealing the need for cell isolation to tune
deposited silica thickness. Utilizing these mechanistic study insights, silica was
deposited onto adherent HeLa cells under biocompatible conditions with micron scale
control over silica thickness, minimal cell manipulation steps, and retained cell
viability over several days.
</p><p id="P2">Silica sols are generated via vapor deposition of tetramethylorthosilicate
into buffer.
By varying the buffer ionic consituents, concentration, pH, and sol aging temperature,
silica particle size in silica sols can be controlled, facilitating deposition of
silica layers with tunable thickness on mammalian HeLa cells (represented by red fluorescense).
</p><p id="P3">
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