2 research outputs found
On the Effect of Monomer Chemistry on Growth Mechanisms of Nonfouling PEG-like Plasma Polymers
It has been shown that both ions and neutral species
may contribute
to plasma polymer growth. However, the relative contribution from
these mechanisms remains unclear. We present data elucidating the
importance of considering monomer structure with respect to which
the growth mechanism dominates for nonfouling PEG-like plasma polymers.
The deposition rate for saturated monomers is directly linked with
ion flux to the substrate. For unsaturated monomers, the neutral flux
also plays a role, particularly at low power. Increased fragmentation
of the monomer at high power reduces the ability of unsaturated monomers
to grow via neutral grafting. Chemical characterization by X-ray photoelectron
spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry
(ToF-SIMS) confirm the role that plasma phase fragmentation plays
in determining the deposition rate and surface chemistry of the deposited
film. The simple experimental method used here may also be used to
determine which mechanisms dominate plasma deposition for other monomers.
This knowledge may enable significant improvement in future reactor
design and process control
“Thunderstruck”: Plasma-Polymer-Coated Porous Silicon Microparticles As a Controlled Drug Delivery System
Controlling
the release kinetics from a drug carrier is crucial to maintain a
drug’s therapeutic window. We report the use of biodegradable
porous silicon microparticles (pSi MPs) loaded with the anticancer
drug camphothecin, followed by a plasma polymer overcoating using
a loudspeaker plasma reactor. Homogenous “Teflon-like”
coatings were achieved by tumbling the particles by playing AC/DC’s
song “Thunderstruck”. The overcoating resulted in a
markedly slower release of the cytotoxic drug, and this effect correlated
positively with the plasma polymer coating times, ranging from 2-fold
up to more than 100-fold. Ultimately, upon characterizing and verifying
pSi MP production, loading, and coating with analytical methods such
as time-of-flight secondary ion mass spectrometry, scanning electron
microscopy, thermal gravimetry, water contact angle measurements,
and fluorescence microscopy, human neuroblastoma cells were challenged
with pSi MPs in an in vitro assay, revealing a significant time delay
in cell death onset