10.1021/acsami.5b06937.s001
Juho Pokki
Juho
Pokki
Jemish Parmar
Jemish
Parmar
Olgaç Ergeneman
Olgaç
Ergeneman
Hamdi Torun
Hamdi
Torun
Miguel Guerrero
Miguel
Guerrero
Eva Pellicer
Eva
Pellicer
Jordi Sort
Jordi
Sort
Salvador Pané
Salvador
Pané
Bradley J. Nelson
Bradley J.
Nelson
Mobility-Enhancing
Coatings for Vitreoretinal Surgical Devices: Hydrophilic and Enzymatic
Coatings Investigated by Microrheology
American Chemical Society
2015
biomolecular absorption
physicochemical interactions
coatings cause
Vitreoretinal Surgical Devices
vitreous experience nonlinear mobility
control probes
vitreoretinal surgery
vivo porcine vitreous
vitreal macromolecules
vasculature use
Hydrophilic titanium dioxide
Surgical catheters
hyaluronidase enzymes
HA coatings
PEG
Enzymatic Coatings Investigated
CL
TiO 2 coating
activity increase mobility
probe surface
15 min experiments
polymer coatings
decreases mobility
vitreous models
collagen samples
PVP coatings
HA coating
2015-10-07 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Mobility_Enhancing_Coatings_for_Vitreoretinal_Surgical_Devices_Hydrophilic_and_Enzymatic_Coatings_Investigated_by_Microrheology/2124322
Ophthalmic wireless microrobots are
proposed for minimally invasive vitreoretinal surgery. Devices in
the vitreous experience nonlinear mobility as a result of the complex
mechanical properties of the vitreous and its interaction with the
devices. A microdevice that will minimize its interaction with the
macromolecules of the vitreous (i.e., mainly hyaluronan (HA) and collagen)
can be utilized for ophthalmic surgeries. Although a few studies on
the interactions between the vitreous and microdevices exist, there
is no literature on the influence of coatings on these interactions.
This paper presents how coatings on devices affect mobility in the
vitreous. Surgical catheters in the vasculature use hydrophilic polymer
coatings that reduce biomolecular absorption and enhance mobility.
In this work such polymers, polyvinylpyrrolidone (PVP), polyethylene
glycol (PEG), and HA coatings were utilized, and their effects on
mobility in the vitreous were characterized. Hydrophilic titanium
dioxide (TiO<sub>2</sub>) coating was also developed and characterized.
Collagenase and hyaluronidase enzymes were coated on probes’
surfaces with a view to enhancing their mobility by enzymatic digestion
of the collagen and HA of the vitreous, respectively. To model the
human vitreous, ex vivo porcine vitreous and collagen were used. For
studying the effects of hyaluronidase, the vitreous and HA were used.
The hydrophilic and enzymatic coatings were characterized by oscillatory
magnetic microrheology. The statistical significance of the mean relative
displacements (i.e., mobility) of the coated probes with respect to
control probes was assessed. All studied hydrophilic coatings improve
mobility, except for HA which decreases mobility potentially due to
bonding with vitreal macromolecules. TiO<sub>2</sub> coating improves
mobility in collagen by 28.3% and in the vitreous by 15.4%. PEG and
PVP coatings improve mobility in collagen by 19.4 and by 39.6%, respectively,
but their improvement in the vitreous is insignificant at a 95% confidence
level (CL). HA coating affects mobility by reducing it in collagen
by 35.6% (statistically significant) and in the vitreous by 16.8%
(insignificant change at 95% CL). The coatings cause similar effects
in collagen and in the vitreous. However, the effects are lower in
the vitreous, which can be due to a lower concentration of collagen
in the vitreous than in the prepared collagen samples. The coatings
based on enzymatic activity increase mobility (i.e., >40% after
15 min experiments in the vitreous models) more than the hydrophilic
coatings based on physicochemical interactions. However, the enzymes
have time-dependent effects, and they dissolve from the probe surface
with time. The presented results are useful for researchers and companies
developing ophthalmic devices. They also pave the way to understanding
how to adjust mobility of a microdevice in a complex fluid by choice
of an appropriate coating.