4 research outputs found
Customizable Optical and Biofunctional Properties of a Medical Lens Based on Chemical Vapor Deposition Encapsulation of Liquids
An
innovative intraocular lens (IOL) device was fabricated based
on a chemical vapor deposition encapsulation process using functionalized
poly-<i>p</i>-xylylenes. The advanced IOL device provides
noncompromised design parameters for both its optical and biological
properties. As an excellent optical device, it provides a high refractive
index and a tunable effective focal length that is realized by manipulating
the wetting properties of the encapsulated liquids; the device also
offers protection from UV radiation. As a key medical device, it exhibits
excellent biocompatibility and reduced postoperative calcification
through the intrinsic properties of poly-<i>p</i>-xylylenes.
In addition, these synergic functions are provided with precise surface
chemistry for location to a guided attachment or repellent properties
for eye epithelial cells, which is important in preventing device-associated
complications
Switching the Biointerface of Displaceable Poly‑<i>p</i>‑xylylene Coatings
A new class of functionalized poly-<i>p</i>-xylyene coating has been synthesized to provide switchable
and displaceable surface properties for biomaterials. The switchability
is achieved through a mechanism for detaching/attaching biomolecules
and/or a mechanism through which the programmed restoration of functions
or their replacement by other functions can be carried out. This advanced
version of poly-<i>p</i>-xylylene comprises an integrated
disulfide moiety within the functional side group, and the switching
phenomenon between the immobilized functional molecules is triggered
by the redox thiol–disulfide interchange reaction. These dynamically
well-defined molecules on the surfaces respond simultaneously to altered
biological properties and controlled biointerfacial functions, for
example, switching wettability or reversibly altered cell adhesion
activity. Poly-<i>p</i>-xylylenes are a key player in controlling
surface properties for many important applications, such as medical
implants, biosensors, bioMEMS devices, and microfluidics. The introduction
of this new facet of poly-<i>p</i>-xylylenes enables the
dynamic mimicry of biological functions relevant to the design of
new biomaterials
Fabrication of Functional Polymer Structures through Bottom-Up Selective Vapor Deposition from Bottom-Up Conductive Templates
An
electrically induced bottom-up process was introduced for the
fabrication of multifunctional nanostructures of polymers. Without
requiring complicated photolithography or printing techniques, the
fabrication process first produced a conducting template by colloidal
lithography to create an interconnected conduction pathway. By supplying
an electrical charge to the conducting network, the conducting areas
were enabled with a highly energized surface that generally deactivated
the adsorbed reactive species and inhibited the vapor deposition of
poly-<i>p</i>-xylylene polymers. However, the template allowed
the deposition of ordered poly-<i>p</i>-xylylene nanostructures
only on the confined and negative areas of the conducting template,
in a relatively large centimeter-scale production. The wide selection
of functionality and multifunctional capability of poly-<i>p</i>-xylylenes naturally rendered the synergistic and orthogonal chemical
reactivity of the resulting nanostructures. With only a few steps,
the construction of a nanometer topology with the functionalization
of multiple chemical conducts can be achieved, and the selected deposition
process represents a state-of-the-art nanostructure fabrication in
a simple and versatile approach from the bottom up
Topologically Controlled Cell Differentiation Based on Vapor-Deposited Polymer Coatings
In
addition to the widely adopted method of controlling cell attachment
for cell patterning, pattern formation via cell proliferation and
differentiation is demonstrated using precisely defined interface
chemistry and spatial topology. The interface platform is created
using a maleimide-functionalized parylene coating (maleimide-PPX)
that provides two routes for controlled conjugation accessibility,
including the maleimide–thiol coupling reaction and the thiol–ene
click reaction, with a high reaction specificity under mild conditions.
The coating technology is a prime tool for the immobilization of sensitive
molecules, such as growth factor proteins. Conjugation of fibroblast
growth factor 2 (FGF-2) and bone morphogenetic protein (BMP-2) was
performed on the coating surface by elegantly manipulating the reaction
routes, and confining the conjugation reaction to selected areas was
accomplished using microcontact printing (ÎĽCP) and/or UV irradiation
photopatterning. The modified interface provides chemically and topologically
defined signals that are recognized by cultured murine preosteoblast
cells for proliferation (by FGF-2) and osteogenesis (by BMP-2) activities
in specific locations. The reported technique additionally enabled
synergistic pattern formation for both osteogenesis and proliferation
activities on the same interface, which is difficult to perform using
conventional cell attachment patterns. Because of the versatility
of the coating, which can be applied to a wide range of materials
and on curved and complex devices, the proposed technology is extendable
to other prospective biomaterial designs and material interface modifications