2 research outputs found
Patterned Enzymatic Degradation of Poly(ε-caprolactone) by High-Affinity Microcontact Printing and Polymer Pen Lithography
This
paper reports deposition of Candida antarctica Lipase B (CALB) on relatively thick polyÂ(ε-caprolactone) (PCL)
films (300–500 nm) to create well-defined patterns using two
different writing techniques: high-affinity microcontact (HA-μCL)
and polymer pen (PPL) lithography. For both, an aqueous CALB ink is
absorbed onto a polydimethylsiloxane (PDMS) writing implement (PDMS
stamp or a PDMS pen tip), which is transferred to a spun-cast PCL
film. HA-μCL experiments demonstrated the importance of applied
pressure to obtain high-resolution patterns since uniform contact
is needed between raised 20 μm parallel line regions of the
PDMS stamp and the surface. AFM imaging shows pattern formation evolves
gradually over incubation time only in areas stamped with CALB cutting
through spherulites without apparent influence by grain boundaries.
Strong binding of CALB to PCL is postulated as the mechanism by which
lateral diffusion is limited. PPL enables formation of an arbitrary
image by appropriate programming of the robot. The PDMS pen tips were
coated with an aqueous CALB solution and then brought into contact
with the PCL film to transfer CALB onto the surface. By repeating
the ink transfer step multiple times where pen tips are brought into
contact with the PCL film at a different locations, a pattern of dots
is formed. After printing, patterns were developed at 37 °C and
95% RH. Over a 7-day period, CALB progressively etched the PCL down
to the silicon wafer on which it was spun (350 nm) giving round holes
with diameters about 10 μm. AFM images show the formation of
steep PCL walls indicating CALB degraded the PCL film in areas to
which it was applied. This work demonstrates that high-resolution
patterns can be achieved without immobilizing the enzyme on the surface
of polymeric stamps that limits the depth of features obtained as
well as the throughput of the process