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Biomedical subjects

William P King

Publications and source records attributed to William P King.

5 recordsLinked to original sources
PubMed2006

Direct writing of a conducting polymer with molecular-level control of physical dimensions and orientation.

Polymer nanostructures composed of poly(3-dodecylthiophene) (PDDT) have been directly written with control of polymer strand alignment and monolayer-by-monolayer thickness down to a single molecular monolayer (2.6 nm). The molecularly ordered nanostructures were written on silicon oxide surfaces using thermal dip-pen nanolithography, where an atomic force microscope cantilever with integrated tip heater was precoated with solid PDDT. The PDDT was precisely deposited onto the surface when the tip temperature was set close to PDDT's melting temperature.

Journal Article↗
PubMed2005

Combined microscale mechanical topography and chemical patterns on polymer cell culture substrates.

This paper presents a technique to independently form mechanical topography and surface chemical patterns on polymer cell substrates, and studies the response of osteoblast cells to these surface patterns. The patterns were formed in two separate steps: hot embossing imprint lithography formed the mechanical topography and microcontact printing created the chemical pattern. The resulting substrate had surface features consisting of embossed grooves 4 microm deep and 8 microm wide spaced by 16 microm wide mesas and microcontact printed adhesive lanes 10 microm wide with spacings that ranged from 10 to 100 microm. When presented with either mechanical topography or chemical patterns alone, the cells significantly aligned to the pattern presented. When presented with mechanical topography overlaid with an orthogonal chemical pattern, the cells aligned to the mechanical topography. As the chemical pattern spacing was increased, osteoblasts remained aligned to the mechanical topography. Unlike traditional microfabrication approaches based on photolithography and wet chemistry, the patterning technique presented is compatible with a large number of biomaterials, could form patterns with features much smaller than 1 microm, and is highly scalable to large substrates.

3T3 Cells↗
PubMed2004

Hot embossing for micropatterned cell substrates.

This paper reports the development of a technique for preparing microtextured polymer substrates for cell growth and studies the response of osteoblast cells grown on these surfaces. The surfaces were manufactured with hot embossing, where a silicon micromachined printing master was pressed into a thermoplastic polymer substrate at elevated temperature, forming a regular microgroove pattern in the polymer. The grooves were approximately 5 microm deep, 4 microm wide, and had a periodicity of 34 microm. The polymer substrate was polyimide, which can be spincast and printed in its uncured form, and is mechanically rigid and chemically nonreactive after full cure. Osteoblast cells were grown on the textured polymer substrate and their responses to grooved and smooth surfaces were observed with fluorescence microscopy. Alignment and aspect ratio were analyzed for the cell body, cell nucleus, and focal adhesions. Cell membrane body, cell nucleus, and focal adhesions all strongly aligned with the microgrooves, while only the cell body shape changed on the microgrooved surface. This novel substrate preparation technique offers the opportunity for low-cost and rapid manufacture of microtextured surfaces that can be used to control cell shape and alignment.

3T3 Cells↗