Biomimetic Polymer Nanostructures by Injection Molding

Abstract

The nanometer scale topography of self‐assembling structural protein complexes in animals is believed to induce favorable cell responses. An important example of such nanostructured biological complexes is fibrillar collagen that possesses a cross‐striation structure with a periodicity of 69 nm and a peak‐to‐valley distance of 4–6 nm. Bovine collagen type I was assembled into fibrillar structures in vitro and sedimented onto solid supports. Their structural motif was transferred into a nickel replica by physical vapor deposition of a small‐grained metal layer followed by galvanic plating. The resulting inverted nickel structure was found to faithfully present most of the micrometer and nanometer scale topography of the biological original. This nickel replica was used as a die for the injection molding of a range of different thermoplastic polymers. Total injection molding cycle times were in the range of 30–45 seconds. One of the polymer materials investigated, polyethylene, displayed poor replication of the biological nanotopographical motif. However, the majority of the polymers showed very high replication fidelity as witnessed by their ability to replicate the cross‐striation features of less than 5 nm height difference. The latter group of materials includes poly(propylene), poly(methyl methacrylate), poly(L‐lactic acid), polycaprolactone, and a copolymer of cyclic and linear olefins (COC). This work suggests that the current limiting factor for the injection molding of nanometer scale topography in thermoplastic polymers lies with the grain size of the initial metal coating of the mold rather than the polymers themselves. magnified image

Adhesion formation of primary human osteoblasts and the functional response of mesenchymal stem cells to 330 nm deep microgrooves

“…That layer acted as an electrode in the subsequent electroplating process. The shims were plated to a thickness of approximately 300 nm (for more information about the procedure see Gadegaard et al (2003)). The shims were finally trimmed to approximately 30!30 mm sizes using a metal guillotine.…”

Nanopatterned Surfaces for Biomedical Applications

“…Flemming et al prepared PMMA replicas of decelluralised blood vessels containing the 3-dimensional structure of the extra cellular matrix (Flemming, Murphy et al 1999). Gadegaard et al demonstrated the ability to replicate the nanometric structure of collagen fibrils and fibres (Gadegaard, Mosler et al 2003). Although, there is a range of alternative technologies available for patterning surfaces for biological applications, the majority of the research is still applying semiconductor techniques such as photolithography and electron beam lithography.…”

“…The sample is inserted into a tank with nickel ions and when drawing a current a layer of nickel www.intechopen.com can be deposited in the master substrate. This shim will then be fixed in the cavity of the injection moulding tool (Gadegaard, Mosler et al 2003).…”

Hydrogen silsesquioxane mold coatings for improved replication of nanopatterns by injection molding

“…A wide range of applications has been explored including microfluidic devices [3,4], diffractive optical elements [5], anti-reflective surfaces [6,7], superhydrophobic surfaces [8][9][10], and functional cell culture substrates [11][12][13][14]. Commercial injection molding is routinely used to replicate features with details down to 150 nm in the case of Blu-Ray discs, while replication demonstrating lateral resolution as low as 5 nm has been demonstrated in research [15][16][17][18][19][20]. This suggests that the lower limit of replication is determined by the structural detail of the mold surface.…”