Functional micropatterns

In 2D cell culture on chip, cell adhesion has been extensively studied on patterned surfaces for it is critical to cellular functions. Micropatterns have been used to study the cellular interactions with various materials such as metals, polymers, self-assembled monolayers, extracellular matrix proteins, cell-adhesion peptides, and other bioactive molecules. The physical and chemical proper-... 

Yao, L, Wang, S, Cui, W et al. 2009. Effect of functionalized micropatterned PLGA on guided neurite growth. Acta Biomater 5(2) 580-588. 

In a first experiment with fibroblasts in culture, an extended 73-nm-spaced pattern was compared with a 2-pm-patterned 58-nm array. Although the total nanoparticle density of the micropatterned surface was considerably lower than that of the homogeneously coated one, the cells could only form FAs on 58-nm-spaced RGD motives. It is thus obvious that integrin function critically depends on the spatial confinement of integrins to favour clustering but not on the total number of bound integrins [82],... 

Covalent immobilization of cytophilic proteins by iCP can be also used to pattern cells on substrates. Cytophilic proteins can be printed in micropatterns on top of reactive SAMs using, for example, imine chemistry.109 Aldehyde-functionalized... 

Fabrication of a micropattern with three kinds of surface functional groups was confirmed by SFM observation. Fig. 10 shows (a) AFM and (b) LFM... 

Chen CS, Mrksich M, Huang S, Whitesides GM, Ingber DE. Micropatterned surfaces for control of cell shape, position, and function. Biotechnol Prog 1998 14 356-63. 

We have performed FLIC microscopy for all cell types that have been Hsted in Table 2 in order to quantify their individual distance to the growth substrate. It is an inherent problem of this approach that the cells had to be grown on micropatterned silicon for FLIC measurements and not on a quartz resonator as used in QCM. But the imcertainty whether the cells behave differently on either substrate cannot be bypassed in principle. Figure 11 shows the change in load impedance A Zl for the different cell types studied here as a function of their individual cell-substrate separation distance extracted from FLIC measurements. If the hypothesis appUes that cells provide a more sustained QCM response the closer they are to the surface, one would have to expect a decrease of A Zl with increasing distance d. The graph in Fig. 11, however, shows no obvious correlation between the acoustic load of the resonator and the distance between lower cell membrane and its surface. Please note that, for instance, BAEC and NRK cells show very similar distances from the surface of approximately 75 nm but the change in load impedance A Zl differs by more than a factor of four. 

In many cases it is necessary to synthesize porous materials in a well-defined preordered shape or within confined geometries, which introduces a pathway to fabricate hierarchically ordered porous materials. The techniques mentioned above have been shown to be capable of producing structured and well-ordered templates [61] within capillaries [50], thin plates [62], micromolds [63], or photoresist patterns [64,65]. Spatial adjustment of the surface functionality on the substrate and its wetting properties can yield patterned colloidal films [66,67]. Finally, confining the particle dispersion itself by printing techniques produces micropatterned arrays [68]. This was also shown to work without the necessity of preceding surface patterning steps [69]. 

Ubukata T, Hara M, Ichimura K, Seki T. 2004. Phototactic transport motions of polymer film for micropatterning and alignment of functional materials. Adv Mater 16 220 224. 

PDMS emerged as the polymer of choice for micropatterned surfaces and microfluidic devices. Fabrication is particularly straightforward since PDMS can be cast against a suitable mold with high fidelity. The optical, thermal, interfacial, permeability, and reactivity properties of PDMS make possible numerous functionalities including optical detection, reversible deformation, reversible wetting, and management of cell proliferation. "... 

Biological systems provide numerous examples of micropatterned inorganic materials that directly develop into their intricate architectures, as illustrated by skeleton formation in echinoderms with component function of speciahzed photosensory organs [19,248]. Each skeletal structural unit (spines, test plates) is composed of a single caldte crystal delicately patterned on the micrometer scale, which is composed of a close-set array of hemispherical caldtic structures (40-50 pm in diameter) with a characteristic double-lens design (Fig. 20). 

As demonstrated above, polymer micropatterned with plasma or UV irradiation can be used without any further treatment for cell culture application. However, functional groups created at the modified surface can be subsequently used for the selective graft coupling of biomolecules, suitable for cell adhesion enhancement [62]. 

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