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Shape-memory surfaces for cell mechanobiology

View Article: PubMed Central - PubMed

ABSTRACT

Shape-memory polymers (SMPs) are a new class of smart materials, which have the capability to change from a temporary shape ‘A’ to a memorized permanent shape ‘B’ upon application of an external stimulus. In recent years, SMPs have attracted much attention from basic and fundamental research to industrial and practical applications due to the cheap and efficient alternative to well-known metallic shape-memory alloys. Since the shape-memory effect in SMPs is not related to a specific material property of single polymers, the control of nanoarchitecture of polymer networks is particularly important for the smart functions of SMPs. Such nanoarchitectonic approaches have enabled us to further create shape-memory surfaces (SMSs) with tunable surface topography at nano scale. The present review aims to bring together the exciting design of SMSs and the ever-expanding range of their uses as tools to control cell functions. The goal for these endeavors is to mimic the surrounding mechanical cues of extracellular environments which have been considered as critical parameters in cell fate determination. The untapped potential of SMSs makes them one of the most exciting interfaces of materials science and cell mechanobiology.

No MeSH data available.


Time-dependent changes in the orientation angles of cells on the PCL film after shape-memory transition from a temporal grooved pattern to the permanent grooved patterns which is perpendicular to the original shape.
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Figure 7: Time-dependent changes in the orientation angles of cells on the PCL film after shape-memory transition from a temporal grooved pattern to the permanent grooved patterns which is perpendicular to the original shape.

Mentions: The author’s group has also been developing a SMS system with dynamically tunable nanopatterns to direct cell fate [35]. The shape-memory nanopatterns were prepared by chemically crosslinking semi-crystalline PCL in a mold to show shape-memory effects over its melting temperature (Tm = 33 °C). Permanent surface patterns were first generated by crosslinking the PCL macromonomers in a mold, and temporary surface patterns were then embossed onto the permanent patterns (figure 5). The temporary surface patterns could be easily triggered to transition quickly to the permanent surface patterns by a 37 °C heat treatment. One of the great advantages of PCL over other temperature-responsive polymers is that surface properties such as wettability and charge are independent of temperature. Using this substrate, we have successfully demonstrated time-dependent cell orientation changes by inducing nanotopographical transition from grooves with a height of 300 nm to flat. Upon transition from the grooved topography to a flat surface, cell alignment was lost and random cell migration and growth ensued. We have also succeeded in inducing a 90° rotation of the cell orientation by using shape-memory nanogrooves, the direction of which was transitioned 90° to the temporary grooves (figure 6) [36]. Interestingly, 90% of cells did not change their direction 1 h after the topographic transition. By 36 h, however, 70% of cells realigned parallel to the permanent grooves that emerged. To understand the effects of pattern dimension (nm versus μm) on the interlude between the topographic transition of shape-memory nanopatterns and cell response on them, we have also monitored time-dependent changes in surface nanotopographic features associated with shape-memory transition as well as the cell morphology or alignment [37]. Holographic microscope revealed that the application of heat to PCL SMP quickly and completely transitioned temporary surface patterns substrate to permanent patterns within 30 s. However, it took more than 2 and 8 h for cells on substrate with 500 and 2000 nm grooves to induce 90°-rotation of the cell orientation, respectively (figure 7). This different alignment behavior can be explained by the different adhesion strength and reorganization of cytoskeletal proteins on nano versus micropatterns. To our best knowledge, we first revealed that dynamic control of geometrical shape exert a dramatic effect on the realignment of adhered cells even using the same material.


Shape-memory surfaces for cell mechanobiology
Time-dependent changes in the orientation angles of cells on the PCL film after shape-memory transition from a temporal grooved pattern to the permanent grooved patterns which is perpendicular to the original shape.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036502&req=5

Figure 7: Time-dependent changes in the orientation angles of cells on the PCL film after shape-memory transition from a temporal grooved pattern to the permanent grooved patterns which is perpendicular to the original shape.
Mentions: The author’s group has also been developing a SMS system with dynamically tunable nanopatterns to direct cell fate [35]. The shape-memory nanopatterns were prepared by chemically crosslinking semi-crystalline PCL in a mold to show shape-memory effects over its melting temperature (Tm = 33 °C). Permanent surface patterns were first generated by crosslinking the PCL macromonomers in a mold, and temporary surface patterns were then embossed onto the permanent patterns (figure 5). The temporary surface patterns could be easily triggered to transition quickly to the permanent surface patterns by a 37 °C heat treatment. One of the great advantages of PCL over other temperature-responsive polymers is that surface properties such as wettability and charge are independent of temperature. Using this substrate, we have successfully demonstrated time-dependent cell orientation changes by inducing nanotopographical transition from grooves with a height of 300 nm to flat. Upon transition from the grooved topography to a flat surface, cell alignment was lost and random cell migration and growth ensued. We have also succeeded in inducing a 90° rotation of the cell orientation by using shape-memory nanogrooves, the direction of which was transitioned 90° to the temporary grooves (figure 6) [36]. Interestingly, 90% of cells did not change their direction 1 h after the topographic transition. By 36 h, however, 70% of cells realigned parallel to the permanent grooves that emerged. To understand the effects of pattern dimension (nm versus μm) on the interlude between the topographic transition of shape-memory nanopatterns and cell response on them, we have also monitored time-dependent changes in surface nanotopographic features associated with shape-memory transition as well as the cell morphology or alignment [37]. Holographic microscope revealed that the application of heat to PCL SMP quickly and completely transitioned temporary surface patterns substrate to permanent patterns within 30 s. However, it took more than 2 and 8 h for cells on substrate with 500 and 2000 nm grooves to induce 90°-rotation of the cell orientation, respectively (figure 7). This different alignment behavior can be explained by the different adhesion strength and reorganization of cytoskeletal proteins on nano versus micropatterns. To our best knowledge, we first revealed that dynamic control of geometrical shape exert a dramatic effect on the realignment of adhered cells even using the same material.

View Article: PubMed Central - PubMed

ABSTRACT

Shape-memory polymers (SMPs) are a new class of smart materials, which have the capability to change from a temporary shape ‘A’ to a memorized permanent shape ‘B’ upon application of an external stimulus. In recent years, SMPs have attracted much attention from basic and fundamental research to industrial and practical applications due to the cheap and efficient alternative to well-known metallic shape-memory alloys. Since the shape-memory effect in SMPs is not related to a specific material property of single polymers, the control of nanoarchitecture of polymer networks is particularly important for the smart functions of SMPs. Such nanoarchitectonic approaches have enabled us to further create shape-memory surfaces (SMSs) with tunable surface topography at nano scale. The present review aims to bring together the exciting design of SMSs and the ever-expanding range of their uses as tools to control cell functions. The goal for these endeavors is to mimic the surrounding mechanical cues of extracellular environments which have been considered as critical parameters in cell fate determination. The untapped potential of SMSs makes them one of the most exciting interfaces of materials science and cell mechanobiology.

No MeSH data available.