**3. Cellular response to surfaces**

For the cells, the surface is the most important part of the material. Cell-biomaterial interactions depend on the surface energy, chemical composition and surface morphology [40, 41]. Moreover, cell growth, spreading and viability were shown to be closely linked to their adhesion on the surface [42]. Consequently, suitable surface properties contribute to better cell adhesion and subsequent proliferation. It is well established that for numerous cell types surface wettability is a paramount factor that influences cell adhesion, with this being more favorable on hydrophilic surfaces compared to hydrophobic surfaces. **Figure 1** shows micrographs of fibroblast cells cultured on untreated (hydrophobic) and argon plasma treated (hydrophilic) UHMWPE substrate. As seen in this **Figure 1**, cells are significantly more spread on the hydrophilic treated surface compared to the hydrophobic untreated one [43]. Additionally, surface charge has also been shown to have a significant influence on cell adhesion [44, 45].

A promising way to achieve optimal surface attributes (e.g., surface wettability and charge) is plasma polymerization which has already been used successfully to enhance cell adhesion on various substrates.

**Figure 1.** Overall cell morphology of fibroblasts cultured on (a) untreated and (b) argon plasma-treated UHMWPE.

In this section, previous works on the bio-application of plasma polymers and their interactions with cells will be reviewed.

#### *Biological applications of plasma polymers*

Plasma polymerization is a convenient way to introduce desired functional groups on a surface. Plasma polymers are frequently used to immobilize biomolecules and enhance cell adhesion. NH<sup>2</sup> and COOH based plasma polymers are most commonly used since these groups are known for their good chemical reactivity. Moreover, in aqueous solution at physiological pH value, amino/carboxyl groups can introduce a positive/negative charge to the surface thus increasing its affinity for biological components [46–48]. For example, DNA [49, 50], heparin [46], glucose oxidase [51], and collagen [52] have been immobilized on amine or carboxyl based plasma polymers. Hydroxyl and aldehyde groups have also been used to bind heparin [53] and collagen/albumin [54], respectively. However, plasma polymers with these groups are less extensively investigated due to their lower reactivity.

For the effect of plasma polymers on cell attachment and proliferation, various studies on different substrates using numerous plasma media and cell types have been performed. A summary of some of these studies is presented in **Table 1**.

Furthermore, plasma polymer films were used for bacterial adhesion and biofilm prevention by coating the surface with a suitable antibacterial agent (e.g., silver nanoparticle).

Xiaolong et al. [55] produced PET fabrics with antibacterial properties by depositing a plasma polymer organosilicon film where silver nanoparticles were incorporated. A similar study was also conducted on PET meshes by plasma polymerization of acrylic acid followed by incorporation of Ag nanoparticles [56]. Results showed excellent mesh antibacterial properties with a decrease of more than 99.7% in bacterial concentration compared to an untreated mesh. In another study, Degoutin et al. [57] used plasma to graft acrylic acid onto nonwoven polypropylene and the carboxyl groups were used to immobilize an antibiotic "gentamicin." Results showed a 99% efficacy against *E. coli* bacteria.

These results and discussions strongly support the idea that polymer coatings represent a very promising way to modify a biomaterial surface in order to adapt it to a specific biomedical application.


In this section, previous works on the bio-application of plasma polymers and their interac-

**Figure 1.** Overall cell morphology of fibroblasts cultured on (a) untreated and (b) argon plasma-treated UHMWPE.

Plasma polymerization is a convenient way to introduce desired functional groups on a surface. Plasma polymers are frequently used to immobilize biomolecules and enhance cell adhe-

are known for their good chemical reactivity. Moreover, in aqueous solution at physiological pH value, amino/carboxyl groups can introduce a positive/negative charge to the surface thus increasing its affinity for biological components [46–48]. For example, DNA [49, 50], heparin [46], glucose oxidase [51], and collagen [52] have been immobilized on amine or carboxyl based plasma polymers. Hydroxyl and aldehyde groups have also been used to bind heparin [53] and collagen/albumin [54], respectively. However, plasma polymers with these groups are less

For the effect of plasma polymers on cell attachment and proliferation, various studies on different substrates using numerous plasma media and cell types have been performed. A

Furthermore, plasma polymer films were used for bacterial adhesion and biofilm prevention

Xiaolong et al. [55] produced PET fabrics with antibacterial properties by depositing a plasma polymer organosilicon film where silver nanoparticles were incorporated. A similar study was also conducted on PET meshes by plasma polymerization of acrylic acid followed by incorporation of Ag nanoparticles [56]. Results showed excellent mesh antibacterial properties with a decrease of more than 99.7% in bacterial concentration compared to an untreated mesh. In another study, Degoutin et al. [57] used plasma to graft acrylic acid onto nonwoven polypropylene and the carboxyl groups were used to immobilize an antibiotic "gentamicin." Results

These results and discussions strongly support the idea that polymer coatings represent a very promising way to modify a biomaterial surface in order to adapt it to a specific biomedical

by coating the surface with a suitable antibacterial agent (e.g., silver nanoparticle).

and COOH based plasma polymers are most commonly used since these groups

tions with cells will be reviewed.

74 Recent Research in Polymerization

sion. NH<sup>2</sup>

application.

*Biological applications of plasma polymers*

extensively investigated due to their lower reactivity.

showed a 99% efficacy against *E. coli* bacteria.

summary of some of these studies is presented in **Table 1**.

**Table 1.** Summary of some of the studies on plasma surface modification of materials and their effect on cell adhesion and growth.
