Experimental study on the influence of PDA-modified PDMS on the biological behavior of mouse fibroblasts

Polydimethylsiloxane (PDMS) is widely used across various fields due to its biocompatibility and chemical inertness. However, its surface hydrophobicity limits its application in cell culture. This study modifies PDMS surfaces with polydopamine (PDA) to mitigate hydrophobicity, with a primary focus on evaluating fibroblast biocompatibility on the modified substrate at a selected concentration (0.2%) and exploring its potential for wound healing applications. PDMS was surface-modified with PDA solutions at concentrations of 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% (W/V%) to evaluate its wettability. Based on the preliminary screening of material contact angle and cell viability after material-cell interaction, 0.2% PDA-PDMS was chosen for all subsequent biological tests. Mouse fibroblasts L929 were cultured on the selected substrate. Cell proliferation was determined by the CCK-8 assay. FITC/DAPI fluorescent staining, scratch assay, and RT-qPCR were used to evaluate cell spreading, migration, and gene expression. Statistical analysis employed t-test, one-way ANOVA, and two-way ANOVA. All PDA concentrations significantly reduced material contact angles (P < 0.01). At 48 h of interaction, the 0.2% PDA-PDMS exhibited the highest cell viability in CCK-8 assay among all concentrations (P < 0.0001), with significantly increased cell viability observed at 48 and 72 h (P < 0.05). The cell scratch assay showed that L929 cultured on 0.2% PDA-PDMS had largely recovered by 36 h post-scratch, with no significant difference compared to cells cultured on PDA-PDMS from 0 h to 18 h (P > 0.05). RT-qPCR indicated significantly elevated expression of transforming growth factor-β1 (TGF-β1) and collagen α-1 (III) chain (COL3A1) at 24 h and 36 h, and α-smooth muscle actin (α-SMA) at 48 h, compared to control (P < 0.05). PDA significantly decreased the hydrophobicity of the PDMS and enhanced its wettability. Based on preliminary assessment across concentrations, 0.2% PDA-PDMS demonstrated the highest cell proliferation and viability among the tested groups. PDA surface modification at this concentration also enhanced cell migration ability, improved cell morphology and spreading, and increased the expression of related genes.