Table 5.
Literature overview of the effects of silicon on ECs
| Silicon | |||||||
|---|---|---|---|---|---|---|---|
| Tested material | Effective conc./ion release Si4+ | In vitro cell line/In vivo species | Assays—Direct (D)/indirect (I) | Incubation time | Other material properties | Results | Ref |
| Ti‐Si‐N coating on Ti6Al4V | SC: 20 at%; No IRP | EA.hy926 | CCK proliferation (D); cell morphology and spreading (D); NO release (D) | 1, 5 d; 5 d; 5 d | Decreasing nanoroughness with increasing Si content may affect the attachment properties. | Better morphology and greater spreading, increased proliferation and endothelialisation. | [ 92 ] |
| Si‐micro/nano‐structured titanium | SC: 0.86 at%; IRP: 23 mg L−1; (after 7 d) | EA.hy926 | Cell adhesion (D); actin assay (D); cell morphology (D); live/dead viability (D); MTT proliferation (D); ELISA (D); tube formation in EC Matrix (I); RT‐qPCR (D) | 0.5, 1, 4 h; 1, 4, 24 h; 1 d; 1, 3, 5 d; 1, 4, 7 d 24 h; 4, 8, 15 h; 3 d | Micro‐ and nanostructures from MAO and HT treatment respectively influenced the cell adhesion and the Si release profile. | Nanostructures secured a more constant Si release profile and improved the angiogenic behavior of HUVECs. | [ 111 ] |
| Ti‐Si‐N coating on Ti6Al4V | SC: 12 at%; No IRP | EA.hy926 | NO release (D); cell morphology and spreading (D) | 3 d; 24 h | Decreasing nanoroughness with increasing Si content. | Enhanced adhesion of endothelial cells on the coating. | [ 112 ] |
| Silk fiber w. Zn + Si‐BrC brushite | MC: 0.5 wt%; No IRP | Porcine ECs; New Zealand white rabbits | Tube formation in collagen (D); Alamar Blue proliferation (D); viability assay with PI (D); NO release (D); femur defect | N/A; 1, 3, 7 d; 7 d; 1, 7 d; 1, 3 month | ‐ | Positive effect of Si (and synergistic effect of Si/Zn) on angiogenesis. | [ 68 ] |
| Bioactive glass nanoporous structure | MC: 40 mol% (85 mol% SiO2); IRP: 21 mg L−1 (after 7 d) | HUVECs; SD rats | Scratch migration (I); tube formation in Matrigel (I); subcutaneous implantation | 24 h; 3, 6 h; 2, 4 w | Nanofibrous structure enhances neo‐blood vessel formation. | Stable delivery of Ca and Si and their synergistic effect with the nano‐sites of improved angiogenesis. | [ 120 ] |
| Si‐DLC coating on Ti6Al7Nb | SC: 14–22 at%; No IRP | EA.hy926 | Live/dead viability (D); XTT viability (I,D) | 48 h; 48 h | Increasing wettability with higher Si content. | Si is tolerated by cells up to the limit between 14 and 22 at%. | [ 113 ] |
| Si‐TiO2 nanotubes | SC: 2.8 at%; IRP: 7 mg L−1 (after 1 d) | EA.hy926 | Live/dead viability (D); tube formation in ECMatrix (I); NO release (I); ELISA (I) | 1, 3, 5 d; 4, 7, 17 h; 24 h; 24 h | Increase of Si content increases the hydrophilicity. | The incorporation of Si into the material boosted the angiogenic capacity of ECs. | [ 65 ] |
| Strontium‐HT‐Gahnite | 1.6–6.6 mg L−1 (diluted extracts) | HUVECs | MTT proliferation (I); transwell migration (I); RT‐qPCR (I); calvarial defect | 1, 4, 7 d; 18 h (7 d preculture); 4 d; 4–6 w | ‐ | Increased metabolic activity at day 7, migration capacity, and mRNA expression of HUVECs with the dissolution products. | [ 77 ] |
| Ti‐Si‐N coating on titanium | SC: ≈11–13 at%; No IRP | EA.hy926 | Cell morphology and spreading (D); CCK‐8 proliferation (D); NO release (D); RT‐qPCR (D); Western blotting (D) | 24 h; 1, 6 d; 6 d; 6 d; N/A | ‐ | Si promoted endothelial proliferation and upregulates VEGF in ECs. | [ 114 ] |
| Si‐TiO2 | SC: 1.8 wt%; IRP: 3.5 mg L−1 (after 7 d) | HUVECs | Alamar Blue proliferation (D); cell morphology, live/dead viability (D); scratch migration (D); tube formation in Matrigel (I); ELISA (D); RT‐qPCR (D) | 1, 4, 7 d; 7 d; 8 h (1 d preculture); 12 h; 1, 3, 5, 7 d; 4, 7, 14 d | ‐ | The coating with 1.8 wt% of Si improved the proliferation, migration, and VEGF, tube formation of HUVECs. | [ 115 ] |
| Mesoporous silica microspheres | IRP: ≈22 mg L−1 (after 7 d) | HUVECs; domestic chicken embryos | CCK‐8 proliferation (I); RT‐qPCR (I); Western blotting (I); immunohistochemistry (I); tube formation in Matrigel (I); scratch migration (I); transwell migration (I); angiogenesis in chick chorioallantoic membrane (CAM) | 1, 3, 7 d; 24 h; 24 h; 24 h; 0, 4, 6, 12 h; 12, 24 h; 12 h; 11 d | ‐ | The presence of Si promoted angiogenic capacity of HUVECs through stimulating expression of HIF1‐alpha, especially in combination with the delivery of VEGF. | [ 119 ] |
| Si‐oxynitro‐phosphide coating | SC: 53–62 at%; No IRP | HUVECs | Cell attachment (D); MTS viability (D); MTS growth (D); proliferation with Calcein‐AM (I); transwell migration (I); matrix deposition (D); tube formation in Matrigel (D); RT‐qPCR (D) | 4 h; 24 h; 1, 3, 7 d; 24, 48 h; 24 h; 5 d; 6 h; 24, 72 h | Surface wettability correlated with the number of attached cells. | The silica‐based coatings enhanced proliferation, migration, matrix deposition, and tube formation VEGF expression of HUVECs. | [ 137 ] |
| Cu/Si‐TiO2 | SC: 16 at%; IRP: ≈27 mg L−1 (after 7 d) | EA.hy926 | Live/dead viability (D); MTT proliferation (D); cell morphology (D); ELISA (D); tube formation in ECMatrix (I); RT‐qPCR (I) | 1, 3, 5 d; 1, 4, 7 d; 1 d; 24 h; 4, 8, 18 h; 3 d | ‐ | The implant with 16 at% of Si showed the best proangiogenic property by stimulating the proliferation, favorable morphology, and gene expression of ECs. | [ 73 ] |
| Ca–Mg–Si bioceramics | 1.18–4.44 mg L−1 (diluted extracts) | HAECs | WST‐1 proliferation assay (I); NO release (I); tube formation in ECMatrix (I); RT‐qPCR (I) | 4 d; 24 h; 2.5, 5.5, 17 h; 4 d | ‐ | Ceramics releasing higher amount of Si had greater stimulatory effect on angiogenic behavior of ECs. | [ 116 ] |
| Ca–Mg–Si bioceramics | 0.6–2.1 mg L−1 (diluted extracts) | HAECs; New Zealand rabbits | WST‐1 proliferation (I); tube formation in ECMatrix (I); RT‐qPCR (I) NO release (I); scaffold implantation near distal femur | 4 d; 2.5, 5.5, 17 h; 4 d 24 h; 8, 16 w | ‐ | Presence of Si stimulated angiogenic behavior of ECs in vitro and neovascularization in vivo. | [ 117 ] |
| Si‐HA | SC: 6.15 at%; IRP: 17 mg L−1 (after 7 d) | HUVECs; white leghorn chicken eggs; Wistar rats | Viability with Calcein AM (D); cell adhesion (D); proliferation with PicoGreen (D); NO release (D); ELISA (D); chicken chorioallantoic membrane assay; subcutaneous implantation | 24 h; 24 h; 1, 7 d; 1, 7 d; 1, 7 d; 4 d; 2 w | ‐ | Scaffold with Si had stimulatory effects on functionality and viability of ECs. | [ 118 ] |
| (Si‐)Mg‐Ca alloy | SC: 10 at%; IRP: 2.0 mg L−1 (after 5 d) | C166‐GFP EC line | Cell morphology (D); Alamar Blue cytocompatibility (I) | 30 min; 5 d | The samples differed in surface roughness (0.7–4.3 µm), thickness, and porosity. | The Si topography promoted the cellular organization. | [ 75 ] |