Representative SEM images of 200 µg/ml collagen self-assembly in DPBS with different pH values (A–B: 7, C–D: 9, E–F: 11) on Mg surface (A, C, E) and AZ31 (B, D, F).

<p>Representative SEM images of 200 µg/ml collagen self-assembly in DPBS with different pH values (A–B: 7, C–D: 9, E–F: 11) on Mg surface (A, C, E) and AZ31 (B, D, F).</p

Representative fluorescent images of MC 3T3 cells growing on collagen self-assembled at AZ31 with different surface roughness for 1, 4 and 7 d. Live cells are in green color and dead cells are in red color.

<p>Representative fluorescent images of MC 3T3 cells growing on collagen self-assembled at AZ31 with different surface roughness for 1, 4 and 7 d. Live cells are in green color and dead cells are in red color.</p

3-D surface topography of Mg sample polished by different SiC paper (A: 180 grit; B: 800 grit; C: 1200 grit).

<p>The arithmetic average of surface roughness (R_a) and root mean square (R_q) calculated from 4 different samples are shown on the top left corner.</p

Representative fluorescent image of MC 3T3 cells growing on collagen self-assembled at Mg with different surface roughness for 1, 4 and 7 d. Live cells are in green color and dead cells are in red color.

<p>Representative fluorescent image of MC 3T3 cells growing on collagen self-assembled at Mg with different surface roughness for 1, 4 and 7 d. Live cells are in green color and dead cells are in red color.</p

Mg²⁺ concentration after the materials (A-AZ31; B-Mg) were incubated with collagen solution for 2 h and cocultured with cells for 1, 4 and 7 days.

<p>Error bars were omitted for clarity purpose.</p

Representative SEM images of collagen self-assembly on Mg (left) and AZ31 (right).

<p>The concentration of collagen in each group is shown on the top left corner of each image.</p

Collagen adsorption quantification.

<p>Standard curve for quantification of collagen by Picro-sirius red stain kit (A). The amount of collagen absorbed on Mg with different surface roughness at 0.5, 1, 2, 4, and 8 h (B). The amount of collagen absorbed on AZ31 with different surface roughness at 0.5, 1, 2, 4, and 8 h (C).</p

Representative SEM images of MC 3T3 cell attachment on collagen self-assembled at Mg (A, C, E) and AZ31 (B, D, F) with different surface roughness (A–B: RS; C–D: SR; E–F: SS).

<p>Representative SEM images of MC 3T3 cell attachment on collagen self-assembled at Mg (A, C, E) and AZ31 (B, D, F) with different surface roughness (A–B: RS; C–D: SR; E–F: SS).</p

The pH of the cell culture media after incubated with cells on materials.

<p>The pH of the cell culture media after incubated with cells on materials.</p

Representative SEM images of 200 µg/ml collagen self-assembly on Mg (A, C, E) and AZ31 (B, D, F) with different surface roughness (A–B: RS; C–D: SR; E–F: SS). RS: rough surface; SR: semi-rough surface; SS: smooth surface.

<p>Representative SEM images of 200 µg/ml collagen self-assembly on Mg (A, C, E) and AZ31 (B, D, F) with different surface roughness (A–B: RS; C–D: SR; E–F: SS). RS: rough surface; SR: semi-rough surface; SS: smooth surface.</p