Photographs of the cpMg* and MgY* samples after incubation in PBS under standard cell culture conditions for the prescribed time points.

<p>The sample appearance changed with time, indicating different degradation rate and mode.</p

The pH change of the PBS solution containing the cpMg* and MgY* samples over the prescribed incubation time.

<p>(A) PBS pH at all time points. (B) Zoom into PBS pH at the early time points for clear view. Values are average ± standard deviation; N = 3.</p

Statistical significance of the three factors (alloy composition, sample surface type, immersion media) on sample lifetime and their interactions.

<p>The <i>p</i> values were calculated using three-way factorial ANOVA. All <i>p</i> values were <0.05, indicating statistical significance.</p

Surface microstructure of the (A, B) cpMg* and (C, D) MgY* samples before and after 24 hours of degradation in either DI water or PBS.

<p>Scale bars: 20 µm.</p

Three key interacting factors influence degradation rate and mode of magnesium.

<p>MgY* refer to Mg-Y alloys with either metallic (MgY) or oxide (MgY_O) surfaces. cpMg* refers to commercially pure Mg with either metallic (cpMg) or oxide (cpMg_O) surfaces.</p

The surface elemental composition of the cpMg* and MgY* before and after 24 hours of degradation in DI water or PBS.

<p>The surface elemental composition of the cpMg* and MgY* before and after 24 hours of degradation in DI water or PBS.</p

Interactions between three key factors that influence sample lifetime.

<p>Interaction plots demonstrated the two-way interactions between factors. Two separate interaction plots with different values of the third factor were placed side by side for comparison. The values of the third factor were shown directly above each graph. (A) Alloy and surface type with media type as the third factor. (B) Alloy and media type with surface type as the third factor. (C) Media and surface type with alloy as the third factor.</p

The mass change of the cpMg* and MgY* samples during degradation in PBS.

<p>M_i was the mass after the prescribed incubation time (i) and M₀ was the initial mass. (A) Sample mass change at all time points. (B) Zoom into sample mass change at the early time points for clear view. The green star above the error bar of MgY mass change at 456 hr indicates that one of the triplicate samples completely degraded (i.e., reached 0 mass), causing a greater standard deviation. Values are average ± standard deviation; N = 3.</p

Photographs of the cpMg* and MgY* samples after incubation in DI water under standard cell culture conditions for the prescribed time points.

<p>The sample appearance changed with time, indicating different degradation rate and mode.</p

The mass change of the cpMg* and MgY* samples during degradation in DI water.

<p>M_i was the mass after the prescribed incubation time (i) and M₀ was the initial mass. (A) Sample mass change at all time points. (B) Zoom into sample mass change at the early time points for clear view. Values are average ± standard deviation; N = 3.</p