Sol-Gel-Based Zirconia Bio-Coatings on Metal Structurallyenhanced by Polyethylene Glycol

Sol-gel-based zirconia bio-coatings on metal structurallyenhanced by polyethylene glycol

Han Lee1, Jiunn-Der Liao1,*, Pei-Lin Shao1, Chih-Kai Yao1, Yu-Hui Lin1, Yung-Der Juang2

1Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan

2Department of Materials Science, National University of Tainan,

33 Shu-Lin St. Sec. 2, Tainan 700, Taiwan

*Corresponding author.

Prof. Dr. Jiunn-Der Liao

Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan

E-mail:

Tel.: +886-6-2757575 ext. 62971; Fax: +886-6-2346290

Supporting Data 1

The force levels that produce a defined, reproducible type/level of damage in the coating are defined as the critical scratch load(s), LC. For a given coating/substrate system, one or more critical scratch loads (LCN) can be defined for progressive levels of coating damage(see Fig. S1). Damage in the coating or the substrate is called cohesive failure. Damage at the coating/substrate interface is called adhesive failure.

Figure S1: Friction force versus applied load curves for (a)ZAN_RT_10, (b) ZAN_200_10, and (c) ZAN_400_10. Low critical load (LC1) and high critical load (LC2) are indicated as examples.

Supporting Data 2

XRD analysis results showed that tetragonal ZrO2 appeared at 400 °C in both solutions. In order to determine the upper limit of temperature at which solvents and additives were totally excluded, thermal analysis was carried out to decrease the process temperature. Differential scanning calorimetry was thus used to examine the two as-prepared solutions.

During the test, the heating rate was set at 5 °C/min. The results are shown in Fig. S2. The exothermic peak at 0 to 100 °C is attributed to physical water desorption and solvents (especially isopropanol). However, the peak shape and area are slightly different, showing that the addition of PEG modified the solution constituents. The endothermic peak at 350 °C for ZANP is related to the decomposition of polymers or products involving the long carbon chain. Some studies have indicated that the crystallization of ZrO2 produces an exothermic peak at around 350 to 450 °C[1]. However, there is no such peak in either curve.

To sum up, DSC analysis results indicate that under 400 °C most organic solvents and polymers were eliminated or decomposed. It is thus possible to limit the post-annealing temperature to 400 °C.

Figure S2: DSC curves for ZAN solution (top) and ZANP solution (bottom).

Supporting Data 3

We have made a simple calculationabout the grain sizes by XRD andthe Scherrer formula (Eq. 1); the average grain sizes of ZAN_400_5 and ZANP_400_5 were 15.6 and 25.4 nm, respectively.

Table S1 Calculation of grain size by using XRD

(1)

Where,

τ- is the mean size of the ordered (crystalline) domains, which may be smaller or equal to the grain size.

K - is a dimensionless shape factor, with a value close to unity. The shape factor has a typical value of about 0.9, but varies with the actual shape of the crystallite

λ - is the X-ray wavelength.

β - is the line broadening at half the maximum intensity (FWHM), after subtracting the instrumental line broadening, in radians. This quantity is also sometimes denoted as Δ(2θ).

θ - is the Bragg angle.

Supporting Data 4

The effect of zirconia coatings on 3T3 cells proliferation was investigated by a MTS assay after incubated for 48 hours, which provided a measure of the integrity and activity of mitochondria in the cells that could be linked to the viability and number of cells in a culture. The absorbance was proportional to the amount of the cells, the more the cells on the surface, the larger the absorbance.When the surface roughness was increased from Figure S4 result show that the cells easily growth on the rough surface.

Figure S4: The proliferation activity of 3T3 cell incubated on different specimen after 48 hours. (p > 0.05 indicates a not significant difference compared with ZAN_RT_5, mean±SD, N = 6)

Supporting Data 5

About the adhesion between the sol-gel-prepared ZrO2 coatings and the substrate,we summarized the result in the Supporting Data 5 and demonstratedthe first critical load of cohesive failure (LCC) in the 5-layer coatings from ZAN and ZANP. It is likely that LCC increases with the addition of increasing annealing temperature. Overall, in this study, the optimized sol-gel-prepared ZrO2 coating was well adhered on the substrate and its surface exhibited relatively biocompatible.

Figure S5: The influence of post-annealing temperature on the first critical load of cohesive failure from N5 and P5 specimens.

References

[1] Picquart M, López T, Gómez R, Torres E, Moreno A, Garcia J (2004) Dehydration and crystallization process in sol-gel zirconia,J Therm Anal Calorim76:755-761