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. 2018 Apr 11;5(4):172310.
doi: 10.1098/rsos.172310. eCollection 2018 Apr.

The relationship between substrate morphology and biological performances of nano-silver-loaded dopamine coatings on titanium surfaces

Weibo Zhang  1   2 , Shuang Wang  2 , Shaohua Ge  1 , Jialong Chen  2 , Ping Ji  1
Affiliations

The relationship between substrate morphology and biological performances of nano-silver-loaded dopamine coatings on titanium surfaces

Weibo Zhang et al. R Soc Open Sci. .

Abstract

Biomedical device-associated infection (BAI) and lack of osseointegration are the main causes of implant failure. Therefore, it is imperative for implants not only to depress microbial activity and biofilm colonization but also to prompt osteoblast functions and osseointegration. As part of the coating development for implants, the interest of in vitro studies on the interaction between implant substrate morphology and the coating's biological performances is growing. In this study, by harnessing the adhesion and reactivity of bioinspired polydopamine, nano-silver was successfully anchored onto micro/nanoporous as well as smooth titanium surfaces to analyse the effect of substrate morphology on biological performances of the coatings. Compared with the smooth surface, a small size of nano-silver and high silver content was found on the micro/nanoporous surface. More mineralization happened on the coating on the micro/nanoporous structure than on the smooth surface, which led to a more rapid decrease of silver release from the micro/nanoporous surface. Antimicrobial tests indicated that both surfaces with resulting coating inhibit microbial colonization on them and growth around them, indicating that the coating eliminates the shortcoming of the porous structure which render the implant extremely susceptible to BAI. Besides, the multiple osteoblast responses of nano-silver-loaded dopamine coatings on both surfaces, i.e. attachment, proliferation and differentiation, have deteriorated, however the mineralized surfaces of these coatings stimulated osteoblast proliferation and differentiation, especially for the micro/nanoporous surface. Therefore, nano-silver-loaded dopamine coatings on micro/nanoporous substratum may not only reduce the risk of infection but also facilitate mineralization during the early post-operative period and then promote osseointegration owing to the good osteoblast-biocompatibility of the mineralized surface. These results clearly highlight the influence of the substrate morphology on the biological performances of implant coating.

Keywords: antimicrobial activity; dopamine; micro/nanoporous structure; nano-silver; osteoblast-compatibility; smooth surface.

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Conflict of interest statement

We declare we have no competing interests.

Figures

Figure 1.
Figure 1.
SEM images of sTi (a), pTi (b), sTi/PDA (c), pTi/PDA (d), sTi/PDA/AgNP (e), pTi/PDA/AgNP (f) and mineralized surfaces of sTi-M (g), pTi-M (h), sTi/PDA-M (i), pTi/PDA-M (j), sTi/PDA/AgNP-M (k), pTi/PDA/AgNP-M (l) after incubation for one week in the calcification solution.
Figure 2.
Figure 2.
The XPS wide-scan spectra of sTi (a), pTi (b), sTi/PDA (c), pTi/PDA (d), sTi/PDA/AgNP (e) and pTi/PDA/AgNP (f). Insets present high-resolution spectra of the Ag3d peak.
Figure 3
Figure 3
Water contact angle of different surfaces.
Figure 4.
Figure 4.
The XPS wide-scan spectra of sTi/PDA/AgNP-M and pTi/PDA/AgNP-M after incubation for one week in the calcification solution.
Figure 5.
Figure 5.
The measurement of silver release from nano-silver modified surfaces into calcification solution was sustained for 30 days. Solutions were changed every two days and silver concentration measured via ICP-OES. The inset is cumulative release of silver.
Figure 6.
Figure 6.
Representative confocal laser scanning micrographs of six types of oral microbes on the sTi, pTi, sTi/PDA/AgNP and pTi/PDA/AgNP after incubation at predetermined time points, visualizing live (green), dead (red) and apoptotic (yellow) cells.
Figure 7.
Figure 7.
Zone of inhibition (ZOI) testing of the sTi, pTi, sTi/PDA/AgNP and pTi/PDA/AgNP against six types of oral microbes.
Figure 8.
Figure 8.
Microbial growth curves of six types of oral microbes in LB media with different samples. Comparison of the antimicrobial effect of the samples with and without nano-silver.
Figure 9.
Figure 9.
Immunofluorescent images of cytoskeletal actin for osteoblast (MC3T3-E1) on the different surfaces after 12 h (a), 24 h (b) and 5 day (c) culture. The quantitative analysis of osteoblast cultured on the different surfaces for 12 h (d), 24 h (e) and 5 days (f), measured by MTT assay.
Figure 10.
Figure 10.
ALP quantitative assay of MC3T3-E1 on different samples at days 4, 7 and 10.
See this image and copyright information in PMC

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