Effects of polydopamine coatings on nucleation modes of surface mineralization from simulated body fluid

Giovannimaria Murari,Teresa Liew,Phong A. Tran,Lei Yang,Huan Zhou,Kate Fox,Nathalie Bock

doi:10.1038/s41598-020-71900-3

Abstract

Polydopamine (PDA) has been recently used as a versatile priming layer for further functionalization of a biomaterial surface, particularly in biomimetic mineralization of biomaterials. Yet most of the existing literature is on inorganic substrates and the underlying effects of the PDA layer coatings on the nucleation and mineralization process and the mineral-substrate interface have not been clearly identified. Here we aimed to investigate the effects of the PDA layer on the nucleation and growth and interfacial morphology of calcium phosphate mineral layer (CaP) from 10× simulated body fluid (10× SBF) on polymeric substrates. It is found that the nucleation of CaP on PDA-coated surface favors a mixed “islanding” and planar growth mode (Stranski–Krastanov) while the “islanding” mode (Volmer–Weber) was observed on the surface without PDA. This different early nucleation stage of mineralization was found to correlate with a more “bonded” interface between the mineral layer and the PDA-coated substrates, a slight increase in the interfacial strength and a different delamination mode. This study therefore provided new insights on how polydopamine priming layer influenced the mineralization process and the interface between the mineral layer and the substrate.

Highlights

Polydopamine (PDA) has been recently used as a versatile priming layer for further functionalization of a biomaterial surface, in biomimetic mineralization of biomaterials
This latter study demonstrated that calcium phosphate mineral layer (CaP) formed through co-precipitation with PDA, yet the understanding of how PDA influences this precipitation was lacking
Atomic force microscopy (AFM) showed that PDA appeared as nano-and submicron-clusters on the substrate and that surface roughness (Fig. 1A–D and F) increased with increasing polymerization time

Summary

Introduction

Polydopamine (PDA) has been recently used as a versatile priming layer for further functionalization of a biomaterial surface, in biomimetic mineralization of biomaterials. It is found that the nucleation of CaP on PDA-coated surface favors a mixed “islanding” and planar growth mode (Stranski–Krastanov) while the “islanding” mode (Volmer–Weber) was observed on the surface without PDA This different early nucleation stage of mineralization was found to correlate with a more “bonded” interface between the mineral layer and the PDA-coated substrates, a slight increase in the interfacial strength and a different delamination mode. PDA was mixed with calcium phosphate cement and the mixture was shown to promote mineralization from concentrated SBF s olution[11] This latter study demonstrated that CaP formed through co-precipitation with PDA, yet the understanding of how PDA influences this precipitation was lacking. Is of great interest to investigate the early phase of precipitation/mineralization and correlate the findings with the interface properties between the mineral layer and the substrate

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Conclusion