Elsevier

Materials Letters

Volume 264, 1 April 2020, 127350
Materials Letters

Plasma deposited APTES: A potential film for biomedical application

https://doi.org/10.1016/j.matlet.2020.127350Get rights and content

Highlights

  • APTES films with high density of amino groups are achieved by PECVD.

  • APTES films exhibit good apatite inducing ability.

  • APTES films show highly stable hydrophilicity, low cytotoxicity and hemolysis.

Abstract

Surface modification with polymerization films containing amino groups is a reliable way to improve the bioactivity/biocompatibility of implants or build a drugs immobilization/release system on their surface. In this work, APTES films containing amino groups were achieved using a plasma deposition device. The amine density was adjusted by changing the Ar flow and the highest value of 9.03% was achieved at 50 sccm. Such APTES films showed good bone bioactivity as apatite was significantly induced in 14–28 days’ SBF immersion. Furthermore, the plasma deposited APTES films exhibited high hydrophilicity (WCAAPTES ≈ 21°) with good stability resisting water (WCARinse ≈ 30°–38°), low cytotoxicity (cytotoxicity level = 0), and high anti-hemolysis ability (Hemolysis rate = 1.03%). All the results confirmed APTES films fabricated in our plasma system could be widely used in biomedical area.

Introduction

In order to endow good mechanical property, tribological property, and biocompatibility to the biomedical implants consisted of metals, polymers or ceramics, the surface modification of such substrates has been widely studied in the past years. Surface functionalization by APTES containing high density of primary amino groups was reported to be a reliable way to bound a protective film with good biocompatibility e.g. (graphene oxide [1], silk fibroin [2], poly(lactic-co-glycolic acid) [3], polylactide [4], CaP composite [5], laminin [6]), construct a biosensor [7], or build a drug delivery system [8], [9]. Due to the protonation of amino groups, bioactive matters, or drug carrying nano/micro-structures could be firmly immobilized on the surface through zwitterionic pairs [10]. Although such chemical has been employed for numerous applications in the biomedical area, scholars seldomly pay attention to the biomedical properties of APTES film. Especially, its biocompatibility including hemolysis, cytotoxicity and so on has not been systematically studied until today.

The most commonly used protocol to functionalize with APTES is to treat the surface in a wet-chemical way [11]. Alternatively, plasma deposition method is reported to show advantages e.g. high reproducibility, high efficiency, higher adhesion strength, etc. [12], [13], [14]. Especially, it has been evidenced in our previous work that higher deposition rate, shorter deposition time and more amino groups were achieved in the plasma deposition [15].

In this work, the APTES film was deposited using the plasma deposition method. A high density of amino groups was achieved by adjusting the gas flow rate of Ar. Furthermore, the biomedical properties of the as-deposited film were investigated.

Section snippets

Deposition of APTES films

A homemade plasma device was used for APTES deposition. The details of such device were described elsewhere [16]. Silicon wafers with a dimension of 8 × 8 × 1 mm were used as substrates. The samples were pre-treated (Ar flow: 10 sccm, voltage: 20 W, pressure: 0.7 mbar, duration: 5 s). Then, a gaseous mixture consisted of 30–90 sccm of active gas Ar and 10 sccm of vector gas Ar carrying APTES was injected into the reaction chamber. The deposition was carried out using a voltage of 40 W and a gas

Results and discussion

FTIR spectra were shown in Fig. 1a, the absorption peak at about 1050, 1450, 1620 and 1750 cm−1 could be indexed to Si-O-/Si-O-Si [18], C-N [12], NH2/NH/Cdouble bondC and Cdouble bondO [19], [20], confirming a successful APTES deposition using plasma. An obvious drop of peak intensity at 1620 cm−1 was seen when Ar flow was higher than 50 sccm, indicating the density of primary amino groups on the surface was decreased. The results of the ellipsometry measurement were demonstrated in Fig. 1b, showing that the film

Conclusions

In conclusion, APTES films were successfully deposited via a plasma deposition method. The density of amino groups was changed by varying Ar flow and the maximum density of 9.03% was achieved at 50 sccm. The as-deposited APTES film could induce the formation of apatite in 14 days’ immersion and show highly stable hydrophilicity (WCAAPTES≈ 21° → WCARinse ≈ 30°–38°), low cytotoxicity level (0), and low hemolysis rate (1.03%), indicating such films could be potentially used to improve the

CRediT authorship contribution statement

Zilin Chen: Formal analysis, Investigation, Writing - original draft, Visualization. Junjie Zhao: Data curation. Chen Jin: Data curation. Yidie Yuan: Funding acquisition. Yongping Zhang: Validation, Supervision. Michaël Tatoulian: Methodology, Resources. Xi Rao: Conceptualization, Methodology, Software, Formal analysis, Investigation, Resources, Writing - original draft, Visualization, Supervision, Project administration, Funding acquisition.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

The authors acknowledge support from National Natural Science Foundation of China (Grant 51801164), the Venture & Innovation Support Program for Chongqing Overseas Returnees (Grant cx2018080) and National Training Program of Innovation and Entrepreneurship for Undergraduates (Grant 201810635068).

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