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Materials Science in Additive Manufacturing 3D printing of anti-microbial parts

4. Conclusion Thus, this work demonstrates that the fabrication
of anti-microbial articles is feasible using HSS with a
In this work, we demonstrate a PBF AM method to biocide that is non-toxic to humans. We anticipate that
fabricate plastic articles with anti-microbial activity using this production method for anti-microbial articles can
Mg(OH) NPs as the biocide. Mg(OH) NP is known as a also be applied to parts made using other major PBF
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contact biocide for some bacteria and viruses, and the non- methods, e.g., SLS. Both methods can be tailored to give an
leaching of ions from Mg(OH) would be an advantage in appropriate surface topography (micro-rough surface) that
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preventing toxic side effects. However, the challenge was can naturally retain nanocrystals without the need for heat
to incorporate effectively Mg(OH) into plastic articles so fixation and pressure. However, further work is warranted
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that it remained on the exterior surfaces, securely fixed to to determine if Mg(OH) NPs would adhere effectively to
withstand handling and washing. other polymers used in SLS and HSS, such as PP.
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The traditional fabrication approach involves melt-
compounding Mg(OH) NPs into the polymer and IM. Acknowledgments
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However, the molded parts did not display any anti-microbial Saleh Alkarri would like to express his gratitude to the
activity. In IM articles, the Mg(OH) NPs are mostly buried SABIC Company who had generously funded his doctoral
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inside the article, instead of remaining on the surface, hence studies and all of his research needs at Michigan State
there is little or no contact with the microbe. The fact that IM University. This research work was supported by the
PA 12 with Mg(OH) NPs did not exhibit a major reduction German Research Foundation within the collaborative
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in the bacterial count validates that the biocidal mechanism research center SFB TRR 225 Biofabrication.
of Mg(OH) NPs requires direct contact with the microbe.
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However, the anti-microbial plastic article could be Funding
fabricated by HSS of PA 12 powder, followed by dip-coating This research received no external funding.
in a suspension of Mg(OH) nanocrystals. The coated part
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exhibited a log 4 reduction or 99.99% elimination of Conflicts of interest
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E. coli after 24 h. Furthermore, even after washing the part All authors declare that the research was conducted in the
in running water, the NPs remained fixed to the article; absence of any commercial or financial relationships that
in a second run, the part displayed similar anti-microbial could be construed as a potential conflict of interest.
activity. The non-smooth and slightly porous surface of
the articles made by HSS facilitates the adhesion of the Author contributions
Mg(OH) nanocrystals. Tensile tests indicated a slight Conceptualization: Saleh Alkarri and Marco Wimmer
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deterioration in strength and elongation-to-break after Formal analysis: Saleh Alkarri and Zahir Bashir
dip-coating the HSS part with Mg(OH) nanocrystals. Investigation: Saleh Alkarri, Zahir Bashir, and Marco
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Dip-coating of IM PA 12 articles led to uniform Wimmer
deposition of the Mg(OH) nanocrystals without islanding; Methodology: All authors
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however, these did not adhere and could be wiped off Writing – original draft: Saleh Alkarri
mechanically or during washing. Thus IM could not Writing – review and editing: All authors
be used to fabricate anti-microbial plastic articles with
Mg(OH) NPs, neither directly by melt compounding nor Ethics approval and consent to participate
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by dip-coating. Not applicable.
The HSS production method and dip-coating of
Mg(OH) NPs can be explored for making anti-microbial Consent for publication
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functional parts exposed to handling. The method can be Not applicable.
scaled up, as dip-coating machinery for colored parts made
by SLS (vat dyeing) is industrially available; a Mg(OH) NP Availability of data
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suspension would be used instead of a liquid dye in the vat. All data have been included in the article and the
If further anchoring of the nanocrystals is required supplementary file.
after dip-coating, the parts may be heated in a microwave,
where heating the residual water would soften the plastic References
article’s surface, aiding the embedment of the NPs. Other 1. Babutan I, Lucaci AD, Botiz I. Antimicrobial polymeric
methods of surface melting of the polymer may also be structures assembled on surfaces. Polymers (Basel).
employed. 2021;13:1552.

Volume 3 Issue 4 (2024) 13 doi: 10.36922/msam.4970