Issue 43, 2020

Quantitative mechanics of 3D printed nanopillars interacting with bacterial cells

Abstract

One of the methods to create sub-10 nm resolution metal-composed 3D nanopillars is electron beam-induced deposition (EBID). Surface nanotopographies (e.g., nanopillars) could play an important role in the design and fabrication of implantable medical devices by preventing the infections that are caused by the bacterial colonization of the implant surface. The mechanical properties of such nanoscale structures can influence their bactericidal efficiency. In addition, these properties are key factors in determining the fate of stem cells. In this study, we quantified the relevant mechanical properties of EBID nanopillars interacting with Staphylococcus aureus (S. aureus) using atomic force microscopy (AFM). We first determined the elastic modulus (17.7 GPa) and the fracture stress (3.0 ± 0.3 GPa) of the nanopillars using the quantitative imaging (QI) mode and contact mode (CM) of AFM. The displacement of the nanopillars interacting with the bacteria cells was measured by scanning electron microscopy (50.3 ± 9.0 nm). Finite element method based simulations were then applied to obtain the force-displacement curve of the nanopillars (considering the specified dimensions and the measured value of the elastic modulus) based on which an interaction force of 88.7 ± 36.1 nN was determined. The maximum von Mises stress of the nanopillars subjected to these forces was also determined (3.2 ± 0.3 GPa). These values were close to the maximum (i.e., fracture) stress of the pillars as measured by AFM, indicating that the nanopillars were close to their breaking point while interacting with S. aureus. These findings reveal unique quantitative data regarding the mechanical properties of nanopillars interacting with bacterial cells and highlight the possibilities of enhancing the bactericidal activity of the investigated EBID nanopillars by adjusting both their geometry and mechanical properties.

Graphical abstract: Quantitative mechanics of 3D printed nanopillars interacting with bacterial cells

Article information

Article type
Communication
Submitted
15 Aug 2020
Accepted
03 Sep 2020
First published
04 Sep 2020
This article is Open Access
Creative Commons BY-NC license

Nanoscale, 2020,12, 21988-22001

Quantitative mechanics of 3D printed nanopillars interacting with bacterial cells

M. Ganjian, L. Angeloni, M. J. Mirzaali, K. Modaresifar, C. W. Hagen, M. K. Ghatkesar, P. Hagedoorn, L. E. Fratila-Apachitei and A. A. Zadpoor, Nanoscale, 2020, 12, 21988 DOI: 10.1039/D0NR05984F

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