Investigation of the Biocidal Performance of Multi-Functional Resin/Copper Nanocomposites with Superior Mechanical Response in SLA 3D Printing

Abstract

Metals, such as silver, gold, and copper are known for their biocidal properties, mimicking the host defense peptides (HDPs) of the immune system. Developing materials with such properties has great importance in medicine, especially when combined with 3D printing technology, which is an additional asset for various applications. In this work, copper nanoparticles were used as filler in stereolithography (SLA) ultraviolet (UV) cured commercial resin to induce such biocidal properties in the material. The nanocomposites developed featured enhanced mechanical responses when compared with the neat material. The prepared nanocomposites were employed to manufacture specimens with the SLA process, to be tested for their mechanical response according to international standards. The process followed was evaluated with Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), and thermogravimetric analysis (TGA). The antibacterial activity of the fabricated nanocomposites was evaluated using the agar-well diffusion method. Results showed enhanced mechanical performance of approximately 33.7% in the tensile tests for the nanocomposites filled with 1.0 wt.%. ratios, when compared to the neat matrix material, while this loading showed sufficient antibacterial performance when compared to lower filler loadings, providing an added value for the fabrication of effective nanocomposites in medical applications with the SLA process.

Keywords: 3D printing; additive manufacturing (AM); antibacterial; copper (Cu); mechanical; nanocomposites; resin; stereolithography (SLA).

Figure 1

Workflow presentation of the followed processing using images captured during the study.

Figure 2

Fundamental SLA 3D printing settings, specimens’ dimensions, and images from 3D printed specimens.

Figure 3

(a) Typical tensile stress (MPa) to strain (mm/mm) curves, (b) tensile stress at break (MPa) to filler loading (wt.%), (c) tensile elastic modulus (MPa) to filler ratio (wt.%).

Figure 4

(a) Typical flexural stress (MPa) to strain (mm/mm) curve, (b) Flexural stress (MPa) at 5.0% strain (following the standard instructions) to filler loading (wt.%), (c) flexural elastic modulus (MPa) to filler ratio (wt.%).

Figure 5

(a) Average tensile toughness (MJ/m³) to filler loading (wt.%), (b) Average flexural toughness (MJ/m³) to filler ratios (wt.%).

Figure 6

(a) Charpy’s notched impact toughness (kJ/m²) to filler loadings (wt.%), (b) Vickers microhardness (HV) to filler ratios (wt.%).

Figure 7

(A) Sample’s weight (%) to temperature (°C), (B) weight loss rate (mg/mg) to temperature (°C).

Figure 8

Side surface of tensile specimens in 30× magnification for (a) Pure SC, (c) SC Cu 0.5 wt.%, (e) SC Cu 1.0 wt.%, (g) SC Cu 2.0 wt.%, same surfaces in 150× magnification for (b) Pure SC, (d) SC Cu 0.5 wt.%, (f) SC Cu 1.0 wt.%, (h) SC Cu 2.0 wt.%.

Figure 9

Fracture surface of tensile specimens in 30× magnification for (a) Pure SC, (c) SC Cu 0.5 wt.%, (e) SC Cu 1.0 wt.%, (g) SC Cu 2.0 wt.%, same surfaces in 300× magnification for (b) Pure SC, (d) SC Cu 0.5 wt.%, (f) SC Cu 1.0 wt.%, (h) SC Cu 2.0 wt.%. Arrows in the pictures show the fracture evolution in the section.

Figure 10

Fracture area high magnification captures at 5000× level (a) SC Cu 0.5 wt.%, (b) SC Cu 1.0 wt.%, (c) SC Cu 2.0 wt.% and the corresponding EDS analysis results (d) SC Cu 0.5 wt.%, (e) SC Cu 1.0 wt.%, (f) SC Cu 2.0 wt.%. White squares indicate the areas for EDS analysis.

Figure 11

Three-dimensional graphical presentation of the measured with AFM surfaces of 3D printed specimens for all the tested materials (a–d), (e) measured roughness (nm) to filler ratio (wt.%).

Figure 12

(a) typical E. Coli morphology, (b–e) Vertical captures after 24 h cultivation of tested specimen in Petri dish for each corresponding tested material, (f) Comparative graph of the measured inhibition zones to filler loading (wt.%).

Figure 13

(a) typical S. Aureus morphology, (b–e) Vertical captures after 24 h cultivation of tested specimen in Petri dish for each corresponding tested material, (f) Comparative graph of the measured inhibition zones to filler loading (wt.%).