Printable Resin Modified by Grafted Silver Nanoparticles for Preparation of Antifouling Microstructures with Antibacterial Effect

Abstract

The usage of three-dimensional (3D) printed materials in many bioapplications has been one of the fastest-growing sectors in the nanobiomaterial industry in the last couple of years. In this work, we present a chemical approach for grafting silver nanoparticles (AgNPs) into a resin matrix, which is convenient for 3D printing. In this way, the samples can be prepared and are able to release silver ions (Ag⁺) with excellent antibacterial effect against bacterial strains of E. coli and S. epidermidis. By the proposed process, the AgNPs are perfectly mixed and involved in the polymerization process and their distribution in the matrix is homogenous. It was also demonstrated that this approach does not affect the printing resolution and the resin is therefore suitable for the construction of microstructures enabling controlled silver ion release and antifouling properties. At the same time the physical properties of the material, such as viscosity and elasticity modulus are preserved. The described approach can be used for the fabrication of facile, low-cost 3D printed resin with antifouling-antibacterial properties with the possibility to control the release of Ag⁺ through microstructuring.

Keywords: CAD/CAM; antibacterial activity; antifouling properties; biomaterial; diazonium salt; silver nanoparticles.

Figure 1

Schematic representation of AgNPs grafting with 4-aminostyrene (A); polymerization of the monomers mixed with modified AgNPs (B). Ts = p-toluenesulfonic acid monohydrate; S - styrene, M - monomer.

Figure 2

Confirmation of successful modification of AgNPs by IR spectroscopy (A); morphology of silver nanoparticles (AgNPs) determined by TEM (I) before grafting and (II) after grafting (B); absorbance spectrum of aqueous silver solution (I) and of deionized water in which the samples were soaked (C).

Figure 3

Absorbance spectra of different concentrations of the AgNPs-modified resin (A); viscosity test of the modified samples (liquid) in comparison with the pristine samples (B).

Figure 4

Surface morphology of pristine (I) and modified samples (II) determined by confocal microscopy (A); printed structures on the surface (B); overview of the surface of the modified samples measured by SEM and mapping distribution of AgNPs in different concentrations inside the samples acquired by EDX (C); load-depth of penetration instrumented indentation test data record of pristine samples, modified samples, and modified samples after releasing silver ions for one week and one month (D).

Figure 5

Concentrations of silver ions released into the water as a function of the original concentrations of Ag in solid samples and total soaking time (A); concentration of the Ag⁺ released into water from samples of concentration 15% as a function of the microstructure height and the total period of soaking 0: no microstructure (flat surface), 21, 42 and 84 μm (B); the number of colony-forming units (CFU) of E. coli and S. epidermidis (C).

Figure 6

Results of antifouling tests performed by SEM for bacterial strains of S. epidermidis (A) and E. coli (B); results of analysis of variance one way (ANOVA) between groups for S. epidermidis (C) and E. coli (D).