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. 2023 May 3;15(17):20822-20832.
doi: 10.1021/acsami.3c03826. Epub 2023 Apr 19.

Sulfur-Polymer Nanoparticles: Preparation and Antibacterial Activity

Romy A Dop  1   2 , Daniel R Neill  2 , Tom Hasell  1   3
Affiliations

Sulfur-Polymer Nanoparticles: Preparation and Antibacterial Activity

Romy A Dop et al. ACS Appl Mater Interfaces. .

Abstract

High sulfur content polymers prepared by inverse vulcanization have many reported potential applications, including as novel antimicrobial materials. High sulfur content polymers usually have limited water-solubility and dispersibility due to their hydrophobic nature, which could limit the development of their applications. Herein, we report the formulation of high sulfur content polymeric nanoparticles by a nanoprecipitation and emulsion-based method. High sulfur content polymeric nanoparticles were found to have an inhibitory effect against important bacterial pathogens, including Gram-positive methicillin-resistant Staphylococcus aureus and Gram-negative Pseudomonas aeruginosa. Salt-stable particles were formulated with the addition of a surfactant, which did not inhibit the antibacterial activity of the polymeric particles. Furthermore, the polymeric nanoparticles were found to inhibit S. aureus biofilm formation and exhibited low cytotoxicity against mammalian liver cells. Interaction of the polymeric particles with cellular thiols could be a potential mechanism of action against bacterial cells, as demonstrated by reaction with cysteine as a model thiol. The findings presented demonstrate methods of preparing aqueous dispersions of high sulfur content polymeric nanoparticles that could have useful biological applications.

Keywords: antibacterial; biofilm inhibition; inverse vulcanization; nanoparticles; polysulfides; sulfur.

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Conflict of interest statement

The authors declare no competing financial interest.

Figures

Figure 1
Figure 1
General scheme for the synthesis of copolymers from elemental sulfur and simple organic cross-linkers by inverse vulcanization, with the structures of the comonomers perillyl alcohol and geraniol shown.
Figure 2
Figure 2
(a) DSC traces for S50-Ger showing the first heating cycle to 150 °C (blue), cooling to −80 °C (green), and the second heating cycle to 150 °C (pink). (b) FTIR spectra of geraniol (green), S50-Ger (blue), and S70-Ger (pink). (c) 1H NMR spectra of geraniol and S50-Ger.
Figure 3
Figure 3
(a) Size distribution by intensity and (b) correlogram traces obtained for dispersions of S50-PA formed by a nanoprecipitation method without a surfactant. (c) SEM image of S50-PA dispersion.
Figure 4
Figure 4
(a) S. aureus growth curve in the presence of S50-PA nanoparticles over 24 h in nutrient-rich LB medium. (b) P. aeruginosa growth curve in the presence of S50-PA nanoparticles after 5 h of incubation in nutrient-rich LB medium. (c) Absorbance at 600 nm after staining with crystal violet after 24 and 48 h of incubation at 37 °C with S. aureus (USA300) and P. aeruginosa (PAO1). (d) Cell viability (%) of HepG2 after treatment with S50-PA nanoparticles.
Figure 5
Figure 5
(a) Lead acetate paper after 5 min of exposure and (b) 5 h of exposure to (1) S50-PA nanoparticles and cysteine, (2) S50-PA nanoparticles, and (3) cysteine.
Figure 6
Figure 6
SEM images of S. aureus (a) before and (b) after treatment with S50-PA nanoparticles.
See this image and copyright information in PMC

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