Facile preparation of polyethyleneimine-conjugated silver sulfide nanoparticles as near-infrared-responsive to sterilization of multidrug resistant uropathogens, and cytotoxicity activity

Abstract

We present the chemical synthesis of polyethyleneimine-conjugated silver sulfide nanoparticles (PEI/AS) utilizing an economical solvothermal synthesis method, aimed at developing effective alternative antibacterial agents. The antibacterial efficacy of the synthesized materials, both with and without the application of near-infrared (NIR) laser irradiation, was evaluated in vitro against two distinct clinically relevant multi-drug-resistant (MDR) uropathogenic strains: Escherichia coli and methicillin-resistant Staphylococcus aureus. The bactericidal effects induced by NIR light indicate that the PEI/AS nanoparticles possess an efficiency that is five times greater than that of Ag₂S alone. A suggested antibacterial mechanism posits that the wrapping of PEI increases electrostatic interactions, thereby facilitating the attachment of Ag₂S nanoparticles to the bacterial surface. This process leads to the disruption of the outer membrane through the generation of localized heat and an increased concentration of reactive oxygen species (ROS), including superoxide anions (·O₂ ^-) and hydroxyl radicals (·OH). In addition, the mechanism involves the regulated release of Ag⁺ ions when exposed to NIR light irradiation. The combined action led to an over 95.79% elimination of bacteria at a concentration as low as 50 μg mL^-1, which can be primarily ascribed to the regulated photothermal effect induced by 808 nm near-infrared light irradiation, demonstrating exceptional photothermal conversion efficiency. These results paves a way for manufacturing innovation in future.

Supplementary information: The online version contains supplementary material available at 10.1007/s13205-024-04168-3.

Keywords: Antibacterial activity; Multi-functional; NIR-light; Polyethyleneimine-conjugated silver sulfide.

Fig. 1

Schematic diagram depicting the synthesis process of PEI/AS nanoparticles

Fig. 2

A XRD curves, B FT-IR spectrum of the prepared samples, SEM images of the C AS, and D PEI/AS nanoparticles, and its respective E elemental mapping images

Fig. 3

A UV–vis-NIR DRS spectra, B PL spectra, C Nyquist plot derived from EIS experiments for the prepared samples

Fig. 4

A Time dependent superoxide‒·O₂^– radicals scavenging activity, B fluorescence alterations in the ROS sensor containing PEI/AS and 3-CCA under UV–vis-NIR light illumination

Fig. 5

Photothermal effects of the PEI/AS A UV–visible absorption spectra of supernatant solution exceeding 808 nm of wavelength, B temperature evaluation curves with varying concentrations of PEI/AS under NIR-laser at 2 W cm⁻² power density, C temperature evaluation of the PEI/AS (50 μg mL⁻¹) over 10 on/off NIR-laser irradiation cycles, D heating and cooling curve of the PEI/AS (50 μg mL⁻¹) under 2 W cm⁻² power density of NIR-laser

Fig. 6

Antibacterial activity of the prepared AS (A, B), and PEI/AS (C, D) against E. coli and MRSA bacterial strains with and without NIR-laser illumination treatment conditions. All untreated samples‒0 μg mL⁻¹ were employed as control groups for the experiments

Fig. 7

Schematic depiction of the possible charge transfer mechanism with proposed reactions in the PEI/AS nanoparticles under NIR-laser

Fig. 8

Cytotoxicity evaluation, cell viability of HeLa cells cultured with different concentrations of the PEI/AS nanoparticles sample for one-day incubation (n = 3)