Bioactive silver phosphate/polyindole nanocomposites

Abstract

Materials capable of releasing reactive oxygen species (ROS) can display antibacterial and anticancer activity, and may also have anti-oxidant capacity if they suppress intracellular ROS (e.g. nitric oxide, NO) resulting in anti-inflammatory activity. Herein we report silver phosphate (Ag₃PO₄)/polyindole (Pln) nanocomposites which display antibacterial, anticancer and anti-inflammatory activity, and have therefore potential for a variety of biomedical applications.

Fig. 1. (A and B) Growth kinetics of E. coli and S. aureus in the presence of pure Ag₃PO₄, Pln0 and Ag₃PO₄/polyindole composites in the dark respectively. (C and D) % inhibition efficiency of E. coli and S. aureus after incubation with pure Ag₃PO₄, Pln0 and Ag₃PO₄/polyindole nanocomposites for different time periods respectively. CNTRL is untreated bacteria as a control.

Fig. 2. (A and B) Biofilm inhibition efficiency against E. coli and S. aureus after 4 days exposure of pure Ag₃PO₄, Pln0 and Ag₃PO₄/polyindole nanocomposites.

Fig. 3. Intracellular H₂O₂ generation form (A) E. coli and (B) S. aureus after treatment with Ag₃PO₄, Pln0, Pln1, Pln2 and Pln3 for 24, 48 h and 5, 7 days.

Fig. 4. FL intensity of PI in (A) E. coli and (B) S. aureus induced by Ag₃PO₄, Pln0, Pln1, Pln2 and Pln3 for 24, 48 h and 5, 7 days.

Fig. 5. (A) Cytotoxicity of Ag₃PO₄/Pln nanocomposite against PBMC cell after 24 h treatment, (B–F) cytotoxicity of Ag₃PO₄/Pln nanocomposite against breast cancer cell MCF-7 after 24 and 48 h treatment for comparative assessment.

Fig. 6. Morphology of THP-1 derived macrophages after incubating with PIn or Ag₃PO₄ particles for 3 days. THP-1 cells have been induced by PMA, then stimulated by LPS (1 μg mL⁻¹) and IFN-γ (20 ng mL⁻¹). (A) THP-1 derived macrophage by PMA but without stimulation by LPS and IFN-γ. (B) THP-1 derived macrophage with LPS and IFN-γ stimulation; (C) THP-1 derived macrophage with LPS and IFN-γ stimulation and incubating with Ag₃PO₄; (D) THP-1 derived macrophage with LPS and IFN-γ stimulation and incubating with Pln0; (E) THP-1 derived macrophage with LPS and IFN-γ stimulation and incubating with Pln1; (F) THP-1 derived macrophage with LPS and IFN-γ stimulation and incubating with Pln2; (G) THP-1 derived macrophage with LPS and IFN-γ stimulation and incubating with Pln3. All the nanocomposites concentration in (C–G) groups were counted at a concentration of 50 particles per cell.

Fig. 7. NO secretion from THP-1 derived macrophage with LPS and IFN-γ stimulation and incubation with the various nanoparticles. (A) In the absence of light, (B) in the presence of light. All data are presented as mean ± SD (n = 4).

Fig. 8. Anti-oxidation measurement by DPPH radical scavenging capacity for the various particles. Data are presented as mean ± SD (n = 4).