An antibacterial and biocompatible piperazine polymer

Abstract

Bacterial repellence by biomedical materials is a desirable property that can potentially improve the healing process. In this study, we described a simple and green method to prepare a novel piperazine polymer (PE), which was based on the raw materials piperazine (PA) and ethylenediaminetetraacetic dianhydride (EDTAD). The structure and thermal stability of the obtained material were characterized using Fourier transform infrared spectrometry (FTIR), nuclear magnetic resonance spectroscopy (NMR), elementary analysis, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). To evaluate the antibacterial properties of PE, a strain of Gram-negative Escherichia coli (E. coli) bacteria and a strain of Gram-positive Staphylococcus aureus (S. aureus) bacteria were used. The results indicated that PE exhibited good antibacterial activity against both strains of bacteria in a short time frame. The initial cytotoxicity test of the obtained material was based on the changes in the morphology and proliferation of osteoblasts, and the results demonstrated that the cytotoxicity of PE was concentration-dependent. Combining the experimental results of these two parts, it was shown that bacteria could be inhibited by a certain concentration of PE, while its toxicity toward osteoblasts was very low. In summary, these results revealed the potential usefulness of PE in biomedical applications.

Fig. 1. The molecular structure of and synthetic routes for PE.

Fig. 2. The FTIR spectra of PA (a), EDTAD (b) and PE (c).

Fig. 3. ¹³C NMR spectra of PE.

Fig. 4. The elementary analysis of PE.

Fig. 5. The TGA curve of PE.

Fig. 6. DSC thermograms of PE.

Fig. 7. Colony formation of E. coli treated with PE ((a) control, (b) MIC, (c) 2 MIC, (d) 4 MIC).

Fig. 8. Colony formation of S. aureus treated with PE ((a) control, (b) MIC, (c) 2 MIC, (d) 4 MIC).

Fig. 9. Growth curves for E. coli (a) and S. aureus (b) treated with PE.

Fig. 10. The electron microscopy images of bacteria.

Fig. 11. The rapid killing effect of adhered E. coli (a) and S. aureus (b) by PE ×200.

Fig. 12. The morphology of rat calvarial osteoblasts treated with different materials for 24 h (×400) ((a) ciprofloxacin, (b) PE-4MIC, (c) control, (d) PE-2MIC, (e) PE-MIC).