Enhanced synergic effect of the antibacterial activity and hydrophobicity of polydimethylsiloxane polymer loaded with titanium dioxide nanoparticles and ciprofloxacin

In this study, the effect of titanium dioxide (TiO₂) nanoparticles and ciprofloxacin (CIPRO) addition to Polydimethylsiloxane (PDMS) was investigated in terms of enhancement of the antibacterial activity and hydrophobicity. The nanocomposite of PDMS loaded with TiO₂ nanoparticles and CIPRO was prepared by mixing the TiO₂ nanoparticles and/or CIPRO with the PDMS before the crosslinking step. TiO₂ nanoparticles with a diameter of ~ 21 nm were used in different loading concentrations (1–5) wt%, while CIPRO concentration in the prepared polymer nanocomposite was fixed to 0.5 wt%. The prepared nanocomposites were assessed for their antibacterial activity by using the spread plate method. Surface wettability of the nanocomposites was evaluated by contact angle measurements. Moreover, different characterization techniques including Fourier transform infrared spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy were used to examine the changes between the modified and the pristine polymer. The results revealed that the combined effect of addition of both TiO₂ nanoparticles and Ciprofloxacin to PDMS enhanced the antibacterial activity against Staphylococcus aureus and Escherichia coli. This enhancement represented by the reduction of S. aureus and E. coli colonies to almost 1 × 10⁵ and 1 × 10⁵ CFU/ml, respectively. Furthermore, hydrophobicity enhancement from 114° in pristine PDMS to 125° in PDMS with 5% TiO₂ nanoparticles was also achieved. The XRD results show crystallinity enhancement in the order of ~ 300% for the modified PDMS with 5% TiO₂ nanoparticles (crystallinity ~ 85%) when compared to pristine PDMS (crystallinity ~ 27.2%).