New details of assembling bioactive films from dispersions of amphiphilic molecules on titania surfaces

Abstract

Structure–property relationship of amphiphilic molecules on smooth substrates was explored through a multi-step approach and its influence on biological activity.

Bisphosphonates on Smooth TiO2: Modeling and Characterization

“…Figure 3 presents the XPS high‐resolution C1s, O1s, and N1s spectra for sputtered‐deposited titania. The C1s signal exhibited four contributions at 285.0 eV from aliphatic carbon and contributions at higher binding energy, centered at 285.9 eV, 286.6 eV, and 288.8 eV, also from adventitious carbon, in agreement with previous work [16] . O1s signal showed two contributions centered at 530.1 eV and 531.3 eV, which are oxidic oxygen from titanium dioxide and organic oxygen/ hydroxyl groups, respectively.…”

“…The results from zeta potential measurements are displayed in Figure 6. For pristine titania, the same behavior depicted in a previous work was observed [16] . The bisphosphonates exhibited increased zeta potential values compared to pristine titania with a decreased pH.…”

“…Centered at 286.2 eV, the contribution related to P 2 C*‐O moieties is characteristic of bisphosphonic acids as presented in Figure S3 for bulk etidronate [27] . The decreased area related to carboxyl moieties on the TiO 2 /ETI sample compared with the pristine titania surface is related to competitive adsorption, as observed for ODPA monolayers [16] . No differences were observed with the increased immersion time, indicating that the surface rapidly reached saturation and that 15 m, 2 h, and 24 h may present similar behavior.…”

“…O1 s high‐resolution spectra showed three peaks for all titania samples/BP. Contributions were fitted based on the approach previously published for bulk ODPA; as the molecule has a phosphonate group, the presence of P=O, P−O‐H, and P−O−Ti groups would be expected for adsorbed bisphosphonates [16,25,29] . Thus, the spectrum was fitted considering a third peak at higher binding energy from P−O*−H contribution, related to free phosphonic acid moieties.…”

“…The choice of this specific substrate is due to its common application as an implant cover [15] . The proposed approach was applied with the same substrate using quaternary ammonium‐containing silane and octadecyl phosphonic acid (ODPA), which demonstrated the association between biological activity and layer structure [16] . The use of a smooth substrate aims to reduce the influence of the geometric surface area, which can increase the surface charge or even the interaction between layers and cells [17–19] …”