Nitric oxide‑releasing porous titanium foams fabricated by scalable sintering–dissolution process for antibiofilm activity and cytocompatibility

Orthopaedic implants require surfaces that resist bacterial colonisation while supporting host cell compatibility. In this study, we fabricated highly interconnected porous titanium (Ti) foams using a cost‑effective sintering-dissolution process (SDP) and functionalised them with 11‑aminoundecyltriethoxysilane (AUTES) and covalently tethered N-diazeniumdiolate nitric oxide (NO) donors. Structural characterisation by Scanning electron microscopy, X‑ray micro‑CT, and Brunauer-Emmett-Teller analyses confirmed a hierarchical porous architecture with ~ 73% total porosity and extensive internal surface area, enabling efficient chemical functionalisation. Chemiluminescence analysis demonstrated formulation‑dependent NO payloads and sustained release for over 15 h in bacterial culture medium. The NO‑releasing foams significantly reduced biofilm-associated Escherichia coli and Staphylococcus aureus compared with untreated controls, with the 20% AUTES/NO formulation showing the most persistent antibiofilm activity at 24 h (p < 0.05). Limited effects were observed against planktonic bacteria. Human mesenchymal stem cells (hMSCs) adhered to and remained viable on both unmodified and functionalised foams over 7 days, indicating cytocompatibility of the surface modification following NO release. These findings demonstrate that SDP-derived porous Ti foams can be functionalised for localised NO delivery and effective antibiofilm activity while maintaining initial hMSC compatibility, offering a scalable platform for multifunctional Ti-based implant surfaces.