Access-to-killing relay by wavelength-division Janus nanomotors for biofilm phototherapy.

Biofilm phototherapy is constrained by therapeutic reach, as light-triggered damage is often concentrated near accessible regions while bacteria remain protected within the extracellular matrix. Here we report wavelength-division Janus nanomotors for access-gated biofilm phototherapy, in which asymmetric interfacial energy conversion and wavelength-resolved activation couple active transport with antibacterial action. Janus SiO2/Au/FeTAPP nanomotors (JSAF) combine asymmetric Au and FeTAPP functional domains on dendritic porous silica nanoparticles. Under 808 nm irradiation, the asymmetric Au domain enables 808 nm-responsive active motion consistent with self-thermophoretic transport and contributes to heat-assisted matrix traversal. In mature biofilms, JSA exhibits enhanced penetration and a broader depth distribution than a symmetric SiO2/Au photothermal control, indicating that photothermal matrix disruption alone does not fully reproduce the transport behavior of the Janus architecture. Under 630 nm irradiation, FeTAPP generates singlet oxygen for localized oxidative bacterial killing. Order-dependent irradiation supports an access-first, killing-second relationship, whereas combined dual-wavelength activation enables a continuous access-to-killing process as particle transport progressively extends localized oxidative action into deeper biofilm regions. This wavelength-addressed coupling reduces residual biofilm biomass and improves healing of S. aureus-infected wounds. These findings highlight interfacial asymmetry and wavelength-selective functional coupling as design principles for active colloids operating in transport-limited environments.