Controlled Debundling of Single-Walled Carbon Nanotubes (SWCNTs) by Au@Pt Nanorods Enables Mechanism-Dependent Electrochemical Sensing and Biofouling Response

Single-walled carbon nanotubes (SWCNTs) form intrinsically bundled networks due to strong intertube interactions, yet conventional debundling approaches can disrupt or chemically alter the nanotube structure. Here, Au@Pt nanorods (NRs) were progressively incorporated into SWCNT films as a nondestructive strategy to deliberately debundle the network while preserving the carbon framework and introducing Pt-rich catalytic sites. This approach was used to examine how network restructuring and metal decoration govern biofouling and electrochemical sensing. Increasing NR loading reorganized the SWCNT network into thinner strands, changed conductive pathways, and increased accessible surface features and hydrophilicity. These changes yielded analyte-dependent electrochemical responses: dopamine (DA) oxidation became more adsorption-controlled after debundling, with enhanced faradaic and capacitive currents attributed to improved interfacial accumulation at carbon-rich surfaces, whereas hydrogen peroxide (H₂O₂) oxidation was dominated by Pt-mediated catalysis and increased with NR loading due to higher catalytic site density. Biofouling studies with bovine serum albumin (BSA) showed that high NR contents promoted protein adsorption and suppressed electrochemical activity. Interestingly, DA oxidation was least affected on pristine SWCNT electrodes, whereas H₂O₂ detection benefited from intermediate NR decoration, indicating that biofouling can be mitigated by tailoring the platform to the target analyte to maintain performance after protein exposure, rather than relying on antifouling surfaces.