Hybrid Nanoporous Gold–Cyclodextrin Nanosponge Platforms for Enhanced Model Contaminant Detection

The development of hybrid materials combining functional polymers with nanostructured metals has gained significant attention for environmental and sensing applications. In this study, we present a proof-of-concept demonstration of the first-ever binding of a nanosponge polymer (NS) to nanoporous gold (NPG). The polymer was functionalized with a biodegradable lipoic acid linker, allowing efficient attachment to gold surfaces via sulfide bonds. To achieve successful binding, reducing agents were required during NS synthesis to generate free thiol (−SH) groups. Two synthesis approaches were tested, and optimal binding was confirmed with a polymer-to-surface ratio of 1.1 × 10–3 mg/mm2, as validated by surface-enhanced Raman spectroscopy (SERS) and colorimetric analysis. Additionally, the functionalized NPG was tested for its ability to detect methylene blue, a model contaminant, showing a 19% higher response compared to unmodified gold. These findings establish a foundation for further development of hybrid materials aimed at the detection and potential removal of emerging pollutants from water.