Colloidal Lithography for Tunable Plasmonic Nanostructures in Biosensing Platforms

The development of cost-effective and scalable nanofabrication techniques is crucial for advancing plasmonic biosensors based on Localized Surface Plasmon Resonance (LSPR). LSPR arises from the resonant oscillation of conduction electrons in metallic nanostructures excited by incident light, and its spectral response is highly sensitive to variations in size, shape, periodicity, and local dielectric environment. These unique optical properties make LSPR a powerful platform for label-free detection of biomolecular interactions with high sensitivity and selectivity.

Conventional nanofabrication methods such as electron-beam or focused ion beam lithography provide excellent control over nanoscale features but are often expensive, time-consuming, and limited in throughput, thereby hindering large-scale deployment. To address these challenges, we investigated colloidal lithography as a scalable and versatile bottom-up strategy to fabricate periodic arrays of plasmonic nanostructures. By exploiting the self-assembly of colloidal particles as deposition masks, we produced large-area patterns of gold nanodisks and nanoholes with tunable geometrical parameters. This approach enables reproducible control over resonance features while maintaining compatibility with low-cost and high-throughput manufacturing.

Our results demonstrate that colloidal lithography can generate plasmonic substrates with well-defined and reproducible LSPR responses, suitable for integration into biosensing platforms. The method provides a promising route toward portable, affordable, and robust sensors for applications in medical diagnostics, food safety, and environmental monitoring.