A PEGDA hydrogel nanocomposite to improve gold nanoparticles stability for novel plasmonic sensing platforms

A 3D plasmonic sensing platform that combines the properties of citrate gold nanoparticles (AuNPs) and poly-(ethylene glycol) diacrylate (PEGDA) hydrogels is proposed as a nanocomposite hybrid material for biosensing applications, whose optical properties and sensitivity can be tuned by varying the particle mean diameter as also predicted by the Mie theory. It is found that AuNPs embedded in the hydrogel network are more stable when compared to the colloidal aqueous solutions. PEGDA hydrogel physically retains the gold nanoparticles even after a full swelling process during immersion in liquids. Such a property is confirmed by exposing the AuNPs-containing PEGDA hydrogels to organic solvents and buffers that would usually cause the aggregation of the nanoparticles in solution. Moreover, biotin, as a small molecule model, has been captured, and optically detected with a transmission mode customized setup, by a cysteamine modified AuNPs-containing PEGDA hydrogel layer to achieve a biorecognition hybrid device.