Switchable biomolecule adsorption on 2D thermoresponsive poly(N-isopropylacrylamide)–coated gold nanowire array

This work presents the development of AuNW@pNIPAM, a hybrid platform combining electron beam lithography (EBL)-fabricated gold nanowire arrays (AuNWs) with thermoresponsive poly(N-isopropylacrylamide) (pNIPAM) brushes. A functionalization strategy using aryl diazonium salts, developed in our group, enables the precise confinement of the pNIPAM brushes exclusively on the AuNWs via surface initiated atom transfer radical polymerization (SI-ATRP), achieving an optimized 9 nm polymer thickness. Temperature-induced changes in the hydration state of pNIPAM were characterized using atomic force microscopy (AFM) in liquid phase verus the temperature, revealing a significant collapse of the polymer layer above the lower critical solution temperature (LCST). Concurrently, UV–vis spectroscopy demonstrated a 7-nm red shift in localized surface plasmon resonance (LSPR) due to the phase transition and a 15-nm shift upon bovine serum albumin (BSA) adsorption showcasing enhanced plasmonic sensitivity for real-time biomolecular monitoring. The reversible temperature-controlled adsorption/desorption of BSA on the AuNW@pNIPAM surface highlights the potential of this hybrid platform for applications in biosensing, drug delivery, and other bio-interfacing technologies.

Graphical abstract