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Abstract
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In this study, a highly sensitive and reproducible localized surface plasmon resonance (LSPR)-based sensor was
developed for melamine detection using two-dimensional (2D) titanium dioxide (TiO₂) inverse binary colloidal
crystals (IBCCs) embedded with gold nanoparticles (AuNPs). IBCCs were fabricated via colloidal lithography
with polymethyl methacrylate (PMMA) microspheres (257 nm and 1135 nm) as binary templates. Co-selfassembly
at the air–water interface formed 2D binary colloidal crystals (BCC), followed by TiO₂ infiltration
and calcination. A 50 nm gold film was deposited via magnetron sputtering, forming AuNPs on and within the
pores, enhancing sensitivity by amplifying localized electromagnetic fields. The sensor was functionalized with
p-nitroaniline (p-NA) as a melamine receptor and bovine serum albumin (BSA) to block non-specific binding.
LSPR peak shifts measured by UV–Vis spectroscopy enabled detection, achieving a 0.005 μg L- 1 limit of detection
and 0.015 μg L- 1 limit of quantification. The sensor showed excellent accuracy and selectivity in infant formula
and dairy products. The experimental results were confirmed by FDTD simulation.
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