A molecular finger-imprinting approach for detecting dental enamel amelogenins via surface plasmon resonance and bio-layer interferometry

Amelogenins (AMGs) are extracellular matrix proteins essential for enamel development. During this process, resident proteases cleave the full-length proteins into a heterogeneous mixture of peptides that is retained within mature enamel. Current enamel proteomics primarily focuses on detecting sexually dimorphic AMG peptides for sex identification in archaeological and forensic contexts. In parallel, AMG pattern analysis supports research into enamel-related pathologies and clinical applications. Furthermore, AMG expression in odontogenic epithelium is considered a potential indicator for the histological behavior of tumors. Although their detection is commonly achieved by mass spectrometry, no fast, low-cost, miniaturizable platforms with minimal sample preparation are currently available. To address the complexity of real enamel extracts, we developed synthetic receptors based on molecularly imprinted polynorepinephrine (MIPNE). We integrated them into Surface Plasmon Resonance (SPR) and Bio-Layer Interferometry (BLI) platforms. Leveraging the conventional Single-Epitope Imprinting (SEI) strategy, we introduced an original "Finger-Imprinting" (FI) approach that exploits the direct imprinting of human enamel extracts. SPR binding assays toward standard AMGX revealed superior affinity and capacity for FI-imprinted receptors (KD = 3.6 x 10-8 M, Rmax = 2286 +/- 5 RU) compared with SEI-imprinted counterparts (KD = 4.9 x 10-7 M, Rmax = 157 +/- 6 RU). BLI enabled the selective recognition of AMG-derived fragments in enamel extracts thanks to a higher representation of the binding cavities. We additionally achieved encouraging evidence of sex differentiation in real samples. This work introduces a novel imprinting concept that adapts the complexity of degraded/digested proteins in real samples to pattern analysis via biosensing.