Magnetic Nanoparticle Enhanced Surface Plasmon Resonance Sensing and Its Application for the Ultrasensitive Detection of Magnetic Nanoparticle-Enriched Small Molecules

摘要

Magnetic nanoparticles (MNPs) have been frequentlynused in bioseparation, but their applicability in bioassaysnis limited due to their extremely small size so thatnsensitive detection is difficult to achieve using a generalntechnique. Here, we present an amplification techniquenusing MNPs for an enhanced surface plasmon resonancen(SPR) bioassay. The amplification effect of carboxyl groupnmodified Fe3O4 MNPs of two sizes on SPR spectroscopynis first demonstrated by assembling MNPs on aminongroup modified SPR gold substrate. To further evaluatenthe feasibility of the use of Fe3O4 MNPs in enhancingna SPR bioassay, a novel SPR sensor based on annindirect competitive inhibition assay (ICIA) is developednfor detecting adenosine by employing Fe3O4nMNP-antiadenosine aptamer conjugates as the amplificationnreagent. The results confirm that Fe3O4nMNPs can be used as a powerful amplification agentnto provide a sensitive approach to detect adenosine bynSPR within the range of 10-10 000 nM, which isnmuch superior to the detection result obtained by angeneral SPR sensor. Importantly, the present detectionnmethodology could be easily extended to detect othernbiomolecules of interest by changing the correspondingnaptamer in Fe3O4 MNP-aptamer conjugates. Thisnnovel technique not only explores the possibility of thenuse of SPR spectroscopy in a highly sensitive detectionnof an MNP-based separation product but also offers annew direction in the use of Fe3O4 MNPs as an amplificationnagent to design high performance SPR biosensors.