Ergosterol-Targeted Nanocatcher with High Affinity and Capture Efficiency for Ultrafast SERS Detection of Aspergillus

Aspergillus is more challenging to control than other fungi due to its ability to produce and spread spores that can readily colonize diverse environments. Invasive infection results in severe complications and a terrible mortality of 85.2%, where misdiagnosis can result in critical delays in receiving optimal treatment. The diagnosis relies on laboratory tests, where an accurate and rapid diagnostic method is essential for early detection of invasive Aspergillosis. Surface-enhanced Raman scattering (SERS) is an effective technique for fungal detection. However, its application in Aspergillus detection has been limited due to the low selectivity associated with existing substrates. Based on the mechanism of action of the antifungal drug amphotericin B (AMB), which tightly binds to ergosterol on the cell wall of Aspergillus, our work introduces high-affinity polydopamine (PDA) as a capture carrier, utilizing magnetic nanoparticles (MNP) as magnetic attraction core. Through an in situ polymerization method, PDA was successfully coated onto MNP. The high adhesiveness of PDA enabled the coupling of AMB, enabling the successful preparation of a high-affinity, high-capture efficiency nanocatcher (MNP@PDA-AMB). This approach allowed for in vitro diagnosis (IVD) of Aspergillus with SERS detection using silver nanowire (AgNWs) substrate, demonstrating that the brief capture time (8 min) and entire detection process only takes 20 min. Excitingly, this work also established an enhanced limit of detection (LOD) with 10-10² cells/mL and the requisite reproducibility (RSD < 10%). The proposed method represents a breakthrough in the rapid detection of Aspergillus, offering broad adaptability and significant potential for clinical applications.