Bimetallic Ag–Cu Alloy SERS Substrates as Label-Free Biomedical Sensors: Femtomolar Detection of Anticancer Drug Mitoxantrone with Multiplexing

Abstract

Surface-enhanced Raman spectroscopy (SERS) has been recognized as a promising label-free technology for clinical monitoring due to its high sensitivity and multiplexing ability, which should accelerate the screening of important drugs in the blood and plasma of cancer patients in a simpler, faster, and less-expensive manner. In this work, bimetallic Ag–Au and Ag–Cu alloy microflowers (MFs) with tunable surface compositions were fabricated on a glass cover slip by simple thermolysis of a metal alkyl ammonium halide precursor and used as SERS substrates for the sensitive detection of anticancer drug mitoxantrone (MTO). Two different laser excitation sources, 532 and 632.8 nm, were used to explore the possibility of surface-enhanced resonance Raman scattering. The Ag–Cu substrate showed superior detection capability over Ag–Au, whereby the sensor recorded a noteworthy “limit of detection” value of 1 fM for MTO. Theoretical electromagnetic field maps were simulated on appropriately chosen plasmonic systems to compare the electromagnetic field enhancements with the experimental SERS efficiencies of the substrates. Further, using a 10% Ag–Cu substrate, efficient multiplexing detection of MTO was demonstrated with another anticancer drug doxorubicin (DOX) in water and mouse blood plasma.

Localized Surface Plasmon Resonance Sensing and its Interplay with Fluidics

“…Different nanoarchitectures have been developed to enhance the sensitivity of the LSPR biosensors, i.e., to maximize the Δλ upon interaction of biomolecules with nanostructures. These variations encompass a wide array of nanostructures, including spherical nanoparticles, intricate shapes like cubes and stars, core–shell structures, and even pillared mushroom-like configurations. ,− Additionally, these architectures employ an extensive range of materials, including gold, silver, graphene, bimetallic structures, multimetallic compositions, and emerging 2-D materials like MXenes. − Table also shares some of these LSPR substrates, which are combined with microfluidics to form bioassay chips.…”

Enhanced Superhydrophobic Substrate-Based 3D SERS Platform for a Portable Raman Spectrometer-Assisted Drug Detection in Plasma

“…Surface-enhanced Raman spectroscopy (SERS) is widely used in biomedical analysis due to its ultrasensitivity, rapid measurement speed, nondestructive detection, and molecular fingerprint recognition capabilities . This technique relies on the development and application of colloidal plasmonic noble nanoparticles (NPs), , solid SERS substrates − prepared by etching, sedimentation, and sputtering, and the self-assembly of noble-metal films …”