PSA Detection with Femtomolar Sensitivity and a Broad Dynamic Range Using SERS Nanoprobes and an Area-Scanning Method

Abstract

Recently, surface-enhanced Raman scattering (SERS)-based immunoassays (SIA) have drawn much attention as diagnostic tools with large multiplex capacity and high sensitivity. However, several challengessuch as a low reproducibility, a time-consuming read-out process, and limited dynamic rangeremain. In this study, we report a reliable and sensitive SIA platform for prostate specific antigen (PSA) detection. Reliability and sensitivity were achieved by two approaches: (1) well-established SERS probes, so-called SERS dots that have high sensitivity (single particle detection) and little particle-to-particle variation in SERS intensity; and (2) a whole area-scanning readout method for rapid and reliable chip analysis rather than point scanning. As a feasibility test, PSA could be detected with high sensitivity (ca. 0.11 pg/mL, 3.4 fM LOD), with a wide dynamic range (0.001−1000 ng/mL). Thus, the developed platform will facilitate development of reliable immunoassays with high sensitivity and a wide dynamic range.

Surface-Enhanced Raman Spectroscopy-Based Label-Free Insulin Detection at Physiological Concentrations for Analysis of Islet Performance

“…In order to improve the consistency of SERS measurements, recent focus has been placed on improving the chip-scale measurement uniformity either by implementing better substrates, [31][32][33][34] or employing better measurement strategies such as areal averaging, [35][36] which involves scanning a larger area on the substrate to collect and average more Raman-signal data points as opposed to 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 making a single point measurement. Two-dimensional (2D) mapping of Raman spectra was performed over a 1×1 mm 2 increasing the average scan area from 50×50 µm 2 to 400×400 µm 2 reduces the RSD from 3.6% to 1.7%.…”

Recent Progress of Biomarker Detection Sensors

“…Due to the high enhancement factor of rationally designed plasmonic nanostructures, a single detectable nanotag had been used in the work of Zhang et al And then they fabricated a biosensor for a multiplex of cardiac biomarkers detection with core-shell SERS nanotags which could amplify the signal and was much more stable [ 186 ]. Chang et al demonstrated a sensitive immunoassay using SERS active nanoparticles which were sufficiently sensitive and photostable to be detected at the single probe level [ 187 ]. Combining SERS technology with surface molecularly imprinted polymer (MIP) technology, a novel biosensor was fabricated for CEA detection by Lin et al [ 188 ].…”

Advances in surface‐enhanced Raman spectroscopy for cancer diagnosis and staging

“…SERS detection has been attained through isolation of sandwich complex from clinical samples by using the magnetic nanoparticles as secondary capture probes or by immobilization of protein‐bound nanoparticle complex on two‐dimensional plasmonic capture substrates . In some studies, capture nanostructures have been made from nano‐patterned metal substrates and magnetic core @ metal shell providing generation of multiple EM hot spots after sandwich complex formation .…”

“…Chang et al studied raster scanning of whole substrate area for sandwich immunoassay‐based prostate‐specific antigen (PSA) detection on a glass substrate. Compared with point scanning of a fixed region, rapid whole area scanning showed lower detection limit (3.4 fM) and increased dynamic range (0.001–1,000 ng ml −1 ) for PSA spiked in serum samples (Figure a) . On the other hand, sandwich immunoassay has been integrated with solid‐phase microextraction using nitrocellulose membrane as a capture substrate, allowing filtration‐based isolation of alpha fetoprotein (AFP) in serum .…”