Nanoplasmonic assay platforms for reproducible SERS detection of Alzheimer's disease biomarker

Abstract

With the recent developments in high‐sensitivity optical detection technologies, many studies have been conducted to accurately detect biomarkers with low concentrations of 1.0 pM or less as well as apply them to in vitro diagnostics. The tubulin‐associated unit (tau‐381) protein, a biomarker of Alzheimer's disease, is one such representative example, and its cut‐off value reported in clinical practice is 5.5 fM. Therefore, a robust sensing technology that can stably detect such low concentrations of biomarkers is needed. In this study, tau‐381 was detected with high sensitivity and reproducibility by a plasmonic Au nanopopcorn substrate fabricated via thermal evaporation. Here, aptamer DNAs labeled with Raman reporters on the terminal were used as the receptors. The plasmonic nanopopcorn substrate used in this study is composed of uniform gold nanoparticles (AuNPs) of average size 64 nm. The reproducibility was significantly improved through more uniform nanogaps than those formed by aggregation of AuNPs in solution. An assay was conducted by first reacting tau‐381 with the corresponding aptamers, and the remaining aptamer DNAs were then reacted with capture DNAs immobilized on the surface of the Au substrate. The assay results for tau‐381 showed a limit of detection value of 2.2 fM, which is below the cut‐off value (5.5 fM).

Synthesis of ultra‐small gold nanorods: Effect of reducing agent on reaction rate control

“…Therefore, it is possible to move the LSPR peak from the visible region to the NIR region by adjusting the aspect ratio of the nanorods. This is used in bioimaging, biosensing, and surface‐enhanced Raman scattering (SERS) because of strong LSPR properties in the near‐IR region 6,8–15 . Gold nanorods are also attracting attention in nanomedical fields such as photothermal therapy, 16,17 photoacoustic imaging, 18–20 and drug delivery 21,22 .…”

“…This is used in bioimaging, biosensing, and surface-enhanced Raman scattering (SERS) because of strong LSPR properties in the near-IR region. 6,[8][9][10][11][12][13][14][15] Gold nanorods are also attracting attention in nanomedical fields such as photothermal therapy, 16,17 photoacoustic imaging, [18][19][20] and drug delivery. 21,22 This attention results from their favorable characteristics of strongly absorbing and scattering light in the NIR region as well as stability, 23 biocompatibility, 24 and ease of surface modification.…”

Recent Trends in SERS-Based Plasmonic Sensors for Disease Diagnostics, Biomolecules Detection, and Machine Learning Techniques

“…In our observation, where full cells, tissues, or body fluids are studied, a machine learning algorithm is used hand in hand for accurate identification. SERS has been used for the detection of conditions such as Alzheimer’s [ 68 , 69 , 70 , 71 ], PCOS [ 72 ], diabetes [ 73 , 74 ], inflammation [ 74 ], Crohn’s disease [ 75 ], and single Hb molecule [ 76 ], to name a few. Here we review the progress on SERS for the diagnosis of (a) cancer, paying special attention to lung and breast cancer, as they are the leading causes of deaths due to cancer; and (b) respiratory viruses, including COVID-19.…”

Wet‐chemical synthesis of two‐dimensional complex nanorings for near‐field focusing

“…[1][2][3][4] Among these nanomaterials, plasmonic nanoparticles (NPs) have garnered significant attention due to their unique optical properties, particularly those due to the phenomenon known as localized surface plasmon resonance (LSPR). [5][6][7] The LSPR is the collective oscillation of conducting free electrons in metallic NPs, and it has sparked extensive research in various fields, spanning fundamental science and a wide range of applications, such as optical and biological sensing, [8][9][10] energy production. [11][12][13] Notably, the LSPR is strongly dependent upon the size, shape, and surrounding medium of NPs.…”