A label-free sensing method for phosphopeptides using two-layer gold nanoparticle-based localized surface plasma resonance spectroscopy.
In this study, a new type of localized surface plasmon resonance (LSPR) sensing substrate for phosphopeptides was explored. It has been known that LSPR response for target species is larger in the near-infrared region (NIR) than in the visible region of the electromagnetic spectrum. Several types of noble metal nanoparticles (NPs) with NIR absorption capacities have been previously demonstrated as effective LSPR-sensing nanoprobes. Herein, we demonstrate a straightforward approach with improved sensitivity by simply using layer-by-layer (LBL) spherical Au NPs self-assembled on glass slides as the LSPR-sensing substrates that are responsive in the NIR region of the electromagnetic spectrum. The modified glass slide acquired an LSPR absorption band in the NIR, which resulted from the dipole-dipole interactions between Au NPs. To enable the chip to sense phosphopeptides, the surface of the glass chip was spin-coated with thin titania film (TiO(2)-Glass@Au NPs). Absorption spectrophotometry was employed as a detection tool. Tryptic digest of α-casein was used as a model sample. The feasibility of using the new LSPR approach for detecting a potential risk factor leading to cancers (i.e., phosphorylated fibrinopeptide A) directly from human serum samples was demonstrated. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was used to confirm the results.
Department of Applied Chemistry, National Chiao Tung University, Hsinchu 300, Taiwan.
Jen-Yi
JY
Chen
Yu-Chie
YC
Chen
D005344:Fibrinopeptide A / Q000032:analysis*; D006046:Gold / Q000737:chemistry*; D008567:Membranes, Artificial; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D020349:Surface Plasmon Resonance / Q000379:methods*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry
D008567:Membranes, Artificial; C009495:titanium dioxide; D005344:Fibrinopeptide A; D006046:Gold; D014025:Titanium