Abstract
In this work, we focused on the label-free detection of simple protein binding using near-infrared light-responsive plasmonic nanoshell arrays with a controlled interparticle distance. The nanoshell arrays were fabricated by a combination of colloidal self-assembly and subsequent isotropic helium plasma etching under atmospheric pressure. The diameter, interparticle distance, and shape of nanoshells can be tuned with nanometric accuracy by changing the experimental conditions. The Au, Ag, and Cu nanoshell arrays, having a 240-nm diameter (inner, 200-nm polystyrene (PS) core; outer, 20-nm metal shell) and an 80-nm gap distance, exhibited a well-defined localized surface plasmon resonance (LSPR) peak at the near-infrared region. PS@Au nanoshell arrays showed a 55-nm red shift of the maximum LSPR wavelength of 885 nm after being exposed to a solution of bovine serum albumin (BSA) proteins for 18 h. On the other hand, in the case of Cu nanoshell arrays before/after incubation to the BSA solution, we found a 30-nm peak shifting. We could evaluate the difference in LSPR sensing performance by changing the metal materials.
Highlights
In the last 10 years, we have witnessed a rapid growth in the development of highly selective and sensitive optical biosensors for the medical diagnosis and monitoring of diseases, drug discovery, and the detection of biological agents
For simple research on the present localized surface plasmon resonance (SPR) (LSPR) biosensor study on immunoassay, we focused on bovine serum albumin (BSA) binding onto the surface of metal nanostructures
In summary, we successfully fabricated uniform metal nanoshell arrays in a large area (30 × 60 mm2) on glass substrates and characterized the geometry and the optical properties based on the LSPR of the Au, Ag, and Cu nanoshell arrays
Summary
In the last 10 years, we have witnessed a rapid growth in the development of highly selective and sensitive optical biosensors for the medical diagnosis and monitoring of diseases, drug discovery, and the detection of biological agents. Sensing systems using localized SPR (LSPR) have received significant research attention in recent years as a result of their potential for use as highly sensitive, simple, and label-free bio/chemical binding detection devices [4,5,6]. Major efforts have gone into studying the sensitivity of such structures to changes in the local environments and refractive index The potential for their use as ultrasensitive detectors comes from both their high sensitivity and the short range of the associated optical fields. This property opens a route to the sensing of local biomolecular recognition events where adsorbate-induced changes in the local dielectric environment around the nanostructures are utilized
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