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What Are Gold Nanoshells: What are Their Properties?

Gold nanoshells are surface plasmon resonant (SPR) nanoparticles consisting of a nanoscale silica core surrounded by an ultra-thin gold shell. Changing the ratio of the core diameter and the shell thickness tunes the absorption and scattering properties of the nanoshells across the visible and near-IR (NIR) regions of the electromagnetic spectrum. Increasing the size of the silica core, and decreasing the thickness of the gold shell cause the plasmon resonance to shift toward the NIR.

Gold Nanoshells observed using dark field microscopy
Figure 1 – Gold Nanoshells observed using dark field microscopy
This class of plasmonic nanoparticles has a wide variety of applications, including uses in optical filters, sensing and cancer therapy. For example, one of our most popular nanoshells products has a strong plasmon resonance at 800 nm and the very high absorption in the NIR is the basis for therapies that utilize the localized heating of nanoparticles to eradicate cancer cells.
Gold nanoshells exhibiting different optical properties from different light sources
Figure 2 – Gold nanoshells exhibiting different optical properties from different light sources
Further tuning of the nanoshell size results in particles that scatter different portions of the spectrum, which can be readily observed using dark field microscopy (see image right). The tunable plasmonic properties make nanoshells of interest for Surface Enhanced Raman Scattering (SERS) applications, or as optical sensors where a shift in color of the nanoshell is indicative of the presence of a target analyte in solution.

Due to the difference in the scattering and absorption properties of the nanoshells, many variants are bichromic: for example, when a solution of 800 nm-resonant nanoshells are viewed in transmission (back lit) the nanoshells solution appears blue, but when viewed with reflected light the same solution can appear a rusty red due to scattering by the particles.

Gold nano shells resonant at 660–980 nm and are available with either polyethylene glycol (PEG) or polyvinylpyrollidone (PVP) capping agents, or in a dried formulation.

Particles with other optical properties, core/shell dimensions, or different surface capping agents are available on request. Contact us for more information about our custom fabrication abilities.

Additional Resources

Publications featuring Gold Nanoshells:

  1. Srinivasan, B.; Nanus, D.; Erickson; D.; Mehta, S. Highly portable quantitative screening test for prostate-specific antigen at point of care Current Research in Biotechnology. 2021, DOI: 10.1016/j.crbiot.2021.11.003.
  2. Muñoz‐Ortiz, T.; Hu, J.; Ortgies, D. H.; Shrikhande, S.; Zamora‐Perez, P.; Granado, M.; González‐Hedström, D.; de la Fuente‐Fernández, M.; García‐Villalón, Á. L.; Andrés‐Delgado, L.; Martín Rodríguez, E.; Aguilar, R.; Alfonso, F.; García Solé, J.; Rivera, P.; Jaque, D.; Rivero, F. Molecular Imaging of Infarcted Heart by Biofunctionalized Gold Nanoshells Adv. Healthcare Mater. 2021, 2002186.
  3. Simón, M.; Jørgensen, J. T.; Norregaard, K.; Kjaer, A. 18F-FDG Positron Emission Tomography and Diffusion-Weighted Magnetic Resonance Imaging for Response Evaluation of Nanoparticle-Mediated Photothermal Therapy Sci. Rep. 2020, 10 (1), 7595.
  4. Frew E, Roberts D, Barry S, et al. A SARS-CoV-2 antigen rapid diagnostic test for resource limited settings. Sci Reports. 2021; 11:23009.
  5. Tan E, Frew E, Cooper J, et al. Use of lateral flow immunoassay to characterize SARS-CoV-2 RBD-specific antibodies and their ability to react with the UK, SA and BR P.1 variant RBDs. Diagnostics (Basel). 2021; 11(7):1190. Published 2021 Jun 30.
  6. Behrouzi K and Lin L. Gold nanoparticle based plasmonic sensing for the detection of SARS-CoV-2 nucleoclapsid proteins. Biosensors and Bioelectronics. 2022; 195:113669.
  7. Lake D, Roeder A, Kaleta E, et al. Development of a rapid point-of-care test that measures neutralizing antibodies to SARS-CoV-2. Journal of Clinical Virology. 2021; 145:105024.
  8. Gonzalez-Moa M, Van Dorst B, Lagatie O, et al. A proof-of-concept rapid diagnostic test for onchocerciasis: Exploring Peptide Biomarkers and the Use of Gold Nanoshells as Reporter Nanoparticles
  9. Maria J. Gonzalez-Moa, Bieke Van Dorst, Ole Lagatie, et al. Exploring new peptide biomarkers and the use of gold nanoshells as novel reporter nanoparticles. ACS Infectious Diseases. 2018: 4, 6:912–917.
  10. Kight E, Hussain I, Bowden A, et al. Recurrence monitoring for ovarian cancer using a cell phone‑integrated paper device to measure the ovarian cancer biomarker HE4/CRE ratio in urine. Scientific Reports. 2021; 11:21945.
  11. Dalirirad S and Steckl J. Lateral flow assay using aptamer-based sensing for on-site detection of dopamine in urine. Analytical Biochemistry. 2020; 596:113637.
  12. Dalirirad S, Han D, Steckl J. Apatmer-based lateral flow biosensor for rapid detection of salivary cortisol. ACS Omega. 2020; 5 (51): 32890-32898. DOI: 10.1021/acsomega.0c03223
  13. Bradbury D, Kita A, Hirota K, et al. Rapid diagnostic test kit for point-of-care cerebrospinal fluid leak detection. SLAS Technology. 2020; 25(I)67-74.
  14. Féraudet Tarisse C, Goulard-Huet C, Nia Y, et al. Highly Sensitive and Specific Detection of Staphylococcal Enterotoxins SEA, SEG, SEH, and SEI by Immunoassay. Toxins. 2021; 13:130.
  15. Viet Tran T, Do B, Nguyen T, et al. Development of an IgY-based lateral flow immunoassay for detection of fumonisin B in maize. F1000 Research. 2019; 8:1042.

Frequently Asked Questions

The peak resonance wavelength of my nanoshells is not exactly at the wavelength advertised.  Are these nanoshells out of specification and will this affect my experiment?

For gold nanoshells, our specification is that the OD at the advertised wavelength is at least 90% of the value of the peak OD.  We set it this way to make sure that the particles are functionally equivalent between lots even if the peak wavelength varies slightly from the advertised wavelength.  For example, if a gold nanoshell has a peak resonance at 830 nm with an OD of 1.0, the OD value at 800 nm should be at least 0.90.  

Gold nanoshells have a relatively broad peak, so even if the peak resonance is shifted from 800 nm they retain most of their absorption and scattering properties across a wide range of wavelengths.  This is why nanoshells with peak wavelengths of 750–850 nm will perform nearly identically to a nanoshell peaked at 800 nm.   

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