Au@pNIPAM SERRS Tags for Multiplex Immunophenotyping Cellular Receptors and Imaging Tumor Cells

Abstract

Detection technologies employing optically encoded particles have gained much interest toward clinical diagnostics and drug discovery, but the portfolio of available systems is still limited. The fabrication and characterization of highly stable surface-enhanced resonance Raman scattering (SERRS)-encoded colloids for the identification and imaging of proteins expressed in cells are reported. These plasmonic nanostructures are made of gold octahedra coated with poly(N-isopropylacrylamide) microgels and can be readily encoded with Raman active dyes while retaining high colloidal stability in biofluids. A layer-by-layer polyelectrolyte coating is used to seal the outer surface of the encoded particles and to provide a reactive surface for covalent conjugation with antibodies. The targeted multiplexing capabilities of the SERRS tags are demonstrated by the simultaneous detection and imaging of three tumor-associated surface biomarkers: epidermal growth factor receptor (EGFR), epithelial cell adhesion molecule (EpCAM), and homing cell adhesion molecule (CD44) by SERRS spectroscopy. The plasmonic microgels are able to discriminate tumor A431 (EGFR+/EpCAM+/CD44+) and nontumor 3T3 2.2 (EGFR-/EpCAM-/CD44+) cells while cocultured in vitro.

Cancer characterization and diagnosis with SERS-encoded particles

“…Therefore, a more robust coating was also developed and applied on such constructs, such as a silica layer (Bohndiek et al 2013;Jokerst et al 2011;MirSimon et al 2015) or polymers like poly(N-isopropyl acrylamide) (NIPAM) (Álvarez-Puebla et al 2009;Bodelon et al 2015) (Fig. 2f, g, respectively).…”

“…Multimodal SEPs for fast and multiplexed imaging of cancer cells in vitro were also previously employed by , who, in this case, integrated fluorescence and SERS signal read-outs. On the other hand, the multiplexing capabilities of SERS imaging with SEPs were further investigated by Bodelon et al (2015), who discriminated human epithelial carcinoma A431 and nontumoral murine fibroblast 3T3 2.2 cells in mixed Fig. 3 a Outline of the fabrication steps of silver-coated gold nanorods (Au@Ag nanorods) and corresponding SERS spectra of four different SEPs.…”

Au@Ag SERRS tags coupled to a lateral flow immunoassay for the sensitive detection of pneumolysin

“…Additionally, this type of probes presents the multiplexing and quantitative abilities of the SERS technique, showing extraordinary features for bioanalysis. 25 Au and Ag NPs are the most commonly materials employed for the preparation of SERS tags, being silver the material with higher SERS efficiency, from 10-fold to 100-fold times, than those of similar gold nanostructures. 26,27 Therefore, the integration of a SERS-encoded nanoparticles within an immunoassay test will lead to an immunoassay with improved sensing capabilities.…”

Spatial Analysis of Metal–PLGA Hybrid Microstructures Using 3D SERS Imaging

“…Recent examples have been reported for a variety of systems, where, e.g., a thin polymer shell acts as the particle stabilizer, the polymer itself being used as the SERS tag, or where gold particles are embedded in SERS tag-loaded hydrogels. [6,[11][12][13] These systems are often too specific and intrinsically limited to specific shapes, sizes, and surface functionalizations. Embedding metal nanoparticles in a biodegradable polymeric system, which can be modulated in shape and size, would offer more versatile alternatives for applications in nanomedicine.…”