RESUMEN
Enzyme-linked immunosorbent assays (ELISA) are commonly used for detecting cancer proteins at concentration in the range of about ng-µg/mL. Hence it often fails to detect tumor markers at the early stages of cancer and other diseases where the amount of protein is extremely low. Herein, we report a novel photonic crystal fiber (PCF) based surface enhanced Raman scattering (SERS) sensing platform for the ultrasensitive detection of cancer proteins in an extremely low sample volume. As a proof of concept, epidermal growth factor receptors (EGFRs) in a lysate solution from human epithelial carcinoma cells were immobilized into the hollow core PCF. Highly sensitive detection of protein was achieved using anti-EGFR antibody conjugated SERS nanotag. This SERS nanotag probe was realized by anchoring highly active Raman molecules onto the gold nanoparticles followed by bioconjugation. The proposed sensing method can detect low amount of proteins at â¼100 pg in a sample volume of â¼10 nL. Our approach may lead to the highly sensitive protein sensing methodology for the early detection of diseases.
Asunto(s)
Técnicas Biosensibles/métodos , Proteínas de Neoplasias/análisis , Espectrometría Raman/métodos , Cristalización , Receptores ErbB/análisis , Oro/química , Humanos , Nanopartículas del Metal/química , Fibras Ópticas , Fotones , Sensibilidad y EspecificidadRESUMEN
SERS nanotags have been prepared to accomplish the multiplex detection of cancer cells. Herein we evaluated the adequacy of lipoic acid-containing cyanine derivatives (Cy3LA and Cy5LA) to function as multiplex partners with a triphenylmethine Raman reporter (B2LA) under a single excitation wavelength. SERS experiments enabled the multiplex recognition of two different cancer cells with antibody-conjugated nanotags that were derivatized with optimized cyanine and triphenylmethine reporters.
Asunto(s)
Carbocianinas/química , Separación Celular/métodos , Colorantes/química , Nanoestructuras , Péptidos/química , Espectrometría Raman/métodos , Anticuerpos/inmunología , Carbocianinas/metabolismo , Línea Celular Tumoral , Colorantes/metabolismo , Humanos , Péptidos/metabolismo , Propiedades de SuperficieRESUMEN
Biocompatible surface-enhanced Raman scattering (SERS) nanotag has been developed by chemisorption of novel Raman reporters on gold colloid. We modified our previously published best five reporter molecules (B2, B7, C3, C7 and C9) from triphenylmethine (TM) library using lipoic acid (LA) as a linker to covalently attach the reporters on gold colloid. Among these TM-LA molecules, B2LA showed the highest SERS signal intensity and stability over time. Further, time course SERS intensity of B2LA was compared with currently popular Raman reporter malachite green isothiocyanate (MGITC). The results demonstrated that signal intensity from B2LA was even stable over a period of one month. In vitro SERS screening was performed in cancer cell lines using B2LA containing nanotag conjugated with selective antibodies recognizing HER2 and EGFR cancer proteins. We found reasonably strong SERS signals from both HER2 and EGFR positive cells whereas no signal was measured from respective negative cells. Moreover, we successfully proved this recognition by cell imaging using fluorescein isothiocyanate (FITC) labeled antibody conjugated nanotag. Both SERS and cell-imaging study further confirmed the selective binding of antibody conjugated nanotag to cancer cells over-expressing HER2 and EGFR. In addition, as a proof of concept, in vivo SERS measurement in a mouse model was carried out to detect the nanotag-anchored cancer cells that are subcutaneously injected to the animal.