rapid isolation and detection of erythropoietin in blood plasma by magnetic core gold nanoparticles and portable raman spectroscopy
isolating, purifying, and identifying proteins in complex biological matrices are often difficult, time consuming, and unreliable. herein we describe a rapid screening technique for proteins in biological matrices that combines selective protein isolation with direct surface enhanced raman spectroscopy (sers) detection. magnetic core gold nanoparticles were synthesized, characterized, and subsequently functionalized with recombinant human erythropoietin (rhuepo)-specific antibody. the functionalized nanoparticles were used to capture rhuepo from horse blood plasma within 15 min. the selective binding between the protein and the functionalized nanoparticles was monitored by sers. the purified protein was then released from the nanoparticles’ surface and directly spectroscopically identified on a commercial nanopillar sers substrate. elisa independently confirmed the sers identification and quantified the released rhuepo. finally, the direct sers detection of the extracted protein was successfully demonstrated for in-field screening by a handheld raman spectrometer within 1 min sample measurement time.
the efficient and accurate analysis of biomolecules found in complex biological matrices like blood or urine is essential for many applications, including protein characterization, clinical diagnostics, and drug dosing protein analysis, but current methods are usually expensive and time consuming.1–4 simultaneous methods for sample separation and detection must exhibit sufficiently high resolution, high sensitivity and wide dynamic range to detect low concentrations of proteins.5–7 ideally, these methods should also be easy to perform, rapid, non-toxic, environment-friendly, and cost-effective. no current protein detection technique meets all these demands.5–7 although mass spectrometry (ms) is sensitive and accurate for the analysis of proteins,8,9 it is relatively expensive, requires specialized skills, and cannot be field adapted.
