title: Core-shell hydrogel particles harvest, concentrate and preserve labile low abundance biomarkers.
abstract: BACKGROUND
  The blood proteome is thought to represent a rich source of biomarkers for early stage disease detection. Nevertheless, three major challenges have hindered biomarker discovery: a) candidate biomarkers exist at extremely low concentrations in blood; b) high abundance resident proteins such as albumin mask the rare biomarkers; c) biomarkers are rapidly degraded by endogenous and exogenous proteinases.
  
  
  RESULTS
  Hydrogel nanoparticles created with a N-isopropylacrylamide based core (365 nm)-shell (167 nm) and functionalized with a charged based bait (acrylic acid) were studied as a technology for addressing all these biomarker discovery problems, in one step, in solution. These harvesting core-shell nanoparticles are designed to simultaneously conduct size exclusion and affinity chromatography in solution. Platelet derived growth factor (PDGF), a clinically relevant, highly labile, and very low abundance biomarker, was chosen as a model. PDGF, spiked in human serum, was completely sequestered from its carrier protein albumin, concentrated, and fully preserved, within minutes by the particles. Particle sequestered PDGF was fully protected from exogenously added tryptic degradation. When the nanoparticles were added to a 1 mL dilute solution of PDGF at non detectable levels (less than 20 picograms per mL) the concentration of the PDGF released from the polymeric matrix of the particles increased within the detection range of ELISA and mass spectrometry. Beyond PDGF, the sequestration and protection from degradation for a series of additional very low abundance and very labile cytokines were verified.
  
  
  CONCLUSIONS
  We envision the application of harvesting core-shell nanoparticles to whole blood for concentration and immediate preservation of low abundance and labile analytes at the time of venipuncture.
authors.affiliation: Department of Dermatology, University of Modena and Reggio Emilia, Modena, Italy.
authors.forename: Caterina
authors.initials: C
authors.lastname: Longo
authors.forename: Alexis
authors.initials: A
authors.lastname: Patanarut
authors.forename: Tony
authors.initials: T
authors.lastname: George
authors.forename: Barney
authors.initials: B
authors.lastname: Bishop
authors.forename: Weidong
authors.initials: W
authors.lastname: Zhou
authors.forename: Claudia
authors.initials: C
authors.lastname: Fredolini
authors.forename: Mark M
authors.initials: MM
authors.lastname: Ross
authors.forename: Virginia
authors.initials: V
authors.lastname: Espina
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pellacani
authors.forename: Emanuel F
authors.initials: EF
authors.lastname: Petricoin
authors.forename: Lance A
authors.initials: LA
authors.lastname: Liotta
authors.forename: Alessandra
authors.initials: A
authors.lastname: Luchini
mesh_terms: D015415:Biomarkers / Q000097:blood*; D001798:Blood Proteins / Q000032:analysis / Q000378:metabolism; D019411:Clinical Laboratory Techniques; D016207:Cytokines / Q000097:blood / Q000378:metabolism; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D053758:Nanoparticles / Q000737:chemistry; D010982:Platelet-Derived Growth Factor / Q000032:analysis / Q000378:metabolism; D040901:Proteomics / Q000379:methods
chemical_list: D015415:Biomarkers; D001798:Blood Proteins; D016207:Cytokines; D010982:Platelet-Derived Growth Factor; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate