Competitive surface-enhanced Raman scattering assay for the 1,25-dihydroxy metabolite of vitamin D3.
This paper describes the development and preliminary testing of a competitive surface-enhanced Raman scattering (SERS) immunoassay for calcitriol, the 1,25-dihydroxy metabolite (1,25-(OH)(2)-D(3)) of vitamin D(3). Deficiencies in 1,25-(OH)(2)-D have been linked to renal disease, while elevations are linked to hypercalcemia. Thus, there has been a sharp increase in the clinical demand for measurements of this metabolite. The work herein extends the many attributes of SERS-based sandwich immunoassays that have been exploited extensively in the detection of large biolytes (e.g., DNA, proteins, viruses, and microorganisms) into a competitive immunoassay for the low level determination of a small biolyte, 1,25-(OH)(2)-D(3) (M(w) = 416 g mol(-1)). The assay uses surface modified gold nanoparticles as SERS labels, and has a dynamic range of 10-200 pg mL(-1) and a limit of detection of 8.4 ± 1.8 pg mL(-1). These analytical performance metrics match those of tests for 1,25-(OH)(2)-D(3) that rely on radio- or enzyme-labels, while using a much smaller sample volume and eliminating the disposal of radioactive wastes. Moreover, the SERS-based data from pooled-patient sera show strong agreement with that from radioimmunoassays. The merits and potential utility of this new assay are briefly discussed.
Dufek
Eric J
EJ
Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA.
Ehlert
Brian
B
Granger
Michael C
MC
Sandrock
Tanya M
TM
Legge
Samuel L
SL
Herrmann
Mark G
MG
Meikle
A Wayne
AW
Porter
Marc D
MD
D002117:Calcitriol / Q000031:analogs & derivatives / Q000032:analysis* / Q000378:metabolism*; D006801:Humans; D007118:Immunoassay; D015394:Molecular Structure; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties
D002117:Calcitriol