Signal amplification on planar and gel-type sensor surfaces in surface plasmon resonance-based detection of prostate-specific antigen

G.A.J. Besselink, R.P.H. Kooyman, Peter J.H.J. van Os, G.H.M. Engbers, Richardus B.M. Schasfoort

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This article describes surface plasmon resonance (SPR)-based detection of prostate-specific antigen (PSA), comparing amplification with colloidal gold (10 nm diameter) and latex microspheres (120 nm diameter) on planar- and gel-type sensor surfaces. As matrix, 3% BSA in PBS was used. Experimental data were compared with model calculations that predict the SPR signal that results from covering of the different sensor surfaces with each of the particles used. Amplification with latex particles gave a higher signal than did that with colloidal gold. However, the limit of detection (LOD) attained by latex amplification was not as good as that obtained after gold amplification, and this was unexpected. LOD and sensitivity of the amplified PSA assays when performed with the planar-type sensor disc were equally good or better compared with those when performed with the gel-type sensor disc. Indirect evidence indicates a restricted accessibility of the gel layer on the gel-type sensor toward the colloidal gold. Application of colloidal gold led to a sensitivity increase of approximately three orders of magnitude compared with nonamplified detection. The corresponding LOD was approximately 0.15 ng PSA/ml, which is sufficient for measuring enhanced, clinically relevant PSA levels (>4 ng/ml).
Original languageUndefined
Pages (from-to)165-173
Number of pages9
JournalAnalytical biochemistry
Issue number1
Publication statusPublished - 2004


  • METIS-218829
  • Latex micro spheres
  • Prostate-specific antigen
  • Surface plasmon resonance
  • Colloidal gold
  • Amplification
  • IR-76192

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