Quantitative measurement of cardiac markers in undiluted serum.
Two mycocardial infarction biomarkers, myoglobin (MG) and cardiac troponin I (cTnI), were quantified at biological levels and in undiluted serum without sample pretreatment using surface plasmon resonance (SPR) sensors. To achieve detection of biomarkers in undiluted serum (72 mg/mL total protein concentration), minimization of the nonspecific signal from the serum protein was achieved by immobilizing the antibody for the biomarkers on an N-hydroxysuccinimide activated 16-mercaptohexadecanoic acid self-assembled monolayer. This monolayer reduces the nonspecific signal from serum proteins in such a manner that short exposure of the sensor to serum prior to analysis prevents any further nonspecific adsorption during analysis. Thus, sensing of MG and cTnI was achieved on the basis of the difference between signals from the active sensor and a reference sensor that captured background interference. This resulted in direct measurement of these biomarkers in undiluted serum. Detection limits for both markers were below 1 ng/mL, which is below the threshold needed to detect myocardial infarction. Detecting biomarkers in the low ng/mL range without signal amplification in such a complex matrix as serum corresponds to a selectivity of 108. The root-mean-square-error (RMSE) of calibration was below 2 ng/mL.
Masson
Jean-Francois
JF
Department of Chemistry and Biochemistry, Arizona State University, Mail Code 1604, Tempe, Arizona 85287-1604, USA.
Battaglia
Tina M
TM
Khairallah
Philip
P
Beaudoin
Stephen
S
Booksh
Karl S
KS
D000906:Antibodies / Q000737:chemistry; D000941:Antigens / Q000097:blood; D015415:Biomarkers / Q000097:blood; D002138:Calibration; D006801:Humans; D009203:Myocardial Infarction / Q000175:diagnosis*; D009211:Myoglobin / Q000097:blood* / Q000276:immunology; D010169:Palmitic Acids / Q000737:chemistry; D012680:Sensitivity and Specificity; D013388:Succinimides / Q000737:chemistry; D020349:Surface Plasmon Resonance / Q000379:methods* / Q000592:standards; D014336:Troponin / Q000097:blood* / Q000276:immunology
C450319:16-mercaptohexadecanoic acid; D000906:Antibodies; D000941:Antigens; D015415:Biomarkers; D009211:Myoglobin; D010169:Palmitic Acids; D013388:Succinimides; D014336:Troponin; C001426:N-hydroxysuccinimide