KLK3 and myocardial infarction: While the detection of the cancermarker prostate-specific antigen (PSA) was 16-fold improved by usingthe digital readout,11 no significant improvementof the sensitivity was observed for the detection of human cardiactroponin I (cTnI), the most important marker of myocardial infarction.16 These experiments revealed that the sizes ofUCNPs did not influence the assay sensitivity in the buffer but hada strong effect when plasma was used.