Human neutrophil elastase (HNE) is a multifunctional serine protease, involved 
in infection defense, inflammatory process regulation, and physiopathological 
processes of several diseases. We developed aptamer-capture based assays for 
human neutrophil elastase with different substrates and solid supports to meet 
different demands, such as simplicity, sensitivity, and high throughput. 
Aptamers against HNE were immobilized on magnetic beads or microplates as 
affinity ligands to capture HNE, and then the enriched HNE catalyzed the 
conversion of chromogenic substrates or fluorogenic substrates to products. The 
measurement of the generated enzymatic products enabled the final detection of 
HNE. In the assay using chromogenic substrates and aptamer modified magnetic 
beads, 0.4 pM HNE could be successfully detected. The sensitivity of the assay 
was further improved by using fluorogenic substrates, and a detection limit of 
HNE at 20 fM was achieved. The use of aptamer-coated microplates instead of 
aptamer modified magnetic beads in the assays also allowed the sensitive 
detection of HNE, offering advantages in fast sample handling and measurement. 
The established assays for HNE displayed good specificity, and proteins 
including serum albumin, transferrin, immunoglobulin G, thrombin, porcine 
pancreatic elastase, trypsin, proteinase K, chymotrypsin, lysozyme, cathepsin G, 
and proteinase 3 did not cause interference in the detection of HNE.