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Abstract
We describe a set of label‐free piezoelectric biosensors for fast, qualitative, and direct detection of HSP 70 in crude extract of the mussel mantle. A monoclonal anti‐HSP 70 antibody and three heptapeptides chosen using a computational/combinatorial approach were immobilized covalently to gold particles on quartz surfaces using a self‐assembled monolayer (SAM). A clear frequency shift in the presence of standard solutions of HSP 70 from bovine brain was obtained. The difference in signal intensity among the biomimetic sensors (the peptide sensors) was nicely correlated with the computationally predicted binding scores. Moreover, the peptides exhibited a signal comparable to the monoclonal antibody based immunosensor. Regeneration of the affinity sensors was also investigated obtaining a significant loss of signal only after 10 regeneration cycles with repeatability in the 20%–28% range and reproducibility in the 25%–35% range. Cross‐reactivity of the HSP sensors was tested using bovine serum albumin (BSA) and rabbit IgG. All the affinity sensors exhibited low nonspecific binding, compared with a blank sensor and a negative control sensor. The sensitivity pattern with the real sample (mussel mantle) reflected the one obtained from the standard solution of HSPs 70, demonstrating that all the sensors are able to detect the target analyte in a complex matrix as in a crude extract.
Work supported by MIUR (COFIN 03, DM n. 21, 20 February 2003).
