Antimicrobial Peptides for Use in Biosensing Applications

Current pathogen detection systems lack the stability, sensitivity, and time-independent functionality required for real-time biosensing in the field. Antibodies exhibit specificity for pathogenic bacteria but lack the sensitivity to detect reduced pathogen levels and the stability needed for detection in harsh environments. We are investigating naturally occurring antimicrobial peptides (AMPs) for pathogen detection due to their intrinsic stability in harsh environments, ease of synthesis, and broad range of activity and affinity towards microorganisms, including gram-negative and gram-positive bacteria. The focus of our research is the tailoring of AMPs not for antimicrobial activity but for selective binding to target pathogenic bacteria. We envision these tailored peptides will replace existing molecular recognition elements in current pathogen detection platforms. Preliminary studies encompassed six full-length peptides (pleurocidin, cecropin P1, PGQ, cecropin A, ceratotoxin A, and SMAP-29) chemically synthesized with the addition of a c-terminal cysteine for site-directed immobilization onto a maleimide reactive plate and subsequent determination of whole cellbinding. Shorter peptide fragments of the native AMPs were also investigated to assess the putative discriminatory binding affinity for the gram-negative food pathogen Escherichia coli O157:H7. All six fulllength peptides preferentially bound to E. coli O157:H7 over gram-positive Staphylococcus aureus 27217. In addition, two fragments exhibited equivalent or greater affinity than their corresponding full-length peptides identifying potential E. coli O157:H7 bacterial binding domains within the full-length AMPs. The ability to impart selectivity of antimicrobial peptides is an important initial step toward developing selective peptides for use in applications such as homeland security, food safety, drug therapeutics, and water monitoring.