Selective Detection of Legionella pneumophila Serogroup 1 and 5 with a Digital Photocorrosion Biosensor Using Antimicrobial Peptide-Antibody Sandwich Strategy

Abstract

Rapid detection of Legionella pneumophila (L. pneumophila) is important for monitoring the presence of these bacteria in water sources and preventing the transmission of the Legionnaires’ disease. We report improved biosensing of L. pneumophila with a digital photocorrosion (DIP) biosensor functionalized with an innovative structure of cysteine-modified warnericin antimicrobial peptides for capturing bacteria that are subsequently decorated with anti-L. pneumophila polyclonal antibodies (pAbs). The application of peptides for the operation of a biosensing device was enabled by the higher bacterial-capture efficiency of peptides compared to other traditional ligands, such as those based on antibodies or aptamers. At the same time, the significantly stronger affinity of pAbs decorating the L. pneumophila serogroup-1 (SG-1) compared to serogroup-5 (SG-5) allowed for the selective detection of L. pneumophila SG-1 at 50 CFU/mL. The results suggest that the attractive sensitivity of the investigated sandwich method is related to the flow of an extra electric charge between the pAb and a charge-sensing DIP biosensor. The method has the potential to offer highly specific and sensitive detection of L. pneumophila as well as other pathogenic bacteria and viruses.

Detection of Bacillus group spores in an aqueous environment using an aptamer based digital photocorrosion biosensor

“…As it can be seen, the increasing concentration of immobilized spores accelerates the photocorrosion rate, which is manifested by the accelerated positions of PL intensity maxima. These results contrast with our previously reported experiments concerning DIP of GaAs/AlGaAs biochips exposed to bacteria, such as E. coli and L. pneumophila [19][20][21][22][23][24][25], all of which demonstrated delayed photocorrosion rates with the increasing concentration of surface immobilized bacteria. This qualitative difference cannot be explained, e.g., by the (zeta)-potential of the investigated spores ranging between -12.28 and -44.51 mV at pH 7.0 [34], as it compares to -10 mV and -30 mV, respectively, for L. pneumophila and E. coli at similar pH [21].…”

“…This translates in the formation of a PL intensity maximum when the photocorrosion front crosses the GaAs/AlGaAs interface. The temporal position of PL intensity maximum (PLmax) depends on the presence of charged molecules, such as bacteria, immobilized in the vicinity of a DIP biosensor surface, and delayed PLmax positions have been systematically observed in proportion to the increasing concentration of surface immobilized bacteria [21][22][23][24][25]. The detection performance of biosensors depends on the capturing efficiency of the biorecognition molecules [26].…”

“…The detection performance of biosensors depends on the capturing efficiency of the biorecognition molecules [26]. In the case of DIP biosensors, it is also a reduced distance of the immobilized charged biomolecule from the semiconductor surface that is important to achieving enhanced sensitivity, as demonstrated the results obtained with antimicrobial peptides and antibody functionalized DIP biosensors [24,27]. Aptamer-based biosensors have been investigated for their superior affinity towards target molecules, stability and reproducibility [28,29].…”

Design of an optical nanobiosensor for detection of Legionella pneumophila in water samples

“…PCR and Real-time PCR based are also used to diagnose Legionella pneumophila , but are time-consuming and require equipment ( 8 , 10 ). Gold nanoparticles based on optical sensing due to their unique optical properties have recently attracted much attention in detection cases ( 11 , 12 ).…”