Sodium dodecyl sulfate decorated Legionella pneumophila for enhanced detection with a GaAs/AlGaAs nanoheterostructure biosensor

Abstract

The net electric charge associated with a bacterial strain is primarily defined by the number of available functional groups at its surface and we observed that it can determine the limit of detection of a charge-sensing biosensor. We have investigated the dynamic range of bacterial electric charge variations through binding negatively charged sodium dodecyl sulphate (SDS) molecules, with the objective of improving the detection limit of a charge-sensing GaAs/AlGaAs nanoheterostructure biosensor designed for detection of Legionella pneumophila. A twofold increased zeta potential of L. pneumophila was measured at pH 7.4 following the exposure of these bacteria to an SDS solution at 0.02 mg/mL. Subsequently, it was possible to detect SDS decorated and heatinactivated L. pneumophila at 10 3 CFU/mL. This illustrates the fundamental role of the bacterial electric charge in the operation of photocorrosion-based III-V semiconductor biochips. We discuss the mechanisms of bacterial interaction with SDS, critical aspects of decorating bacteria with this anionic surfactant and the channels responsible for charge transfer.

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

“…We also observed similar response of the GaAs/AlGaAs biochips to 50 CFU/mL of L. pneumophila SG1 and SG5 decorated with pAbs, as shown in Table 1 (see Figure S5 in Supplementary Information ). These results are consistent with the observation that decorating L. pneumophila SG1 with negatively charged SDS molecules significantly enhanced the sensitivity of DIP biosensors as reported in [ 23 ].…”

“…A significant delay of the PL maximum position was observed for the MHDA-pAb architecture compared to the PL maximum observed for the MHDA-only-functionalized biochip. This behaviour is consistent with the flow of a negative charge to the biochip surface also observed for other GaAs/AlGaAs nanoheterostructures [ 23 , 42 , 43 , 45 ].…”

“…An innovative biosensing method based on digital photocorrosion (DIP) of GaAs/AlGaAs semiconductor nanoheterostructures has been recently introduced for rapid detection of L. pneumophila [ 21 , 22 ]. The method is sensitive to charge transfer between semiconductor and immobilized biomolecules, and decorating L. pneumophila with negatively charged sodium dodecyl sulfate (SDS) permitted detection at 10 3 CFU/mL with polyclonal antibody (pAb) functionalized DIP biochips [ 23 ].…”

Short Ligand, Cysteine-Modified Warnericin RK Antimicrobial Peptides Favor Highly Sensitive Detection of Legionella pneumophila

“…In this system, the rate of photocorrosion of GaAs/AlGaAs nanoheterostructures is delayed due to the charge transfer between bacteria and the semiconductor, as suggested previously. 21 , 70 A mixed suspension of B. subtilis at 10 5 CFU/mL with L. pneumophila at 10 2 CFU/mL was used as a control to demonstrate the specificity of a proposed biosensor. When mixed together, the bacteria showed a PL maximum at 21 min, whereas L. pneumophila alone at 10 2 CFU/mL yielded a PL maximum at 20 min, which illustrates that the PL maxima were not affected in a measurable manner by the presence of non-target bacteria.…”

“…Aziziyan et al 33 detected 10 4 CFU/mL of L. pneumophila using an Ab functionalized GaAs/AlGaAs DIP biosensor. In their subsequent study, 21 they improved the detection limit to 10 3 CFU/mL by decorating bacteria with sodium dodecyl sulfate (SDS). However, a decoration step of bacteria with SDS increases the complexity of a detection protocol, and thus, it may not be entirely advantageous in comparison to the simple process of detecting L. pneumophila with a Cys-AMP-based biosensor.…”