title: Electrochemical detection of quorum sensing signaling molecules by dual signal confirmation at microelectrode arrays.
abstract: n-Acyl homoserine lactones (AHLs) are produced by gram-negative bacteria to regulate gene expression in a cell density dependent manner. For instance, expression of virulence factors by pathogens such as Pseudomonas aeruginosa is induced only when a threshold concentration of AHLs is reached, which indicates that the bacterial population is big enough to promote infection. In this study, the indicator strain Agrobacterium tumefaciens NTL4 (pZLR4), which carries a β-galactosidase (β-gal) reporter gene under the control of a quorum sensing promoter, was used to develop an electrochemical biosensor to detect AHLs using the model n-(3-oxo)-dodecanoyl-L-homoserine lactone (oxo-C12-HSL), an AHL previously detected in cystic fibrosis patients infected with P. aeruginosa. The substrate 4-aminophenyl β-D-galactopyranoside was used to detect β-gal activity by cyclic voltammetry. Furthermore, simultaneous monitoring of substrate consumption and p-aminophenol production by β-gal allowed on-chip result verification by dual-signal confirmation. The sensor exhibited high reproducibility and accurately detected oxo-C12-HSL in a low picomolar to low nanomolar range in spiked liquid cultures and artificial saliva, as well as AHLs naturally released by P. aeruginosa in culture supernatants. Moreover, detection took just 2 h, required no sample pretreatment or preconcentration steps, and was easier and faster than traditional methods.
authors.affiliation: Institut de Microelectrònica de Barcelona (IMB-CNM), CSIC, Campus UAB, 08193 Bellaterra, Barcelona, Spain. eva.baldrich@imb-cnm.csic.es
authors.forename: Eva
authors.initials: E
authors.lastname: Baldrich
authors.forename: Francesc Xavier
authors.initials: FX
authors.lastname: Muñoz
authors.forename: Cristina
authors.initials: C
authors.lastname: García-Aljaro
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000032:analysis / Q000096:biosynthesis / Q000494:pharmacology; D054742:Acyl-Butyrolactones / Q000032:analysis* / Q000378:metabolism / Q000494:pharmacology; D016960:Agrobacterium tumefaciens / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D000627:Aminophenols / Q000378:metabolism; D040761:Biomimetic Materials / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation*; D017077:Culture Media, Conditioned / Q000378:metabolism; D004563:Electrochemistry / Q000295:instrumentation*; D005697:Galactosides / Q000378:metabolism; D006046:Gold / Q000737:chemistry; D006714:Homoserine / Q000031:analogs & derivatives / Q000032:analysis / Q000096:biosynthesis / Q000494:pharmacology; D006868:Hydrolysis; D057230:Limit of Detection; D008839:Microelectrodes; D011550:Pseudomonas aeruginosa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D053038:Quorum Sensing; D012463:Saliva; D013997:Time Factors; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D054742:Acyl-Butyrolactones; D000627:Aminophenols; D017077:Culture Media, Conditioned; D005697:Galactosides; C109860:N-(3-oxododecanoyl)homoserine lactone; C010677:4-aminophenyl-beta-galactoside; D006714:Homoserine; D006046:Gold; D001616:beta-Galactosidase; D015107:4-Butyrolactone; C026729:4-aminophenol