Enhanced Detection of Live Bacteria Using a Dendrimer Thin Film in an Optical Biosensor

• Published in: Analytical chemistry (Washington) 2001-02, Vol.73 (3), p.467-470
• Main Authors: Chang, An-Cheng, Gillespie, James B, Tabacco, Mary Beth
• Format: Article
• Language: English
• Subjects: Analysis; Bacteria; Bacteriological methods and techniques used in bacteriology; Bacteriology; Biological and medical sciences; Biosensing Techniques; Biotechnology; Fluorescence; Fundamental and applied biological sciences. Psychology; Glucose; Methods. Procedures. Technologies; Microbiology; Optics and Photonics; Others; Pseudomonas aeruginosa - isolation & purification; Sensors; Various methods and equipments
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac000460a

Here we describe the detection of live Pseudomonas aeruginosa using a sensing film containing a fourth-generation hydroxy-terminated polyamidoamine (PAMAM) dendrimer (i.e., G4-OH) and SYTOX Green fluorescent nucleic acid stain. The films are configured on simple, disposable plastic coupons or optical fibers and are interrogated using a miniature fiber-optic spectrometer. SYTOX Green is generally considered a dead cell stain because it is not able to cross the membranes of live cells. In the presence of PAMAM-OH (G4-OH) in water, the bacterial cell becomes permeable to the SYTOX dye and the fluorescence is significantly enhanced. The fluorescence increases with the bacteria concentration, and the intensity at 5.4 × 107 cells mL-1 is 350% higher than the liquid controls without PAMAM-OH. We also demonstrate that dendrimers stabilize the sensing film. After drying and desiccation, the SYTOX Green/PAMAM-OH films are still able to quantitatively detect P. aeruginosa in water. Incorporation of glucose into the SYTOX Green/PAMAM-OH film may improve the homogeneity of the film and enhances the fluorescence signal an additional 11−25%.