Optical immunosensors for detection of Listeria monocytogenes and Salmonella enteritidis from food

Abstract

Listeria monocytogenes and Salmonella are two major foodborne pathogens of significant concern. Two optical evanescent wave immunosensors were evaluated for detection: Antibody-coupled fiber-optic biosensor and a surface plasmon resonant (SPR) immunosensor. In the fiber-optic sensor, polyclonal antibodies for the test organisms were immobilized on polystyrene fiber wave -guides using streptavidin -biotin chemistry. Cyanine 5 -labeled monoclonal antibodies C11E9 (for L. monocytogenes) and SF-11 (for Salmonella Enteritidis) were used to generate a specific fluorescent signal. Signal acquisition was performed by launching a laser-light (635 nm) from an Analyte-2000. This immunosensor was able to detect 10 3 -10 9 cfu/ml of L. monocytogenes or 10 6 -10 9 cfu/ml of Salmonella Enteritidis and the assays were conducted at near real-time with results obtained within one hour of sampling. The assays were specific and showed signal even in the presence of other microorganisms such as E. coli, Enterococcus faecalis or Salmonella Typhimurium. In the SPR system, IAsys instrument (resonant mirror sensor) was used. Monoclonal antibody-C11E9 was directly immobilized onto a carboxylate cuvette. Whole Listeria cells at various concentrations did not yield any signal while surface protein extracts did. Crude protein extracts from L. monocytogenes and L. innocua had average binding responses of around 150 arc sec (0.25 ng/mm 2 ), which was significantly different from L. grayi, L. ivanovii, or L. welshimeri with average responses of <48 arc sec. Both fiber-optic and SPR sensors show promise in near real-time detection of foodborne L. monocytogenes and Salmonella Enteritidis.

Development of a Simultaneous Detection Method for Foodborne Pathogens Using Surface Plasmon Resonance Biosensors

“…Many researchers have applied SPR biosensors for the detection of O157 (Meeusen et al, 2005;Subramanian et al, 2006;Taylor et al, 2005), SE (Bhunia et al, 2004;Bokken et al, 2003), and LM (Hearty et al, 2006;Leonard et al, 2004). The lower detection limit was reported to be 10 5 to 10 7 CFU/mL for O157, 10 6 to 10 7 CFU/mL for SE, and 10 5 to 10 7 CFU/mL for LM, respectively.…”

“…Compared with whole bacterial cells, small pieces of cells are easier to detect using an SPR biosensor (Bhunia et al, 2004). Each bacterium contains many antigens.…”

Optical detection of asymmetric bacteria utilizing electro-orientation

“…Current bacteria detection methods include urine cultures [9] and biosensor techniques that detect antigen-antibody, enzyme-substrate, or receptor-ligand complexes by measuring fluorescent light, surface reflection, and electrical properties [10][11][12][13]. These methods can be time and labor consuming (12-24 hours for urine culture), expensive, or complex to operate.…”

Optical Chemical Biosensors for High Throughput Screening of Drugs

“…Polyclonal antibody first immobilized on polystyrene fiber waveguides through biotin-streptavidin reaction to capture Listeria cells on the fiber; cyanine-labeled monoclonal second antibody used to generate specific fluorescent signal, excited by a 635-nm laser; collected by photodetector at 670-710 nm; immunoprobe specific over several other Listeria species; results obtained within 2.5 h of sampling [176] Listeria and Salmonella species Evanescent wave immunosensors; in the fiber-optic approach, polyclonal antibodies for the test organisms were immobilized on polystyrene fiber waveguides using streptavidin-biotin chemistry; cyanine-labeled monoclonal secondary antibodies were used to generate a specific fluorescent signal [177] Molecular recognition of Escherichia coli; screening drugs and diagnosis p-10,12-pentacosadiyne-1-N-(3,6,9-trioxaundecylanide) --D-mannopyranoside (MPDA) was synthesized from 10,12-pentacasadiynoic acid (PDA); mixed monolayer MPDA/PDA was prepared by using Langmuir-Blodgett technique on glass and optical fiber, respectively; change of the film colour can be quantified by UV-VIS absorption spectroscopy [178] E. coli bacteria fiber-optic biosensor using a saccharide-functionalized polydiacetylene as the recognition element; mixed monolayer consisting of a (polypentacosadiyne---mannopyranoside) conjugate and of pentacasadiynoic acid was prepared using the Langmuir-Blodgett technique and deposited on an optical fiber; molecular recognition of E. coli resulted in change in film colour and can be quantified by absorption spectroscopy [179] Detection of E. coli O157:H7 Following PCR reaction [180] Detection of E. coli O157:H7 Same strain can be analyzed in ground beef, chicken carcass, and lettuce samples with an immunomagnetic chemiluminescence fiber-optic biosensor [181] Detection of genomic target sequences from E. coli Via fluorescent intercalating agents such as SYBR 101 that can report hybridization events with target strands [182] Pathogenic toxins Fluorescent biosensor using cyclic polypeptide conjugates; biosensor concept based on competitive binding between native microcystin and its fluorescent analogue at immobilized alkaline phosphatase enzymes [183] Detecting Helicobacter pylori in a sandwich assay at picomolar concentrations Hybridization also was detected by evanescent wave fluorescence excitation using tapered fibers and NIR fluorophores; 20-mer oligonucleotide bound to the surface of a fiber could detect subnanomolar quantities of the complementary sequence [184] Staphylococcus aureus enterotoxin A Using a chemiluminescent fiber-optic biosensor and magnetic particles [185] Detecting staphylococcal enterotoxin B…”

“…A summary of the applications of fiber optic biosensor in HTS protocols related to monitoring of various metabolites , drugs [196,197], pathogens [173][174][175][176][177][178][179][180][181][182][183][184][185][186][187][188][189][190][191][192], DNA [162][163][164][165][166][167][168][169] and other different analytes is shown in Table 2.…”