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Laser-Induced Graphene Electrochemical Immunosensors for Rapid and Label-Free Monitoring of <i>Salmonella enterica</i> in Chicken Broth
摘要： Food-borne illnesses are a growing concern for the food industry and consumers, with millions of cases reported every year. Consequently, there is a critical need to develop rapid, sensitive, and inexpensive techniques for pathogen detection in order to mitigate this problem. However, current pathogen detection strategies mainly include time-consuming laboratory methods and highly trained personnel. Electrochemical biosensors offer a rapid, low-cost alternative to laboratory techniques, but the electrodes used in these biosensors require expensive nanomaterials to increase their sensitivity, such as noble metals (e.g., platinum, gold) or carbon nanomaterials (e.g., carbon nanotubes, or graphene). Herein, we report the fabrication of a highly sensitive and label-free laser-induced graphene (LIG) electrode that is subsequently functionalized with antibodies to electrochemically quantify the food-borne pathogen Salmonella enterica serovar Typhimurium. The LIG electrodes were produced by laser induction on the polyimide film in ambient conditions and, hence, circumvent the need for high-temperature, vacuum environment, and metal seed catalysts commonly associated with graphene-based electrodes fabricated via chemical vapor deposition processes. After functionalization with Salmonella antibodies, the LIG biosensors were able to detect live Salmonella in chicken broth across a wide linear range (25 to 105 CFU mL?1) and with a low detection limit (13 ± 7 CFU mL?1; n = 3, mean ± standard deviation). These results were acquired with an average response time of 22 min without the need for sample preconcentration or redox labeling techniques. Moreover, these LIG immunosensors displayed high selectivity as demonstrated by nonsignificant response to other bacteria strains. These results demonstrate how LIG-based electrodes can be used for electrochemical immunosensing in general and, more specifically, could be used as a viable option for rapid and low-cost pathogen detection in food processing facilities before contaminated foods reach the consumer.
关键词： biosensor,foodborne pathogens,graphene,food safety,Salmonella Typhimurium,electrochemical impedance spectroscopy
更新于2025-09-23 15:21:01
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A Microfluidic Biosensor Based on Magnetic Nanoparticle Separation, Quantum Dots Labeling and MnO2 Nanoflower Amplification for Rapid and Sensitive Detection of Salmonella Typhimurium
摘要： Screening of foodborne pathogens is an effective way to prevent microbial food poisoning. A microfluidic biosensor was developed for rapid and sensitive detection of Salmonella Typhimurium using quantum dots (QDs) as fluorescent probes for sensor readout and manganese dioxide nanoflowers (MnO2 NFs) and as QDs nanocarriers for signal amplification. Prior to testing, amino‐modified MnO2 nanoflowers (MnO2‐NH2 NFs) were conjugated with carboxyl‐modified QDs through EDC/NHSS method to form MnO2‐QD NFs, and MnO2‐QD NFs were functionalized with polyclonal antibodies (pAbs) to form MnO2‐QD‐pAb NFs. First, the mixture of target Salmonella Typhimurium cells and magnetic nanoparticles (MNPs) modified with monoclonal antibodies (mAbs) was injected with MnO2‐QD‐pAb NFs into a microfluidic chip to form MNP‐bacteria‐QD‐MnO2 complexes. Then, glutathione (GSH) was injected to dissolve MnO2 on the complexes into Mn2+, resulting in the release of QDs. Finally, fluorescent intensity of the released QDs was measured using the fluorescent detector to determine the amount of Salmonella. A linear relationship between fluorescent intensity and bacterial concentration from 1.0 × 102 to 1.0 × 107 CFU/mL was found with a low detection limit of 43 CFU/mL and mean recovery of 99.7% for Salmonella in spiked chicken meats, indicating the feasibility of this biosensor for practical applications.
关键词： quantum dots,manganese dioxide nanoflowers,Salmonella Typhimurium,Microfluidic biosensor,magnetic nanoparticles
更新于2025-09-23 15:19:57
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Response surface methodology can be used to predict photoinactivation of foodborne pathogens using Rose Bengal excited by 530?nm LED
摘要： In this work, the photodynamic bactericidal effect of Rose Bengal (RB), combined with green LED light, against Staphylococcus aureus and Salmonella Typhimurium, was investigated. The interaction of RB concentration and illumination time was evaluated using a response surface methodology, and a second-order polynomial empirical model was adjusted to the experimental data. The derived model predicted the combined influences of these factors on S. aureus and S. Typhimurium counts, in accordance with predictions and experimental observations (R2 = 0.8483 and p = .0013 for S. aureus; R2 = 0.9191 and p = .0001 for S. Typhimurium). Total inhibition of S. aureus and S. Typhimurium was observed when applying a light dose of 0.125 J cm?2 and 152.0 J cm?2, respectively. The treatments also showed loss of membrane integrity, morphological changes, and internal cell structural alterations. In sum, the polynomial model developed could provide accurate information on the combined influences of RB and green LED light in aPDT treatment and, that this combination was able to inactivate S. aureus and S. Typhimurium.
关键词： Rose Bengal,green LED light,Salmonella Typhimurium,response surface methodology,Staphylococcus aureus,photodynamic bactericidal effect
更新于2025-09-11 14:15:04
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Colorimetric-Fluorescent-Magnetic Nanosphere-Based Multimodal Assay Platform for Salmonella Detection
摘要： Rapid and sensitive foodborne pathogen detection assay, which can be applied in multiple fields, is essential to timely diagnosis. Herein, we proposed a multi-signal readout lateral flow immunoassay for Salmonella typhimurium (S. typhi) detection. The assay employs colorimetric-fluorescent-magnetic nanospheres (CFMNs) as labels, which possess multi-functional: target separation and enrichment, multi-signal readout and two formats of quantitation. The assay for S. typhi detection involves magnetic separation and chromatography. First, the S. typhi were separated and enriched from matrix by antibody labelled CFMNs, and then the S. typhi-containing suspension is added onto the sample pad to flow up the test strip. The introduction of magnetic separation enhances anti-interference ability and 10-fold sensitivity, making the assay possible for practical application. The assay has realized naked eye detection of 1.88×104 CFU/mL S. typhi, and 3.75×103 CFU/mL S. typhi can be detected with a magnetic assay reader, which is 2–4 orders of magnitude lower than other label-based LFIAs, with a quantitation range of 1.88×104 to 1.88×107 CFU/mL by measuring the fluorescence intensity and magnetic signal. Moreover, the successful detection of S. typhi in complex matrix (tap water, milk, fetal bovine serum and whole blood) indicated its potential application in real samples.
关键词： colorimetric-fluorescent-magnetic nanospheres,lateral flow immunoassay,Salmonella typhimurium,multimodal assay,pathogen detection
更新于2025-09-09 09:28:46