| Autor: |
Oliveira DA; Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843, USA., Althawab S; Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843, USA.; Department of Nutrition and Food Science, Texas A&M University, College Station, TX 77843, USA., McLamore ES; Department of Agricultural Sciences, Clemson University, Clemson, SC 26631, USA., Gomes CL; Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843, USA.; Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, USA. |
| Abstrakt: |
Bacterial contamination in food-processing facilities is a critical issue that leads to outbreaks compromising the integrity of the food supply and public health. We developed a label-free and rapid electrochemical biosensor for Listeria monocytogenes detection using a new one-step simultaneous sonoelectrodeposition of platinum and chitosan (CHI/Pt) to create a biomimetic nanostructure that actuates under pH changes. The XPS analysis shows the effective co-deposition of chitosan and platinum on the electrode surface. This deposition was optimized to enhance the electroactive surface area by 11 times compared with a bare platinum-iridium electrode ( p < 0.05). Electrochemical behavior during chitosan actuation (pH-stimulated osmotic swelling) was characterized with three different redox probes (positive, neutral, and negative charge) above and below the isoelectric point of chitosan. These results showed that using a negatively charged redox probe led to the highest electroactive surface area, corroborating previous studies of stimulus-response polymers on metal electrodes. Following this material characterization, CHI/Pt brushes were functionalized with aptamers selective for L. monocytogenes capture. These aptasensors were functional at concentrations up to 10 6 CFU/mL with no preconcentration nor extraneous reagent addition. Selectivity was assessed in the presence of other Gram-positive bacteria ( Staphylococcus aureus ) and with a food product (chicken broth). Actuation led to improved L. monocytogenes detection with a low limit of detection (33 CFU/10 mL in chicken broth). The aptasensor developed herein offers a simple fabrication procedure with only one-step deposition followed by functionalization and rapid L. monocytogenes detection, with 15 min bacteria capture and 2 min sensing. |
