Sustainable, Alginate-Based Sensor for Detection of Escherichia coli in Human Breast Milk

Sensors

Matthew Zweber¹  Maryam Mobed-Miremadi¹  Nicholas Kikuchi¹  Margaret May¹  Jerard Madamba¹  Unyoung Kim¹  Craig Stephens² 

[1] Department of Bioengineering, Santa Clara University, Santa Clara, CA 95053, USA;Department of Biology, Santa Clara University, Santa Clara, CA 95053, USA;

关键词: bioassay;    breast milk;    alginate;    optimization;    sustainable;    e. coli;    pathogen detection;    taguchi method;    biosensor;   

DOI  :  10.3390/s20041145

来源: DOAJ

【 摘 要 】

There are no existing affordable diagnostics for sensitive, rapid, and on-site detection of pathogens in milk. To this end, an on-site colorimetric-based sustainable assay has been developed and optimized using an L₁₆ (5⁴) Taguchi design to obtain results in hours without PCR amplification. To determine the level of Escherichia coli (E. coli) contamination, after induction with 150 µL of breast milk, the B-Per bacterial protein extraction kit was added to a solution containing an alginate-based microcapsule assay. Within this 3 mm spherical novel sensor design, X-Gal (5-Bromo-4-Chloro-3-Indolyl β-d-Galactopyranoside) was entrapped at a concentration of 2 mg/mL. The outward diffusing X-Gal was cleaved by β-galactosidase from E. coli and dimerized in the solution to yield a blue color after incubation at 40 °C. Color intensity was correlated with the level of E. coli contamination using a categorical scale. After an 8 h incubation period, a continuous imaging scale based on intensity normalization was used to determine a binary lower limit of detection (LOD), which corresponded to 10² colony forming unit per mL (CFU/mL) and above. The cost of the overall assay was estimated to be $0.81 per sample, well under the $3 benchmark for state-of-the-art immune-based test kits for pathogen detection in biofluids. Considering the reported binary LOD cutoff of 10² CFU/mL and above, this proposed hydrogel-based assay is suited to meet global requirements for screening breast milk or milk for pathogenic organisms of 10⁴ CFU/mL, with a percentage of false positives to be determined in future efforts.

【 授权许可】

Unknown