title: Development of magnetic nanoparticle based calorimetric assay for the detection of bovine mastitis in cow milk.
abstract: Mastitis in dairy cattle is an inflammatory reaction of the udder tissue. Mastitis increases plasmin levels, leading to an increased proteolysis of milk proteins such as casein, resulting in a significant decrease in milk quality and related dairy products. Due to its key-role in mastitis, we used plasmin proteolytic activity as a biomarker for the detection of mastitis in bovine mastitic milk. Inspired by earlier studies on protease activity using mastitic milk samples, we developed a simple colorimetric assay to distinguish mastitic milk from milk derived from healthy animals. The plasmin substrate coupled to magnetic nanoparticles form a black self-assembled monolayer on a gold sensor surface. In the presence of increased levels of plasmin, the substrate is cleaved and the peptide fragment attached to the magnetic beads, will be attracted by the magnet which is present under the sensor strips revealing the golden surface. We found the area of the golden color surface proportional to plasmin activity. The sensitivity of this method was determined to be 1 ng/ml of plasmin in vitro. Next, we tested the biosensor using mastitis positive milk of which infection is confirmed by bacterial cultures. This newly developed colorimetric biosensor has high potential in applications for the diagnosis of mastitis with potential spin offs to health, food and environmental sectors.
authors.affiliation: Department of Chemistry, Alfaisal University, Al Zahrawi Street, Al Maather, Al Takhassusi Rd, Riyadh 11533, Saudi Arabia.
authors.forename: Raja
authors.initials: R
authors.lastname: Chinnappan
authors.affiliation: Department of Biological Sciences, College of Science, King abdulAziz University, Jeddah, Saudi Arabia.
authors.forename: Sana
authors.initials: S
authors.lastname: Al Attas
authors.affiliation: Department of Oral Biochemistry, Academic Centre for Dentistry Amsterdam, University of Amsterdam and VU University Amsterdam, Gustav Mahlerlaan 3004, 1081 LA Amsterdam, The Netherlands; Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Center, Wytemaweg 80, 3015 CE Rotterdam, The Netherlands.
authors.forename: Wendy E
authors.initials: WE
authors.lastname: Kaman
authors.affiliation: Department of Medical Microbiology and Infectious Diseases, Erasmus Medical Center, Wytemaweg 80, 3015 CE Rotterdam, The Netherlands.
authors.forename: Floris J
authors.initials: FJ
authors.lastname: Bikker
authors.affiliation: Department of Chemistry, Alfaisal University, Al Zahrawi Street, Al Maather, Al Takhassusi Rd, Riyadh 11533, Saudi Arabia; King Faisal Specialist Hospital and Research Center, Zahrawi Street, Al Maather, Riyadh 12713, Saudi Arabia. Electronic address: mzourob@alfaisal.edu.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Zourob
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods*; D015374:Biosensing Techniques; D002151:Calorimetry / Q000379:methods*; D002417:Cattle; D005260:Female; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008414:Mastitis, Bovine / Q000175:diagnosis*; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000032:analysis*
chemical_list: D058185:Magnetite Nanoparticles; D008894:Milk Proteins
keywords: Colorimetric biosensor; Mastitis; Plasmin