title: Aptamer-based sensing of β-casomorphin-7.
abstract: β-Casomorphin-7 (BCM-7), a seven amino acid peptide, is released during digestion of β-casein A1 variant of milk which is speculated to be associated with certain diseases. Fifteen ssDNA aptamers having high affinity toward BCM-7 were identified from a 72 nt long random library after ten rounds of systematic evolution of ligands by exponential enrichment. Dissociation constant values of selected aptamers were in the range of 7.7-156.7 nM. Seq6 aptamer exhibited the lowest Kd value. Nine aptamers were evaluated for their binding toward BCM-7, BCM-9A1, and BCM-9A2 peptides, and binding was variable. SeqU5 exhibited the lowest binding with BCM-9A1 and BCM-9A2. Aptamer-coated gold nanoparticles (GNPs) resulted in color change of GNPs in the presence of BCM-7, thereby establishing recognition of BCM-7 by aptamers. The enzyme-linked aptamer-sorbent assay (ELASA) was evaluated as an assay of BCM-7 in biological fluids. BCM-7-peroxidase competed with BCM-7 in ELASA, performed with BCM-7 solution and BCM-7 spiked urine pretreated with urease, plasma, and β-casein digest samples.
authors.affiliation: †Animal Biochemistry Division, National Dairy Research Institute, Karnal-132001, India.
authors.forename: Abhishek
authors.initials: A
authors.lastname: Parashar
authors.affiliation: †Animal Biochemistry Division, National Dairy Research Institute, Karnal-132001, India.
authors.forename: Yudhishthir S
authors.initials: YS
authors.lastname: Rajput
authors.affiliation: ‡Dairy Chemistry Division, National Dairy Research Institute, Karnal-132001, India.
authors.forename: Rajan
authors.initials: R
authors.lastname: Sharma
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D002364:Caseins / Q000032:analysis; D002417:Cattle; D004723:Endorphins / Q000032:analysis* / Q000097:blood / Q000652:urine; D006801:Humans; D008892:Milk / Q000737:chemistry; D052156:SELEX Aptamer Technique / Q000379:methods*
chemical_list: D052157:Aptamers, Nucleotide; D002364:Caseins; D004723:Endorphins; C021968:beta-casomorphins
keywords: ELASA; SELEX; aptamer; gold nanoparticles; β-casein; β-casomorphin-7