title: Determination of endotoxin through an aptamer-based impedance biosensor.
abstract: Lipopolysaccharide (LPS) often referred to endotoxin is an undesirable impurity frequently entrained with various recombinant protein therapeutics and plasmid DNA (pDNA) vaccines of bacterial origin. The inherent toxicities (e.g. fever, hypotension, shock and death) of LPS render its early and sensitive detection essential for several biological assays and/or parenteral administrations of biotherapeutics. In this study, an electrochemical biosensor using an LPS specific single stranded DNA (ssDNA) aptamer as a probe was developed. Amine-terminated aptamer exhibiting high affinity (K(d)=11.9 nM) to LPS was immobilized on a gold electrode using 3-mercaptopropionic acid (MPA) as a linker. Each step of the modification process was characterized by cyclic voltammetry (CV) and electrochemical impendence spectroscopy (EIS). A good linear relationship of the changes in the charge-transfer resistance (ΔR(et)) and the logarithmic value of LPS concentration was demonstrated in a broad dynamic detection range of 0.001-1 ng/ml. Furthermore, the aptasensor showed a high selectivity to LPS despite the presence of pDNA, RNA and bovine serum albumin (BSA) and could be regenerated in low pH condition, offering a promising option for detecting LPS often present in a complex milieu.
authors.affiliation: School of Chemical Engineering, Sungkyunkwan University, 440-746 Suwon, Republic of Korea.
authors.forename: Wenqiong
authors.initials: W
authors.lastname: Su
authors.forename: Meng
authors.initials: M
authors.lastname: Lin
authors.forename: Hyuck
authors.initials: H
authors.lastname: Lee
authors.forename: MiSuk
authors.initials: M
authors.lastname: Cho
authors.forename: Woo-Seok
authors.initials: WS
authors.lastname: Choe
authors.forename: Youngkwan
authors.initials: Y
authors.lastname: Lee
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000379:methods*; D002417:Cattle; D004277:DNA, Single-Stranded / Q000737:chemistry; D017097:Electric Impedance; D055664:Electrochemical Techniques / Q000379:methods; D004566:Electrodes; D004926:Escherichia coli / Q000737:chemistry; D008070:Lipopolysaccharides / Q000032:analysis*; D012680:Sensitivity and Specificity
chemical_list: D052157:Aptamers, Nucleotide; D004277:DNA, Single-Stranded; D008070:Lipopolysaccharides