Biacore biosensor immunoassay for 4-nonylphenols: assay optimization and applicability for shellfish analysis.
A rapid Biacore biosensor immunoassay of 4-nonylphenols was developed. Two types of antibodies were used in the study: polyclonal antibodies with high cross-reactivity towards technical 4-nonylphenol and a monoclonal antibody very specific to 4-n-nonylphenol. 9-(p-Hydroxyphenyl)nonanoic acid was immobilized onto surface of a sensor chip. The best assay sensitivity was achieved using a flow rate of 50 microl min(-1) and injection time of 2 min. For the assay incorporating monoclonal antibodies a limit of detection 2 ng ml(-1) for 4-n-nonylphenol was achieved. With polyclonal antibodies one order lower sensitivity was observed for 4-nonylphenols. High background level of calibration curve for technical 4-nonylphenol was decreased by using IgG fraction of polyclonal antibodies in combination with lower amount of immobilised 9-(p-hydroxyphenyl)nonanoic acid. Sensitivity of the assay was improved by using a chip with a new derivative on a surface-N-aminobutyl [2-(4-hydroxyphenyl)ethylamine] (limit of detection--5 ng ml(-1)). Applicability of the developed assays to ecological monitoring was checked in experiments using shellfish samples. 4-n-Nonylphenol from spiked samples was extracted into hexane followed by clean-up on NH2 SPE columns. Calibration curves generated for cockles, mussels and oyster samples were identical (limit of detection about 10 ng g(-1)) whereas for scallop samples a slight decrease (about 5-10%) of absolute response was observed. In the assay using the monoclonal antibody specific to 4-n-nonylphenol 31 shellfish samples were found to be negative. Results obtained with polyclonal antibodies indicated that two scallop samples contained a quantity of 4-nonylphenols. The developed biosensor assay could be applied for shellfish analysis as a preliminary screening method.
Samsonova
Jeanne V
JV
Department of Chemical Enzymology, Chemistry Faculty, M.V. Lomonosov Moscow State University, 119992 Moscow, Russia. jvs@enz.chem.msu.ru
Uskova
Natalya A
NA
Andresyuk
Alexey N
AN
Franek
Milan
M
Elliott
Christopher T
CT
D000818:Animals; D000906:Antibodies / Q000737:chemistry; D002138:Calibration; D004784:Environmental Monitoring / Q000379:methods*; D007118:Immunoassay / Q000379:methods*; D010636:Phenols / Q000032:analysis* / Q000737:chemistry; D012680:Sensitivity and Specificity; D012758:Shellfish / Q000032:analysis*
D000906:Antibodies; D010636:Phenols; C041594:4-nonylphenol