Heavy metal adsorption onto graphene oxide, amino group on magnetic nanoadsorbents and application for detection of Pb(II) by strip sensor

ABSTRACT

Paper-based lateral flow immunoassays (LFIAs) are an interesting on site technique for detecting heavy metals. Pb(II) is one of the toxic heavy metals in polluted environmental water. This paper reports the synthesis and characterization of three Fe₃O₄-based nanoadsorbents that show different performance to Pb(II), Cu(II), Cd(II), Hg(II), As(V), Zn(II), Fe(III), Ca(II), Mg(II), Mn(II), and Al(III) when a GO or an amino group is introduced. Compared with Fe₃O₄, Fe₃O₄-GO showed higher adsorption percentage to many heavy metal ions under slightly acid condition. The negative surface on Fe₃O₄@NH₂ had favourable interactions for four main divalent metal ion adsorption, which followed the order: Pb(II) > Cu(II) > Hg(II) > Cd(II). Combined with antibody-functionalized AuNPs showed high affinity and specificity toward Pb(II), an Fe₃O₄@NH₂-based LFIA with five times greater sensitivity for detecting Pb(II) in lake water was developed. The cut-off value of this Fe₃O₄@NH₂-combined LFIA method for detection Pb(II) in lake water was 20 ng/mL and the detection result for 10 ng/mL Pb(II) was obviously observable by the naked eye or a strip reader machine. This detection strategy could be readily adapted for other small molecules or biomolecules as an ultrasensitive screening tool.

KEYWORDS:

• Magnetic nanoadsorbents
• Fe₃O₄@NH₂-based LFIA
• Pb(II) detecting

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is financially supported by the National Natural Science Foundation of China [grant number 31601547], the project from Jiangsu Education Department [grant number 16KJB550003], National Key Research and Development Program of China [grant number 2017YFD0401404] and Support Plan of National Science and Technology of China [grant number 2014BAD04B10], A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD) [grant number JSYXK201403] and Postgraduate Research and Practice Innovation Program of Jiangsu Province [grant number KYCX17-1218, KYCX17-1219]. Finally, we appreciated Xiaoxu Zhao’s help, a full engineer of Beijing Huaan Magnech Bio-Tech Co., Ltd, in the strip development.