A functionalized nanoporous alumina membrane electrochemical sensor for DNA detection with gold nanoparticle amplification

Nucleic acids based detection has become increasingly important for biomedical diagnostics, environmental monitoring and food screening. A nanoporous alumina membrane based sensing platform with gold nanoparticle amplification has been developed for direct DNA detection. The purpose of this study is to develop a functionalized nanoporous alumina membrane based sensor for direct DNA detection with gold nanoparticle amplification via impedance spectroscopy. Single stranded DNA was first covalently immobilized on the nanopore walls via silane-PEG-NHS linker. The residual NHS group was hydrolyzed to form PEG layer which could minimize the unspecific DNA binding during hybridization process. Using this nanoporous alumina membrane based device, single strand DNA (ssDNA) immobilization, double strand DNA (dsDNA) hybridization and gold nanoparticle conjugated dsDNA hybridization were successfully monitored via impedance spectroscopy. The result showed that the conjugation of gold nanoparticle with dsDNA could significantly increase the impedance signal. This portable PDMS device integrated with functionalized nanoporous alumina membrane with gold nanoparticle amplification has the potential for nucleic acid in field detection in the application of food screening and environmental monitoring with high sensitivity.