Gold nanoparticles coated with DNA-metalloenzyme as target-responsive and signal-amplification material for sensitive detection of β-lactoglobulin

β-lactoglobulin (β-Lg) is the most allergenic allergen in milk and can affect the health of infants and young children seriously. Detecting β-Lg in food products is an urgent requirement. The coordination of Cu(II) with single-strand DNA as metalloenzyme was used to catalyze TMB (3, 3′, 5, 5′-tetramethylbenzidine)-H 2 O 2 reaction to generate electrochemistry signal. Firstly, DNA 1 self-assembly on the electrode and hybridized with DNA 2 to form DNA 1 /DNA 2 double-stranded complex. Secondly, β-Lg combined with DNA 2 (aptamer) which partially complementary with DNA 1 via target-ligand interaction, β-Lg/DNA 2 complex formed and released, DNA-Cu(II)-AuNPs nanocomposites as catalysis for TMB-H 2 O 2 reaction was introduced subsequently. Thus, AuNPs coated with DNA-metalloenzyme as target-responsive and signal-amplification material for β-Lg detection was obtained. The detection limit of 1.69 pg/mL and linear range of 0.01—100 ng/mL was obtained. This aptasensor exhibits excellent selectivity for interfering ingredients, even if their concentration is 1000 times that of β-Lg. The recovery of standard addition experiment at three levels for four kinds of foods is in the range of 84.50–93.70 %, and RSD of 4.23–11.58 % was obtained. More importantly, β-Lg content detected in another six kinds of food products is consistent with β-Lg content reported which indicated good accuracy was obtained. In a word, this aptasensor exhibits prominent sensitivity, selectivity, accuracy, stability and repeatability which should be provided a universal substitution combination strategy for food allergens detection in future.