Ultrasensitive DNA monitoring by Au–Fe3O4 nanocomplex

Recent advances in the synthesis of Fe3O4@AU core/shell nanoparticles

“…[35,23,36,37,38,39,40,41,42,43,44,45,46] For example, small Fe 3 O 4 (9-20 nm) nanoparticles were first synthesized using the co-precipitation of FeCl 2 and FeCl 3 in diluted NH 3 solution. Next, a HAuCl 4 solution was boiled and Fe 3 O 4 nanoparticles were added, followed by the addition of sodium citrate as a reducing agent for Au shell formation.…”

“…Before the precipitate was rinsed, sodium citrate was added, and then, the solution was stirred. [39,40,41] A HAuCl 4 solution was heated until boiling, and then, Fe 3 O 4 citrate coated nanoparticles were added to the solution. [39,40] The other modification of this method is the sonication of Fe 3 O 4 and citrate and then heating until boiling before the addition of HAuCl 4 .…”

“…[41] Additionally, sodium citrate can be added after the precipitate was rinsed. In this case, the solution was stirred overnight to exchange adsorbed OH ˗ with citrate anions [42], which is much longer than in the methods of [39,40,41]. Subsequently, HAuCl 4 was added using hydroxylamine as a reducing agent.…”

Dual-Mode SERS-Fluorescence Immunoassay Using Graphene Quantum Dot Labeling on One-Dimensional Aligned Magnetoplasmonic Nanoparticles

“…3 The sandwichtype of immunoassay is popular since it is based on nanomaterials substrates. [4][5][6][7] Recently, multiplex immunoassay using nanomaterials have attracted significant interest. [8][9][10][11][12] Especially, SERS-fluorescence dual mode nanoprobes were expected to improve the imaging quality and detection sensitivity of the fluorescence signal, quick indicator; meanwhile SERS could help to distinguish specific targets in multiplex interactions.…”

Fe3O4@Au nanoparticles as a means of signal enhancement in surface plasmon resonance spectroscopy for thrombin detection

“…Ten minutes later, we added 4.4 g of trisodium citrate and the reaction temperature was raised to 90 • C, and maintained at that temperature with continuous stirring for 30 min. A black precipitate was obtained by cooling the reaction mixture to room temperature [24]. The precipitate was then thoroughly rinsed with ethanol for three times.…”