Direct Synthesis of Water-Dispersible Magnetic/Plasmonic Heteronanostructures for Multimodality Biomedical Imaging

Abstract

Magnetic/plasmonic hybrid nanoparticles are highly desirable for multimodal bioimaging and biosensing. Although the synthesis of heterodimeric nanoparticles has been reported, the products are usually hydrophobic so that post-treatment procedures are required to transfer them into water which are often difficult to perform and cause damages to the structures. Direct synthesis of hydrophilic hybrid nanostructures has remained a grand challenge albeit its immediate advantage of biocompatibility. Herein we report a general seed-mediated approach to the synthesis of hydrophilic and biocompatible M−Fe 3 O 4 (M = Au, Ag, and Pd) heterodimers, in which the size of metals and Fe 3 O 4 can be independently regulated in a wide range. Benefiting from the aqueous synthesis, this approach can be further extended to design more complex heterodimeric structures such as AgPt alloy −Fe 3 O 4 , Au core @Pd shell −Fe 3 O 4 , and Au shell −Fe 3 O 4 . The hydrophilic nature of our heterodimers makes them readily useful for biomedical applications without the need of additional ligand exchange processes in contrast to those prepared in nonpolar solvents. These nanoscale magnetic/ plasmonic heterostructures were shown to be ideally suited for integrated biomedical diagnoses, such as magnetic resonance imaging, photoacoustic imaging, optical coherence tomography, and computed tomography, in virtue of their biocompatibility and combined tunable magnetic and plasmonic properties.

Metal/semiconductor interfaces in nanoscale objects: synthesis, emerging properties and applications of hybrid nanostructures

“…4h) or /Ag, /Pd and /Pt heterodimers or metaldecorated Fe 3 O 4 since Fe 2+ on the surface can reduce Au(III) to Au(0). 108 Another strategy for forming SC/M HNSs is chemical anchoring. A covalently attached molecule to the SC, with an appropriate Lewis base moiety such as an amine or sulde, can donate its electrons to colloidal metal NPs, thus initiating a selfassembly process.…”

Plasmonic Metallic Heteromeric Nanostructures

“…Zeng et al have prepared a series of plasmonic–Fe 3 O 4 heteromers, the LSPR of which are tuned by the composition control of plasmonic domains. [ 81 ] Au Hollow –Fe 3 O 4 heteromers can penetrate longer depth of tissues in vitro leading to a significantly enhanced OCT imaging (Figure 15b) and particularly high photoacoustic signal intensity (Figure 15c). As a proof of concept, plasmonic–magnetic heteromeric NPs are excellent contrast agents for multi‐modality bioimaging.…”

Shell‐Isolated Plasmonic Nanostructures for Biosensing, Catalysis, and Advanced Nanoelectronics

“…Due to the unique physiochemical properties of LSPR, plasmonic nanostructures have been widely used in various fields, including photo(electro)catalysis, [ 1,2 ] biosensing, [ 3–5 ] bioimaging, [ 6,7 ] cancer therapy, [ 8,9 ] nanoelectronics, [ 10–12 ] and optical spectroscopy, such as surface enhanced Raman spectroscopy (SERS) [ 13,14 ] and photoluminescence (PL) ( Figure ). [ 15,16 ] Among all plasmonic nanoparticles (NPs), shell‐isolated plasmonic nanostructures (abbreviated to SHIPNSs, a class of plasmonic core–shell NPs), consisting of plasmonic metal cores and transparent protective layers that does not significantly damp the electromagnetic enhancement, have attracted great attentions in various applications due to the following several outstanding characteristics: 1) multifunctionality and tunability: the shell‐isolated plasmonic NPs possess inner plasmonic metal cores and outer shells made of various inert materials, such as silica, aluminum oxide, MnO 2 , or polymers, in which the properties of the shell and the resulting core/shell NPs can be tuned and modulated much more easily than the metallic cores by shell nanoengineering of various functional materials (e.g., upconversion nanocrystal, [ 17 ] Cu 2 O, [ 18 ] et.…”

“…Panel (c) is reproduced with permission. [ 7 ] Copyright 2019, American Chemical Society. Panel d) is reproduced with permission.…”