Design of Magnetic‐Plasmonic Nanoparticle Assemblies via Interface Engineering of Plasmonic Shells for Targeted Cancer Cell Imaging and Separation

Abstract

decade, many approaches for synthesizing multifunctional NPs with combined properties have been developed, such as heterogeneous crystal growth, [3][4][5] coassembly of different building blocks, [6,7] and the template-based method involving chemical and/or physical binding. [8,9] In particular, the template-based method is advantageous for utilizing the size-and shape-dependent properties of individual NPs, [8][9][10] new properties resulting from inter-particle coupling, [8,10,11] and independently additional modification of different NPs and the template. [11,12] Among the various multifunctional NPs, magnetic-plasmonic (MP) NPs are regarded as emerging materials that are suitable for a broad range of applications, such as catalysis, [12,13] detection, [14,15] optical devices, [9,16] and therapy. [17][18][19] In particular, MP NPs simultaneously exhibiting magnetic and surface-enhanced Raman scattering (SERS) activities have been researched due to their synergistic properties in biomedical applications. [20][21][22][23][24] In detail, non-destructive and sensitive analysis of the SERS technique and separating ability based on the magnetic properties could provide convenient and significant tools in sensing of target molecules or cells. [20][21][22][23][24][25] However, it is difficult to satisfy the designing criteria for high performances in bio-applications: low remanence for preventing particle aggregation, maximized magnetic Magnetic-plasmonic nanoparticles have received considerable attention for widespread applications. These nanoparticles (NPs) exhibiting surfaceenhanced Raman scattering (SERS) activities are developed due to their potential in bio-sensing applicable in non-destructive and sensitive analysis with target-specific separation. However, it is challenging to synthesize these NPs that simultaneously exhibit low remanence, maximized magnetic content, plasmonic coverage with abundant hotspots, and structural uniformity. Here, a method that involves the conjugation of a magnetic template with gold seeds via chemical binding and seed-mediated growth is proposed, with the objective of obtaining plasmonic nanostructures with abundant hotspots on a magnetic template. To obtain a clean surface for directly functionalizing ligands and enhancing the Raman intensity, an additional growth step of gold (Au) and/or silver (Ag) atoms is proposed after modifying the Raman molecules on the as-prepared magnetic-plasmonic nanoparticles. Importantly, one-sided silver growth occurred in an environment where gold facets are blocked by Raman molecules; otherwise, the gold growth is layer-by-layer. Moreover, simultaneous reduction by gold and silver ions allowed for the formation of a uniform bimetallic layer. The enhancement factor of the nanoparticles with a bimetallic layer is approximately 10 7 . The SERS probes functionalized cyclic peptides are employed for targeted cancer-cell imaging and separation.

Nanoparticle Surface Functionalization: How to Improve Biocompatibility and Cellular Internalization

“…Medical imaging techniques have evolved very quickly over the past 20 years, overall in cancer disease, to identify very little tumor masses for an early diagnosis (Kumar et al, 2019;Li et al, 2019c;Vaidya et al, 2019). This evolution has occurred through the combined use of classical imaging techniques (like MRI, PET and SPECT) with NPs (Forte et al, 2019;Song et al, 2020) and advancing toward the use of innovative imaging techniques like photoacoustic (PA), surface-enhanced Raman scattering (SERS), and near infrared light up-conversion (NIR-Up) (Silvestri et al, 2019;Ge et al, 2020;Kim et al, 2020). All these techniques are very useful in combination with NPs-mediated delivery in order to accumulate CAs in the tissues of interest.…”

In Situ Growth of AuNPs on Glass Nanofibers for SERS Sensors

“…The deposition of a Ag 0 monolayer on specific Au facets via UPD inhibits or slows the deposition of Au onto these facets, while Au growth occurs on other facets. According to another mechanism, the reduction of Au ions to Au 0 leaves many Cl ions in solution. , In the presence of Ag ions, AgCl precipitates on the surface of the growing AuNPs, thereby blocking those surface sites. , The final result of both mechanisms is that certain Au surface sites are blocked from Au growth by precipitated Ag, either in the form of a Ag 0 monolayer or as AgCl, thus leading to the anisotropic in situ growth of the AuNPs on our nanofibers. Furthermore, it has been reported that increasing the amount of Ag + slows the rate of AuNP growth, which is consistent with the smaller AuNPs synthesized using the highest Ag + concentration (Figure e).…”

“…According to another mechanism, the reduction of Au ions to Au 0 leaves many Cl ions in solution. 66,67 In the presence of Ag ions, AgCl precipitates on the surface of the growing AuNPs, thereby blocking those surface sites. 68,69 The final result of both mechanisms is that certain Au surface sites are blocked from Au growth by precipitated Ag, either in the form of a Ag 0 monolayer or as AgCl, thus leading to the anisotropic in situ growth of the AuNPs on our nanofibers.…”

Magneto-Optical Nanostructures for Viral Sensing

“…Various strategies have been designed to fabricate diverse magneto-plasmonic nanostructures by growing Au shells over the MPs or by attaching isolated Au nanoparticles (Au NPs) onto the surface of MPs [37,[45][46][47][48][49][50]. The obtained nanocomposites exhibit the typical core-shell "gold-coated magnetic" nanostructures.…”