Invited: Dual-Faced Nano-Mushrooms for Multi-Functional Cell Diagnosis
Authors: Hsieh Hsin-Yi , Tseng Fan-Gang 
Published: February 2020

Ushering as miniature nanodevices in biological research, smart nanoparticles remarkably execute parallel multifuntions, such as combining two or more characteristics of high image contrast, fluorescent emission, thermal therapy, cancer targeting, and/or drug delivery, leading to simultaneously investigate complicated cell behaviors, visualize particle distribution, and/or cure cancer. In the past decade, label-free Raman spectroscopy incorperated with surface enhanced Raman scattering (SERS) techniques have also made a great progress for dynamic monitoring cell performances, including the differentiation of stem cells, the observation of biomolecule dynamics, and the transport pathways of endocytosed nanoparticle. Undoubtedly, new-smart-nanoparticles (NSNPs) merging of the conventional smart nanoparticle with the Raman sensing function will possess more widely applications for cell theranostics.

This work introduces a monodispersed mushroom-like fluorescent nanoparticle with dual-faces and tri-functions for SERS-active Raman sensing, fluorescence detecting, cancer marker targeting, and drug carrying and delivering inside a cell [1]. A one-step oxygen plasma process was employed to tailor commercial-available fluorescent PS beads into corrugated hemispheres and simultaneously modify the entire surface with carboxylic groups, and then a gold film was coated on the corrugated hemisphere for SEARs. By employing a robust one-step process for surface roughness treatment on polystyrene NPs with self-grafted carboxyl surface functional groups, a smart particle, AuFNM, is carried out and consists of SERS/fluoresence sensing ability with dual molecule conjugation flexibility (Fig. 1 (a)-(c)). We also successfully demonstrate the multifunctions on the AuFNMs for cancer cells targeting, drug delivering into cells, and SERS Raman sensing [2]. For live cell applications, it can perform Raman mapping of biomolecule dislocation (Fig. 1(d)) and 3-D visualization of the AuFNMs (Fig. 1(e)) through the upper SERS-active gold nanocorrugations and the lower anti-CD 44 modified fluorescent polystyrene, respectively. Therefore, it becomes a powerful platform not only useful for tumor cells treatment but also for real-time monitoring cells metabolism.

Vigorous oxygen plasma etching on pure polystyrene beads (PSBs) without intrinsic carboxyl groups can reportedly undergo surface conversion via the cleaving of C-C-C bonds to form carboxylic functional groups.[1] and result in highly corrugated nanostructures.[1] In this paper, we combined the outstanding characteristics of the oxygen-plasma-treated PSBs (surface roughness and carboxyl functional groups) with Au deposition, to produce the dual-faced polystyrene beads (DFPSBs), as shown in Figure 2. When the rough upper surface was covered with gold, a localized enhanced electric field accumulated on the inter-gaps (hotspots) between the neighboring nanopillar structures

Sulfo-NHS-SS-biotin disulfide linker and anti-CD44 monoclonal antibody could be modified simultaneously onto the top gold surfaces and bottom carboxyl groups through Au-S and peptide bonds, respectively. The AuFNMs can be employed to target cell-surface glycoproteins CD44 on cancer cells and release the loads inside cell membrane via cleaving the disulfide bonds in cytoplasm after endocytosis of 30minutes. For the applications of 3D confocal particle tracking and Raman mapping, the AuFNMs demonstrate excellent long-lasting single-particle fluorescence and superior biomolecule sensing ability.

Authors would like to thank National Science Council, Taiwan for research grant and financial support for traveling.

[1] H.-Y. Hsieh, J.-L. Xiao, C.-H. Lee, T.-W. Huang, C.-S. Yang, P.-C. Wang and F.-G. Tseng, J. Phys. Chem. C, 2011, 115, 16258.

[2] Hsin-Yi Hsieh, et. Al., , Journal of Materials Chemistry, 2012,.22 (39), 20918 - 20928