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Hierarchical assembly of gold nanorod stripe patterns for sensing and cells alignment

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Nanotechnology
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Shuang Wang
Shuang Wang
Shuang Wang
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Zefang Wang at NYU Langone Medical Center
Zefang Wang
Ning Tang at Shanghai Jiao Tong University
Ning Tang
Chang Liu
Chang Liu
Chang Liu
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Abstract and Figures

Hierarchical assemblies of nanomaterial superstructures with controlled orientation affords a multitude of novel properties of plasmonics and broad applications. Yet constructing multi-functional superstructures with nanoparticles positioned in desired locations remains challenging. Herein, gold nanorods (GNRs) assembled in stripe patterns with controlled orientation and structures in millimeter scale for versatile application have been achieved. Applications of patterned GNRs in sensing enhancement and engineering mammalian cells alignment are investigated experimentally. The performance of patterned GNRs in surface enhanced Raman scattering (SERS) and electrical sensing are found in orientational dependence. The SERS signals of vertically arranged GNR arrays exhibit double the folder intensity than those horizontally arranged. In contrast, the horizontally arranged GNRs exhibit twice as much electrical conductivity. The system is further explored to pattern mammalian cells. For the first time, we reveal the nanostructured topography of GNR confined cells to a specific region, and direct the adhesion and extension of living cells, which opens up broad applications in tissue engineering and biosensing.
Fabrication procedure and images of the GNR stripe pattern. (a) Schematic of the fabrication procedure for preparing the GNR stripe pattern, images of (b) SEM and (c) dark field microscopy of GNR stripe patterns. (d)–(f) are SEM images of the silicon wafer (inset is the side view of the GNR stripe pattern), PDMS molds and GNR patterns, and (g) average width of each strip.
Fabrication procedure and images of the GNR stripe pattern. (a) Schematic of the fabrication procedure for preparing the GNR stripe pattern, images of (b) SEM and (c) dark field microscopy of GNR stripe patterns. (d)–(f) are SEM images of the silicon wafer (inset is the side view of the GNR stripe pattern), PDMS molds and GNR patterns, and (g) average width of each strip.
… 
SEM images of GNR assembly into stripe patterns with aspect ratios of (a) 2.0, (b) 2.7, (c) 3.5, and (d) 4.5. (e) Morphology and (f) UV–vis spectrum of synthesized GNRs with different aspect ratios. Insets show high magnification of GNR assemblies in a single strip, with a scale bar of 200 nm.
SEM images of GNR assembly into stripe patterns with aspect ratios of (a) 2.0, (b) 2.7, (c) 3.5, and (d) 4.5. (e) Morphology and (f) UV–vis spectrum of synthesized GNRs with different aspect ratios. Insets show high magnification of GNR assemblies in a single strip, with a scale bar of 200 nm.
… 
Surface chemistry mediated the assembly of GNRs. (a) Schematic illustration of GNRs capped with a bi-surfactant of CTAB and NaOL. (b) Zeta potential of neutral, negative, and positive value of GNRs with different numbers of CTAB/NaOL capped, respectively. (c) Mean spatial distance of neighboring GNRs. (d) SEM images of (I) neutral, (II) negative, and (III) positive charge GNR assembly patterns (insets show high magnification of single-strip GNR assemblies, with a scale bar of 200 nm). (e) Schematic illustration of the surface surfactant of the GNRs partly replaced by 16-Mercaptohexadecanoic Acid (16-MHDA), 6-Mercaptopyridine-3-carboxylic Acid (6-MHA), and cystamine. (f) Zeta potential of chemically functionalized GNRs. (g) Mean spatial distance of neighboring GNRs under different chemical functionalization. (h) SEM images of assembled (I) 16-MHDA, (II) 6-MHA, and (III) cystamine functionalized GNRs (insets show a high magnification of single-strip GNRs assemblies, with a scale bar of 200 nm).
Surface chemistry mediated the assembly of GNRs. (a) Schematic illustration of GNRs capped with a bi-surfactant of CTAB and NaOL. (b) Zeta potential of neutral, negative, and positive value of GNRs with different numbers of CTAB/NaOL capped, respectively. (c) Mean spatial distance of neighboring GNRs. (d) SEM images of (I) neutral, (II) negative, and (III) positive charge GNR assembly patterns (insets show high magnification of single-strip GNR assemblies, with a scale bar of 200 nm). (e) Schematic illustration of the surface surfactant of the GNRs partly replaced by 16-Mercaptohexadecanoic Acid (16-MHDA), 6-Mercaptopyridine-3-carboxylic Acid (6-MHA), and cystamine. (f) Zeta potential of chemically functionalized GNRs. (g) Mean spatial distance of neighboring GNRs under different chemical functionalization. (h) SEM images of assembled (I) 16-MHDA, (II) 6-MHA, and (III) cystamine functionalized GNRs (insets show a high magnification of single-strip GNRs assemblies, with a scale bar of 200 nm).
… 
(a) Raman spectrum of 4-mercaptobenzoic acid (4-MBA) conjugated with (I) sparse, (II) random, (III) horizontal, and (IV) vertical alignment of GNR patterns. (b) Raman spectrum of 4-MBA conjugated on (I) multilayers, (II) a few layers, and (III) single layer of GNR patterns with horizontal arrangement. (c) Scheme for electrical property studying and SEM image of electrode patterning on the end of GNR arrays. (d) I–V characteristics curves of the GNR array with vertical (red) and horizontal (blue) orientation.
(a) Raman spectrum of 4-mercaptobenzoic acid (4-MBA) conjugated with (I) sparse, (II) random, (III) horizontal, and (IV) vertical alignment of GNR patterns. (b) Raman spectrum of 4-MBA conjugated on (I) multilayers, (II) a few layers, and (III) single layer of GNR patterns with horizontal arrangement. (c) Scheme for electrical property studying and SEM image of electrode patterning on the end of GNR arrays. (d) I–V characteristics curves of the GNR array with vertical (red) and horizontal (blue) orientation.
… 
Adhesion of 3T3 cells on a (a) PDMS patterned substrate, (b) randomly assembled GNR substrate, and (c) stripe-patterned GNR substrate. (d) Cells grown on a substrate which was modified with stripe-patterned GNRs and random GNRs; the boundary is highlighted with a red dotted line. (e) SEM image of cells adhered to GNR stripe patterns with high magnification. (f) Mean aspect ratio of cells adhered to different substrates.
Adhesion of 3T3 cells on a (a) PDMS patterned substrate, (b) randomly assembled GNR substrate, and (c) stripe-patterned GNR substrate. (d) Cells grown on a substrate which was modified with stripe-patterned GNRs and random GNRs; the boundary is highlighted with a red dotted line. (e) SEM image of cells adhered to GNR stripe patterns with high magnification. (f) Mean aspect ratio of cells adhered to different substrates.
… 
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Hierarchical assembly of gold nanorod
stripe patterns for sensing and cells
alignment
Shuang Wang
1
, Zefang Wang
2
, Ning Tang
1
, Chang Liu
1
, Shan He
1
,
Bohua Liu
1
, Hemi Qu
1
, Xuexin Duan
1
, Wei Pang
1
and Yanyan Wang
1
1
State Key Laboratory of Precision Measuring Technology & Instruments, School of Precision Instruments
and Optoelectronics Engineering, Nanchang Institute for Microtechnology, Tianjin University, 300072,
People’s Republic of China
2
School of Life Sciences, Tianjin University, Tianjin 300072, People’s Republic of China
E-mail: yanyanwang@tju.edu.cn
Received 8 November 2018, revised 25 December 2018
Accepted for publication 11 January 2019
Published 18 February 2019
Abstract
Hierarchical assemblies of nanomaterial superstructures with controlled orientation affords a
multitude of novel properties of plasmonics and broad applications. Yet constructing multi-
functional superstructures with nanoparticles positioned in desired locations remains
challenging. Herein, gold nanorods (GNRs)assembled in stripe patterns with controlled
orientation and structures in millimeter scale for versatile application have been achieved.
Applications of patterned GNRs in sensing enhancement and engineering mammalian cells
alignment are investigated experimentally. The performance of patterned GNRs in surface
enhanced Raman scattering (SERS)and electrical sensing are found in orientational dependence.
The SERS signals of vertically arranged GNR arrays exhibit double the folder intensity than
those horizontally arranged. In contrast, the horizontally arranged GNRs exhibit twice as much
electrical conductivity. The system is further explored to pattern mammalian cells. For the first
time, we reveal the nanostructured topography of GNR confined cells to a specific region, and
direct the adhesion and extension of living cells, which opens up broad applications in tissue
engineering and biosensing.
Supplementary material for this article is available online
Keywords: gold nanorods, controllable orientation, surface enhanced Raman scattering, cell
patterns
(Some figures may appear in colour only in the online journal)
1. Introduction
Plasmonic nanoparticles of gold nanorods (GNRs)have been
attracting significant attention owing to their anisotropic
shape showing polarization dependent optical and electrical
properties [1–3], which can be used in various applications of
biochemical sensing [4,5], biomedical technologies [6–8],
and electro-optical devices [9–11]. Exploiting such applica-
tions requires the organization of GNRs into superstructures,
as ordered structures of GNRs bring extremely large electric
field enhancements [12,13]and distinct collective plasmonic
modes [14,15]owing to the localized surface plasmonic
resonant (LSPR)coupling of the neighboring GNR. The
plasmonic coupling property of GNRs is strongly dependent
on the orientation and position relative to neighboring GNRs
[16,17]. Thus, significant research efforts have been directed
toward controlling the alignment of GNRs.
During recent years, plenty of methods have been sug-
gested for manipulating the alignment of nanorod super-
structures. Top-down approaches with a lithography technique
containing a focused ion beam and electron-beam have been
utilized to fabricate arrays of nanorods [18,19]. But cost, time,
Nanotechnology
Nanotechnology 30 (2019)175302 (9pp)https://doi.org/10.1088/1361-6528/aafddd
0957-4484/19/175302+09$33.00 © 2019 IOP Publishing Ltd Printed in the UK1
... It is reported that the fluid shear force stimulation can be transmitted by rearrangements of the cytoskeletal network and transduced into biochemical signals to promote cell mechanical motion. 8,9 Gold nanorods (AuNRs), rod-like nanostruc- tures, have also shown promise in modulating cell growth and migration 10,11 by inhibiting the progress of cell mechanical motion. 12 It was found that intracellular AuNRs can inhibit Factin cytoskeletal assembly 1 and change cell stiffness, 13 which further suppresses cell mechanical motion. ...
... AuNRs with an aspect ratio of 3.0 were synthesized according to previous reports. 10 To modify the thiolated polyethylene glycol with fluorescein isothiocyanate (SH-PEG-FITC, Shanghai Yuanye Bio-Technology) with a molecular weight of 1 K on the surface of AuNRs, 150 μL SH-PEG 1K -FITC (5 mg/mL) was added to 1 mL AuNRs (50 nM) and incubated for 8 min. To modify the Arg-Gly-Asp (RGD, NJPeptide) peptide on the surface of AuNRs, 50 μL thiolated arginine-glycineaspartic acid with fluorescein isothiocyanate (RGD-FITC, 5 mg/mL) was added to 1 mL of AuNRs (50 nM) and incubated for 5 min. ...
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Cell mechanical motion is a key physiological process that relies on the dynamics of actin filaments. Herein, a localized shear-force system based on gigahertz acoustic streaming (AS) is proposed, which can simultaneously realize intracellular delivery and cellular mechanical regulation. The results demonstrate that gold nanorods (AuNRs) can be delivered into the cytoplasm and even the nuclei of cancer and normal cells within a few minutes by AS stimulation. The delivery efficiency of AS stimulation is four times higher than that of endocytosis. Moreover, AS can effectively promote cytoskeleton assembly, regulate cell stiffness and change cell morphology. Since the inhibitory effect of AuNRs on cytoskeleton assembly, this AuNRs-AS system is able to inhibit or promote cell mechanical motion in a controlled manner by regulating the mechanical properties of cells. The bidirectional regulation of cell motion is further verified via scratch experiments, in which AuNRs-treated cells recover their motion ability through AS stimulation. In particular, the results of AuNRs-AS mechanical regulation on cell are related to the intrinsic properties of cell lines, revealing to more obvious effects on the cells with higher motor capacities. In summary, this acoustic technology has shown superiorities in controllable cell-motion manipulation, indicating its potential in building a multifunctional, integrated cytomechanics regulation platform.
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... 23,24 The formation of a uniform deposit pattern is desirable owing to its industrial applications in inkjet printing, [8][9][10] coating, 11 thin film devices 12 and biological assays. 25,26 The report by Deegan et al., 27 providing the mechanism for coffee ring deposit, has been a source of numerous experimentations in this field. 28,29 The commonly observed surface morphologies of dried particulates, such as the coffee stain, periodic patterns and uniform depositions, are primarily controlled by the drying dynamics of the three-phase contact line (TPCL). ...
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The surface pattern in dried droplets of nanoparticle suspension possesses direct correlation with the evaporation profile, which apart from the bulk parameters, can also be altered by tuning the nanoscale interactions. Here, we show that, for sessile drops of DNA-coated gold nanoparticle (DNA-AuNP) solution, the alteration in evaporation pathway of TPCL (three-phase contact line) from stick-slip to mixed mode leads to a surface morphological transition from concentric rings with stripes to radial crack formation within the coffee ring deposit. A freshly cleaned silicon substrate offers hydrophilic/favorable substrate-nanoparticle interaction and produces multiple ordered stripes due to stick-slip motion of the TPCL. Using a SiO2/Si substrate with ∼200 nm of oxide layer leads to an increase in the initial water contact angle θi-w by ∼40°, due to increased hydrophobicity of the substrate. Three distinct modes of evaporation are observed - constant contact radius (CCR), constant contact angle (CCA) and mixed mode, resulting in the formation of radial cracks on a thick coffee ring structure. The critical thickness (hc), beyond which the cracks start to appear, was measured to be ∼600 nm and is in close agreement with the theoretical estimate of ∼510 nm. Through in situ contact angle and ex situ SEM measurements, we provide an understanding of the observed surface morphological transition in the dried particulate at various nanoparticle densities. Further analysis of the coffee ring width (d), linear crack density (σ) and crack spacing (λ) provides insight into the mechanism of crack formation for droplets dried on oxide-coated substrates.
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... Au NRs in solutions can spontaneously fill in almost every channel and finally assemble into a stripe pattern. 744 One can realize the assembly of Au NR arrays with various characteristic sizes and periodicities using PDMS stamps. Au NRs dispersed in ethanol−water mixtures can be arranged into SS-packed lamellae (Figure 13a). ...
View
... SERS can be used for chemical analysis, detection of pollutants or bacteria, photochemical studies or vibrational spectroscopy [20] down to the single-emitter level [21,22]. The search for efficient and inexpensive SERS metallic substrates is a very active field and many different substrates and fabrication methods have been proposed, as exemplified most recently by Au nanoparticles obtained by femtosecond exposure of a Au film [23], by bipyramid Au nanoparticles [24], by Agnanoparticles growth on Si by replacement method [25] or by stripes of vertical or horizontal Au nanorods [26]. The key element is the presence of sharp tips or dips on the surface of the metallic substrate, where plasmonic modes can be strongly confined and create "hot spots". ...
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  • APPL PHYS A-MATER
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