Au@pNIPAM Thermosensitive Nanostructures: Control over Shell Cross‐linking, Overall Dimensions, and Core Growth

Contreras‐Cáceres, Rafael; Pacífico, Jessica; Pastoriza‐Santos, Isabel; Pérez‐Juste, Jorge; Fernández-Barbero, A.; Liz‐Marzán, Luis M.

doi:10.1002/adfm.200900481

Cited by 149 publications

(175 citation statements)

References 34 publications

(39 reference statements)

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“…No such huge spectral shifts (Δλ > 200 nm) were seen in previous attempts to use pNIPAM to reversibly tune the spacing between Au NPs for switching of plasmons (19)(20)(21)(22)(23)(24)(25)(26)(27). It is thus critical to clarify how pNIPAM promotes assembly and disassembly in solution, how fast the assembly can be, and what configurations are selected.…”

Section: Significancementioning

confidence: 99%

Light-induced actuating nanotransducers

Ding

Valev

Salmon

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

145

149

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Nanoactuators and nanomachines have long been sought after, but key bottlenecks remain. Forces at submicrometer scales are weak and slow, control is hard to achieve, and power cannot be reliably supplied. Despite the increasing complexity of nanodevices such as DNA origami and molecular machines, rapid mechanical operations are not yet possible. Here, we bind temperatureresponsive polymers to charged Au nanoparticles, storing elastic energy that can be rapidly released under light control for repeatable isotropic nanoactuation. Optically heating above a critical temperature T c = 32°C using plasmonic absorption of an incident laser causes the coatings to expel water and collapse within a microsecond to the nanoscale, millions of times faster than the base polymer. This triggers a controllable number of nanoparticles to tightly bind in clusters. Surprisingly, by cooling below T c their strong van der Waals attraction is overcome as the polymer expands, exerting nanoscale forces of several nN. This large force depends on van der Waals attractions between Au cores being very large in the collapsed polymer state, setting up a tightly compressed polymer spring which can be triggered into the inflated state. Our insights lead toward rational design of diverse colloidal nanomachines.ctuators are needed to turn energy sources into physical movement. These can be for microrobotics, sensing, storage devices, smart windows and walls, or more general functional and active materials. Such artificial muscles have gained rapidly increasing interest (1, 2) leading to micropropellers (3, 4), gas jets from catalytic surfaces (5), and DNA machines (6). However, the actuation methods, delivery of energy, and forces obtained (typically 10 fN/nm 2 ) are limited so far (7): Magnetic fields are inconvenient to apply locally for actuation, as is >200°C heating to actuate polymer fibers; the nanocatalysis of chemical fuels lacks controllability, whereas DNA machines rely on "fuel" DNA strands to competitively bind and operate on very slow (second) timescales. Piezoelectric-type materials used in high-end instrumentation (such as atomic force microscopy or nanopositioning stages) provide short travel but with inorganic materials that are dense, delicate, expensive, hard to fabricate, and demand high voltages (150-300 V), as is also true for electrostrictive rubbers and relaxor ferroelectrics (8, 9). Many biological systems such as Escherichia coli (10), cilia (11), or nematocysts (12) provide sophisticated models for nanomachines (13). Although molecular motors and artificial muscles from hydrogels (14, 15), colloids (16), or liquid crystalline elastomers (17, 18) successfully mimic such behaviors, they are very slow (on the order of seconds) and the forces generated are very small (∼ pN). This is because either the energy density stored in the system is low or the energy release is inefficient.To overcome this we design a colloidal actuating transducer system with high-energy storage (1,000 k B T/cycle) and fast (>MHz) release mechanism....

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Section: Significancementioning

confidence: 99%

Light-induced actuating nanotransducers

Ding

Valev

Salmon

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

145

149

View full text Add to dashboard Cite

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“…Later, the same group presented a one-step procedure where butenoic acid was used not only as reducing agent but also as a polymerization propagating agent (monomer), because it readily provides the particles with a vinyl functionality, which was applied for the direct polymerization of pNIPAM around the particles, while avoiding complicated surface functionalization steps. The authors could demonstrate that this procedure was versatile for coating gold nanoparticles of different shapes, including Au spheres [162] and nanorods [155] . Similar approach was also employed by Karg et al to grow an pNIPAM microgel on smaller gold nanoparticles (10 -15 nm, citrate synthesis) by functionalizing them with butenylamine prior to polymerization [163] .…”

Section: Microgels/nanogels Network Composed Of Crosslinked Polymersmentioning

confidence: 99%

“…Hence, one of the main advantages of this technique is that nanoparticles of designed size and shape can be employed, defi ning the optical properties from the very beginning. Furthermore, the gold cores encapsulated with the porous microgel shells can also be further grown in situ into different shapes [162] , but also with different metals, such as silver [155] , platinum [164] or nickel [164] , due to the favored catalytic reduction of the metal salt complexes selectively at the gold particle surface (the cores).…”

Section: Microgels/nanogels Network Composed Of Crosslinked Polymersmentioning

confidence: 99%

Coating matters: the influence of coating materials on the optical properties of gold nanoparticles

Chanana¹,

Liz‐Marzán²

2012

Nanophotonics

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An essential element in the synthesis of nanomaterials based on gold nanoparticles comprises the control over parameters such as size, shape and composition, due to their strong infl uence on the properties of the particles. However, it is the coating material which often plays the primary role in tuning the size, morphology, and even plasmon resonance wavelength or mode multiplicity, as well as colloidal stability and functional versatility, ultimately determining the physical, chemical, optical, electronic and catalytic properties of the nanoparticles. Therefore, it is utterly important to select the adequate wet chemistry synthetic approach with the most suitable coating material for the preparation of gold nanoparticles with the desired requirements. Within this context, this review is focused on describing various types of organic and inorganic coating materials for gold nanoparticles that may notably affect their optical properties by either directly infl uencing the synthesis procedure or by changing their chemical and physical properties upon post-synthetic modifi cations, such that they exhibit novel and useful optical properties.

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“…Nanosized cubic ferrites can be used as remotely-driven heaters [41] while providing remote temperature sensing using temperaturedependent magnetic properties [32][33][34][35]. Likewise, the metallic nanoparticle-based platform can be used for remote heating [44][45][46] as well as for remote temperature sensing [47,48]. In this regard the gold nanoparticle-based thermometer already reported involves the surface functionalization of the nanoparticle with molecular species presenting temperature sensitive refractive index, thus modulating the surface gold plasmon resonance peak position.…”

Section: Nanoparticle-based Hyperthermiamentioning

confidence: 99%

Remote Hyperthermia, Drug Delivery and Thermometry: The Multifunctional Platform Provided by Nanoparticles

Qi¹,

Morais

2014

J Nanomed Nanotechno

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The huge demand for biocompatible, robust, accurate and noninvasive technology to assess the temperature of a biological targeted site for monitoring the hyperthermia effect brings the topic of remote thermometry to a very high level of interest. There are already promising research directions to fulfil such demand in the short term and a review of the achievements in this issue is certainly worth. This report offers an overview of the research regarding the most promising nanothermometers nowadays, with emphasis on those addressed to remote operation while using optical or magnetic responses of nanosized materials as the thermometric property. More specifically the optical emission intensity, optical emission peak shift and optical emission lifetime will be covered as far as the optical-based nanothermometers are concerned. Additionally, for the magnetic-based nanothermometers the magnetization or the magnetic susceptibility are the thermometric properties covered in this review. Furthermore, the review includes the hyperthermia effect based on nanosized metallic or magnetic particles plus a couple of thermally-responsive polymeric drug delivery systems, aiming to provide an integrated view of the multipurpose platform offered by actuating-sensing nanoparticles. As far as the regulatory system is concerned the availability of noninvasive thermometry incorporating biocompatibility, robustness and accuracy will establish the grounds needed for the approval of the hyperthermia technology for therapeutic purposes, thus allowing the market of this technological option on a global scale.hyperthermia and thermoresponsive drug delivery systems for clinical use.Although nanothermometry is at its infancy considerable progress has been made recently in regard to its use for remote assessing the temperature at the site the nanomaterials are incorporated to. Nanoprobes allowing remote temperature-sensing using optical or magnetic properties are among the most promising directions nowadays. Most of the optical-based nanothermometers use the light-emitting intensity [15][16][17][18][19][20][21][22][23], light-emitting peak shift [24][25][26], or lifetime decay of a suitable optical band as the thermometric property [27][28][29][30]. As far as the clinical use is concerned the drawbacks of the actual optical-based nanothermometers rely on biocompatibility (usual semiconductor-based core nanoprobes or dye-based shell moieties are toxic), robustness (typical bleaching of organic-based shell moieties) or temperature accuracy (no better than 0.3°C nowadays), or even combination of these factors. Moreover, due to limitations imposed by living tissues on the optical penetration of light (optical therapeutic window in the 700-1100 nm wavelength range), noninvasive clinical use of optical excitation and signal pickup is a huge challenge, not yet solved, except for very special therapeutic applications, as for instance the photodynamic therapy for treatment (heating monitoring) of skin cancer and follow up [31]. Alternatively, ...

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Au@pNIPAM Thermosensitive Nanostructures: Control over Shell Cross‐linking, Overall Dimensions, and Core Growth

Cited by 149 publications

References 34 publications

Light-induced actuating nanotransducers

Light-induced actuating nanotransducers

Coating matters: the influence of coating materials on the optical properties of gold nanoparticles

Remote Hyperthermia, Drug Delivery and Thermometry: The Multifunctional Platform Provided by Nanoparticles

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