Photo-, Thermally, and pH-Responsive Microgels

García, Antonio; Márquez, Manuel; Cai, Tong; Rosario, Rohit; Hu, Zhibing; Gust, Devens; Hayes, Mark A.; Vail, Scan A.; Park, Choong Do

doi:10.1021/la061632n

Cited by 217 publications

(149 citation statements)

References 24 publications

Supporting

Mentioning

144

Contrasting

Unclassified

Order By: Relevance

“…27 Since the propagation of sound is dependent on the mechanical properties of the material it traverses, these pliable elastic material parameters are ideal for tunable phononic structures. EM stimuli of PNIPAm have been demonstrated using infrared 28,29 and ultraviolet 30,31 light but are restricted to relatively small-scale structures. 32,33 PNIPAm does not, however, innately possess adequate RF sensitivity for RF actuation.…”

Section: Rf Actuated Acoustic Materialsmentioning

confidence: 99%

Radio-frequency actuated polymer-based phononic meta-materials for control of ultrasonic waves

Walker

Wang²,

Neogi

2017

NPG Asia Mater

View full text Add to dashboard Cite

Radio-frequency (RF) control of an ultrasonic phononic crystal was achieved by encapsulating it in a composite of high k-10% KF-doped BaTiO 3 dielectric nanoparticles with poly(N-isopropylacrylamide) (PNIPAm)-based hydrogel. The combination of the nanoparticles and hydrogel produced a composite with elastic properties susceptible to RF actuation. The novel acoustic meta-material enables the regulation of sound waves by electromagnetic waves, which is not possible in a conventional medium as elasto-mechanical waves, and electromagnetic waves do not directly couple. Compared with light waves, radio waves can penetrate deeper into bulk structures and enable the control of propagation of ultrasonic waves through a macroscale phononic crystal. An RF antenna emitting at 318.6 and 422.5 kHz was used to modulate the device in water and ambient air, respectively. An increased transparency of the ultrasonic wave in the material was observed due to an increase in the bandwidth of the modulated device exceeding 8 kHz with a 30-fold increase in the signal modulation at select frequencies. The radio waves induced changes in the transmission and demonstrated the control of ultrasound with applied RF. The synthetic acoustic properties in the resultant meta-material device were actively manipulated through the interaction of electromagnetic waves with the material.

show abstract

Section: Rf Actuated Acoustic Materialsmentioning

confidence: 99%

Radio-frequency actuated polymer-based phononic meta-materials for control of ultrasonic waves

Walker

Wang²,

Neogi

2017

NPG Asia Mater

View full text Add to dashboard Cite

show abstract

“…Light responsive materials are typically triggered by two methods: 1) due to conformational changes of certain dye molecules found either in the polymer backbones or as pendent groups in the polymer chemical structure (Higuchi et al, 2004;Edahiro et al, 2005;Jiang et al, 2006;Nayak et al, 2006;Garcia et al, 2007;Zhu et al, 2007); 2) due to local heat generation of dyes linked to a thermally responsive polymer or hydrogel (Nayak and Lyon, 2004;Slocik et al, 2007). However, dyes are usually chemically reactive, susceptible to bleaching, and their responses are generally very slow (Kungwatchakun and Irie, 1988;Hugel et al, 2002;Shimoboji et al, 2002;Brinker, 2004).…”

Section: Constructing Non-mechanical Valves Using Locally-triggered Rmentioning

confidence: 99%

Environmentally responsive polymeric "intelligent" materials: the ideal components of non-mechanical valves that control flow in microfluidic systems

Morones‐Ramírez¹

2010

Braz. J. Chem. Eng.

View full text Add to dashboard Cite

-Miniaturization and commercialization of integrated microfluidic systems has had great success with the development of a wide variety of techniques in microfabrication, since they allowed their construction at a low cost and by following simple step-series procedures. However, one of the major challenges in the design of microfluidic systems is to achieve control of flow and delivery of different chemical reagents. This feature is especially important when using microfluidic systems in the development of cell culture systems, the construction of labs on a chip and the fabrication and design of chemical microreactors. Spatiotemporal control of the microenvironment in microfluidic devices has been only partially achieved by incorporating actuator parts (mechanical and non-mechanical) within these devices; nevertheless, recently there has been enormous progress due to advances in the materials sciences, and the development of novel polymeric "intelligent" materials. These materials have proved to be excellent candidates in the construction of non-mechanical actuators in the form of environmentally responsive valves. These valves can more efficiently control flows because these "intelligent" materials are capable of undergoing conformational changes and phase transitions in response to different local or external environmental stimuli; allowing them to turn the valves from "on" to "off". In addition, these valves have very simple designs, and are easy and cheap to incorporate into microfluidic systems. Therefore, although there are many reviews that focus on the development and design of non-mechanical actuators, the following review proceeds to describe the exciting characteristics, potential uses and synthesis methods of the building blocks of the most recent and innovative non-mechanical valves, environmentally responsive polymeric "intelligent" materials. In addition, the last section of this review will focus on the synthesis of composite materials that are capable of responding to more than one type of stimulus, since these materials are believed to be the future components that will boost the development of microfluidic systems with spatiotemporal controlled microenvironments.

show abstract

“…For example, a material comprising both thermoresponsive poly(N-isopropylacrylamide) (pNIPAM) and photoresponsive spirobenzopyran (SP) enables both control over the spatial direction of cellular growth with UV light and the removal of cells via low temperature washing [14]. This strategy has been taken a step further by combining light, temperature, and pH to control tuneable microgels comprising a temperature/pH sensitive pNIPAM-allylamine copolymer microgel functionalized with the SP photosensitive molecule [21]. The optical properties of the copolymer changes the thermal threshold for volume changes of the microgel, as well as a photochromic change when switched.…”

Section: Introductionmentioning

confidence: 99%

Optical switching of protein interactions on photosensitive–electroactive polymers measured by atomic force microscopy

et al. 2013

View full text Add to dashboard Cite

The ability to switch the physico-chemical properties of conducting polymers opens up new possibilities for a range of applications. Appropriately functionalised materials can provide routes to multi-modal switching, for example, in response to light and/or electrochemical stimuli. This capability is important in the field of bionics wherein remote and temporal control of the properties of materials is becoming attractive. The ability to actuate a film via photonic stimuli is particularly interesting as it facilitates the modulation of interactions between host binding sites and potential guest molecules. In this work, we studied two different polyterthiophenes: one was functionalised with a spiropyran photoswitch (pTTh-SP) and the second with a nonphotoswitchable methyl acetate moiety (pTTh-MA). These substrates were exposed to several cycles of illumination with light of different wavelengths and the resulting effect studied with UV-vis spectroscopy, contact angle and atomic force microscopy (AFM). The AFM tips were chemically activated with fibronectin (FN) and the adhesion force of the protein to the polymeric surface was measured. The pTTh-MA (no SP incorporated) showed a slightly higher average maximum adhesion (0.96 ± 0.14 nN) than the modified pTTh-SP surface (0.77 ± 0.08 nN), but after exposure of the pTTh-SP polymer to UV, the average maximum adhesion of the pTTh-MC (merocyanine form) was significantly smaller (0.49 ± 0.06 nN) than both the pTTh-MA and pTTh-SP. In addition, the tip-sample separation distances of the adhesive interactions are indicative of the FN interaction occurring over a distance more closely related to the average dimensions of its compact conformation. The results suggest that surface energy and hydrophobic forces are predominant in determining the protein adhesion to the films studied and that this effect can be photonically tuned. By extension, this further implies that it should be possible to obtain a degree of spatial and temporal control of the surface binding behaviour of certain proteins with these functionalised surfaces through photo-activation/ deactivation, which, in principle, should facilitate patterned growth behaviour (e.g. using masks or directional illumination) or photocontrol of protein uptake and release. AbstractThe ability to switch the physico-chemical properties of conducting polymers opens up new possibilities for a range of applications. Appropriately functionalised materials can provide routes to multi-modal switching, for example, in response light and/or electrochemical stimuli. This capability is important in the field of bionics wherein remote and temporal control of the properties of materials is becoming attractive. The ability to actuate a film via photonic stimuli is particularly interesting as it facilitates the modulation of interactions between surface host binding sites and potential guest molecules. In this work, we studied two different poly-terthiophenes: one was functionalized with a spiropyran photoswitch (pTTh-SP) and the sec...

show abstract

Photo-, Thermally, and pH-Responsive Microgels

Cited by 217 publications

References 24 publications

Radio-frequency actuated polymer-based phononic meta-materials for control of ultrasonic waves

Radio-frequency actuated polymer-based phononic meta-materials for control of ultrasonic waves

Environmentally responsive polymeric "intelligent" materials: the ideal components of non-mechanical valves that control flow in microfluidic systems

Optical switching of protein interactions on photosensitive–electroactive polymers measured by atomic force microscopy

Contact Info

Product

Resources

About