Electrical signature of the deformation and dehydration of microgels during translocation through nanopores

Holden, Deric A.; Hendrickson, Grant R.; Lan, Wen−How; Lyon, L. Andrew; White, Henry S.

doi:10.1039/c1sm05680h

Cited by 52 publications

(66 citation statements)

References 29 publications

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“…If biocompatible microgels are available such Pickering emulsions become promising systems for food, cosmetics, and oil recovery. Capsule formation can also benefit from the unique properties of soft microgels at liquid interfaces [42].…”

Section: Applicationsmentioning

confidence: 99%

Responsive Microgels at Surfaces and Interfaces

Wellert

Richter

Hellweg

et al. 2014

Zeitschrift Für Physikalische Chemie

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Stimuli responsive surface structures attract increasing attention due to a large variety of envisioned applications. The controlled organization of poly(N-isopropyl acrylamid), PNIPAM microgel particles at solid surfaces inspired numerous research activities. In this review article, we briefly discuss the swelling/deswelling properties of adsorbed microgel particles in comparison to the behavior in the bulk phase. The presence of the solid interface highly influences and changes their behavior with respect to the properties in solution. Furthermore, the confinement on a solid substrate allows the direct and in-situ investigation of the mechanical properties of the microgel particles. Additionally, we briefly review the research on microgel particles at liquid interfaces. At these interfaces new interesting effects occur. Moreover, we discuss some interesting work on potential applications. In this context, microgel particles are often used as an active component for responsive coatings of various functionality envisioning applications, e.g. in medicine, biotechnology, and nanooptics.Zusammenfassung: Responsive Oberflächenmaterialien finden aufgrund der damit verbundenen potentiellen technischen Anwendungsmöglichkeiten große Beachtung in der aktuellen Forschung. Die Möglichkeit, kolloidale Gelpartikel aus poly(N-Isopropylacrylamid), PNIPAM an festen Oberflächen kontrolliert anzuordnen, inspirierte vielfältige Forschungsakivitäten. In diesem Übersichtsartikel diskutieren wir das Quellverhalten adsorbierter Mikrogelpartikel im Vergleich zu

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Section: Applicationsmentioning

confidence: 99%

Responsive Microgels at Surfaces and Interfaces

Wellert

Richter

Hellweg

et al. 2014

Zeitschrift Für Physikalische Chemie

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“…36 Pressure-driven microgel translocation was monitored, measuring the change in ion current as microgels (dispersed in an electrolyte solution) passed through the pore. Microgels ( R H ∼ 570 nm) were composed of pNIPAm, AAc (10% mol), and BIS (1% mol).…”

Section: Mechanical Response To Environmentmentioning

confidence: 99%

Microgel Mechanics in Biomaterial Design

2014

Self Cite

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ConspectusThe field of polymeric biomaterials has received much attention in recent years due to its potential for enhancing the biocompatibility of systems and devices applied to drug delivery and tissue engineering. Such applications continually push the definition of biocompatibility from relatively straightforward issues such as cytotoxicity to significantly more complex processes such as reducing foreign body responses or even promoting/recapitulating natural body functions. Hydrogels and their colloidal analogues, microgels, have been and continue to be heavily investigated as viable materials for biological applications because they offer numerous, facile avenues in tailoring chemical and physical properties to approach biologically harmonious integration. Mechanical properties in particular are recently coming into focus as an important manner in which biological responses can be altered.In this Account, we trace how mechanical properties of microgels have moved into the spotlight of research efforts with the realization of their potential impact in biologically integrative systems. We discuss early experiments in our lab and in others focused on synthetic modulation of particle structure at a rudimentary level for fundamental drug delivery studies. These experiments elucidated that microgel mechanics are a consequence of polymer network distribution, which can be controlled by chemical composition or particle architecture. The degree of deformability designed into the microgel allows for a defined response to an imposed external force. We have studied deformation in packed colloidal phases and in translocation events through confined pores; in all circumstances, microgels exhibit impressive deformability in response to their environmental constraints.Microgels further translate their mechanical properties when assembled in films to the properties of the bulk material. In particular, microgel films have been a large focus in our lab as building blocks for self-healing materials. We have shown that their ability to heal after damage arises from polymer mobility during hydration. Furthermore, we have shown film mobility dictates cell adhesion and spreading in a manner that is fundamentally different from previous work on mechanotransduction. In total, we hope that this Account presents a broad introduction to microgel research that intersects polymer chemistry, physics, and regenerative medicine. We expect that research intersection will continue to expand as we fill the knowledge gaps associated with soft materials in biological milieu.

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“…A typical nanopore set-up involves placing a thin insulating membrane, with a solitary nanopore, between two electrolyte chambers. 34,35 For liposome translocation, conical pores of variable sizes were used and liposome translocation as a function of nanopore diameter and lipid bilayer transition temperature was studied. When nanoparticles are added to one of the chambers, they translocate through the pore causing resistive spikes.…”

Section: Introductionmentioning

confidence: 99%

Use of solid-state nanopores for sensing co-translocational deformation of nano-liposomes

Goyal

Darvish

Kim

2015

Analyst

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Membrane deformation of nano-vesicles is crucial in many cellular processes such as virus entry into the host cell, membrane fusion, and endo- and exocytosis; however, studying the deformation of sub-100 nm soft vesicles is very challenging using the conventional techniques. In this paper, we report detecting co-translocational deformation of individual 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) nano-liposomes using solid-state nanopores. Electrokinetic translocation through the nanopore caused the soft DOPC liposomes (85 nm diameter) to change their shape, which we attribute to the strong electric field strength and physical confinement inside the pore. The experiments were performed at varying transmembrane voltages and the deformation was observed to mount up with increasing applied voltage and followed an exponential trend. Numerical simulations were performed to simulate the concentrated electric field strength inside the nanopore and a field strength of 14 kV cm(-1) (at 600 mV applied voltage) was achieved at the pore center. The electric field strength inside the nanopore is much higher than the field strength known to cause deformation of 15-30 μm giant membrane vesicles. As a control, we also performed experiments with rigid polystyrene beads that did not show any deformation during translocation events, which further established our hypothesis of co-translocational deformation of liposomes. Our technique presents an innovative and high throughput means for investigating deformation behavior of soft nano-vesicles.

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Electrical signature of the deformation and dehydration of microgels during translocation through nanopores

Cited by 52 publications

References 29 publications

Responsive Microgels at Surfaces and Interfaces

Responsive Microgels at Surfaces and Interfaces

Microgel Mechanics in Biomaterial Design

Use of solid-state nanopores for sensing co-translocational deformation of nano-liposomes

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