Microgel PAINT – nanoscopic polarity imaging of adaptive microgels without covalent labelling

Purohit, Ashvini; Centeno, Silvia P.; Wypysek, Sarah; Richtering, Walter; Wöll, Dominik

doi:10.1039/c9sc03373d

Cited by 27 publications

(33 citation statements)

References 48 publications

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“…Another class of methods covers the so-called "true SRFM," which can in fact overcome the diffraction limit. Examples include stimulated emission depletion (STED) microscopy 45 , photoactivated localization microscopy (PALM) 46 , stochastic optical reconstruction microscopy (STORM) 47 , and some more recent advanced implementations based on similar principles, such as (d)irect-STORM 48 , PAINT (point accumulation for imaging in nanoscale topography), and others 41,49 . Here, we will focus on these nanoscopy techniques 50,51 .…”

Section: Microgel Characterization With Nanoscale Resolutionmentioning

confidence: 99%

“…Using solvent additives needed for best imaging results means that low ionic-strength conditions, e.g., for studies of ionic microgels 60 , cannot be easily accessed. We note in passing that some covalently bound switchable labels do neither require a particular buffer 61 nor does the more recent PAINT approach (point accumulation for imaging in nanoscale topography) 41,49 . In practice, nanoscopy of individual solid particles has been performed early on as proof-of-principle for the method and to determine the optical resolution 45 , but the efforts usually ended there.…”

Section: Microgel Characterization With Nanoscale Resolutionmentioning

confidence: 99%

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Pathways and challenges towards a complete characterization of microgels

Scheffold

2020

Nat Commun

106

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Due to their controlled size, sensitivity to external stimuli, and ease-of-use, microgel colloids are unique building blocks for soft materials made by crosslinking polymers on the micrometer scale. Despite the plethora of work published, many questions about their internal structure, interactions, and phase behavior are still open. The reasons for this lack of understanding are the challenges arising from the small size of the microgel particles, complex pairwise interactions, and their solvent permeability. Here we describe pathways toward a complete understanding of microgel colloids based on recent experimental advances in nanoscale characterization, such as super-resolution microscopy, scattering methods, and modeling. T he term "microgel" usually refers to a cross-linked polymer network of colloidal size that is swollen in a good solvent and has a diameter between~100 nm and several micrometers 1-3 (Fig. 1). Colloidal hydrogels are a common subtype where the continuous phase is water. Often, but not always, these networks exhibit conformational changes in response to changes in their environment, such as the solvent composition or temperature 1,4,5. The sensitivity to external stimuli, such as temperature, pH, or solvent conditions, is an essential feature of many microgels, in particular for the most widely studied type of microgels, based on pNIPAM (poly-N-isopropylacrylamide) and its derivatives 1,6 (Fig. 1b). Here, we consider homogeneous suspensions of these particles at different densities from the dilute to the highly packed regime, as well as microgels adsorbed at surfaces. It is also possible to synthesize larger, millimeter-sized, gel particles 7 , or to study two-dimensional assemblies at an interface 8,9. Additional functions, for example, for chemical transformation or sensing applications 10,11 , can be added using core-shell particles or by decorating the microgels with inorganic nanoparticles 12,13. Microgels are already used in several applications as viscosity modifiers and lubricants 14 , for CO 2 capturing 15 or 3D bioprinting 16 , as biocompatible additives and delivery vehicles 17 , sensors, or stimuli-responsive color-changing systems 18,19. Despite their popularity and widespread application, the internal structure of microgels is not well-understood. During the microgel synthesis, the degrees of freedom for the polymer strands are intentionally reduced by forming covalent cross-links between polymer chains. The chemical crosslinking itself is a nonequilibrium process, and it does not necessarily progress uniformly, which may lead to spatial fluctuations, gradients, and heterogeneities in the microgel particle architecture 20. For a complete understanding of a microgel colloid as a material building block or a carrier, it is imperative to know the spatial distribution of polymer and cross-link densities on the nanoscale. Initially, many studies assumed that microgels could be described simply as spherical, homogeneous gel particles, as discussed in ref. 1. Based on this assumption, t...

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Section: Microgel Characterization With Nanoscale Resolutionmentioning

confidence: 99%

Section: Microgel Characterization With Nanoscale Resolutionmentioning

confidence: 99%

Pathways and challenges towards a complete characterization of microgels

Scheffold

2020

Nat Commun

106

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“…81,82 The use of 3D sPAINT imaging even allows the determination of local polarity of a material in 3dimensions. 83 As discussed before, correlative microscopy combining SRM with EM/AFM, can unveil new information about the samples combining the quantitative readouts of multiple techniques. Recently, it has been shown that TEM and SMLM can be combined into a super-resCLEM workflow, to obtain additional information about heterogeneity in a PLGA-PEG based nanoparticle system, functionalized with ssDNA.…”

Section: Informative and Quantitative Outputmentioning

confidence: 96%

Can super-resolution microscopy become a standard characterization technique for materials chemistry?

et al. 2022

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“…Die Polaritätsunterschiede machte hierbei der solvatochrome Effekt des eingebrachten Farbstoffs Nil-Rot sichtbar. 51) Mechanische Kräfte bewirken entweder auf molekularer oder auf makroskopischer Ebene ein direktes Antwortsignal der Makromoleküle. Göstl und Mitarbeiter untersuchen mechanophore Systeme, die ihre Fluoreszenz anschalten und somit kraftinduzierte Bindungsspaltungen mit hoher Empfindlichkeit anzeigen.…”

Section: Wissenschaft + Forschungunclassified

Trendbericht: Makromolekulare Chemie

Gallei¹,

Schmidt²

2020

Nachr Chem

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Das Jahr 2020 steht im Zeichen der Polymere, deren erste Beschreibung auf Hermann Staudinger zurückgeht.1,2) Dieser Trendbericht behandelt die Forschung des wissenschaftlichen Nachwuchses, also von Habilitanden, Juniorprofessoren, Postdoktoranden, Privatdozenten und Gruppenleitern. Es geht um Biopolymere und biomedizinische Anwendungen von Polymeren, Polymermaterialien und ‐synthese sowie stimuliresponsive Polymersysteme und Polymerarchitekturen und deren Selbstanordnung.

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Microgel PAINT – nanoscopic polarity imaging of adaptive microgels without covalent labelling

Abstract: The 3D structure and the local environment of stimuli-responsive microgels were investigated with the superresolution fluorescence microscopy method PAINT using Nile Red as solvatochromic dye.

Cited by 27 publications

References 48 publications

Pathways and challenges towards a complete characterization of microgels

Pathways and challenges towards a complete characterization of microgels

Can super-resolution microscopy become a standard characterization technique for materials chemistry?

Trendbericht: Makromolekulare Chemie

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