Orthogonal Nanoprobes Enabling Two-Color Optical Super-Resolution Microscopy Imaging of the Two Domains of Diblock Copolymer Thin Film Nanocomposites

Abstract

Multicolor optical super-resolution microscopy (OSRM) describes an emerging set of techniques for the specific labeling of distinct constituents of multicomponent systems with compatible optical probes, elucidating proximity relationships from far-field imaging of diffraction-limited features with nanometer-scale resolution. While such approaches are well established in the study of biological systems, their implementation in materials science has been considerably slower. In large part, this gradual adoption is due to the lack of appropriate OSRM probes that, e.g., by facile mixing or surface modification, enable orthogonal labeling of specific nanostructures in the condensed state, rather than in aqueous conditions as with biology. Here, OSRM probes in the form of ultrasmall (diameters <10 nm) aluminosilicate nanoparticles encapsulating different fluorescent dyes are tailored to visualize both nanodomains of polystyrene-block-poly­[(allyl glycidyl ether)-co-(ethylene oxide)] (PS-b-P­(AGE-co-EO)) diblock copolymer thin films. Careful design of nanoprobe surface chemical properties facilitates either selective compatibilization with the nonpolar PS matrix or preferential reactivity with surface allyl groups of the hydrophilic P­(AGE-co-EO) minority block. Stochastic optical reconstruction microscopy (STORM) of the resulting polymer–inorganic nanocomposite thin films shows nanodomain features of the two chemically dissimilar blocks consistent with atomic force microscopy results. This work paves the way for multiplexed OSRM analysis of polymer nanocomposite bulk structures.

Triblock Terpolymer Thin Film Nanocomposites Enabling Two-Color Optical Super-Resolution Microscopy

“…The OSRM work presented here makes use of high-brightness blinking and high-photostability STORM probes from encapsulated dyes in the particle cores with tunable surface chemistries in the ligand shells that require only one laser and no imaging solution additives to generate OSRM images. , Taken together, these results demonstrate that polymer-specific optical probes can facilitate multicolor STORM imaging of nanostructured polymer surfaces via a facile physical solution mixing approach with the BCP, showcasing the potential of tunable probes to facilitate OSRM in synthetic polymers. Coupled with earlier results for two-color STORM imaging based on a combination of physical mixing and click-chemistry-based polymer association, this work further expands the toolbox of available strategies using potent optical probes for OSRM-based nanostructure characterization in polymer science.…”

“…In contrast, from earlier studies, PEGylated aC' dots further surface-modified with benzyl groups ("BaC' dots") are expected to associate with the PS block. 41 STORM imaging of the resulting nanocomposite thin film surfaces supports these hypotheses. In analogy to biological studies, the mixing of orthogonal, high-brightness, and high-photostability core−shell OSRM probes, which ■ EXPERIMENTAL METHODS Materials.…”

“…Previous work showed successful attachment of dye-encapsulating core–shell silica nanoparticles via various click chemistries to one domain within a diblock copolymer thin film surface for STORM. Subsequent experiments demonstrated selective incorporation of similar nanoparticle probes with nonpolar surface ligands into the nonpolar PS block of the same BCP and their characterization with STORM . Here, PEGylated aluminosilicate nanoparticles termed aC’ dots synthesized as previously reported, with polar PEG surface ligands and encapsulating Cy3 dye, were used to passively label the polar PDMAEMA block of the ISA 85 to enable STORM imaging (Scheme S1).…”

“…PEGylated aluminosilicate nanoparticles (Cy3-aC’ dots) were synthesized and subsequently characterized with fluorescence correlation spectroscopy (FCS) employing previously published methods . Benzyl-group-modified/PEGylated aluminosilicate nanoparticles were synthesized and subsequently characterized with various techniques, including FCS, as described elsewhere . Double-polished <100> silicon wafers were purchased from WRS Materials.…”

“…Functional aluminosilicate core–organic ligand shell (core–shell) aC’ dots and BaC’ dots were synthesized as previously reported. , In this work, the aC’ dot encapsulates Cy3 dye and is stabilized by an organic shell composed solely of PEG-silanes (see Scheme S1a), while the BaC’ dot encapsulates Cy5 dye and is stabilized by a combination of PEG- and benzyl-silanes (see Scheme S1b). As-synthesized particles were up-concentrated using GE Healthcare Vivaspin MWCO 30 kDa centrifuge spin filters before two runs through a GPC column with Sephacryl S-300 High Resolution resin (GE Healthcare) using a 0.9 wt % NaCl aqueous solution (see Figure S3a).…”