Functional Nanoassemblies of Cyclic Polymers Show Amplified Responsiveness and Enhanced Protein-Binding Ability

Abstract

The physicochemical properties of cyclic polymer adsorbates are significantly influenced by the steric and conformational constraints introduced during their cyclization. These translate into a marked difference in interfacial properties between cyclic polymers and their linear counterparts when they are grafted onto surfaces yielding nanoassemblies or polymer brushes. This difference is particularly clear in the case of cyclic polymer brushes that are designed to chemically interact with the surrounding environment, for instance, by associating with biological components present in the medium, or, alternatively, through a response to a chemical stimulus by a significant change in their properties. The intrinsic architecture characterizing cyclic poly(2-oxazoline)-based polyacid brushes leads to a broad variation in swelling and nanomechanical properties in response to pH change, in comparison with their linear analogues of identical composition and molecular weight. In addition, cyclic glycopolymer brushes derived from polyacids reveal an enhanced exposure of galactose units at the surface, due to their expanded topology, and thus display an increased lectin-binding ability with respect to their linear counterparts. This combination of amplified responsiveness and augmented protein-binding capacity renders cyclic brushes invaluable building blocks for the design of "smart" materials and functional biointerfaces.

Hydrogels Generated from Cyclic Poly(2‐Oxazoline)s Display Unique Swelling and Mechanical Properties

“…In particular, at relatively low C 0 (5 wt%) C ‐PEOXA showed significantly higher GF with respect to L ‐PEOXA ( p < 0.001), which could be attributed to the inherently different conformation of linear and cyclic polymer precursors in solutions. The steric constraints within cyclic PEOXA precursors in solution presumably lead to an enhanced exposure of functional side chains, [ 49 ] and thus to an augmented accessibility of cross‐linkable moieties (SH and VS) with respect to that characteristic of their linear counterparts. This phenomenon could determine a more efficient cross‐linking reaction and incorporation of cyclic PEOXA precursors within the network, eventually providing higher values of GF, especially at relatively low polymer contents ( C 0 ≤ 10 wt%).…”

Determination of Nanosized Adsorbate Mass in Solution Using Mechanical Resonators: Elimination of the So Far Inseparable Liquid Contribution

“…9 Still, the rich information contained in combined Δf n and ΔD n measurements, especially when complemented with theoretical models representing the response for viscoelastic films, 10−12 has turned out to be very valuable in multiple research areas, including hydration analysis of organic polymers, 13,14 proteins, 15 and biological membranes. 15,16 QCM has also been widely applied to monitor and characterize thin films, including porosity determination, 17,18 monitoring the growth of mesoporous materials, 19 probing responsiveness of polymeric coatings, 20 and characterization of biomimetic membranes. 21,22 Additionally, QCM has been extensively employed to study discrete adsorbates such as abiotic and biological macromolecules and nanoparticles (NPs).…”

“…Still, the rich information contained in combined Δ f n and Δ D n measurements, especially when complemented with theoretical models representing the response for viscoelastic films, − has turned out to be very valuable in multiple research areas, including hydration analysis of organic polymers, , proteins, and biological membranes. , QCM has also been widely applied to monitor and characterize thin films, including porosity determination, , monitoring the growth of mesoporous materials, probing responsiveness of polymeric coatings, and characterization of biomimetic membranes. , Additionally, QCM has been extensively employed to study discrete adsorbates such as abiotic and biological macromolecules and nanoparticles (NPs). These studies included investigations of biomolecular interactions of proteins , and viruses; , structure, , confirmation , and orientation changes of biomacromolecules; spatial distribution, size, − deformation , and dissolution of NPs; protein corona formation on amyloids; interactions between NPs and biomimetic membranes; , as well as bioanalytical sensor development. − …”

Topology and Molecular Architecture of Polyelectrolytes Determine Their pH-Responsiveness When Assembled on Surfaces

“…26 On surfaces, a very recent report from our group suggested that the intramolecular steric constraints characterizing cyclic, weak polyacid brushes lead to a broadening in their pHresponsiveness. 27 Despite this initial study, a comprehensive understanding about the effect of PE-brush topology on its pH-responsive properties has not been achieved yet, and to what extent pHinduced swelling can be tuned through the combined modulation of polymer topology and composition has not been determined.…”