Veronika Kozlovskaya

Abstract Recent years have seen increasing interest in the construction of nanoscopically layered materials involving aqueous‐based sequential assembly of polymers on solid substrates. In the booming research area of layer‐by‐layer (LbL) assembly of oppositely charged polymers, self‐assembly driven by hydrogen bond formation emerges as a powerful technique. Hydrogen‐bonded (HB) LbL materials open new opportunities for LbL films, which are more difficult to produce than their electrostatically assembled counterparts. Specifically, the new properties associated with HB assembly include: 1) the ease of producing films responsive to environmental pH at mild pH values, 2) numerous possibilities for converting HB films into single‐ or two‐component ultrathin hydrogel materials, and 3) the inclusion of polymers with low glass transition temperatures (e.g., poly(ethylene oxide)) within ultrathin films. These properties can lead to new applications for HB LbL films, such as pH‐ and/or temperature‐responsive drug delivery systems, materials with tunable mechanical properties, release films dissolvable under physiological conditions, and proton‐exchange membranes for fuel cells. In this report, we discuss the recent developments in the synthesis of LbL materials based on HB assembly, the study of their structure–property relationships, and the prospective applications of HB LbL constructs in biotechnology and biomedicine.

We explore responsive properties of hollow multilayer shells of tannic acid assembled with a range of neutral polymers, poly(N-vinylpyrrolidone) (PVPON), poly(N-vinylcaprolactam) (PVCL) or poly(N-isopropylacrylamide) (PNIPAM). We found that properties of the nanoscale shells fabricated through hydrogen-bonded layer-by-layer (LbL) assembly can be tuned changing the interaction strength of a neutral polymer with tannic acid, and by a change in counterpart hydrophobicity. Unlike most hydrogen-bonded LbL films with two polymer components, the produced tannic acid-based multilayer shells are extremely stable in the wide pH range from 2 to 10. We demonstrate that gold nanoparticles can be grown within tannic acid-containing shell walls under mild environmental conditions paving the way for further modification of the capsule walls through thiol-based surface chemistry. Moreover, these shells show reversible pH-triggered changes in surface charge and permeability towards FITC-labeled polysaccharide molecules. The permeability of these LbL containers can be controlled by changing pH providing an opportunity for loading and release of a functional cargo under mild conditions.

Hydrogen-bonded multilayers of a neutral polymer (poly(N-vinylpyrrolidone), PVPON) with poly(methacrylic acid) (PMAA) were used as templates to introduce cross-links between PMAA layers using carbodiimide chemistry and ethylenediamine as a cross-linking agent. Upon exposure to high pH, PVPON is completely released from the hydrogel matrix, producing surface-attached PMAA hydrogels. When such hydrogels are deposited at the surface of silica particles, and the particle core is subsequently dissolved, hollow one-component hydrogel capsules are produced. PMAA hydrogel films and hollow capsules underwent reversible, large (factors of 2 or 3) changes in size in response to changes in solution pH and/or ionic strength. The capsules were used for entrapment and storage of macromolecules such as 500 kDa FITC-dextran by “locking” the capsule wall with an electrostatically associating polycation, poly-N-ethyl-4-vinylpyridinium bromide (QPVP). The release of the encapsulated macromolecules was achieved under high salt concentrations (0.6 M NaCl) when QPVP dissociated from the capsule wall. The pH and salt response of these PMAA hydrogel capsules and the polycation-controlled encapsulation of macromolecules hold promise for applications in biomedicine and biotechnology.

Layer-by-layer assembly of polyelectrolyte multilayer (PEM) films represents a bottom-up approach for re-engineering the molecular landscape of cell surfaces with spatially continuous and molecularly uniform ultrathin films. However, fabricating PEMs on viable cells has proven challenging owing to the high cytotoxicity of polycations. Here, we report the rational engineering of a new class of PEMs with modular biological functionality and tunable physicochemical properties which have been engineered to abrogate cytotoxicity. Specifically, we have discovered a subset of cationic copolymers that undergoes a conformational change, which mitigates membrane disruption and facilitates the deposition of PEMs on cell surfaces that are tailorable in composition, reactivity, thickness, and mechanical properties. Furthermore, we demonstrate the first successful in vivo application of PEM-engineered cells, which maintained viability and function upon transplantation and were used as carriers for in vivo delivery of PEMs containing biomolecular payloads. This new class of polymeric film and the design strategies developed herein establish an enabling technology for cell transplantation and other therapies based on engineered cells.

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTHydrogen-Bonded Polymer Capsules Formed by Layer-by-Layer Self-AssemblyVeronika Kozlovskaya, Salim Ok, Alioscka Sousa, Matthew Libera, and Svetlana A. SukhishviliView Author Information Department of Chemistry and Chemical Biology, Stevens Institute of Technology, Hoboken, New Jersey 07030 Cite this: Macromolecules 2003, 36, 23, 8590–8592Publication Date (Web):October 25, 2003Publication History Received26 July 2003Revised7 October 2003Published online25 October 2003Published inissue 1 November 2003https://pubs.acs.org/doi/10.1021/ma035084lhttps://doi.org/10.1021/ma035084lrapid-communicationACS PublicationsCopyright © 2003 American Chemical SocietyRequest reuse permissionsArticle Views2084Altmetric-Citations154LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Deposition,Layers,Polymer particles,Polymers,Thin films Get e-Alerts