1
|
Wu X, Teng F, Firlar E, Zhang T, Libera M. Elasto-plastic effects on shape-shifting electron-beam-patterned gel-based micro-helices. MATERIALS HORIZONS 2024; 11:3427-3436. [PMID: 38712865 DOI: 10.1039/d4mh00208c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Shape-shifting helical gels have been created by various routes, notably by photolithography. We explore electron-beam lithography as an alternative to prescribe microhelix formation in tethered patterns of pure poly(acrylic acid). Simulations indicate the nanoscale spatial distribution of deposited energy that drives the loss of acid groups and crosslinking. Upon exposure to buffer, a patterned line converts to a 3D helix whose cross section comprises a crosslinked and hydrophobic core surrounded by a high-swelling pH-responsive corona. Through-thickness asymmetries generate out-of-plane bending to drive helix formation. The relative core and corona fractions are determined by the electron dose which in turn controls the helical radius and pitch. Increasing pH substantially raises the swelling stress and the rod elongates plastically. The pitch concurrently changes from minimal to non-minimal. The in-plane asymmetry driving this change can be attributed to shear-band formation in the hydrophobic core. Subsequent pH cycling drives elastic cycling of the helical properties. These findings illustrate the effects of elastoplastic deformation on helical properties and elaborate unique attributes of electron lithography as an alternate means to create shape-shifting structures.
Collapse
Affiliation(s)
- Xinpei Wu
- Department of Chemical Engineering & Materials Science, Stevens Institute of Technology, Hoboken, NJ, USA.
| | - Feiyue Teng
- Department of Chemical Engineering & Materials Science, Stevens Institute of Technology, Hoboken, NJ, USA.
- presently with the Brookhaven National Laboratory, Upton, NY, USA
| | - Emre Firlar
- Rutgers CryoEM & Nanoimaging Facility and Institute for Quantitative Biomedicine, Rutgers University, Piscataway, NJ, USA
- presently with Bristol Myers Squibb, Molecular Structure & Design, Princeton, NJ, USA
| | - Teng Zhang
- Department of Mechanical and Aerospace Engineering, Syracuse University, Syracuse, NY, USA
| | - Matthew Libera
- Department of Chemical Engineering & Materials Science, Stevens Institute of Technology, Hoboken, NJ, USA.
| |
Collapse
|
2
|
Zhao W, Lin JS, Nielsen JE, Sørensen K, Wadurkar AS, Ji J, Barron AE, Nangia S, Libera MR. Supramolecular Peptoid Structure Strengthens Complexation with Polyacrylic Acid Microgels. Biomacromolecules 2024; 25:1274-1281. [PMID: 38240722 PMCID: PMC11046531 DOI: 10.1021/acs.biomac.3c01242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2024]
Abstract
We have studied the complexation between cationic antimicrobials and polyanionic microgels to create self-defensive surfaces that responsively resist bacterial colonization. An essential property is the stable sequestration of the loaded (complexed) antimicrobial within the microgel under a physiological ionic strength. Here, we assess the complexation strength between poly(acrylic acid) [PAA] microgels and a series of cationic peptoids that display supramolecular structures ranging from an oligomeric monomer to a tetramer. We follow changes in loaded microgel diameter with increasing [Na+] as a measure of the counterion doping level. Consistent with prior findings on colistin/PAA complexation, we find that a monomeric peptoid is fully released at ionic strengths well below physiological conditions, despite its +5 charge. In contrast, progressively higher degrees of peptoid supramolecular structure display progressively greater resistance to salting out, which we attribute to the greater entropic stability associated with the complexation of multimeric peptoid bundles.
Collapse
Affiliation(s)
- Wenhan Zhao
- Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
| | - Jennifer S Lin
- Department of Bioengineering, School of Medicine & School of Engineering, Stanford University, Stanford, California 94305, United States
| | - Josefine Eilsø Nielsen
- Department of Bioengineering, School of Medicine & School of Engineering, Stanford University, Stanford, California 94305, United States
- Department of Science and Environment, Roskilde University, Roskilde DK-4000, Denmark
| | - Kristian Sørensen
- Department of Bioengineering, School of Medicine & School of Engineering, Stanford University, Stanford, California 94305, United States
| | - Anand Sunil Wadurkar
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Jingjing Ji
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Annelise E Barron
- Department of Bioengineering, School of Medicine & School of Engineering, Stanford University, Stanford, California 94305, United States
| | - Shikha Nangia
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Matthew R Libera
- Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, New Jersey 07030, United States
| |
Collapse
|
3
|
Chremos A, Mussel M, Douglas JF, Horkay F. Ion Partition in Polyelectrolyte Gels and Nanogels. Gels 2023; 9:881. [PMID: 37998971 PMCID: PMC10670699 DOI: 10.3390/gels9110881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/02/2023] [Accepted: 11/04/2023] [Indexed: 11/25/2023] Open
Abstract
Polyelectrolyte gels provide a load-bearing structural framework for many macroscopic biological tissues, along with the organelles within the cells composing tissues and the extracellular matrices linking the cells at a larger length scale than the cells. In addition, they also provide a medium for the selective transportation and sequestration of ions and molecules necessary for life. Motivated by these diverse problems, we focus on modeling ion partitioning in polyelectrolyte gels immersed in a solution with a single type of ionic valence, i.e., monovalent or divalent salts. Specifically, we investigate the distribution of ions inside the gel structure and compare it with the bulk, i.e., away from the gel structure. In this first exploratory study, we neglect solvation effects in our gel by modeling the gels without an explicit solvent description, with the understanding that such an approach may be inadequate for describing ion partitioning in real polyelectrolyte gels. We see that this type of model is nonetheless a natural reference point for considering gels with solvation. Based on our idealized polymer network model without explicit solvent, we find that the ion partition coefficients scale with the salt concentration, and the ion partition coefficient for divalent ions is higher than for monovalent ions over a wide range of Bjerrum length (lB) values. For gels having both monovalent and divalent salts, we find that divalent ions exhibit higher ion partition coefficients than monovalent salt for low divalent salt concentrations and low lB. However, we also find evidence that the neglect of an explicit solvent, and thus solvation, provides an inadequate description when compared to experimental observations. Thus, in future work, we must consider both ion and polymer solvation to obtain a more realistic description of ion partitioning in polyelectrolyte gels.
Collapse
Affiliation(s)
- Alexandros Chremos
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Matan Mussel
- Department of Physics, University of Haifa, Haifa 3103301, Israel
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Ferenc Horkay
- Section on Quantitative Imaging and Tissue Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| |
Collapse
|
4
|
Xiao X, Ji J, Wang H, Nangia S, Wang H, Libera M. Self-Defensive Antimicrobial Surfaces Using Polymyxin-Loaded Poly(styrene sulfonate) Microgels. ACS Biomater Sci Eng 2022; 8:4827-4837. [PMID: 36256955 DOI: 10.1021/acsbiomaterials.2c00783] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Self-defensive antimicrobial surfaces are of interest because they can inhibit bacterial colonization while minimizing unnecessary antimicrobial release in the absence of a bacterial challenge. One self-defensive approach uses self-assembly to first deposit a submonolayer coating of polyelectrolyte microgels and subsequently load those microgels by complexation with small-molecule antimicrobials. The microgel/antimicrobial complexation strength is a key parameter that controls the ability of the antimicrobial both to remain sequestered within the microgels when exposed to medium and to release in response to a bacterial challenge. Here we study the relative complexation strengths of two FDA-approved cationic antibiotics─colistin (polymyxin E) and polymyxin B─with microgels of poly(styrene sulfonate) (PSS). These polymyxins are similar cyclic polypeptides with +5 charge at pH 7.4. However, polymyxin B substitutes an aromatic ring for a dimethyl moiety in colistin, and this aromaticity can influence complexation via π and hydrophobic interactions. Coarse-grained molecular dynamics shows that the free-energy change associated with polymyxin B/PSS complexation is more negative than that of colistin/PSS complexation. Experimentally, in situ optical microscopy of microgel deswelling shows that both antibiotics load quickly from low-ionic-strength phosphate buffer. The enhanced polymyxin B/PSS complexation strength is then manifested by subsequent exposure to flowing antibiotic-free buffer with varying NaCl concentration. Microgels loaded with polymyxin B remain stably deswollen to higher salt concentrations than do colistin/PSS microgels. Importantly, exposing loaded microgels to E. coli in nutrient-free-flowing phosphate buffer shows that bacteria are killed by physical contact with the loaded microgels consistent with the contact-transfer mechanism of self-defensiveness. In vitro culture experiments show that these same surfaces, nevertheless, support the adhesion, spreading and proliferation of human fetal osteoblasts. These findings suggest a pathway to create a self-defensive antimicrobial surface effective under physiological conditions based on the nonmetabolic bacteria-triggered release of FDA-approved antibiotics.
Collapse
Affiliation(s)
- Xixi Xiao
- Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, New Jersey07030, United States
| | - Jingjing Ji
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York13244, United States
| | - Haoyu Wang
- Department of Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey07030, United States
| | - Shikha Nangia
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York13244, United States
| | - Hongjun Wang
- Department of Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey07030, United States.,Center for Healthcare Innovation, Stevens Institute of Technology, Hoboken, New Jersey07030, United States
| | - Matthew Libera
- Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, New Jersey07030, United States
| |
Collapse
|