skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Photochemical Control of Network Topology in PEG Hydrogels
Abstract Hydrogels are often synthesized through photoinitiated step‐, chain‐, and mixed‐mode polymerizations, generating diverse network topologies and resultant material properties that depend on the underlying network connectivity. While many photocrosslinking reactions are available, few afford controllable connectivity of the hydrogel network. Herein, a versatile photochemical strategy is introduced for tuning the structure of poly(ethylene glycol) (PEG) hydrogels using macromolecular monomers functionalized with maleimide and styrene moieties. Hydrogels are prepared along a gradient of topologies by varying the ratio of step‐growth (maleimide dimerization) to chain‐growth (maleimide‐styrene alternating copolymerization) network‐forming reactions. The initial PEG content and final network physical properties (e.g., modulus, swelling, diffusivity) are tailored in an independent manner, highlighting configurable gel mechanics and reactivity. These photochemical reactions allow high‐fidelity photopatterning and 3D printing and are compatible with 2D and 3D cell culture. Ultimately, this photopolymer chemistry allows facile control over network connectivity to achieve adjustable material properties for broad applications.  more » « less
Award ID(s):
2348856
PAR ID:
10582234
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publisher / Repository:
Wiley-VCH
Date Published:
Journal Name:
Advanced Materials
Volume:
36
Issue:
46
ISSN:
0935-9648
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; (, Journal of Materials Chemistry B)
    Click chemistry reactions have become an important tool for synthesizing user-defined hydrogels consisting of poly(ethylene glycol) (PEG) and bioactive peptides for tissue engineering. However, because click crosslinking proceeds via a step-growth mechanism, multi-arm telechelic precursors are required, which has some disadvantages. Here, we report for the first time that this requirement can be circumvented to create PEG–peptide hydrogels solely from linear precursors through the use of two orthogonal click reactions, the thiol–maleimide Michael addition and thiol–norbornene click reaction. The rapid kinetics of both click reactions allowed for quick formation of norbornene-functionalized PEG–peptide block copolymers via Michael addition, which were subsequently photocrosslinked into hydrogels with a dithiol linker. Characterization and in vitro testing demonstrated that the hydrogels have highly tunable physicochemical properties and excellent cytocompatibility. In addition, stoichiometric control over the crosslinking reaction can be leveraged to leave unreacted norbornene groups in the hydrogel for subsequent hydrogel functionalization via bioorthogonal inverse-electron demand Diels–Alder click reactions with s -tetrazines. After selectively capping norbornene groups in a user-defined region with cysteine, this feature was leveraged for protein patterning. Collectively, these results demonstrate that our novel chemical strategy is a simple and versatile approach to the development of hydrogels for tissue engineering that could be useful for a variety of applications. 
    more » « less
  2. ; ; ; (, MRS Advances)
    Abstract Hydrogel materials can be used to integrate bacteria cells into biohybrid systems. Here, we investigate the use of polyethylene glycol-based hydrogels that employ different Michael-type addition crosslinking chemistries, including thiol-acrylate, thiol-vinyl sulfone, and thiol-maleimide click reactions, for covalent hydrogel network formation and bacteria encapsulation. All crosslinking chemistries generated hydrogels that provided stable encapsulation and culture ofBacillus subtilis; however, significant differences in cell viability and cell morphology after encapsulation were identified. Thiol-acrylate hydrogels provided the highest cell viability and favored encapsulation of single cells, while thiol-maleimide hydrogels had the lowest cell viability and favored encapsulation of larger aggregates. These findings demonstrate the impact of crosslinking strategies for encapsulation of microorganisms into hydrogel networks and suggest that thiol-acrylate chemistries are favorable for many applications. Graphical abstract 
    more » « less
  3. ; ; ; ; ; (, Macromolecules)
    Not AvailableReversible photochemical reactions are a promising approach for integrating reprocessability and circularity into polymeric materials. To enable photochemical reprocessing, poly(ethylene glycol) star polymers are end-functionalized with photoreversible anthracene (PEG-anthracene). Ultraviolet A (UVA) light promotes anthracene dimerization and polymer network formation, whereas ultraviolet C (UVC) light drives anthracene dimer dissociation and network deconstruction. We demonstrate multiple cycles of network formation, deconstruction, and reformation. Network formation and deconstruction dynamics are monitored using in situ photorheology and ultraviolet–visible (UV–vis) absorbance to connect bulk mechanical properties with molecular-scale anthracene conversion. Network formation is faster for star polymers with more arms due to a greater number of reactive end groups per macromolecule. Subsequent reprocessing of solid networks into liquid resins is fastest for polymer samples with fewer arms and lower concentrations, highlighting an interplay between polymer architecture and anthracene dimerization dynamics. The photochemical processing insights provided by this work advance the rational molecular design and formulation of light-responsive polymers toward material circularity. 
    more » « less
  4. ; ; ; ; ; ; ; ; ; ; et al (, Advanced Healthcare Materials)
    Abstract Granular hydrogels composed of hydrogel microparticles are promising candidates for 3D bioprinting due to their ability to protect encapsulated cells. However, to achieve high print fidelity, hydrogel microparticles need to jam to exhibit shear‐thinning characteristics, which is crucial for 3D printing. Unfortunately, this overpacking can significantly impact cell viability, thereby negating the primary advantage of using hydrogel microparticles to shield cells from shear forces. To overcome this challenge, a novel solution: a biphasic, granular colloidal bioink designed to optimize cell viability and printing fidelity is introduced. The biphasic ink consists of cell‐laden polyethylene glycol (PEG) hydrogel microparticles embedded in a continuous gelatin methacryloyl (GelMA)‐nanosilicate colloidal network. Here, it is demonstrated that this biphasic bioink offers outstanding rheological properties, print fidelity, and structural stability. Furthermore, its utility for engineering complex tissues with multiple cell types and heterogeneous microenvironments is demonstrated, by incorporating β‐islet cells into the PEG microparticles and endothelial cells in the GelMA‐nanosilicate colloidal network. Using this approach, it is possible to induce cell patterning, enhance vascularization, and direct cellular function. The proposed biphasic bioink holds significant potential for numerous emerging biomedical applications, including tissue engineering and disease modeling. 
    more » « less
  5. ; ; ; ; ; ; (, Advanced Healthcare Materials)
    Abstract Cardioids are 3D self‐organized heart organoids directly derived from induced pluripotent stem cells (hiPSCs) aggregates. The growth and culture of cardioids is either conducted in suspension culture or heavily relies on Matrigel encapsulation. Despite the significant advancements in cardioid technology, reproducibility remains a major challenge, limiting their widespread use in both basic research and translational applications. Here, for the first time, we employed synthetic, matrix metalloproteinase (MMP)‐degradable polyethylene glycol (PEG)‐based hydrogels to define the effect of mechanical and biochemical cues on cardioid development. Successful cardiac differentiation is demonstrated in all the hydrogel conditions, while cardioid cultured in optimized PEG hydrogel (3 wt.% PEG‐2mM RGD) underwent similar morphological development and comparable tissue functions to those cultured in Matrigel. Matrix stiffness and cell adhesion motif play a critical role in cardioid development, nascent chamber formation, contractile physiology, and endothelial cell gene enrichment. More importantly, synthetic hydrogel improved the reproducibility in cardioid properties compared to traditional suspension culture and Matrigel encapsulation. Therefore, PEG‐based hydrogel has the potential to be used as an alternative to Matrigel for human cardioid culture in a variety of clinical applications including cell therapy and tissue engineering. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Text Encoded Conversion
  • XML
  • Save / Share this Record
  • Send to Email