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: Ultrasonic characterization and beyond: How to select a hydrogel for tissue engineering
Hydrogels have emerged as a crucial class of materials within the field of tissue engineering. There is growing interest in matching the mechanical properties of hydrogel scaffolds to tissues in the human body and optimizing these properties for cell growth and differentiation. Gelatin methacrylate (GelMA) is a well-accepted, biocompatible hydrogel with tunable mechanical properties. However, the effects of various formulation parameters on its mechanical properties are not well understood. In this study, an array of GelMA scaffold fabrication parameters is evaluated by varying GelMA concentration and ultraviolet light exposure time. Our overarching goal is to characterize the mechanical properties through ultrasound and rheological measurements, providing a framework for GelMA scaffold selection. Pulse-echo ultrasound techniques were used to non-invasively determine the sound speed and attenuation of the scaffolds, revealing significant dependence on GelMA concentration. Steady shear rate and strain- and frequency-controlled oscillatory shear tests using a rotational rheometer (Model: DHR-2, TA Instruments) revealed a range in the levels of shear-thinning as well as viscoelasticity and showed moduli-dependence on both GelMA concentration and light exposure time. Together, this acoustic and rheological characterization can be used to inform the selection of GelMA scaffolds in tissue engineering applications.  more » « less
Award ID(s):
1854415
PAR ID:
10456046
Author(s) / Creator(s):
; ; ; ;
Date Published:
Journal Name:
The Journal of the Acoustical Society of America
Volume:
153
Issue:
3_supplement
ISSN:
0001-4966
Page Range / eLocation ID:
A237 to A237
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, Gels)
    Gelatin methacryloyl (GelMA) hydrogels have been used in tissue engineering and regenerative medicine because of their biocompatibility, photopatternability, printability, and tunable mechanical and rheological properties. However, low mechanical strength limits their applications in controlled drug release, non-viral gene therapy, and tissue and disease modeling. In this work, a dual crosslinking method for GelMA is introduced. First, photolithography was used to pattern the gels through the crosslinking of methacrylate incorporated amine groups of GelMA. Second, a microbial transglutaminase (mTGase) solution was introduced in order to enzymatically crosslink the photopatterned gels by initiating a chemical reaction between the glutamine and lysine groups of the GelMA hydrogel. The results showed that dual crosslinking improved the stiffness and rheological properties of the hydrogels without affecting cell viability, when compared to single crosslinking with either ultraviolet (UV) exposure or mTGase treatment. Our results also demonstrate that when treated with mTGase, hydrogels show decreased swelling properties and better preservation of photolithographically patterned shapes. Similar effects were observed when three dimensional (3D) printed and photocrosslinked substrates were treated with mTGase. Such dual crosslinking methods can be used to improve the mechanical properties and pattern fidelity of GelMA gels, as well as dynamic control of the stiffness of tissue engineered constructs. 
    more » « less
  2. ; ; ; (, Gels)
    The generation of 3D tissue constructs with multiple cell types and matching mechanical properties remains a challenge in cardiac tissue engineering. Recently, 3D bioprinting has become a powerful tool to achieve these goals. Decellularized extracellular matrix (dECM) is a common scaffold material due to providing a native biochemical environment. Unfortunately, dECM’s low mechanical stability prevents usage for bioprinting applications alone. In this study, we developed bioinks composed of decellularized human heart ECM (dhECM) with either gelatin methacryloyl (GelMA) or GelMA-methacrylated hyaluronic acid (MeHA) hydrogels dual crosslinked with UV light and microbial transglutaminase (mTGase). We characterized the bioinks’ mechanical, rheological, swelling, printability, and biocompatibility properties. Composite GelMA–MeHA–dhECM (GME) hydrogels demonstrated improved mechanical properties by an order of magnitude compared to the GelMA–dhECM (GE) hydrogels. All hydrogels were extrudable and compatible with human induced pluripotent stem cell derived cardiomyocytes (iCMs) and human cardiac fibroblasts (hCFs). Tissue-like beating of the printed constructs with striated sarcomeric alpha-actinin and connexin 43 expression was observed. The order of magnitude difference between the elastic modulus of these hydrogel composites offers applications in in vitro modeling of the myocardial infarct boundary. Here, as a proof of concept, we created an infarct boundary region with control over the mechanical properties along with the cellular and macromolecular content through printing iCMs with GE bioink and hCFs with GME bioink. 
    more » « less
  3. ; ; ; (, Small)
    Abstract The convergence of nanotechnology and bioprinting is redefining the landscape of tissue engineering, with nanocomposite gelatin methacryloyl (GelMA) bioinks emerging as a transformative platform for the biofabrication of multifunctional tissue‐specific constructs. GelMA, a photocrosslinkable hydrogel, has rapidly gained attention due to its intrinsic bioactivity, tunable mechanical properties, and compatibility with living cells. However, despite its wide applicability regenerating muscle, cartilage, bone, vascular, cardiac, and neural tissues, native GelMA suffers from limited mechanical strength and insufficient biofunctionality to recapitulate the complexity of specialized tissues. To overcome these shortcomings, recent strategies have focused on the incorporation of nanomaterials into GelMA matrices, ranging from inorganic and carbon‐based to metallic, polymeric, and lipidic nanomaterials. These nanocomposite bioprinted scaffolds impart critical enhancements, including improved mechanical robustness, electrical conductivity, stimuli‐responsiveness, and bioactivity, while also enabling advanced functionalities such as controlled drug release and real‐time responsiveness to the cellular microenvironment. This review examines the bioprinting parameters, material synergies, and design strategies governing the performance of nanocomposite GelMA bioinks. By integrating the tunability of photocrosslinkable bioinks with the multifunctionality of nanomaterials, nanocomposite GelMA bioinks represent a next‐generation platform capable of addressing the complex demands of tissue repair and regeneration. 
    more » « less
  4. ; ; ; (, MRS Advances)
    ABSTRACT Hydrogels have been widely used in many applications from tissue engineering to drug delivery systems. For both tissue engineering and drug delivery, the mechanical properties are important because they would affect cell-materials interactions and injectability of drugs encapsulated in hydrogel carriers. Therefore, it is important to study the mechanical properties of these hydrogels, particularly at physiological temperature (37°C). This study adopted strain sweep and frequency sweep rotational rheological tests to investigate the rheological characteristics of various tissue engineering relevant hydrogels with different concentrations at 37°C. These hydrogels include alginate, RGD-alginate, and copolymerized collagen/alginate/fibrin. It has revealed that the addition of RGD has negligible effect on the elastic modulus and viscosity of alginate. Alginate gels have demonstrated shear thinning behavior which indicates that they are suitable candidates as carriers for cells or drug delivery. The addition of collagen and fibrin would reinforce the mechanical properties of alginate which makes it a strong scaffold material. 
    more » « less
  5. ; ; (, Proceedings of the IISE Annual Conference & Expo 2023)
    Babski-Reeves, K; Eksioglu, B; Hampton, D. (Ed.)
    Extrusion-based three-dimensional (3D) bio-printing is one of the several 3D bioprinting methods that is frequently used in current times. This method enables the accurate deposition of cell-laden bio-ink while ensuring a predetermined scaffold architecture that may allow living tissue regeneration. Natural hydrogels are a strong choice for bio-ink formulation for the extrusion-based 3D bioprinting method because they have a combination of unique properties, which include biocompatibility, reduced cell toxicity, and high-water content. However, due to its low mechanical integrity, hydrogel frequently struggles to retain structural stability. To overcome this challenge, we evaluated the rheological characteristics of distinct hybrid hydrogels composed of carboxymethyl cellulose (CMC), a widely used alginate, and nanofibers generated from cellulose (TEMPO-mediated nano-fibrillated cellulose, TONFC). Therefore, to examine the rheological properties, a set of compositions was developed incorporating CMC (1%–4%), alginate (1%–4%), and higher and lower contents of TONFC (0.5%) and (0.005%) respectively. From the flow diagram, the shear thinning coefficients of n and K were calculated, which were later linked to the 3D printability. With the guidance of diverse nanofiber ratios, it is possible to regulate the rheological properties and create 3D bioprinted scaffolds with well-defined scaffold architecture. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email