Application Note | ElastoSens™ Bio
Gelatin Hydrogels: Properties, Applications & Mechanical Behavior
by Maya Salame and Dimitria Camasao
Application Scientists
What is a Gelatin Hydrogel?
Gelatin hydrogels are three-dimensional, water-swollen polymer networks derived from gelatin, a natural polypeptide obtained by partial hydrolysis of collagen. Collagen is one of the most abundant structural proteins in the extracellular matrix of mammalian tissues, and its denaturation yields gelatin with a linear molecular structure rich in Gly–X–Y amino acid sequences, primarily glycine, proline, and hydroxyproline. Gelatin is typically sourced from animal tissues such as porcine skin or bovine bone and is extracted through either acidic or alkaline hydrolysis, resulting in materials with different isoelectric points and charge characteristics. Due to its natural origin, biochemical similarity to native extracellular matrix, and ease of processing, gelatin readily forms hydrogels that are widely used in biomedical and biotechnological applications.
Key Properties of Gelatin Hydrogels
Physicochemical Characteristics
Gelatin hydrogels form through a combination of physical and chemical interactions that govern network structure and stability. Native gelatin undergoes thermoreversible gelation driven by partial renaturation of collagen-like triple helices upon cooling. However, this physical gelation alone provides limited thermal and mechanical stability, motivating the use of additional crosslinking strategies.
Common gelation and crosslinking mechanisms include:
- Physical gelation: temperature-dependent helix formation and hydrogen bonding.
- Chemical crosslinking: covalent bonding using small-molecule crosslinkers or enzymatic reactions.
- Enzymatic crosslinking: formation of amide bonds between gelatin chains under mild conditions.
- Photocrosslinking: light-activated polymerization of functionalized gelatin derivatives.
Environmental factors such as temperature, pH, polymer concentration, and ionic strength strongly influence gel formation, network density, and final hydrogel properties.
Mechanical Properties
Gelatin hydrogels are inherently soft and viscoelastic, reflecting their hydrated polymeric nature. Their stiffness and elasticity depend on gelatin concentration, molecular weight distribution, degree of crosslinking, and network architecture. Physically gelled gelatin exhibits low mechanical stability and rapid softening at physiological temperatures, whereas chemically or enzymatically crosslinked systems display enhanced stiffness, improved structural integrity, and prolonged stability. As gelatin hydrogels degrade through enzymatic cleavage, their mechanical properties evolve over time, typically showing gradual softening and loss of load-bearing capacity. This dynamic mechanical behavior is particularly relevant for applications that require controlled degradation and tissue remodeling.
Biological Interactions
Gelatin hydrogels exhibit excellent biological performance due to their biochemical similarity to native extracellular matrix components. They naturally present cell-adhesive motifs, including arginine–glycine–aspartic acid (RGD) sequences, which promote cell attachment, spreading, and migration. Gelatin is generally biocompatible, shows low immunogenicity, and supports high cell viability across a wide range of cell types. In biological environments, gelatin is enzymatically degraded by matrix metalloproteinases, enabling cell-mediated remodeling and gradual replacement by newly formed tissue.
Applications of Gelatin Hydrogels
Tissue Engineering
In tissue engineering, gelatin hydrogels serve as scaffolds that provide structural support while actively interacting with cells. Their tunable mechanical properties, enzymatic degradability, and cell-adhesive nature make them suitable for regenerating bone, cartilage, muscle, nerve, and skin tissues. Gelatin-based hydrogels can be processed into porous scaffolds, injectable matrices, or printed constructs that closely mimic native tissue microenvironments.
3D Cell Culture & Disease Models
Gelatin hydrogels are widely used to create three-dimensional cell culture systems that better replicate in vivo conditions compared to traditional two-dimensional substrates. Their porous and hydrated structure facilitates nutrient diffusion, waste removal, and cell–cell interactions. These properties enable the development of physiologically relevant disease models, including tumor microenvironments and stromal cocultures, supporting long-term cell viability and functional behavior.
Drug, Gene & Cell Delivery
Because gelatin degrades enzymatically and can interact with charged biomolecules, gelatin hydrogels are effective platforms for controlled delivery of drugs, genes, growth factors, and living cells. Release kinetics can be tuned through crosslinking density, hydrogel composition, and network architecture, allowing sustained and localized therapeutic delivery. Injectable gelatin hydrogels are particularly attractive for minimally invasive treatments and regenerative therapies.
Why the Viscoelasticity of Gelatin Hydrogels Matters
Gelatin hydrogels exhibit pronounced viscoelastic behavior, combining elastic energy storage with time-dependent stress relaxation. This viscoelasticity plays a critical role in how cells sense mechanical cues, remodel their surroundings, and regulate processes such as migration, differentiation, and matrix deposition. From a functional perspective, viscoelasticity influences load dissipation, mechanical stability, and durability under cyclic or dynamic loading. Understanding and controlling the viscoelastic response of gelatin hydrogels is therefore essential for designing biomimetic environments that accurately reproduce native tissue mechanics and for predicting long-term performance in biomedical applications.
Methods to Characterize the Viscoelasticity of Gelatin Hydrogels
The mechanical and viscoelastic properties of gelatin hydrogels are commonly assessed using bulk rheometry, compression testing, tensile testing, and indentation-based methods. These techniques provide measurements of elastic modulus, storage and loss moduli, and failure behavior. However, traditional approaches often require physical contact, large deformations, or destructive sample handling. As a result, they are limited in their ability to monitor gelation kinetics, identify liquid–gel transition points, or track mechanical evolution over time in the same sample, particularly under sterile or cell-laden conditions.
Case study: Mechanical Characterization of Gelatin Hydrogel Using ElastoSens™ Bio
ElastoSens™ Bio: A Non-Destructive Tool to Measure Soft Gelatin Hydrogels
The ElastoSens™ Bio is a non-destructive mechanical characterization platform specifically designed for soft and highly hydrated materials such as gelatin hydrogels. It operates by inducing gentle mechanical vibrations and measuring the resulting resonance response, enabling precise determination of viscoelastic properties without direct contact or sample damage. This approach is ideally suited for soft hydrogels, offering high sensitivity and repeatability across a wide range of stiffness values. The instrument allows real-time monitoring of gelation kinetics, identification of the liquid–gel transition point, and measurement of final hydrogel stiffness. Because the same sample can be tested repeatedly over time, ElastoSens™ Bio supports longitudinal studies of mechanical evolution under controlled or sterile conditions, making it particularly valuable for cell-laden and dynamically remodeling gelatin hydrogels.
To demonstrate the capabilities of the ElastoSens™ Bio, we performed a series of tests on gelatin-based hydrogels. The following section outlines the materials and methods employed, followed by the results, providing a practical example of the instrument’s ability to non-destructively monitor viscoelastic properties over time.
Material and methods
Gelatin type B from bovine skin (Sigma-Aldrich, USA) was prepared at 15% (w/v) by dispersing the powder in deionized water and heating to boiling (95–100 °C) under continuous stirring until fully dissolved. The solution was then held at 60 °C in a water bath to maintain a liquid state prior to measurement. Gelation measurements were performed using an ElastoSens™ Bio system equipped with the macro sample holder (6 mL per test). The instrument temperature chamber was set to 15°C, and viscoelastic properties were recorded for 120 min with a 5 s acquisition interval.
Results and discussion
At 15 °C, 15% (w/v) gelatin had the expected gelation profile: G′ remained low initially, then increased through the sol–gel transition and approached a plateau within the 120 min window (Figure 1, left). Endpoint measurements confirmed solid-like behavior, with G′ = 11719 ± 1780 Pa and G″ = 888 ± 47.8 Pa at 15 °C (mean ± SD, n = 3; Figure 1, right), corresponding to a low damping ratio (tan δ ≈ 0.076) and a predominantly elastic network. Gelatin gelation can be readily tuned by adjusting experimental parameters—most notably polymer concentration, temperature/cooling rate, and sample geometry/heat transfer—which shift both (i) gelation kinetics (time to reach the transition/plateau) and (ii) plateau stiffness (G′), enabling the formulation to be tailored for either faster setting or higher final mechanical strength depending on the application.
Figure 1. Time-dependent gelation kinetics of 15% (w/v) gelatin measured over 120 min at 15 °C (left; mean ± SD, dashed lines) and final viscoelastic moduli at 15°C (right; storage modulus G′ and loss modulus G″, n = 3).
Conclusions and perspectives
The mechanical behavior of gelatin hydrogels—governed by their viscoelasticity, thermoreversible gelation, and crosslinking-dependent stability—is critical to their performance in biomedical systems. As soft, hydrated, and dynamically evolving materials, gelatin hydrogels require non-invasive mechanical monitoring.
- ElastoSens™ Bio enables non-destructive viscoelastic characterization tailored to soft gelatin-based systems.
- High sensitivity and repeatability allow precise measurement of gelation kinetics, liquid–gel transition, and final stiffness.
- Longitudinal testing of the same sample supports studies of mechanical evolution under sterile or cell-laden conditions.
- An integrated photostimulation module enables real-time monitoring of photocrosslinking in functionalized gelatin systems (e.g., GelMA).
Together, these capabilities support improved control, reproducibility, and translation of gelatin hydrogel platforms across research and biomedical applications.
References
Lukin, I., Erezuma, I., Maeso, L., Zarate, J., Desimone, M. F., Al-Tel, T. H., … & Orive, G. (2022). Progress in gelatin as biomaterial for tissue engineering. Pharmaceutics, 14(6), 1177.
Jaipan, P., Nguyen, A., & Narayan, R. J. (2017). Gelatin-based hydrogels for biomedical applications. Mrs Communications, 7(3), 416-426.
Bello, A. B., Kim, D., Kim, D., Park, H., & Lee, S. H. (2020). Engineering and functionalization of gelatin biomaterials: From cell culture to medical applications. Tissue Engineering Part B: Reviews, 26(2), 164-180.
Discover how our technology non-destructively measures the viscoelastic properties of soft biomaterials and tissues using micro-volumes of samples
Related Posts
Extracellular matrix (ECM) hydrogels are biomaterials derived from native tissues after removal of cellular components through decellularization. The remaining matrix preserves key structural proteins (such as collagens, elastin, fibronectin, and laminin), proteoglycans, and glycosaminoglycans that define the biochemical and architectural identity of the source tissue. ECM is naturally produced by cells in all tissues and provides both mechanical support and biochemical signaling cues.
Superabsorbent polymer (SAP) hydrogels are three-dimensional, crosslinked polymer networks capable of absorbing and retaining extremely large amounts of water—often hundreds to thousands of times their own weight—while remaining insoluble. Their structure is based on hydrophilic polymer chains containing functional groups such as carboxylate, hydroxyl, or amide moieties, which generate strong osmotic driving forces for water uptake.
Polyacrylamide (PAM) hydrogels are synthetic, water-swollen polymer networks formed from acrylamide monomers chemically or physically crosslinked into a three-dimensional structure. Polyacrylamide itself is an organic polymer composed of repeating acrylamide subunits, and when crosslinked in aqueous environments, it forms soft, highly hydrated gels with tissue-like mechanical behavior. PAM hydrogels are entirely synthetic and industrially produced, offering high batch-to-batch reproducibility and tunable properties.
Polymethyl methacrylate (PMMA) is a synthetic, thermoplastic polymer belonging to the acrylic resin family. It is formed by the free-radical polymerization of methyl methacrylate (MMA) monomers, resulting in a linear, amorphous polymer with high optical clarity and structural rigidity. PMMA is entirely industrially produced, with MMA synthesized from petrochemical feedstocks and polymerized using controlled thermal, chemical, or photochemical initiation.