Microscopic view of hydrogel particles delivering medication within the body.

Smart Swelling: How Hydrogels Are Changing Drug Delivery

Elliot Brynn in Tech & Innovation August 2025 • 4 min read.

"Unlock the potential of polyacrylamide hydrogels in revolutionizing drug delivery systems – a deep dive into temperature and crosslinking optimization."

Hydrogels, three-dimensional networks of hydrophilic polymers, are revolutionizing various fields due to their ability to retain large amounts of water. These materials, known for their softness, flexibility, and biocompatibility, are ideal for applications such as drug delivery systems, contact lenses, and wound dressings. Researchers are constantly exploring new ways to enhance their properties and broaden their uses.

Traditional methods of creating hydrogel polymer networks include thermal polymerization and electromagnetic radiation exposure. A more recent technique gaining traction is photo-polymerization, prized for its fast reaction rate and ability to occur at room temperature without organic solvents. This method reduces environmental pollutants, aligning with green chemistry principles.

Eosin Y, a highly absorbent xanthene dye, is emerging as a key component in photo-polymerization. When combined with triethanolamine (TEOA) as a co-initiator and visible light, Eosin Y facilitates the creation of crosslinked polyacrylamide hydrogels. These hydrogels exhibit stimulus sensitivity, changing volume in response to external factors like temperature and pH, making them ‘smart’ materials.

Decoding the Science: How Temperature and Crosslinking Affect Swelling

Microscopic view of hydrogel particles delivering medication within the body.

Swelling behavior is key to hydrogel applications, especially in drug delivery. Researchers have traditionally studied crosslinked polyacrylamides made by thermal polymerization or UV radiation. These hydrogels' swelling depends on temperature and degree of crosslinking. This article analyzes the effects of visible light on polyacrylamide hydrogels, and determines how polymer chain structure affects swelling.

The study optimizes a central composite design (CCD) approach to predict experimental conditions of temperature and crosslinker to synthesize polyacrylamide hydrogel using visible light with a pre-defined equilibrium swelling ratio. This approach efficiently reduces the number of wet chemistry experiments, saving significant experimental time and material.

Temperature: Higher temperatures generally lead to increased swelling, allowing for greater drug release.
Degree of Crosslinking: A lower degree of crosslinking results in a looser network, facilitating higher swelling ratios.
Eosin Y concentration: impacts the rate of polymerization and the final structure of the hydrogel.

Using a model that includes factors of temperature and crosslinking, scientists can predefine values for the equilibrium swelling ratio in crosslinked PAM. The values were obtained within intervals of temperature [21–78 °C] and crosslinking [0.75–9%]. These models facilitate the application of drug delivery technology.

The Future of Hydrogels: Precision Medicine and Beyond

With the ability to fine-tune hydrogel properties through adjustments in temperature, crosslinking, and visible light, the future of drug delivery looks promising. Researchers are continuing to explore these smart materials for precision medicine, creating tailored treatments that respond to individual patient needs. As technology advances, hydrogels have the potential to revolutionize medical treatments, offering improved efficacy and reduced side effects.

About this Article -

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This article is based on research published under:

DOI-LINK: 10.1007/s12588-018-9224-9, Alternate LINK

Title: Prediction Of Equilibrium Swelling Ratio On Synthesized Polyacrylamide Hydrogel Using Central Composite Design Modeling

Subject: Polymers and Plastics

Journal: International Journal of Plastics Technology

Publisher: Springer Science and Business Media LLC

Authors: S. Hamri, D. Lerari, M. Sehailia, B. Dali-Youcef, T. Bouchaour, K. Bachari

Published: 2018-10-13

Everything You Need To Know

What are hydrogels and why are they considered useful for drug delivery and other biomedical applications?

Hydrogels are three-dimensional networks of hydrophilic polymers known for their ability to retain large amounts of water, making them soft, flexible, and biocompatible. These properties make them suitable for drug delivery systems, contact lenses, and wound dressings. Researchers are continuously working to enhance these properties for broader applications.

What are the advantages of using photo-polymerization over traditional methods for creating hydrogel polymer networks?

Photo-polymerization offers a faster reaction rate and can occur at room temperature without the need for organic solvents, which aligns with green chemistry principles by reducing environmental pollutants. This method uses visible light to initiate the polymerization process, which can be more energy-efficient and less harmful compared to traditional thermal polymerization or electromagnetic radiation exposure.

What role does Eosin Y play in the creation of stimulus-sensitive polyacrylamide hydrogels?

Eosin Y, a highly absorbent xanthene dye, acts as a key component in photo-polymerization. When combined with triethanolamine (TEOA) and visible light, it facilitates the creation of crosslinked polyacrylamide hydrogels. These hydrogels are stimulus-sensitive, which means they change volume in response to external factors like temperature and pH, classifying them as ‘smart’ materials. The concentration of Eosin Y impacts the rate of polymerization and the final structure of the hydrogel.

How do temperature and degree of crosslinking affect the swelling behavior of polyacrylamide hydrogels, and why is this important for drug delivery?

Temperature affects swelling because higher temperatures generally lead to increased swelling, which can be beneficial for greater drug release. The degree of crosslinking impacts swelling inversely; a lower degree of crosslinking results in a looser network, facilitating higher swelling ratios. The ability to control these factors allows scientists to predefine values for the equilibrium swelling ratio in crosslinked PAM, optimizing drug delivery technology.

How might hydrogels contribute to the future of precision medicine, and what are the potential benefits for patients?

Researchers are exploring these smart materials for precision medicine to create tailored treatments that respond to individual patient needs. This involves fine-tuning hydrogel properties through adjustments in temperature, crosslinking, and visible light. The goal is to revolutionize medical treatments by offering improved efficacy and reduced side effects, ultimately leading to more personalized and effective healthcare solutions.