Self-healing Hydrogels & its industrial applications - WorldOfChemicals

Self-healing hydrogels and its industrial applications


Hydrogels are water-swollen, cross-linked polymeric structures produced by reactions of monomers or by hydrogen bonding. Hydrogels are composed of two constituents. One constituent is hydrophilic polymers like polyvinyl alcohol, sodium polyacrylate, acrylate polymers and copolymers, while the second constituent is water.

Hydrogels possess the hydrophilic quality which makes them a good analog for natural tissues and they even tend to mimic the flexibility and other textural qualities of biological media.

Cross linked structure of hydrogels is characterized by junctions or tie points, which may be formed from strong chemical linkages (such as covalent and ionic bonds), permanent or temporary physical entanglements, microcrystallite formation, and weak interactions (such as hydrogen bonds).

Hydrogels under mechanical stress can exhibit a range of responses from rapid, elastic recovery following an applied stress or strain to a time-dependent recovery approaching viscous behaviour.


  • Effective in hydrating wound surfaces and liquefying necrotic tissue on the wound surface
  • Non-adherent and can be removed without trauma to the wound bed
  • "Soothing" effect promotes patient acceptance
  • Easy to modify
  • Biocompatible
  • Good transport properties
  • Hydrogels provide suitable semi-wet, three-dimensional environments for molecular-level biological interactions
  • Hydrogel mechanical properties are highly tunable, for example elasticity can be tailored by modifying cross-link densities
  • Hydrogels can be designed to change properties (e.g. swelling/ collapse or solution-to-gel transitions) in response to externally applied triggers, such as temperature, ionic strength, solvent polarity, electric/magnetic field, light, or small (bio) molecules.


  • Low mechanical strength
  • Hard to handle
  • Difficult to load
  • Hydrogels are the first biomaterials designed for use in the human body. Applications of hydrogels include
  • Tissue Engineering (TE)
  • Synthetic extracellular matrix
  • Implantable devices
  • Biosensors
  • Materials controlling the activity of enzymes
  • Phospholipid bilayer destabilizing agents
  • Soft contact lenses
  • Pills/Capsules
  • Bioadhesive carriers
  • Implant coatings
  • Electrophoresis gels
  • Chromatographic packing material

Hydrogels as barriers

To improve the healing response following tissue injury, hydrogels have been used as barriers in order to prevent restenosis or thrombosis. Restenosis thickening can be reduced by forming a thin hydrogel layer intravascularly via the process of interfacial photopolymerization.

The process behind the restenosis thickening is by preventing platelets, coagulation factors and plasma proteins from contacting the vascular wall.

Hydrogels in drug delivery

Hydrogels are often used as localized drug storehouses because they are hydrophilic, biocompatible, and their drug release rates can be controlled and triggered intelligently by interactions with bio-molecular stimuli.

Characteristics of hydrogels like drug delivery capability and barrier role can be used simultaneously to deliver therapeutic agents.

Hydrogels formed on the inner surface of blood vessels via interfacial photopolymerization have been utilized for intravascular drug delivery.

Current research work

[1] Shyni Varghese’s at University of California, San Diego has developed smart, self-healing hydrogels that binds in seconds to achieve extensive applications including medial sutures, targeted drug delivery, industrial sealents and self-healing plastics. 

Self-healing is one of the most fundamental properties of living tissues that allows them to sustain repeated damage. To achieve the self-healing capacity of hydrogels Varghese's laboratory scientists performed computer simulations to modify the side chain molecules of hydrogels. 

These computer simulations revealed that the ability of hydrogel to self-heal depended critically on the length of the side chain molecules, or fingers, and that hydrogels having an optimal length of side chain molecules exhibited the strongest self-healing.

[2] Professor Langer's group at the Massachusetts Institute of Technology contributed their work towards hydrogel at the tissue engineering level and reviewed the use of microengineered hydrogels for tissue engineering applications.

Microengineered hydrogels are hydrogels with dimensions as small as a few tens of nanometre. These can be prepared by emulsification, photolithography, microfluidic synthesis and micromolding. Applications of microengineered hydrogels may be classified into two categories: "top-down tissue engineering" and "bottom-up tissue engineering". 

Top-down tissue engineering approach controls the microscale features of large pieces of hydrogels, whereas bottom-up tissue engineering approach generates scaffolds by assembly of small functional units.

Microengineered hydrogels can potentially be applied in tissue engineering to recreate the complexities of in vivo tissue constructs either by engineering the microvasculature and cellular organization in large microscale scaffolds, or by assembling the building blocks in the shape of microgel tissue units to generate larger structures.


[1] © From University of California, website -

[2] © From Massachusetts Institute of Technology, website -

[3] By Brandon V. Slaughter, Shahana S. Khurshid, Omar Z. Fisher, Ali Khademhosseini, and Nicholas A. Peppas, Hydrogels in Regenerative Medicine, Available from -

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