Hidrogél

Hidrogél, also known as hydrogel, is a three-dimensional network of hydrophilic polymers that can absorb and retain substantial amounts of water while maintaining structure. The water content can exceed 90% by weight, giving a soft, tissue-like consistency. Hidrogéls derive their properties from crosslinked polymers; the network’s hydrophilic groups (such as hydroxyl, carboxyl, and amide groups) interact with water through hydrogen bonding and other polar interactions.

Hidrogéls are formed by crosslinking polymers either physically (reversible interactions such as ionic bonds or hydrogen bonds) or chemically (covalent bonds formed by crosslinkers or photo-initiated polymerization). They can be natural polymers (alginate, gelatin, chitosan, agarose) or synthetic polymers (polyethylene glycol, polyacrylamide, polyvinyl alcohol). Some hydrogels comprise interpenetrating networks or are reinforced with nanoparticles to improve mechanical strength.

Many hidrogéls are stimuli-responsive, changing their swelling, porosity, or mechanical properties in response to pH, temperature, ionic strength, or biomolecules. This tunability underpins numerous applications in biomedicine and beyond, including wound dressings, controlled drug delivery, tissue engineering scaffolds, contact lenses, and biosensors. Hydrogels are also used in agriculture, cosmetics, and soft robotics.

Key considerations for design include biocompatibility, degradability, sterilization, and mechanical properties. Natural polymer hydrogels tend to be more biocompatible but less tailorable chemically, while synthetic hydrogels offer greater control over network structure at the cost of compatibility concerns that must be addressed. By adjusting crosslink density and composition, hydrogels can achieve a wide range of swelling and stiffness suitable for specific applications.