Tissue adhesives, often referred to as surgical glues, are specialized medical compounds designed to bond biological tissues. They offer an alternative to traditional wound closure methods like sutures or staples, providing a way to join tissue surfaces without puncturing them. These fluid or semi-fluid mixtures are capable of sealing wounds of various shapes, whether uniform or irregular. Their development has significantly impacted modern medicine by offering new platforms for wound closure and tissue repair.
How Tissue Adhesives Work
Tissue adhesives create a strong bond with biological tissues, often through chemical reactions. A common mechanism involves polymerization, where small molecules called monomers link together to form larger, long chains called polymers. This transformation gives adhesives their bonding capabilities. For instance, cyanoacrylate adhesives polymerize rapidly upon contact with moisture, forming a strong bond between tissues.
Another key principle is cross-linking, which refers to the formation of chemical bonds between or within molecules, creating a network structure. This network enhances the mechanical properties and durability of the adhesive. While chemical bonds provide adhesion, some adhesives also rely on physical interpenetration and electrostatic interactions to bind to the substrate.
Major Types of Tissue Adhesives
Several main categories of tissue adhesives are in clinical use, each with distinct origins and characteristics.
Cyanoacrylates: These synthetic glues polymerize rapidly when exposed to water or blood. They are known for their rapid bonding and high strength. Two primary types used are N-butyl-2-cyanoacrylate and 2-Octyl-cyanoacrylate, with the latter being more flexible and about three times stronger.
Fibrin Sealants: Also called fibrin glues, these are derived from human or animal plasma and mimic the body’s natural clotting process. These biological adhesives typically consist of two components: thrombin and fibrinogen, sometimes with factor XIII and fibronectin. They are biocompatible due to their natural ingredients.
Albumin/Glutaraldehyde Adhesives: These combine bovine albumin with glutaraldehyde to form a strong bond. Another albumin-based adhesive uses human albumin and poly(ethylene glycol) as crosslinking agents, working within eight seconds and able to withstand significant pressure.
Polyethylene Glycol (PEG)-based Sealants: These are hydrophilic, biocompatible synthetic polymers. They are often used with other polymers to create layered structures and function as sealants to prevent fluid and gas leakage. Some PEG-based adhesives use UV light to trigger photopolymerization for activation.
Medical Applications
Tissue adhesives are widely used across various medical fields.
In wound closure, they are a common alternative to sutures or staples for small incisions, lacerations, or surgical wounds, especially in areas like the face or scalp where cosmetic outcomes are a concern. They offer a less invasive option with reduced tissue trauma.
These adhesives also play a role in hemostasis, effectively stopping bleeding during surgical procedures. Fibrin glues, for instance, are widely used for this purpose. Beyond external wounds, tissue adhesives are employed internally to seal leaks of fluids or air, such as patching punctures in the lung or sealing large blood vessels in vascular surgery.
Adhesives are also utilized for the fixation of grafts, aiding in their adherence to wounded skin, such as in burn cases, or attaching tissue flaps during reconstructive surgeries. Specific applications extend to dermatology for minor skin procedures like mole removal, dentistry for bonding restorations or as a suture replacement in oral surgery, and ophthalmology for closing small corneal or conjunctival incisions. They are also used in areas like gastrointestinal endoscopy for hemostasis and fistula repair.
Benefits and Practical Considerations
Tissue adhesives offer several advantages over traditional wound closure methods. They can reduce surgical time due to rapid application. Their use can also lead to improved cosmetic outcomes by reducing scarring. They result in less foreign body reaction compared to sutures.
While offering many benefits, there are also practical considerations for their use. Adhesives may not be suitable for wounds under high tension. Skin irritation can occur with some types of adhesives. Furthermore, while reducing infection risk by avoiding skin perforations, if exudate cannot drain, the wound may have a higher infection risk. The mechanical strength, swelling, and stability of some adhesives can also pose limitations for their broader application.