Biomedical

Among the wide variety of synthetic polymers with medical applications polymerising medical devices are those non-pharmaceutical medical aids which are based on monomers which can be polymerised after (or during) application to the body. The resultant polymers perform roles in wound management, repair, stabilisation and hemostasis. They can also support tissue re-growth, as well as being used for drug delivery. The synthetic systems most commonly used are based around acrylic ester chemistries, analogous to their non-medical uses as plastics and adhesives. 

Tissue adhesives represent a group of natural and artificial compounds that are currently used for a variety of local applications including hemostasis, wound closure, and fistula repair. The most commonly utilized tissue adhesives in GI endoscopy include cyanoacry- lates, fibrin glues, and thrombin. Other adhesives, such as collagen-based sealants and PEG polymers, are beginning to be studied in various surgical disciplines and may one day find a role in endoscopic practice as well.

This CICAD on methyl cyanoacrylate and ethyl cyanoacrylate was based on a review of human health concerns (primarily occupational) prepared by the United Kingdom’s Health and Safety Executive (HSE) (Cary et al., 2000). Hence, this document focuses on exposures via routes relevant to occupational settings. Data identified as of September 1999 were covered. A further literature search was performed up to February 2000 to identify any extra information published since this review was completed.

By using fluorescent polysorbate 80 coated poly(n-butylcyanoacrylate) (PBCA) nanoparticles in an in vivo study, direct evidence was found for the presence of nanoparticles entering the brain and retina of rats. The nanoparticles, prepared with a miniemulsion process, were labeled in situ with a fluorescent dye and coated with polysorbate 80. After preparation the particle size, ζ potential, and the molecular weight distribution were determined. BMEC cells were used as an in vitro model for the BBB.

Although liquid adhesives or glue have been used as embolic agents for nearly three decades, experience with them outside of neurointerventional indications is generally limited. Cyanoacrylates are the main liquid adhesives used in the vascular system and have an important role in managing vascular abnormalities, especially arteriovenous malformations. Vascular occlusion results as these agents polymerize on exposure to the ions in blood.

Cyanoacrylate glues are easily applied to wounds with good cosmetic results. However, they tend to be brittle and can induce local tissue toxicity. A series of cyanoacrylate monomers with a flexible ether linkage and varying side-chain lengths was synthesized and characterized for potential use as tissue adhesives. The effect of side-chain length on synthesis yield, physical and mechanical properties, formaldehyde generation, cytotoxicity in vitro and biocompatibility in vivo were examined.

Despite the latest polymer materials and surgical suturing techniques, the knot will always be the weakest point of the tied suture loop. In theory, the knot must be as small as possible to prevent an excessive amount of tissue reaction and a delay in healing. There have been reports suggesting that topical cyanoacrylate adhesives could have a reinforcing effect on a surgeon’s knot. Such an outcome could lead to the elimination of knot slippage and the unsatisfactory performance of some surgical knots.