Synthesis and characterisation of poly(glycerol sebacate)-co-lactic acid as surgical sealants Qizhi Chen, * ab Shuling Liang a and George A. Thouas c Received 27th February 2011, Accepted 3rd May 2011 DOI: 10.1039/c1sm05350g Surgical sealants are currently used in conjunction with sutures to reduce the incidence of air or fluid leaks. Although fibrin and collagen sealants can effectively promote wound healing, there are serious concerns about blood-borne virus contamination. Hence, synthetic sealants have been considered a safer alternative. In this work, a new family of synthetic surgical sealant copolymers were derived from poly(glycerol sebacate) (PGS) and lactic acid (LA). The newly developed PGS-co-LA tissue sealants had significantly higher adhesive strength than either fibrin sealants or synthetic PleuraSealÔ. Secondly, the addition of lactic acid to PGS significantly improved the cytocompatibility of the materials, compared with pure PGS. Thirdly, the new sealants were able to be pasted in liquid form at 45  C, which subsequently solidified into a soft wax-like patch at body temperature. These properties make the PGS-co-LA materials promising candidates for soft tissue sealants. Introduction The need for an effective, biocompatible and degradable sealant for rapid sutured closure has been widely recognized. 1 Preventing alveolar air leaks after pulmonary resections 2 and cerebrospinal fluid leak after neurosurgery 3 represent two clinical application scenarios which require surgical sealants. The incidence of pulmonary air leakage during lung surgery is reported to be as high as 70%. 4 Persistent air leakage, lasting longer than 7 days, occurs in 15–25% of patients and is a major limiting factor for discharge from hospital due to the need for prolonged chest tube drainage. 2,5 Cerebrospinal fluid leak post-operative occurrence has also been reported in up to 11% cases. 3 These complications may lead to greater post-operative pain, longer hospital stays and increased mortality. Surgical sealants have been developed to prevent or to reduce the incidence of air or fluid leaks. Surgical sealants are applied during the operation over the tissue surfaces that show air or fluid leaks. When used in conjunction with sutures, in situ setting sealant technologies should allow for the creation of leak-free closures. In order to function adequately, sealants must have sufficient tissue adherent strength which is adequate to withstand leaks through needle holes, whilst the suture line heals naturally underneath. 6 Sealant materials must also be flexible and compliant to accommodate the geometric changes of the elastic tissue. Ideally, tissue sealants should also be bioresorbable to obviate the long term detrimental effects associated with persisting foreign substances within the body, and eliminate the need for a second operation to remove a non-degradable device. Over the last decade, a number of surgical sealants have been introduced for prevention and reduction of air leaks. 7 These include naturally occurring proteins, such as fibrin-based seal- ants 8–10 and collagen fleece-bound sealants; 11–14 and synthetic sealants including cyanoacrylates and polyethylene glycol (PEG)-based compounds. 15–17 Although fibrin and collagen sealants effectively promote wound healing, much like their natural role in clot formation, there are serious concerns about blood-borne virus contamination (e.g. hepatitis B, HIV-1, and parvovirus), 18 and for this reason synthetic sealants have been considered a safer alternative. Moreover, fibrin, collagen and cyanoacrylate sealants are all used in situ, and become chemically crosslinked onto the target tissue. These sealants begin to cure immediately upon application to tissues, thus limiting the ability of the surgeon to adjust their position as required. 8–10 Light cured sealants, on the other hand, have the advantage of allowing controlled adhesion when required by the surgeon. The PEG- based sealants are an example of photo-crosslinkable synthetic sealants that become polymerised onto tissue surfaces upon crosslinking. However, it takes time to apply and set such a sealant, and photoactivation is not feasible in some situations such as during haemorrhaging. 18,19 Hence it is highly desirable to develop a pre-polymerised sealant that can be applied as a liquid and subsequently solidified and bond to tissue surface in a controllable manner. Further to our previous work in using elastomers as a struc- tural scaffold for cardiac repair, 20 we have also been working towards developing this family of synthetic materials into tissue sealants, using poly(glycerol sebacate) (PGS) and poly(glycerol a Department of Materials Engineering, Monash University, Clayton, Victoria, 3800, Australia. E-mail: Qizhi.chen@monash.edu b Division of Bioengineering, Monash University, Clayton, Victoria, 3800, Australia c Department of Zoology, The University of Melbourne, Parkville, Victoria, 3010, Australia 6484 | Soft Matter , 2011, 7, 6484–6492 This journal is ª The Royal Society of Chemistry 2011 Dynamic Article Links C < Soft Matter Cite this: Soft Matter , 2011, 7, 6484 www.rsc.org/softmatter PAPER Downloaded by Monash University on 03 August 2011 Published on 09 June 2011 on http://pubs.rsc.org | doi:10.1039/C1SM05350G View Online