title: Solder doped polycaprolactone scaffold enables reproducible laser tissue soldering.
abstract: OBJECTIVE
  In this in vitro feasibility study we analyzed tissue fusion using bovine serum albumin (BSA) and Indocyanine green (ICG) doped polycaprolactone (PCL) scaffolds in combination with a diode laser as energy source while focusing on the influence of irradiation power and albumin concentration on the resulting tensile strength and induced tissue damage.
  
  
  METHODS
  A porous PCL scaffold doped with either 25% or 40% (w/w) of BSA in combination with 0.1% (w/w) ICG was used to fuse rabbit aortas. Soldering energy was delivered through the vessel from the endoluminal side using a continuous wave diode laser at 808 nm via a 400 microm core fiber. Scaffold surface temperatures were analyzed with an infrared camera. Optimum parameters such as irradiation time, radiation power and temperature were determined in view of maximum tensile strength but simultaneously minimum thermally induced tissue damage. Differential scanning calorimetry (DSC) was performed to measure the influence of PCL on the denaturation temperature of BSA.
  
  
  RESULTS
  Optimum parameter settings were found to be 60 seconds irradiation time and 1.5 W irradiation power resulting in tensile strengths of around 2,000 mN. Corresponding scaffold surface temperature was 117.4+/- 12 degrees C. Comparison of the two BSA concentration revealed that 40% BSA scaffold resulted in significant higher tensile strength compared to the 25%. At optimum parameter settings, thermal damage was restricted to the adventitia and its interface with the outermost layer of the tunica media. The DSC showed two endothermic peaks in BSA containing samples, both strongly depending on the water content and the presence of PCL and/or ICG.
  
  
  CONCLUSIONS
  Diode laser soldering of vascular tissue using BSA-ICG-PCL-scaffolds leads to strong and reproducible tissue bonds, with vessel damage limited to the adventitia. Higher BSA content results in higher tensile strengths. The DSC-measurements showed that BSA denaturation temperature is lowered by addition of water and/or ICG-PCL.
authors.affiliation: Department of Neurosurgery, Inselspital Bern, University of Bern, 3010 Bern, Switzerland.
authors.forename: Amadé
authors.initials: A
authors.lastname: Bregy
authors.forename: Serge
authors.initials: S
authors.lastname: Bogni
authors.forename: Vianney J P
authors.initials: VJ
authors.lastname: Bernau
authors.forename: Istvan
authors.initials: I
authors.lastname: Vajtai
authors.forename: Felix
authors.initials: F
authors.lastname: Vollbach
authors.forename: Alke
authors.initials: A
authors.lastname: Petri-Fink
authors.forename: Mihai
authors.initials: M
authors.lastname: Constantinescu
authors.forename: Heinrich
authors.initials: H
authors.lastname: Hofmann
authors.forename: Martin
authors.initials: M
authors.lastname: Frenz
authors.forename: Michael
authors.initials: M
authors.lastname: Reinert
mesh_terms: D000818:Animals; D001011:Aorta / Q000502:physiology / Q000601:surgery* / Q000648:ultrastructure; D002152:Calorimetry, Differential Scanning; D002417:Cattle; D005240:Feasibility Studies; D066298:In Vitro Techniques; D007208:Indocyanine Green; D017075:Laser Coagulation; D011091:Polyesters; D011817:Rabbits; D012710:Serum Albumin, Bovine; D013696:Temperature; D013718:Tensile Strength; D054457:Tissue Scaffolds
chemical_list: D011091:Polyesters; C016240:polycaprolactone; D012710:Serum Albumin, Bovine; D007208:Indocyanine Green