title: Quantification of aldehyde terminated heparin by SEC-MALLS-UV for the surface functionalization of polycaprolactone biomaterials.
abstract: A straight forward strategy of heparin surface grafting employs a terminal reactive-aldehyde group introduced through nitrous acid depolymerization. An advanced method that allows simultaneously monitoring of both heparin molar mass and monomer/aldehyde ratio by size exclusion chromatography, multi-angle laser light scattering and UV-absorbance (SEC-MALLS-UV) has been developed to improve upon heparin surface grafting. Advancements over older methods allow quantitative characterization by direct (aldehyde absorbance) and indirect (Schiff-based absorbance) evaluation of terminal functional aldehydes. The indirect quantitation of functional aldehydes through labeling with aniline (and the formation of a Schiff-base) allows independent quantitation of both polymer mass and terminal functional groups with the applicable UV mass extinction coefficients determined. The protocol was subsequently used to synthesize an optimized heparin-aldehyde that had minimal polydispersity (PDI<2) and high reaction yields (yield >60% by mass). The 8 kDa weight averaged molar mass heparin-aldehyde was then grafted on polycaprolactone (PCL), a common implant material. This optimized heparin-aldehyde retained its antithrombin activity, assessed in freshly drawn blood or surface immobilized on PCL films. Anticoagulant activity was equal to or better than the 24 kDa unmodified heparin it was fragmented from.
authors.affiliation: Nanyang Technological University, Materials and Science Engineering, Division of Materials Technology, N4.1-01-30, 50 Nanyang Ave, Singapore 639798, Singapore. Electronic address: sairvine@ntu.edu.sg.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Irvine
authors.affiliation: Nanyang Technological University, Materials and Science Engineering, Division of Materials Technology, N4.1-01-30, 50 Nanyang Ave, Singapore 639798, Singapore. Electronic address: wjsteele@ntu.edu.sg.
authors.forename: Terry W J
authors.initials: TW
authors.lastname: Steele
authors.affiliation: Nanyang Technological University, Materials and Science Engineering, Division of Materials Technology, N4.1-01-30, 50 Nanyang Ave, Singapore 639798, Singapore. Electronic address: BRamya@ntu.edu.sg.
authors.forename: Ramya
authors.initials: R
authors.lastname: Bhuthalingam
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 117576, Singapore. Electronic address: chelim@nus.edu.sg.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.affiliation: Nanyang Technological University, Materials and Science Engineering, Division of Materials Technology, N4.1-01-30, 50 Nanyang Ave, Singapore 639798, Singapore; Sorbonne Universités, UPMC Univ Paris 6, UMR CNRS 7197, Laboratoire de Réactivité de Surface, F75005 Paris, France; CNRS, UMR 7197, Laboratoire de Réactivité de Surface, F75005 Paris, France. Electronic address: souhir.boujday@upmc.fr.
authors.forename: Souhir
authors.initials: S
authors.lastname: Boujday
authors.affiliation: Nanyang Technological University, Materials and Science Engineering, Division of Materials Technology, N4.1-01-30, 50 Nanyang Ave, Singapore 639798, Singapore. Electronic address: melissa.ps@gmail.com.
authors.forename: Melissa
authors.initials: M
authors.lastname: Prawirasatya
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Kent Ridge, Singapore 117576, Singapore; National University Hospital, Kent Ridge, Singapore 117576, Singapore. Electronic address: chenkg@nus.edu.sg.
authors.forename: Koon Gee
authors.initials: KG
authors.lastname: Neoh
authors.affiliation: Nanyang Technological University, Materials and Science Engineering, Division of Materials Technology, N4.1-01-30, 50 Nanyang Ave, Singapore 639798, Singapore. Electronic address: mycboey@e.ntu.edu.sg.
authors.forename: Freddy Yin Chiang
authors.initials: FY
authors.lastname: Boey
authors.affiliation: Nanyang Technological University, Materials and Science Engineering, Division of Materials Technology, N4.1-01-30, 50 Nanyang Ave, Singapore 639798, Singapore. Electronic address: assubbu@ntu.edu.sg.
authors.forename: Subbu S
authors.initials: SS
authors.lastname: Venkatraman
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D001672:Biocompatible Materials; D006493:Heparin / Q000032:analysis* / Q000737:chemistry; D011091:Polyesters / Q000737:chemistry*; D012545:Schiff Bases / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D013499:Surface Properties
chemical_list: D000447:Aldehydes; D001672:Biocompatible Materials; D011091:Polyesters; D012545:Schiff Bases; C016240:polycaprolactone; D006493:Heparin
keywords: Aniline; Heparin; Size exclusion chromatography; Surface functionalization