title: Collagen-collagen interactions mediated by plant-derived proanthocyanidins: A spectroscopic and atomic force microscopy study.
abstract: Collagen cross-linkings are determinant of biological tissue stability and function. Plant-derived proanthocyanidins (PACs) mimic different hierarchical levels of collagen cross-links by non-enzymatic interactions resulting in the enhancement to the biomechanics and biostability of collagen-rich tissues such as dentin. This study investigated the interaction of PACs from Vitis vinifera grape seed extract with type I collagen in solubilized form and in the demineralized dentin matrix (DDM) by fluorescence spectral analysis; collagen-collagen binding forces in presence of cross-linking solutions by atomic force microscopy (AFM); and spectroscopic analysis of the DDM using attenuated total reflectance Fourier transform-infrared spectroscopy (ATR-FTIR). Glutaraldehyde (GA) and carbodiimide hydrochloride (EDC) with known cross-linking mechanisms were selected for comparative analyses. Changes in fluorescence upon interaction of solubilized type I collagen with PACs, EDC and GA reflected pronounced modifications in collagen conformation. PACs also promoted stronger collagen-collagen fibrils interaction than EDC and GA. A new feature was observed using ATR-FTIR spectroscopic analysis in PACs-treated collagen and DDM. The findings suggest covalent interactions between collagen and PACs. The mechanisms of interaction between PACs-collagen hold attractive and promising tissue-tailored biomedical applications and the binding forces that potentially drive such interaction were characterized.
  
  
  
  Connective tissues such as skin, bone and dentin are mainly composed of type I collagen, which is cross-linked to promote tissue stability, strength and function. Novel therapies using substances that mimic cross-links have been proposed to promote repair of collagen-based-tissues. In dentistry, naturally occurring proanthocyanidins (PACs) have the potential to enhance dentin mechanical properties and reduce its enzymatic degradation, but their mechanisms of cross-linking are unclear. The present study investigated the specific interactions between PACs-type I collagen in purified and dentin collagen and compared to the well described cross-linking mechanisms promoted by synthetic chemical substances. Findings reveal that covalent-like bonds are induced by plant PACs in type I collagen as well as in complex dental native tissue, promoting strong collagen-collagen interactions.
authors.affiliation: College of Dentistry, University of Illinois at Chicago, 801 South Paulina Street, Chicago, IL 60612, USA.
authors.forename: Cristina M P
authors.initials: CM
authors.lastname: Vidal
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, IL 60607, USA.
authors.forename: Weiying
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Biomedical Engineering Department, McCormick School of Engineering, Northwestern University, Technological Institute, 2145 Sheridan Road, Evanston, IL 60208, USA.
authors.forename: Suresh
authors.initials: S
authors.lastname: Manohar
authors.affiliation: College of Dentistry, University of Illinois at Chicago, 801 South Paulina Street, Chicago, IL 60612, USA.
authors.forename: Berdan
authors.initials: B
authors.lastname: Aydin
authors.affiliation: Department of Chemistry, University of Illinois at Chicago, 845 West Taylor Street, Chicago, IL 60607, USA.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Keiderling
authors.affiliation: Biomedical Engineering Department, McCormick School of Engineering, Northwestern University, Technological Institute, 2145 Sheridan Road, Evanston, IL 60208, USA; Departments of Materials Science and Engineering and Bioengineering, College of Engineering, University of California, 210 Hearst Mining Building, Berkeley, CA 94720-1760, USA.
authors.forename: Phillip B
authors.initials: PB
authors.lastname: Messersmith
authors.affiliation: College of Dentistry, University of Illinois at Chicago, 801 South Paulina Street, Chicago, IL 60612, USA. Electronic address: bedran@uic.edu.
authors.forename: Ana K
authors.initials: AK
authors.lastname: Bedran-Russo
mesh_terms: D000818:Animals; D003094:Collagen / Q000378:metabolism*; D006046:Gold / Q000494:pharmacology; D018625:Microscopy, Atomic Force / Q000379:methods*; D044945:Proanthocyanidins / Q000494:pharmacology*; D051381:Rats; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D044945:Proanthocyanidins; D006046:Gold; D003094:Collagen
keywords: ATR-FTIR spectroscopy; Atomic force microscopy; Collagen cross-linking; Dentin; Proanthocyanidins