The microstructure of collagen type I gel cross-linked with gold nanoparticles

Scanning electron microscopy, transmission electron microscopy, rheometry, and electrochemistry were used to provide insight into the microstructure of collagen type I gel (1%, w/v) modified with the tiopronin-protected (N-(2-mercaptopropionyl)glycine) gold nanoparticles (TPAu), a multivalent crosslinker. The cross-linking reaction, performed via EDC (1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide) coupling, results in compliant, mechanically stable and continuous gels. The gels contain unusual interconnected collagen-TPAu particles. Electrochemical measurements of 4-hydroxy-(2,2,6,6-tetramethylpiperidine-1-oxyl) (4HT) diffusion within the gel reveal that the gel hindrance is nearly independent of the TPAu concentration. The properties of the collagen-TPAu gel make it suitable for potential biomedical applications, such as delivery of small molecule drugs.

Graphical abstract. SEM and TEM images of collagen gel modified with gold nanoparticles.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Collagen gels cross-linked with Au-nanoparticles were synthesized and characterized. ► The gels contain unusual morphology: interconnected collagen-Au-nanoparticle particles (150–400 nm). ► The gels are compliant, mechanically stable, and continuous. ► Electrochemical measurements show the gel hindrance nearly independent of the Au-nanoparticle concentration.