title: Incorporation of quantum dots in silk biomaterials for fluorescence imaging.
abstract: Tracking the distribution and degradation of biomaterials afterin vivoimplantation or injection is important for tissue engineering and drug delivery. Intrinsic and externally labeled fluorescence has been widely used for these purposes. In the present study, 3-mercaptopropionic acid (MPA)-coated CdTe quantum dots (QDs) were incorporated into silk materials via strong interactions between QDs and silk, likely involving the hydrophobic beta-sheet structures in silk. MPA-QDs were pre-mixed with silk solution, followed by ultrasonication to induce silk gelation or by blending with polyvinyl alcohol (PVA) to generate silk microspheres. Silk structural changes and hydrogel/microsphere morphologies were examined by ATR-FTIR and SEM, respectively. The fluorescence of QDs-incorporated silk hydrogels and microspheres remained stable in PBS pH 7.4 for more than 4 days. The amount of QDs released from the materials during the incubation was dependent on loading; no QDs were released when loading was below 0.026 nmol/mg silk. After subcutaneous injection in mice, the fluorescence of QDs-incorporated silk microspheres was quenched within 24 h, similar to that of free QDs. In contrast, the QDs-incorporated silk hydrogels fluoresced for more than 4 daysin vivo.
authors.affiliation: National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, China 215123.
authors.forename: Z Z
authors.initials: ZZ
authors.lastname: Zheng
authors.affiliation: The Cyrus Tang Hematology Center, Jiangsu Institute of Hematology, Soochow University, Suzhou, China 215123.
authors.forename: M
authors.initials: M
authors.lastname: Liu
authors.affiliation: National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, China 215123.
authors.forename: S Z
authors.initials: SZ
authors.lastname: Guo
authors.affiliation: National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, China 215123.
authors.forename: J B
authors.initials: JB
authors.lastname: Wu
authors.affiliation: College of Chemical Engineering and Material Chemistry, Heilong jiang University, Harbin, China 150086.
authors.forename: D S
authors.initials: DS
authors.lastname: Lu
authors.affiliation: National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, China 215123.
authors.forename: G
authors.initials: G
authors.lastname: Li
authors.affiliation: National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, China 215123.
authors.forename: S S
authors.initials: SS
authors.lastname: Liu
authors.affiliation: National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, China 215123.
authors.forename: X Q
authors.initials: XQ
authors.lastname: Wang
authors.affiliation: National Engineering Laboratory for Modern Silk, Soochow University, Suzhou, China 215123 ; Department of Biomedical Engineering, Tufts University, Medford, Massachusetts, USA 02155.
authors.forename: D L
authors.initials: DL
authors.lastname: Kaplan
keywords: fluorescence imaging; hydrogel; quantum dots; silk