title: In vivo imaging of the morphology and changes in pH along the gastrointestinal tract of Japanese medaka by photonic band-gap hydrogel microspheres.
abstract: Colloidal crystalline microspheres with photonic band-gap properties responsive to media pH have been developed for in vivo imaging purposes. These colloidal crystalline microspheres were constructed from monodispersed core-shell nano-size particles with poly(styrene-co-acrylic acid) (PS-co-PAA) cores and poly(acrylic acid-co-N-isopropylacrylamide) (PAA-co-PNIPAM) hydrogel shells cross-linked by N,N'-methylenebisacrylamide. A significant shift in the photonic band-gap properties of these colloidal crystalline microspheres was observed in the pH range of 4-5. This was caused by the discontinuous volume phase transition of the hydrogel coating, due to the protonation/deprotonation of its acrylic acid moieties, on the core-shell nano-sized particles within the microspheres. The in vivo imaging capability of these pH-responsive photonic microspheres was demonstrated on a test organism - Japanese medaka, Oryzia latipes - in which the morphology and change in pH along their gastrointestinal (GI) tracts were revealed under an ordinary optical microscope. This work illustrates the potential of stimuli-responsive photonic band-gap materials in tissue-/organ-level in vivo bio-imaging.
authors.affiliation: Advanced Laboratory for Environmental Research & Technology, USTC-CityU, Suzhou 215123, China.
authors.forename: Xuemin
authors.initials: X
authors.lastname: Du
authors.forename: Ngai-Yu
authors.initials: NY
authors.lastname: Lei
authors.forename: Peng
authors.initials: P
authors.lastname: Hu
authors.forename: Zhang
authors.initials: Z
authors.lastname: Lei
authors.forename: Daniel Hock-Chun
authors.initials: DH
authors.lastname: Ong
authors.forename: Xuewu
authors.initials: X
authors.lastname: Ge
authors.forename: Zhicheng
authors.initials: Z
authors.lastname: Zhang
authors.forename: Michael Hon-Wah
authors.initials: MH
authors.lastname: Lam
mesh_terms: D000818:Animals; D041981:Gastrointestinal Tract / Q000737:chemistry* / Q000196:embryology*; D020100:Hydrogels / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008863:Microspheres; D055620:Optical Phenomena; D009924:Organ Culture Techniques; D009990:Oryzias / Q000196:embryology*
chemical_list: D020100:Hydrogels
keywords: Gastrointestinal tract; In vivo imaging; Japanese medaka; Photonic band-gap microspheres; pH-responsive