title: Monitoring sol-to-gel transitions via fluorescence lifetime determination using viscosity sensitive fluorescent probes.
abstract: The sol-to-gel transition was monitored via the use of time-resolved recording of the fluorescence emission of viscosity-sensitive probes. Two dyes were chosen for the study, water-soluble DASPMI and a hydrophobic BODIPY, and steady-state, time-resolved and time-tagged fluorescence measurements were performed. These techniques, coupled with the probes different solubility, allowed complementary fluorescence lifetime and intensity data to be obtained from the dyes introduced into the matrix-forming mixture to produce sol-gel derived monoliths. Two different precursors were used as examples. A hydrogel was formed from a commercially available gellan gum (Gelrite), and a glass-like monolith was formed using tetraethyl orthosilicate. Changes in fluorescence lifetime could be related to those in the local viscosity sensed by the probe. The combination of this type of probe with time-resolved measurements is extremely useful in monitoring the microscopic changes that occur during the sol-to-gel transition within this important class of materials.
authors.affiliation: HORIBA Jobin Yvon IBH Ltd., Glasgow G3 8JU, U.K. graham.hungerford@ibh.co.uk
authors.forename: Graham
authors.initials: G
authors.lastname: Hungerford
authors.forename: Archie
authors.initials: A
authors.lastname: Allison
authors.forename: David
authors.initials: D
authors.lastname: McLoskey
authors.forename: Marina K
authors.initials: MK
authors.lastname: Kuimova
authors.forename: Gokhan
authors.initials: G
authors.lastname: Yahioglu
authors.forename: Klaus
authors.initials: K
authors.lastname: Suhling
mesh_terms: D001896:Boron Compounds / Q000494:pharmacology*; D002627:Chemistry, Physical / Q000379:methods; D005456:Fluorescent Dyes / Q000494:pharmacology*; D005990:Glycerol / Q000737:chemistry; D008274:Magnesium / Q000737:chemistry; D008956:Models, Chemical; D015233:Models, Statistical; D008962:Models, Theoretical; D044367:Phase Transition; D011726:Pyridinium Compounds / Q000494:pharmacology*; D017640:Silicates / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D005456:Fluorescent Dyes; D011726:Pyridinium Compounds; D017640:Silicates; D014867:Water; C011786:2-(4-(dimethylamino)styryl)-1-methylpyridinium; D008274:Magnesium; D005990:Glycerol