title: Labeling the Structural Integrity of Nanoparticles for Advanced In Situ Tracking in Bionanotechnology.
abstract: Observing structural integrity of nanoparticles is essential in bionanotechnology but not always straightforward to measure in situ and in real-time. Fluorescent labels used for tracking intrinsically nonfluorescent nanomaterials generally do not allow simultaneous observation of integrity. Consequently, structural changes like degradation and disassembly cannot easily be followed in situ using fluorescence signals. We show that thioflavin T (ThT), a fluorophore and molecular rotor known to tag specific fibril structures in amyloids, can "label" the structural integrity of widely used and intrinsically nonfluorescent, silica nanoparticles (SiNPs). Entrapment of ThT in SiNPs controls the fluorohphore's relaxation pathway and leads to a red-shifted fluorescence spectrum providing real time information on SiNP integrity. The dynamic change of ThT fluorescence during degradation of doped SiNPs is found much higher than that of common labels fluorescein and rhodamine. Degradation kinetics of core-shell structures recorded by ThT fluorescence and light scattering prove the capability to clearly distinguish structural features during SiNPs degradation and allow obtaining degradation kinetics in vitro, in biological media, in serum, and in cells. The effect is transferable to different types of materials, here shown for ThT incorporated SiNPs with tightly tailorable sizes (9-100 nm), poly(lactic-co-glycolic acid) (PLGA) nanoparticles, poly(9-vinylcarbazole) (PVK) nanoparticles, and iron-doped-SiNPs (FeSiNPs). We thus suggest molecular rotors such as ThT as additional labels to effectively and easily sense nanoparticle structural status in situ and to enhance understanding and development of programmed nanoparticle disassembly in bionanotechnology.
authors.affiliation: Centre for BioNano Interactions, University College Dublin , School of Chemistry and Chemical Biology, Belfield 4, Dublin, Ireland.
authors.forename: Fabian
authors.initials: F
authors.lastname: Meder
authors.affiliation: Centre for BioNano Interactions, University College Dublin , School of Chemistry and Chemical Biology, Belfield 4, Dublin, Ireland.
authors.forename: Steffi S
authors.initials: SS
authors.lastname: Thomas
authors.affiliation: Centre for BioNano Interactions, University College Dublin , School of Chemistry and Chemical Biology, Belfield 4, Dublin, Ireland.
authors.forename: Laurence W
authors.initials: LW
authors.lastname: Fitzpatrick
authors.affiliation: Centre for BioNano Interactions, University College Dublin , School of Chemistry and Chemical Biology, Belfield 4, Dublin, Ireland.
authors.forename: Amirah
authors.initials: A
authors.lastname: Alahmari
authors.affiliation: Functional Nanomaterials, University College Dublin , School of Chemistry and Chemical Biology, Belfield 4, Dublin, Ireland.
authors.forename: Suxiao
authors.initials: S
authors.lastname: Wang
authors.affiliation: Functional Nanomaterials, University College Dublin , School of Chemistry and Chemical Biology, Belfield 4, Dublin, Ireland.
authors.forename: Jason G
authors.initials: JG
authors.lastname: Beirne
authors.affiliation: Centre for BioNano Interactions, University College Dublin , School of Chemistry and Chemical Biology, Belfield 4, Dublin, Ireland.
authors.forename: Gizela
authors.initials: G
authors.lastname: Vaz
authors.affiliation: Functional Nanomaterials, University College Dublin , School of Chemistry and Chemical Biology, Belfield 4, Dublin, Ireland.
authors.forename: Gareth
authors.initials: G
authors.lastname: Redmond
authors.affiliation: Centre for BioNano Interactions, University College Dublin , School of Chemistry and Chemical Biology, Belfield 4, Dublin, Ireland.
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Dawson
keywords: biodegradation; bionano interactions; core−shell nanoparticles; differential centrifugal sedimentation; fluorescence labeling; molecular rotors; silica