Aggregation induced emission enhancement and growth of naphthalimide nanoribbons via J-aggregation: insight into disaggregation induced unfolding and detection of ferritin at the nanomolar level. Issue 36 (26th August 2016)

• Record Type: Journal Article
• Authors: Meher, Niranjan; Chowdhury, Sayan Roy; Iyer, Parameswar Krishnan
• Is Part Of: Journal of materials chemistry. Volume 4:Issue 36(2016)
• Page Start: 6023
• Page End: 6031
• Publication Date: 2016-08-26
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Biomedical materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/c6tb01746k
• Languages: English
• ISSNs: 2050-750X

Abstract

Abstract : A core substituted naphthalimide AIEEgen displays unusual nanoribbon growth in aqueous media with ultra-sensitivity towards non-heme protein ferritin at physiological conditions. Abstract : A series of novel V-shaped naphthalimide derivatives are reported herein, designed through a strategy to achieve aggregation induced emission (AIE), giving rise to unexpected self-assembly properties. This includes an aggregation induced emission enhancement (AIEE) active small organic molecule viz. naphthalimide derivative functionalized with 8-hydroxyquinoline (α-NQ ), that spontaneously forms highly fluorescent "nanoribbon" like structures with <100 nm diameter and hundreds of micron length in aqueous media irrespective of concentration and surface at room temperature. The classical head-to-tail π–π stacking, as revealed by the single crystal X-ray study, was found to be the main driving force for the J-type aggregation with unique self-aggregating behavior. A comparative mechanistic study confirms that the N-atom in the hydroxyquinoline moiety is responsible for directing the entire molecular behavior in solution as well as in its aggregated state. Theseα-NQ nanoribbons formed in aqueous media were found to be highly sensitive and selective towards the multi-functional nonheme protein ferritin ( K sv = 0.83 × 10 7 M −1 ) with a limit of detection 67.25 × 10 −11 M (0.33 ng μL −1 ) under physiological conditions, which serves as a well-known inflammatory marker for various diseases. The fluorescent nanoribbons were also found to modify the α-helix content of ferritin, thereby inducing conformational changes in their secondary structure as confirmed through circular dichroism (CD) spectroscopy techniques. Collectively, these findings improve the fundamental understanding of the self-assembly of AIEE active molecules along with the photophysical properties of core substituted naphthalimide derivatives that report the highest sensitivity towards ferritin in the presence of a bright AIEEgen under physiological conditions.