title: Study on photophysical and aggregation induced emission recognition of 1,8-naphthalimide probe for casein by spectroscopic method.
abstract: A novel water-soluble 1,8-naphthalimide derivative 1, bearing two acetic carboxylic groups, exhibited fluorescent turn-on recognition for casein based on the aggregation induced emission (AIE) character. The photophysical properties of 1 consisting of donor and acceptor units were investigated in different solutions. The fluorescence intensity decreased through taking advantage of twisted intramolecular charge transfer (TICT) and self-association emission with increasing solvent polarity. Moreover, the spectral red-shift and intensity quench in protic solvents were caused by the excited-state hydrogen bond strengthening effect. Density Functional Theory (DFT) calculations revealed that 1 exhibited a strong TICT character. The AIE mechanism of 1 with casein was due to 1 docked in the hydrophobic cavity between sub-micelles and bound with Tyr and Trp residues, resulting in the aggregation of 1 on the casein surface and emission enhancement. Based on this, a novel casein assay method was developed. The proposed exhibited a good linear range from 0.1 to 22 μg mL(-1), with the detection limit of 2.8 ng mL(-1). Satisfactory reproducibility, reversibility and a short response time were realized. This method was applied to the determination of casein in milk powder samples and the results were in good agreement with the result of Biuret method.
authors: Department of Chemistry & Chemical Engineering, Xi'an University of Arts and Science, No. 168 Taibai South Road, Xi'an, Shaanxi 710065, China. 66160692@qq.com
authors: Yang
authors: Y
authors: Sun
authors: Zhen
authors: Z
authors: Liu
authors: Xuhua
authors: X
authors: Liang
authors: Jun
authors: J
authors: Fan
authors: Quan
authors: Q
authors: Han
mesh_terms: D000042:Absorption; D000818:Animals; D002364:Caseins / Q000032:analysis*; D002942:Circular Dichroism; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry; D008027:Light; D057230:Limit of Detection; D008892:Milk / Q000737:chemistry; D008958:Models, Molecular; D015335:Molecular Probes / Q000737:chemistry*; D053644:Naphthalimides / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D002364:Caseins; D015335:Molecular Probes; D053644:Naphthalimides; D012997:Solvents; D005998:Glycine