2 research outputs found
Synthesis of pH-Sensitive Fluorescein Grafted Cellulose Nanocrystals with an Amino Acid Spacer
Fluorescent
labeled nanoparticles are expected to have potential applications
in biological and imaging systems. In this study, in order to construct
the fluorescent nanoparticles for pH-sensing, l-leucine amino
acid is used as a spacer linker between cellulose nanocrystals (CNCs)
and a pH-indicator dye (5 (and 6)-carboxy-2′,7′-dichloroÂfluorescein,
CDCF). Characterization by Fourier transform infrared (FTIR), nuclear
magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS)
is adopted to follow the chemical modification, whereas the morphology
is determined by atomic force microscopy (AFM). The crystallinity
determined by NMR for the CNCs, A-CNCs, and F-A-CNCs is 78.32, 79.84,
and 79.52, respectively. The quantitative analysis by elemental analysis
revealed that the degree of cellulose hydroxyl group substitution
(DS) of A-CNCs and F-A-CNCs is 0.05 and 0.27, respectively. According
to the obtained results, CDCF fluorescein could be successfully labeled
onto CNCs via l-leucine amino acid spacer linking, and the
cellulose structure is stable during the labeling reaction. The fluorescent
properties of the yielding pH-sensitive fluorescent CNCs (F-A-CNCs)
are characterized by fluorescence spectrometer and imaged by confocal
laser scanning microscopy (CLSM). The result shows that the fluorescence
intensity of F-A-CNCs increases with increasing pH of the buffer from
2.28 to 10.84