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Green synthesis of multi-color emissive carbon dots from Manilkara zapota fruits for bioimaging of bacterial and fungal cells

Bhamore, Jigna R., Jha, Sanjay, Park, Tae Jung, Kailasa, Suresh Kumar
Journal of photochemistry and photobiology 2019 v.191 pp. 150-155
Aspergillus aculeatus, Escherichia coli, Fomitopsis, Manilkara zapota, biocompatibility, carbon quantum dots, color, cytoplasm, cytotoxicity, emissions, fruits, fungi, human cell lines, image analysis, phosphoric acid, sulfuric acid, ultraviolet radiation
Natural resources have widely been used as precursors for the preparation of ultra-small carbon dots (C-dots) due to ease of availability, low cost and C-dots with high quantum yields (QYs). Herein, water dispersible multi-color emissive C-dots were obtained from Manilkara zapota fruits. The emission of C-dots was well tuned by sulphuric acid and phosphoric acids, which results to generate blue-, green- and yellow- C-dots. The fabricated C-dots exhibit blue, green and yellow color emissions when irradiated them under UV light at 365 nm. The emission/excitation peaks of blue-, green-, and yellow- C-dots were observed at 443, 515 and 563 nm when excited at 350, 420 and 440 nm, respectively. The QYs of blue-, green-, and yellow- C-dots are 5.7, 7.9 and 5.2%. The average sizes of blue- green- and yellow- C-dots are 1.9 ± 0.3, 2.9 ± 0.7and 4.5 ± 1.25 nm, respectively. Because of ultra-small size and biocompatibility, three C-dots act as promising bioimaging agents for imaging of cells (E. coli, Aspergillus aculeatus and Fomitopsis sp). The cytotoxicity on HeLa cells indicates that three C-dots have non-toxic nature, which confirms their biocompatibility. The ultra-small C-dots were effectively distributed in the cytoplasm of the cells, ensuring the potential applications in cell imaging and biomedical studies.