Title : Preparation and bio-medical application of highly photoluminescent carbon nanodots derived from carbonized bamboo
In the quest to develop carbon nanomaterials, carbon nanodots (CND) are attracting considerable interest for use in nanoscale material, with applications ranging from high-performance electrochemistry to biomaterials. In this study, we will used carbonized bamboo through thermal dissociation followed by aqueous extraction to obtained highly water dispersible and photoluminescent CNDs. Using this approach, we obtained a highly water dispersible aqueous solution of CNDs from the carbonized bamboo black powder, the concentration of which was 0.516 mg/mL; the yield, after extracting 5 g of carbonized bamboo with 100 mL of water, was approximately 1%. Our CNDs exhibited high photoluminescence with a value of λem of 430 nm, a fluorescence quantum yield (QY) of 4.2 %, a particle size of approximately 3–5 nm, and presented both COOH and OH functionalities. The presence of this nanostructure explains the transparency in aqueous media. Our top-down approach using carbonized bamboo allowed the preparation of CNDs having nano-size particles in aqueous solution. When irradiated with a UV lamp (365 nm, 4.5 W), blue PL emission occurred from the aqueous CND solutions. Fluorescence emission spectra of the aqueous CNDs solutions after excitation at wavelengths from 270 nm with an increment of 10 nm; we also obtained corresponding optical fluorescence images of these solutions under UV irradiation at 365 nm. The emission wavelength exhibited excitation wavelength–dependent PL behavior: it ranged from 412 to 430 nm when the excitation wavelength was increased from 270 to 320 nm. In addition, increasing the excitation wavelength increased the intensity of the PL emission. We suspected that the PL behavior of our CNDs could be attributed to many factors, including emissive traps, quantum confinement, and electronically conjugated structures. The XRD pattern of the CNDs displayed a broad peak centered near a value of 2θ of 23.8°, corresponding to the graphitic (002) lattice spacing. This broad XRD peak suggested that the CNDs featured weakly graphitic crystallinity with a d-spacing of approximately 3.8 Å, arising from to the presence of oxygen-containing functional groups on the CND surface. The Raman spectrum of our CNDs exhibits a graphitic band (G band; sp2-hybridized carbon atoms) at 1580 cm–1 and a disorder band (D band; sp3-hybridized carbon atoms) at 1380 cm–1. The relative intensity of the D and G bands, ID/IG, can be used to characterize the quality of defective disorders or graphitization in CND materials. Our value of ID/IG (1.03) reveals a high degree of defects, which we attribute to oxygen-containing functional groups on the CNDs. All of these characterization data suggest the successful preparation of fluorescent CNDs from biosourced carbonized bamboo. Its excellent photoluminescence and biocompatibility provides a bio-medical potential for the cell-image and drug delivery system.
• 0-dimension CNDs is a photoluminescent carbon-based nanomaterial, possessing low cell toxicity, low photobleaching behavior and stable water dispersity.
• CNDs possess excellent photoluminescence and biocompatibility as potential for cell-image and drug delivery.
• Our CNDs could obtained through carbonized bamboo following by aqueous extraction, which possess highly water dispersible, photoluminescent, and 3-5nm particle size.