On the basis of microwave treatment of chitosan solution, a convenient in situ method is established to form fluorescent carbon dots/chitosan composites which can be directly used in subsequent applications. This method has many benefits including prompt operation, simple equipment, simplified post-treatment, "green" process and low cost, and it allows a convenient way to gain carbon dots/chitosan nanocomposites that can be directly used for wide applications. The analysis results indicate that the carbon dots/chitosan composite solution is transparent and homogeneous. In addition, the carbon dots/chitosan composite solution displays brown color under visible light, while presents clear blue fluorescence under 365 nm UV light. Transmission electron microscopy test exhibits that carbon dots disperse well in the carbon dots/chitosan composite, and the average size of carbon dots is about 7.0 nm. Specially, the obtained carbon dots/chitosan composite not only has attractive properties (e.g., multicolor fluorescence) that belong to carbon dots, but also retains the favorable properties (e.g., pH-responsive properties) of chitosan. Based on these combined properties, it is convenient to employ the carbon dots/chitosan composite to construct fluorescent films by casting method, to prepare fluorescent beads by a convenient dropping procedure, as well as to generate fluorescent coatings on electrodes by electrodeposition technique. Furthermore, the carbon dots/chitosan composite can be directly applied to cell imaging. Thus,this carbon dots/chitosan composite constructed by in situ method has potential applications in fluorescent materials, electrodeposited coatings, drug carriers, bioimaging and biolabeling.
