**1. Introduction**

In recent past, carbon dots have gained considerable importance as a versatile material formultiple applications [1, 2]. Usually they possess a sp2 conjugated core with various oxygencontaining functionalities such as carboxyl, hydroxyl, aldehyde groups etc. [3, 4]., ease of functionalization, and production of fluorescence on UV exposure,carbon dots (CDs) find a number of biomedical applications like bioimaging [5–7], targeteddrug delivery [8, 9], wound dressings [10], cancer theranostics [11], screening the purinemetabolic disorders in human fluid etc. [12]. Carbon dots (luminescent) nanoparticles can be usedto track biological processes inside cells. A thorough literature survey reveals that there has not been even a single study which discussesthe changes in physico-chemical properties of chitosan film due to impregnation of carbon dotsinto film matrix. With this objective, we have previously reported synthesis and characterizationof carbon dots from butane tetra carboxylic acid (BTCA) and preliminary investigation of waterabsorption behavior of chitosan/carbon dots nanocomposite film [13]. In continuation, we hereby report a detailed investigation of physico-chemical properties and biocompatibility of

Ch/CD nanocomposite films, taking plain chitosanfilm as control. As chitosan is a biopolymer with a number of biomedical applications, it may beinteresting to see alteration in its properties upon addition of carbon dots [14].
