Photoluminescent and Anticancer Characteristics of Carbon Nanodots Synthesized from Bovine Gelatin and PHM3 Algal Strain

Abstract

Semi-conductor quantum dots are favorite candidate for many applications specifically for the potential use as optical bioimaging agents. But the major issue for QDs is toxicity. In the present study carbon nanodots were synthesized using a green hydrothermal approach from gelatin protein using a protocol previously established by (Liang, Ma, Shi, Li, & Yang, 2013) however in the present study the native source of gelatin was bovine rather than fish, and were designated as CG (bovine gelatin) nanodots. CG (bovine gelatin) nanodots had sizes greater than Bohor exciton radius, unlike previously reported, but still presented a semiconductor like fluorescence. Further results from fluorescence spectroscopy demonstrated a tunable PL emission profile under various excitation wavelengths with excellent photostability and PL intensity increasing with degree of aromatization. Secondly carbon nanodots were also synthesized from an algal biomass of pectinodesmus sp via a green hydrothermal approach designated as CA (PHM3 algae) nanodots. A detail comparison of PL properties, and surface chemical composition of CG (bovine gelatin) and CA (PHM3 algae) nanodots suggested, that the degree of surface oxidation and surface chemical composition significantly alter the surface states which directly influence their PL properties. Based on results a PL emission mechanism is discussed. The CG (bovine gelatin) nanodots were used for imaging of plant and bacterial cells with good imaging sensitivity comparable to toxic semiconductor quantum dots. Moreover, results from invitro toxicity suggested very good anticancer properties of CA (PHM3 algae) and CG (bovine gelatin) nanodots with minimum IC50 values of 0.6323ng/ml and 12.82ng/ml for HCC 1954 and 1.048ng/ml and 34.13ng/ml for HCT 116 cancer cell lines respectively.