Carbon quantum dots and gold nanostructures on photothermal therapy for cancer treatment

[Display omitted] •The study investigates and compare the photothermal properties of new type of carbon quantum dots with different shapes of gold nanostructures as well known photothermal agents.•Copper-doped carbon quantum dots were synthesized through a hydrothermal method, while gold nanoparticles (AuNPs) and gold nanorods (AuNRs) were synthesized using sodium sulfide reduction and growth methods, respectively.•The results show that carbon quantum dots can reach similar temperatures as gold nanostructures.•Photothermal conversion efficiencies of Cu-CQDs and gold nanostructures were calculated, and their photothermal cell death was examined on MCF-7 cancer cells.•Results showed that CQDs and AuNRs had higher photothermal conversion efficiencies compared to AuNPs, and all synthesized materials demonstrated photothermal therapeutic effect aginst MCF-7 cells.. This study focuses on the comparison of the photothermal (PT) properties of the new carbon quantum dots with two types of gold nanostructures including gold nanoparticles and gold nanorods.We prepared and characterized CQDs doped with copper from ascorbic acid precursor (Cu-aCQDs) with 3 nm diameter and citric acid precursor (Cu-cCQDs) with 5 nm diameter by hydrothermal method, Gold nanoparticles (GNP) were synthesized using sodium sulfide reduction and Gold nanorods (GNR) (aspect ratio of 5) by growth methods. UV–Vis spectrophotometry, spectrofluorimetry, dynamic light scattering (DLS), and transmission electron microscopy (TEM) were used to analyze the optical and morphological properties of the nanoparticles. The fluorescence quantum yields of 2.14 % and 1.55 % were obtained for Cu-aCQDs and Cu-cCQDs respectively. The photothermal conversion efficiencies of 44 %, 66 %, 42 % and 57 % were obtained for Cu-aCQDs, Cu-cCQDs, GNPs and GNRs respectively. We also evaluated the toxicity and the photothermal therapy (PTT) performance of the nanoparticles on MCF-7 breast cancer cells. The ratio of the cell death (from photothermal agent) in the presence of LASER irradiation to its absence for Cu-aCQDs, Cu-cCQDs, GNPS and gold nanorods were 2.5, 5.3, 1.75 and 1.9 respectively. The CQDs had very low toxicity in the absence of LASER irradiation and only 15 % toxicity was obtained for 14.0 mg/mL of Cu-aCQDs and Cu-cCQDs, 350 μg/mL of GNPs and 87.5 of μg/mL gold nano rods. These results indicate that CQDs are less harmful than gold nanostructures in the absence of LASER irradiation and more effective than gold na