Curcumin Complexed with Graphene Derivative for Breast Cancer Therapy.

In recent years, graphene-based materials complexed with drugs have been developed for application in cancer therapy, aimed at gaining synergistic effect. Here, we have prepared graphene oxide (GO) and graphene quantum dots (GQDs) with curcumin (Cur) in three different ratios (1:1, 1:3, and 1:5 w/v). We showed a successful complexation of GO and GQDs with Cur through various spectroscopy and microscopy techniques. The optical density of the complex through UV-vis spectroscopy showed less than 10% (for GQDs-Cur) and less than 20% (for GO-Cur) aggregation in 48 h, which confirms the stability of the complex. The UV-vis result estimates the loading efficiency of Cur to be 80 ± 1 and 83 ± 1% for GO-Cur and GQDs-Cur respectively. We tested the complexes GO-Cur and GQDs-Cur in different ratios as an anticancer drug against human breast cancer cell lines MCF-7 and MDA-MB-468 through the MTT assay. Following 48 h of incubation with the cell lines, a cell viability of more than 75% was observed in the case of GQDs & GO, while it was 40% in the case of Cur at a concentration of 100 µg/mL. The 1:1, 1:3, and 1:5 ratios of complexes enforced cell death ∼60, ∼80, and ∼95% at 100 µg/mL after 48 h of treatment, respectively. The optical images of cancerous cells treated with GO, GQDs, Cur, GO-Cur, and GQDs-Cur, at three different time intervals (0, 24, and 48 h), corroborated well with the results from the MTT assay in terms of the percentage of dead cells. The fluorescence images show a successful delivery of Cur drug inside the cancerous cell. The possible mechanism of killing of the cancerous cell with the complexes GO-Cur and GQDs-Cur is discussed. Moreover, this study opens a window to determine the mechanism of killing the cancerous cell.

Phthalocyanine tetrasulfonates bind to multiple sites on natively-folded prion protein.

The phthalocyanine tetrasulfonates (PcTS), a class of cyclic tetrapyrroles, bind to the mammalian prion protein, PrP. Remarkably, they can act as anti-scrapie agents to prevent the formation and spread of infectious, misfolded PrP. While the effects of phthalocyanines on the diseased state have been investigated, the interaction between PcTS and PrP has not yet been extensively characterized. Here we use multiple, complementary assays (surface plasmon resonance, isothermal titration calorimetry, fluorescence correlation spectroscopy, and tryptophan fluorescence quenching) to characterize the binding of PcTS to natively-folded hamster PrP(90-232), in order to determine binding constants, ligand stoichiometry, influence of buffer ionic strength, and the effects of chelated metal ions. We found that binding strength depends strongly on chelated metal ions, with Al(3+)-PcTS binding the weakest and free-base PcTS the strongest of the three types tested (Al(3+), Zn(2+), and free-base). Buffer ionic strength also affected the binding, with K(d) increasing along with salt concentration. The binding isotherms indicated the presence of at least two different binding sites with micromolar affinities and a total stoichiometry of ~4-5 PcTS molecules per PrP molecule.