Fig 1.
CAG nanocomposite synthesis illustration.
Fig 2.
The proposed reduction sites action of CR.
The O- moieties formed at alkaline pH are assumed to reduce Au+ ions to AuNPs [63].
Fig 3.
TEM images of CAG vs. rGO-AuNP nanocomposites.
(A) CAG composite at 0.5 μm scale, (B) CAG at 100 nm scale with an inset of size distribution histogram. (C) rGO-AuNPs prepared using sodium citrate at 0.5 μm scale, (D) rGO-AuNPs at 100 nm scale.
Fig 4.
Raman spectra of synthesized nanocomposite CAG, GO and graphite.
Fig 5.
(A) FT-IR spectra of GO, CAG, and CR. (B) XRD analysis of GO and CAG.
Fig 6.
Panel of GO, citrate-AuNPs, CAG, and CR.
Fig 7.
TGA curves for CAG in comparison to graphite, CR, and GO.
Fig 8.
Particle size distribution of CAG nanocomposite dispersion in RPMI-1640 medium.
Fig 9.
CAG antioxidant activity compared to raw material GO, and citrate synthesized rGO-AuNPs nanocomposite. Results expressed as mean from triplicate analysis ± SEM. a, b and c indicates a significant increase in DPPH inhibition of respective treatments (CAG, rGO-AuNPs, and GO, respectively) compared to no treatment control (p<0.05). * Significant difference between treatment groups at respective concentration (p<0.05). Statistical analysis was performed using factorial ANOVA tests, SPSS software.
Fig 10.
Optical phase-contrast microscopy images.
Untreated control cells (up; HT-29, bottom; SW-948) compared to CAG nanocomposite treatment at low and high concentrations.
Fig 11.
In vitro viability results after CAG treatment.
Percentage viability of colon cancer cells (HT-29 and SW948 cell lines), normal colon cells (CCD841), and normal liver cells (WRL-68), upon exposure to CAG nanocomposite at different concentrations (62.5–1000 μg/mL), measured at three time points using WST-8 assay. Tests were performed and results were means from triplicate analysis. * Significant decrease (p<0.05) in viability percentage compared to untreated control, as analyzed by factorial ANOVA test, SPSS software.
Table 1.
IC50 values and selectivity index (SI) of cancer cells treated with nanocomposites.
Fig 12.
Schematic illustration of the proposed CAG interaction and mechanism of action on cell.
(a) Antioxidant activity and free radical inhibition, (b) CAG-cell interaction and proposed subsequent mechanism.