Spectinomycin br Fig UV vis spectra of GO before and after
Fig. 1. UV–vis spectra of GO before and after reduction by Euphorbia milii plant extract for different reduction times 12 h, 24 h and 48 h.
were added to cells group (six wells) for 24 h respectively. Olympus CKX41 is employed to measure the fluorescence microscopy of viable cells.
3. Results and Discussion
Fig. 1(a) displayed the UV–vis Spectinomycin spectrum of GO, showing the plasmon peak at about 230 nm with narrow shoulder band at 300 nm which is seldom referred to n–π∗ transitions of the carbonyl groups . The plasmon peak eventually red-shifts to ∼270 nm with the time by Euphorbia milii leaves extract (Fig.1b–f), reflecting the consistently increased π -electron transition and structural ordering, with sp2 carbon restoration and feasible atom rearrangement . This might indicate the increase in the reduction of GO and the gradually restored aromatic structure with the increase in reaction time.
The structural elucidation of the graphene is mainly dependent on the distance between two layers. Fig.2 displayed the XRD patterns of graphite, GO, RGO prepared using Euphorbia milii leaves extract. Fig. 2, indicated that the d-spacing of the GO is around 0.78 nm (2θ ≈ 11.3), which is extremely larger than the d(002) value of graphite (d ≈ 0.34 nm, 2θ ≈ 26.2) as shown in figure which is because of the existence of oxygen-containing functionalities nailed on either side of the RGO along with the roughness of the atomic-scale .The (002) GO peak steadily disappears with the raise of reaction time, while the broad XRD peak at 24.0° (d ≈ 0.37 nm) gradually becomes significant (Fig. 2). This interlayer space shift can be ascribed to the GO deox-ygenation while the RGO pack becomes tighter than the GO due to reduction . On the other hand, the broad XRD peak of RGO is due to the presence of biomolecules of plant extracts that are adsorbed on the surface of formed graphene sheets.
Further, the Raman spectra help to study the structural variations
Fig. 2. XRD spectra of graphite, GO and RGO prepared by Euphorbia milii leaf extract.
Fig. 3. Raman spectra of graphite, GO before and after reduction by Euphorbia milii leaves extract.
before and after the GO reduction. Raman spectra of graphite, GO, and after reduction by Euphorbia milii leaves extract were presented in Fig. 3. As presumed, the graphite Raman spectrum has exhibited a significant G-band at about 1582 cm−1 which upon reduced by Eu-phorbia milii leaf extract, the peak became wide and shifted to 1597 cm−1 followed by prominent D-peak. Interestingly, the Raman spectrum of RGO presented an elevated D/G intensity ratio in contrast to GO (0.94) with the increase in the D/G intensity ratio (0.98, 1.02, 1.08, and 1.17) with the increase of time. This variation attributes to the change in the electronic conjugation state, which in turn implies the raise in the number of sp2 carbon with the GO deoxygenating by Eu-phorbia milii leaves extract.
The TEM images representing the surface morphology of the GO and RGO were represented in Fig. 4. Initially the surface of the GO na-nosheet as shown in Fig. 4a, was smooth. Furthermore, after the
addition of Euphorbia milii leaves extract to the GO solution, followed by incubation for respective time, the GO nanosheet surface became rough (Fig. 4b). Thus there is an apparent evidence of assembly of plant polyphenols the GO nanosheet surface. AFM imaging was further performed in order to analyze the surface roughness of GO nanosheet as well as to know the mean thickness of the GO and RGO prepared using Euphorbia milii leaves extract. The thick-nesses of pure GO was observed to be around 1 nm, which was uniform throughout the height of mono-layer graphene sheet as shown in Fig. 5. Moreover, the thickness of RGO after loading with paclitaxel drug ef-ficiently increased to 10–15 nm, which attributed to the protein at-tachment on the GO nanosheet surface.