Piezoelectric enhanced sulfur doped graphdiyne nanozymes for synergistic ferroptosis–apoptosis anticancer therapy

Abstract

Graphdiyne has excellent potential due to its enzymatic properties. Metal-free sulfur-doped Graphdiyne (S-GDY) has piezoelectric characteristics, and ultrasonic excitation of S-GDY enhances peroxidase activity. It can turn hydrogen peroxide into toxic hydroxyl radicals and induce apoptosis in 4T1 cells. More importantly, the ultrasound (US) enhanced nanozyme induced 4T1 cell ferroptosis by promoting an imbalanced redox reaction due to glutathione depletion and glutathione peroxidase 4 inactivation. S-GDY exhibited enhanced nanozyme activity in vitro and in vivo that may directly trigger apoptosis-ferroptosis for effective tumor therapy. Altogether, this study was expected to provide new insights into the design of piezoelectric catalytic nanozyme and expand their application in the catalytic therapy of tumors. Graphical Abstract

Theoretic Study of Sulfur-Doped Graphdiynes by X-ray Spectroscopy

“…Theoretical calculations show that the excitations in the low-energy region are mainly those of carbon atoms with C–C­(sp2) and C–C­(sp) bonding types while the two peaks in the high-energy region mainly originate from the excitations of carbon atoms bonded to sulfur atoms, which is in agreement with the experimental fitting results. As can be seen in Figure and Table , the two stronger convolution peaks at 284.6 and 285.0 eV are designated as C–C­(sp 2 ) and C–C­(sp), respectively, which are consistent with the two peaks in the experiments. ,,, In addition, the peak of the C–S single bond (shown as a purple spectrum in Figure ) is convolved at 286.2 eV, which is in general agreement with the peaks assigned in the experimental report (285.9 and 286.1 eV). , The weak peak at 287.8 eV is attributed to the convolution of the CS­(O) double bond, which is slightly different from the experimental value. The above research proves that the theoretical calculation results are in good agreement with the experimental results, which not only verifies the rationality of the experimental spectrum fitting and identification but also indicates the accuracy of our calculation.…”

“…Taking configuration 2 (the optimized structure shown in Figure b) as an example, the spectra of three cells (3 × 3 × 1 with “A” configuration, 3 × 3 × 2 with “AB” configuration, and 3 × 3 × 3 with “BAB” configuration) of configuration 2 were simulated to study the influence of multilayer structure, as shown in Figure . The interlayer spacings of each layer of graphdiyne were all set to 3.65 Å, which is consistent with the experimental data. ,,, As can be observed from Figure , there are two stronger convolution peaks at 286.2 and 289.6 eV, and several weak peaks of different intensities at 283.3 eV and 290.5–293.5 eV, respectively. It is clearly observed that the spectra of one, two, and three layers of graphdiyne are almost identical, which makes it reasonable to assume that the results of the spectra will continue to be consistent as the number of molecular layers increases.…”

“…As can be seen in Figure 4 and Table 2, the two stronger convolution peaks at 284.6 and 285.0 eV are designated as C−C(sp 2 ) and C−C(sp), respectively, which are consistent with the two peaks in the experiments. 16,20,40,41 In addition, the peak of the C−S single bond (shown as a purple spectrum in Figure 4) is convolved at 286.2 eV, which is in general agreement with the peaks assigned in the experimental report (285.9 and 286.1 eV). 16,20 The weak peak at 287.8 eV is attributed to the convolution of the C� S(O) double bond, which is slightly different from the experimental value.…”

“…The interlayer spacings of each layer of graphdiyne were all set to 3.65 Å, which is consistent with the experimental data. 20,38,40,68 As can be observed from Figure 6, there are two stronger convolution peaks at 286.2 and 289.6 eV, and several weak peaks of different intensities at 283.3 eV and 290.5−293.5 eV, respectively. It is clearly observed that the spectra of one, two, and three layers of graphdiyne are almost identical, which makes it reasonable to assume that the results of the spectra will continue to be consistent as the number of molecular layers increases.…”

“…In this paper, 10 different S-doped configurations were constructed based on the published literature on sulfur-doped graphdiyne. ,,,− In order to identify different doping configurations, the XPS and NEXAFS spectra of these 10 doping molecules and different bonding types of carbon atoms were simulated theoretically. The fine structure and spectral relationship of S-doped graphene were obtained by spectral analysis, which can help us to accurately identify the various sites of S-doped graphdiyne.…”