Enhanced Photocatalytic Decomposition Efficacy of Novel MgO NPs: Impact of Annealing Temperatures

Facile synthesis of MgO nanoparticles for effective degradation of organic dyes

In the present study, we have synthesized magnesium oxide (MgO) nanoparticles by a facile and cost-effective chemical co-precipitation method with annealing at three different temperatures (350°C, 450°C, and 550°C) for the removal of various organic dyes. X-ray diffraction studies revealed that the prepared samples are having sizes below 20 nm and with pure phase. Phase transformation of hexagonal Mg(OH)₂ nanoparticles to discretely cubical structured MgO nanoparticles has been observed with increasing the annealing temperatures which is also supported by the TGA/DSC analysis. Mg-O stretching vibration peaks in the range of 400-800 cm^-1 obtained by FTIR spectroscopy support the formation of MgO nanoparticles. The observed Raman active bands for the annealed sample at 550°C confirm the formation of the nanocrystalline phase since these bands are typically absent in the bulk MgO as well as in Mg(OH)₂. The surface morphology of the as-prepared Mg(OH)₂ are aggregated nano-petals which changed into spherical shape for MgO annealed at 550°C as studied by field emission scanning electron microscopy (FESEM). The specific surface area of MgO nanoparticles annealed at 550°C using BET isotherms is found to be 37.487 m²g^-1. The optical bandgaps of the prepared samples are found to be in the range of 4.4 to 5.1 eV using the Tauc plot. Adsorption studies with a variation of initial brilliant green dye concentration and contact time are carried out along with the studies of adsorption kinetic and isotherm models. Langmuir isotherm model is the most suitable model on the basis of correlation constant with maximum BG dye adsorption capacity onto MgO@550°C which is found to be 63.9 mg/g. The adsorption kinetics followed the pseudo-second-order model. Also prepared pristine MgO nanoparticles showed significant photocatalytic performance for the degradation of various dyes; brilliant green (BG: 88.91%), methylene blue (MB: 79.05%), crystal violet (CV: 76.49%), methyl orange (MO: 68.62%), and brilliant blue (BB: 40.44%) under visible irradiation. MgO nanoparticles could be a promising adsorbent and photocatalyst that may be employed in the treatment of effluents from industries.

Multifunctional nanocomposites DDMplusAF inhibit the proliferation and enhance the radiotherapy of breast cancer cells via modulating tumor-promoting factors and metabolic reprogramming

Background

Tumor-promoting factors (TPF) and metabolic reprogramming are hallmarks of cancer cell growth. This study is designed to combine the newly synthesized two nanocomposites DDM (HA-FA-2DG@DCA@MgO) and AF (HA-FA-Amygdaline@Fe2O3) with fractionated doses of radiotherapy (6 Gy-FDR; fractionated dose radiotherapy) to improve the efficiency of chemo-radiotherapy against breast cancer cell lines (BCCs; MCF-7 and MDA-MB-231). The physicochemical properties of each nanocomposite were confirmed using energy dispersive XRD, FTIR, HR-TEM, and SEM. The stability of DDMPlusAF was also examined, as well as its release and selective cellular uptake in response to acidic pH. A multiple-MTT assay was performed to evaluate the radiosensitivity of BCCs to DDMPlusAF at 3 Gy (single dose radiotherapy; SDR) and 6 Gy-FDR after 24, 48, and 72 h. Finally, the anti-cancer activity of DDMPlusAF with 6 Gy-FDR was investigated via assessing the cell cycle distribution and cell apoptosis by flow cytometry, the biochemical mediators (HIF-1α, TNF-α, IL-10, P53, PPAR-α, and PRMT-1), along with glycolytic pathway (glucose, HK, PDH, lactate, and ATP) as well as the signaling effectors (protein expression of AKT, AMPK, SIRT-1, TGF-β, PGC-1α, and gene expression of ERR-α) were determined in this study.

Results

The stability of DDMPlusAF was verified over 6 days without nanoparticle aggregation. DDMPlusAF release and selectivity data revealed that their release was amenable to the acidic pH of the cancer environment, and their selectivity was enhanced towards BCCs owing to CD44 and FR-α receptors-mediated uptake. After 24 h, DDMPlusAF boosted the BCC radiosensitivity to 6 Gy-FDR. Cell cycle arrest (G2/M and pre-G1), apoptosis induction, modulation of TPF mediators and signaling effectors, and suppression of aerobic glycolysis, all confirmed DDMPlusAF + 6 Gy’s anti-cancer activity.

Conclusions

It could be concluded that DDMPlusAF exerted a selective cancer radiosensitizing efficacy with targeted properties for TPF and metabolic reprogramming in BCCs therapy.

Dual Hyaluronic Acid and Folic Acid Targeting pH-Sensitive Multifunctional 2DG@DCA@MgO-Nano-Core-Shell-Radiosensitizer for Breast Cancer Therapy

Simple Summary

In this study, we have developed CD44 and folate receptor-targeting multi-functional dual drug-loaded nanoparticles. This comprises hyaluronic acid (HA) and folic acid (FA) conjugated to 2-deoxy glucose (2DG) and a shell linked to a dichloroacetate (DCA) and magnesium oxide (MgO) core (2DG@DCA@MgO; DDM) to enhance the localized chemo-radiotherapy for effective breast cancer (BC) treatment. The physicochemical properties of nanoparticles including stability, selectivity, responsive release to pH, cellular uptake, and anticancer efficacy were comprehensively examined. Mechanistically, we identified multiple component signal pathways as important regulators of BC metabolism and mediators for the inhibitory effects exerted by DDM. Nanoparticles exhibited sustained DDM release properties in bio-relevant media, which was responsive to acidic pH providing edibility to the control of drug release from nanoparticles. DDM-loaded and HA–FA-functionalized nanoparticles exhibited increased selectivity and uptake by BC cells. Cell-based assays indicated that the functionalized DDM significantly suppressed cancer cell growth and boosted radiotherapy (RT) efficacy via inducing cell cycle arrest, enhancing apoptosis, and modulating glycolytic and OXPHOS pathways. Accordingly, the inhibition of glycolysis/OXPHOS by DDM and RT treatment may result in cancer metabolic reprogramming via a novel PI3K/AKT/mTOR/P53NF-κB/VEGF pathway in BC cells. Therefore, the dual targeting of glycolysis/OXPHOS pathways is suggested as a promising antitumor strategy.

Abstract

Globally, breast cancer (BC) poses a serious public health risk. The disease exhibits a complex heterogeneous etiology and is associated with a glycolytic and oxidative phosphorylation (OXPHOS) metabolic reprogramming phenotype, which fuels proliferation and progression. Due to the late manifestation of symptoms, rigorous treatment regimens are required following diagnosis. Existing treatments are limited by a lack of specificity, systemic toxicity, temporary remission, and radio-resistance in BC. In this study, we have developed CD44 and folate receptor-targeting multi-functional dual drug-loaded nanoparticles. This composed of hyaluronic acid (HA) and folic acid (FA) conjugated to a 2-deoxy glucose (2DG) shell linked to a layer of dichloroacetate (DCA) and a magnesium oxide (MgO) core (2DG@DCA@MgO; DDM) to enhance the localized chemo-radiotherapy for effective BC treatment. The physicochemical properties of nanoparticles including stability, selectivity, responsive release to pH, cellular uptake, and anticancer efficacy were thoroughly examined. Mechanistically, we identified multiple component signaling pathways as important regulators of BC metabolism and mediators for the inhibitory effects elicited by DDM. Nanoparticles exhibited sustained DDM release properties in a bio-relevant media, which was responsive to the acidic pH enabling eligibility to the control of drug release from nanoparticles. DDM-loaded and HA–FA-functionalized nanoparticles exhibited increased selectivity and uptake by BC cells. Cell-based assays revealed that the functionalized DDM significantly suppressed cancer cell growth and improved radiotherapy (RT) through inducing cell cycle arrest, enhancing apoptosis, and modulating glycolytic and OXPHOS pathways. By highlighting DDM mechanisms as an antitumor and radio-sensitizing reagent, our data suggest that glycolytic and OXPHOS pathway modulation occurs via the PI3K/AKT/mTOR/NF-κB/VEGF_low and P53_high signaling pathway. In conclusion, the multi-functionalized DDM opposed tumor-associated metabolic reprogramming via multiple signaling pathways in BC cells as a promising targeted metabolic approach.

Facile Synthesis, Characterization, Photocatalytic Activity, and Cytotoxicity of Ag-Doped MgO Nanoparticles

Due to unique physicochemical properties, magnesium oxide nanoparticles (MgO NPs) have shown great potential for various applications, including biomedical and environmental remediation. Moreover, the physiochemical properties of MgO NPs can be tailored by metal ion doping that can be utilized in photocatalytic performance and in the biomedical field. There is limited study on the photocatalytic activity and biocompatibility of silver (Ag)-doped MgO NPs. This study was planned for facile synthesis, characterization, and photocatalytic activity of pure and silver (Ag)-doped MgO NPs. In addition, cytotoxicity of pure and Ag-doped MgO NPs was assessed in human normal umbilical vein endothelial cells (HUVECs). Pure MgO NPs and Ag-doped (1, 2, 5, and 7.5 mol%) MgO NPs were prepared via a simple sol-gel procedure. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS) were used to characterize the prepared samples. XRD results showed the preparation of highly crystalline NPs with no impurity peaks. TEM and SEM studies indicate smooth surfaces with almost spherical morphology of MgO NPs, and Ag-doping did not change the morphology. Elemental composition study suggested that Ag is uniformly distributed in MgO particles. Intensity of the PL spectra of MgO NPs decreased with increasing the concentration of Ag dopants. In comparison to pure MgO NPs, Ag-MgO NPs showed higher degradation of methylene blue (MB) dye under UV irradiation. The improved photocatalytic activity of Ag-MgO NPs was related to the effect of dopant concentration on reducing the recombination between electrons and holes. Cytotoxicity studies showed good biocompatibility of pure and Ag-doped MgO NPs with human normal umbilical vein endothelial cells (HUVECs). These results highlighted the potential of Ag-doped MgO NPs in environmental remediation.