Tetrahedral DNA nanostructures synergize with MnO2 to enhance antitumor immunity via promoting STING activation and M1 polarization

Stimulator of interferon genes (STING) is a cytosolic DNA sensor which is regarded as a potential target for antitumor immunotherapy. However, clinical trials of STING agonists display limited anti-tumor effects and dose-dependent side-effects like inflammatory damage and cell toxicity. Here, we showed that tetrahedral DNA nanostructures (TDNs) actively enter macrophages to promote STING activation and M1 polarization in a size-dependent manner, and synergized with Mn2+ to enhance the expressions of IFN-β and iNOS, as well as the co-stimulatory molecules for antigen presentation. Moreover, to reduce the cytotoxicity of Mn2+, we constructed a TDN-MnO2 complex and found that it displayed a much higher efficacy than TDN plus Mn2+ to initiate macrophage activation and anti-tumor response both in vitro and in vivo. Together, our studies explored a novel immune activation effect of TDN in cancer therapy and its synergistic therapeutic outcomes with MnO2. These findings provide new therapeutic opportunities for cancer therapy.

The biofilm removal effect of MnO₂-diatom microbubbler from the dental prosthetic surfaces: In vitro study / 대한치과보철학회지

PURPOSE: The aim of this study is to evaluate the effectiveness of MnO₂-diatom microbubbler (DM) on the surface of prosthetic materials as a mouthwash by comparing the biofilm removal effect with those previously used as a mouthwash in dental clinic.MATERIALS AND METHODS: DM was fabricated by doping manganese dioxide nanosheets to the diatom cylinder surface. Scanning electron microscopy (SEM) was used to observe the morphology of DM and to analyze the composition of doped MnO₂. Stereomicroscope was used to observe the reaction of DM in 3% hydrogen peroxide. Non-precious metal alloys, zirconia and resin specimens were prepared to evaluate the effect of biofilm removal on the surface of prosthetic materials. And then Streptococcus mutans and Porphyromonas gingivalis biofilms were formed on the specimens. When 3% hydrogen peroxide solution and DM were treated on the biofilms, the decontamination effect was compared with chlorhexidine gluconate and 3% hydrogen peroxide solution by crystal violet staining.RESULTS: Manganese dioxide was found on the surface of the diatom cylinder, and it was found to produce bubble of oxygen gas when added to 3% hydrogen peroxide. For all materials used in the experiments, biofilms of the DM-treated groups got effectively removed compared to the groups used with chlorhexidine gluconate or 3% hydrogen peroxide alone.CONCLUSION: MnO₂-diatom microbubbler can remove bacterial membranes on the surface of prosthetic materials more effectively than conventional mouthwashes.

Electrochemical Detection of Dopamine Based on MnO2 Nanowires/Reduced Graphene Oxide Composites Modified Glassy Carbon Electrode / 分析化学

MnO2nanowires-reduced graphene oxide composite (MnO2-RGO) was used to modify glassy carbon electrodes (GCE) and applied for the electrochemical determination of dopamine (DA). The microstructure of MnO2nanowires and MnO2-RGO nanocomposite material was characterized by scanning microscope and X-ray powder diffraction. Then the electrochemical reduction condition for preparing MnO2-RGO/GCE and experimental conditions for determining DA were optimized systematically. The electrochemical behavior of DA on the bare electrode and RGO or MnO2-RGO modified electrodes was also investigated in pH 3.5 phosphate buffer solution (PBS) by cyclic voltammetry. The results shows that the oxidation peaks of ascorbic acid (AA), dopamine (DA) and uric acid (UA) can be well separated and the peak to peak separations were 268 mV (AA-DA) and 128 mV (DA-UA), respectively. Moreover, the linear response ranges for the determination of DA were 0.06-1.0 μmol/L and 1.0-80 μmol/L with the detection limit of 1.0 nmol/L (S/N=3). The proposed method has been applied to the determination of dopamine in human blood serum sample with satisfactory results.

Exploration of enzyme-MnO2 nanosheets hybridization probe for sensitively colorimetric self-indicating of glucose / 中国药科大学学报

A colorimetric self-indicating probe for glucose was constructed by self-assembly of MnO2 nanosheets (MnO2 NSs) and glucose oxidase(GOD) in this paper.Under the weak acidic medium,glucose oxidase specifically catalyzes glucose into gluconic acid and hydrogen peroxide.The by-product of hydrogen peroxide could efficiently dissolve the MnO2 nanosheets,resulting into a significant decrease of the characteristic absorbance at 374 nm assigned to MnO2 NSs.Furthermore,the absorbance difference was linearly proportional to the concentration of glucose ranging from 1 to 20 μmol/L The fitted curve could be used for quantification of glucose with a correlation coefficient of 0.990 1.And the detection limit as low as 0.1 μmol/L could be reached based on the definition of three times of the deviation of the blank signal (3σ) and there was negligible interference with other co-existing amino acids,anions,cations and protein,which indicated high sensitivity and selectivity of the hybrid probe.The construction strategy of designated probe is readily generalized in principle for detection of numerous analytes in view of reactive property of MnO2 and the diversity of enzymes.