Sonodynamic inactivation of methicillin-resistant Staphylococcus aureus in planktonic condition by curcumin under ultrasound sonication

Methicillin-Resistant Staphylococcus aureus (MRSA) is an important cause of difficult-to-treat infections. The present study aims to investigate sonodynamic inactivation of MRSA in planktonic condition using curcumin under ultrasound sonication. Dark toxicity of curcumin to MRSA was investigated to choose the concentration range of curcumin used in the study. The uptake of curcumin in MRSA was observed before ultrasound sonication. After sonication colony forming units (CFUs) and bacterial viability were investigated using fluorescence assay. Additionally, chromosomal DNA fragmentation was also analyzed. Curcumin showed no dark toxicity to MRSA in the concentration range of ?500 μM. The maximum uptake of curcumin in MRSA occurred in 50 min after curcumin incubation. Counting of CFUs showed that curcumin had significantly sonodynamic killing effect on MRSA in a curcumin dose-dependent manner, and 5-log reduction in CFU was observed after curcumin treatment (40 μM) at room temperature in the dark for 50 min followed by exposure to ultrasound with intensity of 1.56 W/cm² for 5 min. The ratio of green-fluorescent intensity to red-fluorescent intensity was obviously decreased after curcumin treatment under ultrasound sonication. No significant change in chromosomal DNA was found in the cultured MRSA after the combined treatment of curcumin and ultrasound. These results demonstrated that sonodynamic action of curcumin had significant inactivation of MRSA in planktonic condition.     

Sonodynamic action of pyropheophorbide-a methyl ester induces mitochondrial damage in liver cancer cells

Sonodynamic therapy with pyropheophorbide-a methyl ester (MPPa) presents a promising aspect in treating liver cancer. The present study aims to investigate the mitochondrial damage of liver cancer cells induced by MPPa-mediated sonodynamic action. Mouse hepatoma cell line H₂₂ cells were incubated with MPPa (2 μM) for 20 h and then exposed to ultrasound with an intensity of 0.97 W/cm² for 8 s. Cytotoxicity was investigated 24 h after sonodynamic action using MTT assay and light microscopy. Mitochondrial membrane potential (ΔΨm) was analyzed using flow cytometry with rhodamine 123 staining and ultrastructural changes were observed using transmission electron microscopy (TEM).The cytotoxicity of MPPa-mediated SDT on H₂₂ cell line was 73.00 ± 3.42%, greater than ultrasound treatment alone (28.12 ± 5.19%) significantly while MPPa treatment alone had no significant effect on H₂₂ cells. Moreover, after MPPa-mediated SDT cancer cells showed swollen mitochondria under TEM and a significant collapse of mitochondrial membrane potential. Our findings demonstrated that MPPa-mediated SDT could remarkably induce cell death of H₂₂ cells, and highlighted that mitochondrial damage might be an important cause of cell death induced by MPPa-mediated SDT.     

Ultrasound induces cellular destruction of nasopharyngeal carcinoma cells in the presence of curcumin

Objectives

Curcumin, a natural pigment from the traditional Chinese herb, has shown promise as an efficient enhancer of ultrasound. The present study aims to investigate ultrasound-induced cellular destruction of nasopharyngeal carcinoma cells in the presence of curcumin in vitro.

Methods

Nasopharyngeal carcinoma cell line CNE2 cells were incubated by 10 μm curcumin and then were treated by ultrasound for 8 s at the intensity of 0.46 W/cm². Cytotoxicity was evaluated using MTT assay and light microscopy. Mitochondrial damage was analyzed using a confocal laser scanning microcopy with Rhodamine 123 and ultrastructural changes were observed using a transmission electron microscopy (TEM).

Results

MTT assay showed that cytotoxicity induced by ultrasound treatment alone and curcumin treatment alone was 18.16 ± 2.37% and 24.93 ± 8.30%, respectively. The cytotoxicity induced by the combined treatment of ultrasound and curcumin significantly increased up to 86.67 ± 7.78%. TEM showed that microvillin disappearance, membrane blebbing, chromatin condensation, swollen mitochondria, and mitochondrial myelin-like body were observed in the cells treated by ultrasound and curcumin together. The significant collapse of mitochondrial membrane potential (MMP) was markedly observed in the CNE2 cells after the combined treatment of curcumin and ultrasound.

Conclusions

Our findings demonstrated that ultrasound sonication in the presence of curcumin significantly killed the CNE2 cells and induced ultrastructural damage and the dysfunction of mitochondria, suggesting that ultrasound treatment remarkably induced cellular destruction of nasopharyngeal carcinoma cells in the presence of curcumin.     

The Nonlinear Enhancement Effect of Sputered Ag-atoms With FeCl+ Bombardment

Measurements of the angular distributions and yields of atoms sputtered from Ag target by bombardment with FeCl⁺,⁵⁶Fe⁺ and ³⁵Cl⁺ are reported.Large enhancement occurs in the measured Ag atom yield for FeCl⁺ projectile in comparison with the sum of the sputtering yields for ⁵⁶Fe⁺ and ³⁵Cl⁺ bombardment at same impact velocities.The enhanecment can be explained by a model of the thermal spike-evaporation plus surface topography effect.     

5-Aminolaevulinic acid enhances ultrasound-induced mitochondrial damage in K562 cells

Background

Ultrasound therapy is a new modality in the control of malignant cancers. The aim of the present study was to investigate the effect of 5-aminolaevulinic acid on the ultrasonic killing action in the cancer cells.

Materials/methods

The K562 cells as a cancer cell model were subjected to investigate the effect of 5-aminolaevulinic acid (5-ALA) on the ultrasonic killing action, in which the 5-ALA concentration was 2 mM and the ultrasound exposure was 15 s at the intensity of 0.46 W/cm² and the frequency of 1.7 MHz. Cytotoxicity was investigated 24 h after ultrasound exposure using the trypan blue exclusion test. Ultrastructural cell morphology and mitochondrial changes were observed using transmission electron microscopy (TEM). Mitochondrial membrane potential (ΔΨm) was evaluated using Rhodamine 123 assay.

Results

The death rates of the K562 cells in the controls including sham radiation and 5-ALA treatment alone were 1.81 ± 0.13%, 1.27 ± 0.20%, respectively. Those in ultrasound radiation alone and 5-ALA-ultrasound treatment were 12.61 ± 2.63%, 46.87 ± 4.09%, respectively. There were significant differences between 5-ALA-ultrasound treatment, ultrasound radiation alone and the controls (P < 0.05). TEM showed that the mitochondria expanding and some vacuoles were found in the ultrasound-treated cells. After the treatment of ultrasound and 5-ALA together some cells presented typical characteristics of apoptotic cells, such as nuclear condensation and crescent formation. Mitochondria of the cells were damaged more seriously than those treated by ultrasound alone, there were obvious swollen mitochondria and mitochondria in which cristae were almost perfectly disappeared, and more vacuolar mitochondria were founded. Mitochondrial membrane potential (ΔΨm) was more significantly collapsed when the K562 cells were exposed to 2 mM 5-ALA for 4 h and then 0.46 W/cm² irradiation of ultrasound than ultrasound radiation alone.

Conclusion

5-ALA pretreatment significantly enhanced the cytotoxicity of ultrasound radiation in K562 cells. The damage of mitochondria structure and function might be an important cause of cell death in K562 cells induced by the treatment of ultrasound radiation and 5-ALA together.     

Multiplug filtration clean‐up with multiwalled carbon nanotubes in the analysis of pesticide residues using LC–ESI‐MS/MS

A novel design for a rapid clean‐up method was developed for the analysis of pesticide residues in fruit and vegetables followed by LC–ESI‐MS/MS. The acetonitrile‐based sample extraction technique was used to obtain the extracts, and further clean‐up was carried out by applying the streamlined procedure on a multiplug filtration clean‐up column coupled with a syringe. The sorbent used for clean‐up in this research is multiwalled carbon nanotubes, which was mixed with anhydrous magnesium sulfate to remove water from the extracts. This method was validated on 40 representative pesticides and apple, cabbage, and potato sample matrices spiked at two concentration levels of 10 and 100 μg/kg. It exhibited recoveries between 71 and 117% for most pesticides with RSDs < 15%. Matrix‐matched calibrations were performed with the coefficients of determination >0.995 for most studied pesticides between concentration levels of 10–500 μg/L. The LOQs for 40 pesticides ranged from 2 to 50 μg/kg. The developed method was successfully applied to the determination of pesticide residues in market fruit and vegetable samples.     

Apoptosis of ovarian cancer cells induced by methylene blue-mediated sonodynamic action

Objective

The present study aims to investigate apoptosis of ovarian cancer cells induced by methylene blue (MB)-mediated sonodynamic therapy (SDT).

Methods

The MB concentration was kept constant at 100 μM and ovarian cancer HO-8910 cells were exposed to ultrasound therapy for 5 s with an intensity of 0.46 W/cm². The cytotoxicity was investigated 24 h after MB-mediated sonodynamic action. Apoptosis was analyzed using a flow cytometer with Annexin V-FITC and propidium iodine (PI) staining as well as fluorescence microscopy with Hoechst 33258 staining. Intracellular reactive oxygen species (ROS) level was measured by flow cytometer with 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) staining.

Results

The cytotoxicity of MB-mediated SDT on HO-8910 cells after MB-mediated SDT was significantly higher than those of other treatments including ultrasound alone, MB alone and sham treatment. Flow cytometric analysis showed a significant increase in the early and late apoptotic cell populations by MB-mediated SDT of HO-8910 cells. Nuclear condensation and increased ROS levels were also found in HO-8910 cells treated by MB-mediated SDT.

Conclusions

Our findings demonstrated that MB-mediated sonodynamic action significantly induced apoptosis of HO-8910 cells and an increase in intracellular ROS level. This indicates that apoptosis is an important mechanism of cell death induced by MB-mediated SDT. Thus, MB-mediated SDT might be a potential therapeutic strategy for combating ovarian cancer.     

The fluorine-free coating has excellent hydrophobic and oleophobic properties for porous cellulose-based materials

Cellulose - Nanofibrillated cellulose is obtained from cellulose resources (e.g., Natural cellulose, bacterial cellulose) and is deemed to be environmentally friendly, green, and inexhaustible....     

Representative commodity for five brassica vegetables based on the determination and dissipation of six pesticide residues

A Quick, Easy, Cheap, Effective, Rugged and Safe method for determination of thiophanate-methyl, carbendazim, metalaxyl, fluazifop-P-butyl, chlorpyrifos and lambda-cyhalothrin in five brassica vegetables by high performance liquid chromatography-mass spectrometry/mass spectrometry and gas chromatography-electron capture detector has been developed. The average recoveries of six pesticides in five brassica vegetables were in the range of 77.4%–117.4% with relative standard deviation of 3.7–10.8%. Residues of thiophanate-methyl, carbendazim, metalaxyl, fluazifop-P-butyl, chlorpyrifos and lambda-cyhalothrin in five brassica vegetables were studied with the developed method for the classification of crop group and selection of representative commodity of five brassica vegetables. Totally 48 open field trials on five brassica vegetables were conducted at two locations in two different seasons. The residue dynamics and final residues of the six pesticides at three preharvest intervals in different vegetables were compared. All six pesticides had the longest half-lives in cabbage (2.1–3.5 days). Residues of carbendazim (sum of thiophanate-methyl and carbendazim), metalaxyl, chlorpyrifos and lambda-cyhalothrin had similar trend in different brassica vegetables. The maximal concentrations of these pesticide residues were found in kale (0.28–10.9 mg kg^?1). Fluazifop-P-butyl residues were at low levels in all five brassica vegetables (<0.01–0.03 mg kg^?1). Cabbage, red cabbage, Brussels sprouts and kohlrabi had no significant difference in all six pesticide residues and could be classified in a subgroup of Head Brassicas. Cabbage should be selected as the representative commodity. Considering the highest residues in kale and its different morphology, kale should not be classified into the subgroup of Head Brassicas.     

Polyethyleneimine/activated carbon paper-based material for low-concentration hexavalent chromium removal

Activated carbon paper-based materials were prepared from softwood pulp, activated carbon powder, and polyester fiber through wet forming process. Then polyethyleneimine was loaded on the activated carbon paper-based materials using physical impregnation method to fabricate green, low cost, and degradable PEI/activated carbon composite paper-based adsorbent materials (PPCA) for the removal of Cr(VI) from drinking water. The surface characteristics of the adsorbent were analyzed by SEM, EDX, BET, FT-IR, and XPS. It was found that the maximum adsorption capacity of Cr(VI) could reach up to 1.58 mg g^?1 when the PEI immersion concentration is 1%, the contact time is 180 min, the temperature is 30 °C and pH?=?2. The adsorption of Cr(VI) on PPCA conformed to both the freundlich isotherm model and the quasi-second-order kinetic model, indicating that the adsorption was multi-molecular layer adsorption controlled by chemical reaction process. The adsorption mechanism of Cr(VI) on PPCA included electrostatic attraction, redox and chelation. Overall, this study provides a green, large-scalable production way for the preparation of biodegradable adsorption materials for the efficient removal of Cr(VI) from drinking water aiding the safe management of aqueous system.

Graphical abstract