The Effect of Microwave Irradiation on the Representation and Growth of Moulds in Nuts and Almonds

Microwave (MW) irradiation is a non-destructive method that can be applied as an alternative method to inhibit the growth of microorganisms. The present study evaluated the effect of MW irradiation on the occurrence of moulds in nuts and almonds. Samples of unshelled natural almonds, pistachios, and in-shell peanuts were treated with different doses of MW irradiation (2400–4000 W). The effect of MW irradiation on mould counts was evaluated by cultivating immediately after irradiation and after 3 and 6 months of storage. The most represented genera in all analysed samples were Aspergillus (68%), Penicillium (21%), and a small amount of Cladosporium (3%). Mould numbers significantly decreased after MW treatment. The treatments with MW irradiations at 3000 and 4000 W significantly reduced the mould colony counts, and their effect persisted during storage; irradiation at 2400 W was partially effective. The strongest effect of MW irradiation was observed in in-shell peanuts. MW irradiation seems to be a promising method for maintaining the microbiological quality of nuts.

Progressing Ultragreen, Energy-Efficient Biobased Depolymerization of Poly(ethylene terephthalate) via Microwave-Assisted Green Deep Eutectic Solvent and Enzymatic Treatment

Effective interfacing of energy-efficient and biobased technologies presents an all-green route to achieving continuous circular production, utilization, and reproduction of plastics. Here, we show combined ultragreen chemical and biocatalytic depolymerization of polyethylene terephthalate (PET) using deep eutectic solvent (DES)-based low-energy microwave (MW) treatment followed by enzymatic hydrolysis. DESs are emerging as attractive sustainable catalysts due to their low toxicity, biodegradability, and unique biological compatibility. A green DES with triplet composition of choline chloride, glycerol, and urea was selected for PET depolymerization under MW irradiation without the use of additional depolymerization agents. Treatment conditions were studied using Box-Behnken design (BBD) with respect to MW irradiation time, MW power, and volume of DES. Under the optimized conditions of 20 mL DES volume, 260 W MW power, and 3 min MW time, a significant increase in the carbonyl index and PET percentage weight loss was observed. The combined MW-assisted DES depolymerization and enzymatic hydrolysis of the treated PET residue using LCC variant ICCG resulted in a total monomer conversion of ≈16% (w/w) in the form of terephthalic acid, mono-(2-hydroxyethyl) terephthalate, and bis-(2-hydroxyethyl) terephthalate. Such high monomer conversion in comparison to enzymatically hydrolyzed virgin PET (1.56% (w/w)) could be attributed to the recognized depolymerization effect of the selected DES MW treatment process. Hence, MW-assisted DES technology proved itself as an efficient process for boosting the biodepolymerization of PET in an ultrafast and eco-friendly manner.

Synergistic Cascade Strategy Based on Modifying Tumor Microenvironment for Enhanced Breast Cancer Therapy

Background: Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer with very few treatment options. Although tumor-targeted nanomedicines hold great promise for the treatment of TNBC, the tumor microenvironment (TME) continues to be a major cause of failure in nanotherapy and immunotherapy. To overcome this barrier, we designed a new synergistic cascade strategy (SCS) that uses mild hyperthermia and smart drug delivery system (SDDS) to alter TME resistance in order to improve drug delivery and therapeutic efficacy of TNBC.Methods: Mild hyperthermia was produced by microwave (MW) irradiation. SDDS were formulated with thermosensitive polymer-lipid nanoparticles (HA-BNPs@Ptx), composed of polymer PLGA, phospholipid DPPC, hyaluronic acid (HA, a differentiation-44-targeted molecule, also known as CD44), 1-butyl-3-methylimidazolium-L-lactate (BML, a MW sensitizer), and paclitaxel (Ptx, chemotherapy drug). 4T1 breast tumor-bearing mice were treated with two-step MW combined with HA-BNPs@Ptx. Tumors in mice were pretreated with first MW irradiation prior to nanoparticle injection to modify and promote TME and promoting nanoparticle uptake and retention. The second MW irradiation was performed on the tumor 24 h after the injection of HA-BNPs@Ptx to produce a synergistic cascade effect through activating BML, thus, enhancing a hyperthermia effect, and instantly releasing Ptx at the tumor site.Results: Multifunctional CD44-targeted nanoparticles HA-BNPs@Ptx were successfully prepared and validated in vitro. After the first MW irradiation of tumors in mice, the intratumoral perfusion increased by two times, and the nanoparticle uptake was augmented by seven times. With the second MW irradiation, remarkable antitumor effects were obtained with the inhibition rate up to 88%. In addition, immunohistochemical analysis showed that SCS therapy could not only promote tumor cell apoptosis but also significantly reduce lung metastasis.Conclusion: The SCS using mild hyperthermia combined with SDDS can significantly improve the efficacy of TNBC treatment in mice by modifying TME and hyperthermia-mediated EPR effects.

Microwave-Assisted Ionic Liquid-Catalyzed Selective Monoesterification of Alkylphosphonic Acids—An Experimental and a Theoretical Study

It is well-known that the P-acids including phosphonic acids resist undergoing direct esterification. However, it was found that a series of alkylphoshonic acids could be involved in monoesterification with C2–C4 alcohols under microwave (MW) irradiation in the presence of [bmim][BF4] as an additive. The selectivity amounted to 80–98%, while the isolated yields fell in the range of 61–79%. The method developed is a green method for P-acid esterification. DFT calculations at the M062X/6–311+G (d,p) level of theory (performed considering the solvent effect of the corresponding alcohol) explored the three-step mechanism, and justified a higher enthalpy of activation (160.6–194.1 kJ·mol−1) that may be overcome only by MW irradiation. The major role of the [bmim][BF4] additive is to increase the absorption of MW energy. The specific chemical role of the [BF4] anion of the ionic liquid in an alternative mechanism was also raised by the computations.

A Study on Microwave Exposure Effects on Surface Coating Properties of Linden (Tilia cordata) and Spruce (Picea abies) Woods

The quality performance of surface coatings are evaluated with emphasis on Microwave (Mw) irradiation, effects on both wood and oil modified alkyd-based varnish, separately. The surface pencil film hardness value of 2B (5 in metric) found for neat varnish coated linden and spruce control samples. It appears Mw exposure on both woods and varnish were effective for further increasing pencil hardness which are about 4 and 5 unit higher than controls. It is also noticeable that a clear improvement for cross-cut (adhesion) properties were realized with Mw treated varnish coated linden woods. Although cold liquid resistance of coating evaluations have conducted with 11 liquids, but coated surfaces were showed the lowest resistance, assessed grade 1 (considerably changes) for five of these liquids (juice, milk, ketchup, lemon juice, cola) regardless of conditions or wood species. Therefore, results revealed some level correlation between Mw conditions and wood samples for six of the cold liquids involved in the examination. Mw treated spruce samples usually show 1 to 2 unit higher olive oil, vinegar, mayonnaise, ethyl alcohol resistance while no any improvement found for coffee and mineral water. Linden samples usually show 1 to 3 unit improving (higher) resistance against all these six cold liquids, regardless of Mw conditions. It is important to note that all Mw treated and varnish applied wood species subjected to olive oil, mayonnaise and ethyl alcohol show very high resistant properties (graded 4 and 5). Similar results are also realized with applying Mw irradiated vanish to both wood species. These variations and changes could be results of chemical structural changes, including cross-linking by esterification and etherification, promoted by Mw irradiation.

Synergistic Cascade Strategy Based on Modifying Tumor Microenvironment for Enhanced Breast Cancer Therapy

Background: Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer with very few treatment options. Although tumor-targeted nanomedicines hold great promise for the treatment of TNBC, the tumor microenvironment (TME) continues to be a major cause of failure in nanotherapy and immunotherapy. To overcome this barrier, we designed a new synergistic cascade strategy (SCS) that uses mild hyperthermia and smart drug delivery system (SDDS) to alter TME resistance in order to improve drug delivery and therapeutic efficacy of TNBC.Methods: Mild hyperthermia was produced by microwave (MW) irradiation. SDDS were formulated with thermosensitive polymer-lipid nanoparticles (HA-BNPs@Ptx), composed of polymer PLGA, phospholipid DPPC, hyaluronic acid (HA, a differentiation-44 targeted molecule, also known as CD44), 1-butyl-3-methylimidazolium-L-lactate (BML, a MW sensitizer) and paclitaxel (Ptx, chemotherapy drug). 4T1 breast tumor-bearing mice were treated with two-step MW combined with HA-BNPs@Ptx. Tumors in mice were pretreated with 1st MW irradiation prior to nanoparticle injection to modify TME and promote TME and promoting nanoparticle uptake and retention. The 2nd MW irradiation was performed on the tumor 24 h after the injection HA-BNPs@Ptx to produce a synergistic cascade effect through activating BML, thus enhancing hyperthermia effect, and instantly releasing Ptx at the tumor site.Results: Multifunctional CD44-targeted nanoparticles HA-BNPs@Ptx were successfully prepared and validated in-vitro. After the 1st MW irradiation of tumors in mice, the intratumoral perfusion increased by 2 times and the nanoparticle uptake augmented by 7 times. With the 2nd MW irradiation, remarkable anti-tumor effects were obtained with the inhibition rate up to 88%. In addition, immunohistochemical analysis showed that SCS therapy could not only promote the tumor cells apoptosis, trigger the immune response of cytotoxic T lymphocytes, but also significantly reduce the lung metastasis. Conclusions: The SCS using mild hyperthermia combined with smart drug delivery system, can significantly improve the efficacy of TNBC treatment in mice by modifying TME and hyperthermia-mediated EPR effects.

Synthesis of Cyclic Phosphinates by Microwave-Assisted Ionic Liquid-Promoted Alcoholysis

A series of 1-alkoxy-3-methyl- and 3,4-dimethyl-3-phospholene 1-oxides, as well as 1-alkoxy-3-methylphospholane 1-oxides were prepared in good yields by the microwave (MW)-assisted [bmim][PF6]-catalyzed transesterification of the corresponding methyl or ethyl esters. The alcoholyses studied represent another case, where MW irradiation has had a crucial role on the course of the reaction. The method developed is an alternative possibility to other esterifications starting from the corresponding phosphinic chlorides and acids.

Optimized Degradation of Bisphenol A by UV/H2O2 coupled to Microwaves in a Novel Reactional Setup

In this paper, the UV/H2O2/MW (microwave) process was compared with the UV/H2O2 one, using bisphenol A (BPA) as a model-pollutant. The proposed experimental setup was operated in batch recycle mode and allows for the direct comparison among different processes: UV only, H2O2 only, MW only, UV/H2O2, UV/MW, H2O2/MW, and UV/H2O2/MW, as well as temperature control to minimize thermal effects. The degradation of BPA at near-environmental concentration (100 µg L−1) was optimized by an experimental design approach (Response Surface Methodology) and its residual concentration was measured by HPLC. Approximately 95% of the initial BPA amount could be removed in 30 min at the optimal conditions (CH2O2 = 20 mg L−1, flow rate = 700 mL min−1, and MW power = 245 W). The experiments designed for comparing the UV/H2O2 and the UV/H2O2/MW processes showed that the use of MW doubled the initial pseudo-first-order degradation rate (from 0.046 to 0.10 min−1) and significantly increased the maximum oxidation capacity of the system (from 86 to 100%). Although the reasons behind those results are still unclear, it seems that the existence of non-thermal effects of the MW irradiation should be considered.

Pulsed 3.5 GHz high power microwaves irradiation on physiological solution and their biological evaluation on human cell lines

Microwave (MW) radiation is increasingly being used for several biological applications. Many investigations have focused on understanding the potential influences of pulsed MW irradiation on biological solutions. The current study aimed to investigate the effects of 3.5 GHz pulsed MW radiation-irradiated liquid solutions on the survival of human cancer and normal cells. Different physiological solutions such as phosphate buffer saline, deionized water, and Dulbecco’s modified Eagle medium (DMEM) for cell culture growth were irradiated with pulsed MW radiation (45 shots with the energy of 1 mJ/shot). We then evaluated physiological effects such as cell viability, metabolic activity, mitochondrial membrane potential, cell cycle, and cell death in cells treated with MW-irradiated biological solutions. As MW irradiation with power density ~ 12 kW/cm2 mainly induces reactive nitrogen oxygen species in deionized water, it altered the cell cycle, membrane potential, and cell death rates in U373MG cells due to its high electric field ~ 11 kV/cm in water. Interestingly, MW-irradiated cell culture medium and phosphate-buffered saline did not alter the cellular viability and metabolic energy of cancer and normal cells without affecting the expression of genes responsible for cell death. Taken together, MW-irradiated water can alter cellular physiology noticeably, whereas irradiated media and buffered saline solutions induce negligible or irrelevant changes that do not affect cellular health.

Microwaves as “Co-Catalysts” or as Substitute for Catalysts in Organophosphorus Chemistry

The purpose of this review is to summarize the importance of microwave (MW) irradiation as a kind of catalyst in organophosphorus chemistry. Slow or reluctant reactions, such as the Diels-Alder cycloaddition or an inverse-Wittig type reaction, may be performed efficiently under MW irradiation. The direct esterification of phosphinic and phosphonic acids, which is practically impossible on conventional heating, may be realized under MW conditions. Ionic liquid additives may promote further esterifications. The opposite reaction, the hydrolysis of P-esters, has also relevance among the MW-assisted transformations. A typical case is when the catalysts are substituted by MWs, which is exemplified by the reduction of phosphine oxides, and by the Kabachnik–Fields condensation affording α-aminophosphonic derivatives. Finally, the Hirao P–C coupling reaction may serve as an example, when the catalyst may be simplified under MW conditions. All of the examples discussed fulfill the expectations of green chemistry.