Ultrahigh-throughput screening (uHTS) techniques can identify unique functionality from millions of variants. To mimic the natural selection mechanisms that occur by compartmentalization in vivo, we ...developed a technique based on single-cell encapsulation in droplets of a monodisperse microfluidic double water-in-oil-in-water emulsion (MDE). Biocompatible MDE enables in-droplet cultivation of different living species. The combination of droplet-generating machinery with FACS followed by next-generation sequencing and liquid chromatography-mass spectrometry analysis of the secretomes of encapsulated organisms yielded detailed genotype/phenotype descriptions. This platform was probed with uHTS for biocatalysts anchored to yeast with enrichment close to the theoretically calculated limit and cell-to-cell interactions. MDE–FACS allowed the identification of human butyrylcholinesterase mutants that undergo self-reactivation after inhibition by the organophosphorus agent paraoxon. The versatility of the platform allowed the identification of bacteria, including slow-growing oral microbiota species that suppress the growth of a common pathogen, Staphylococcus aureus, and predicted which genera were associated with inhibitory activity.
Nanoparticles (NPs) with a high atomic number (Z) are promising radiosensitizers for cancer therapy. However, the dependence of their efficacy on irradiation conditions is still unclear. In the ...present work, 11 different metal and metal oxide NPs (from Cu (ZCu = 29) to Bi2O3 (ZBi = 83)) were studied in terms of their ability to enhance the absorbed dose in combination with 237 X-ray spectra generated at a 30–300 kVp voltage using various filtration systems and anode materials. Among the studied high-Z NP materials, gold was the absolute leader by a dose enhancement factor (DEF; up to 2.51), while HfO2 and Ta2O5 were the most versatile because of the largest high-DEF region in coordinates U (voltage) and Eeff (effective energy). Several impacts of the X-ray spectral composition have been noted, as follows: (1) there are radiation sources that correspond to extremely low DEFs for all of the studied NPs, (2) NPs with a lower Z in some cases can equal or overcome by the DEF value the high-Z NPs, and (3) the change in the X-ray spectrum caused by a beam passing through the matter can significantly affect the DEF. All of these findings indicate the important role of carefully planning radiation exposure in the presence of high-Z NPs.
Gold nanoparticles (GNPs) emerged as promising antitumor radiosensitizers. However, the complex dependence of GNPs radiosensitization on the irradiation conditions remains unclear. In the present ...study, we investigated the impacts of the dose rate and photon energy on damage of the pBR322 plasmid DNA exposed to X-rays in the presence of 12 nm, 15 nm, 21 nm, and 26 nm GNPs. The greatest radiosensitization was observed for 26 nm GNPs. The sensitizer enhancement ratio (SER) 2.74 ± 0.61 was observed at 200 kVp with 2.4 mg/mL GNPs. Reduction of X-ray tube voltage to 150 and 100 kVp led to a smaller effect. We demonstrate for the first time that the change of the dose rate differentially influences on radiosensitization by GNPs of various sizes. For 12 nm, an increase in the dose rate from 0.2 to 2.1 Gy/min led to a ~1.13-fold increase in radiosensitization. No differences in the effect of 15 nm GNPs was found within the 0.85-2.1 Gy/min range. For 21 nm and 26 nm GNPs, an enhanced radiosensitization was observed along with the decreased dose rate from 2.1 to 0.2 Gy/min. Thus, GNPs are an effective tool for increasing the efficacy of orthovoltage X-ray exposure. However, careful selection of irradiation conditions is a key prerequisite for optimal radiosensitization efficacy.
Gold nanoparticles (GNPs) are promising radiosensitizers for cancer radiotherapy. Moreover, they can be used in the same way for radiation processing and sterilization. Such application of GNPs is of ...practical interest since it may significantly reduce the dose load and expand the application of radiation treatment. In the present study, the high radiosensitization effect of GNPs in relation to viral particles is demonstrated for the first time. The preparations of tobacco mosaic virus (TMV) are used as an experimental model, insofar as this virus has the same properties as animal and human ones but is safe for humans. Irradiation with 45 kVp X‐ray to the doses of 4 and 7 kGy leads to a decrease in the infectious activity of TMV virions up to 1.92‐ and 2.70‐fold, respectively. At the same time, irradiation in the presence of 0.4 mg mL−1 of 12 nm spherical GNPs increases the efficiency of virus inactivation up to 15‐ and 22‐fold. The GNPs enhance both the damage to capsid protein due to the enhanced generation of reactive oxygen species and genome RNA due to the emission of secondary radiation. These results show the great prospects of the application of high‐Z nanoparticles in radiation treatment.
The high radiosensitization effect of gold nanoparticles (GNPs) in relation to viral particles is demonstrated for the first time on the example of tobacco mosaic virus (TMV) model. In the presence of 12 nm GNPs the efficiency of X‐ray irradiation of TMV preparations is increased up to 15‐fold at 4 kGy and up to 22‐fold at 7 kGy.
In this study we have probed the role of different enhancement mechanisms of the nanosensitizers in the X-ray irradiated oxygen-free model aqueous organic systems containing “bare” gold nanoparticles ...(AuNPs) using the spin-trapping technique with electron paramagnetic resonance detection. The observed enhancement effect was found to be ca. 1.67 wp−1 for the AuNPs with an average diameter of 18 nm and 45 kVp X-rays. The comparison with Monte Carlo simulation shows that the sensitizing effect of AuNPs in the X-ray irradiated oxygen-free aqueous organic systems could be attributed to the increasing absorbed dose due to high absorption cross-section of gold atoms. It implies that the radiation-chemical yield of hydroxyl radicals responsible for the oxidative damage in the absence of oxygen remains virtually unchanged in the presence of AuNPs. Also, no clear evidence was found for the dose rate effects upon variation of this parameter by more than an order of magnitude (0.06–1.21 Gy/s). In practical sense, these results urge the development of new efficient approaches for the radiation treatment of hypoxic media using nanoparticles.
•The sensitizing effect of gold NPs under X-ray irradiation in oxygen-free environment was studied.•The effect is reasonably explained by the physical enhancement mechanism.•The experimental results are in agreement with the Monte Carlo simulations.•No evidence for chemical enhancement was found under the hypoxic conditions.
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