Gellan gum gel tissue phantoms and gel dosimeters with tunable electrical, mechanical and dosimetric properties

Brzozowski, Pawel; Penev, Kalin; Mequanint, Kibret

doi:10.1016/j.ijbiomac.2021.03.047

Cited by 10 publications

(13 citation statements)

References 21 publications

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“…The addition of biocide “Latrina” (700 ppm) containing DDAC and PHMG (6.74% in total) to FS inhibits both aerobic and anaerobic microorganisms [ 15 ]. However, FS may also contain microorganisms that are resistant to these biocides.…”

Section: Resultsmentioning

confidence: 99%

“…Due to this structure, QACs are able to effectively concentrate on the surface or at the interface, significantly reducing the surface tension [ 13 ]. The same feature of the QAC structure is also responsible for their antimicrobial effects [ 14 , 15 , 16 ]. These substances are biocidal against a number of microorganisms, including fungi, Gram-negative and Gram-positive bacteria, and lipophilic viruses [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Didecyldimethylammonium Chloride- and Polyhexamethylene Guanidine-Resistant Bacteria Isolated from Fecal Sludge and Their Potential Use in Biological Products for the Detoxification of Biocide-Contaminated Wastewater Prior to Conventional Biological Treatment

Лойко

Kanunnikov²,

Serdyukov

et al. 2022

Biology

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Toxic shock caused by the discharge of biocide-contaminated fecal sludge (FS) from chemical toilets to conventional wastewater treatment plants (WWTP) can be a major problem in activated sludge operation. It is necessary to develop new environmental approaches to mitigate the toxicity of biocides in order to avoid degrading the performance of WWTP. “Latrina”, a chemical toilet additive containing didecyldimethylammonium chloride and polyhexamethylene guanidine, is widely used in environmentally safe toilet complexes (ESTC) on Russian railway trains to deodorize FS and control microbial activity. In this work, seven biocide-resistant bacterial strains were isolated and identified from the FS of ESTC. The values of the minimum inhibitory and bactericidal concentrations of biocides for the isolated strains were 4.5–10 times higher than for the collection microorganisms. The bacterium Alcaligenes faecalis DOS7 was found to be particularly resistant to “Latrina”, the minimum inhibitory concentration of which was almost 30 times higher than recommended for ESTC. Biological products based on isolated bacterial strains proved to be effective for FS biodegradation under both aerobic and anaerobic conditions. The results of the biochemical oxygen demand test and the newly developed disk-diffusion bioassay confirmed that isolated strains contribute to reducing toxicity of biocidal agents in FS. Hyper-resistance, non-pathogenicity, and potential plant growth-promoting ability make A. faecalis DOS7 promising for use in various biological products for wastewater treatment and bioremediation of soils contaminated with biocides, as well as in agriculture to increase plant productivity.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Didecyldimethylammonium Chloride- and Polyhexamethylene Guanidine-Resistant Bacteria Isolated from Fecal Sludge and Their Potential Use in Biological Products for the Detoxification of Biocide-Contaminated Wastewater Prior to Conventional Biological Treatment

Лойко

Kanunnikov²,

Serdyukov

et al. 2022

Biology

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“…In the current study we have compared that previously used BNC with its 5-(4methoxyphenyl) analogue (Figure 1). We have also recently demonstrated that the sensitivity of BNCgellan gum gels can be increased by addition of methylparaben to act as a radical scavenger, while the total solids loading can by cross-linking with lithium salts without compromising with optical clarity [7]. The resulting gels, while mechanically strong, show a tendency to release liquid (syneresis) when subjected to external force.…”

Section: Introductionmentioning

confidence: 99%

New directions for tetrazolium - gellan gum gel dosimeters

Penev

Mequanint

2022

J. Phys.: Conf. Ser.

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Tetrazolium salt-based dosimeters are non-diffusing, gel dosimeters with excellent physical and chemical stability but with relatively low dose sensitivity and a dose rate dependence of the dose response. Both issues are tackled in this study by: (a) the introduction of a new tetrazolium salt with simple synthesis and dose response around 585 nm which may provide the pathway to more sensitive formulations and (b) producing gels with low gellan gum concentration, thus limiting the dose rate effects, and addition of thickening agents to restrain the liquid loss (syneresis) from the resulting gels.

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“…The initial results indicated that the relatively low sensitivity to dose and the dose rate effect of the sensitivity may cause misregistration of the delivered dose plan. To address this issue, we showed that the addition of radical scavengers, such as methyl paraben and lithium formate [ 18 ] and/or use of novel tetrazolium salts [ 19 ] may improve the sensitivity of the dosimeter. However, these results were achieved at the cost of higher initial optical background and/or decreased chemical and structural stability of the gel dosimeters.…”

Section: Introductionmentioning

confidence: 99%

“…In principle, decreasing the dose rate effect could be achieved by decreasing the gellan gum concentration or by increasing the concentration of the tetrazolium salt [ 18 , 20 ]. Radical scavengers (such as alcohols) are also required to be present in the gel for the radiolysis of tetrazolium salts to achieve a high yield of the formazan dye [ 21 ].…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Dose Rate Effect in Tetrazolium Gellan Gel Dosimeters

Penev

Mulligan

Mequanint

2023

Gels

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Tetrazolium salts provide an appealing candidate for 3D gel dosimeters as they exhibit a low intrinsic color, no signal diffusion and excellent chemical stability. However, a previously developed commercial product (the ClearView 3D Dosimeter) based on a tetrazolium salt dispersed within a gellan gum matrix presented a noticeable dose rate effect. The goal of this study was to find out whether ClearView could be reformulated in order to minimize the dose rate effect by optimizing of the tetrazolium salt and gellan gum concentrations and by the addition a thickening agent, ionic crosslinkers, and radical scavengers. To that goal, a multifactorial design of experiments (DOE) was conducted in small-volume samples (4-mL cuvettes). It showed that the dose rate could be effectively minimized without sacrificing the integrity, chemical stability, or dose sensitivity of the dosimeter. The results from the DOE were used to prepare candidate formulations for larger-scale testing in 1-L samples to allow for fine-tuning the dosimeter formulation and conducting more detailed studies. Finally, an optimized formulation was scaled-up to a clinically relevant volume of 2.7 L and tested against a simulated arc treatment delivery with three spherical targets (diameter 3.0 cm), requiring different doses and dose rates. The results showed excellent geometric and dosimetric registration, with a gamma passing rate (at 10% minimum dose threshold) of 99.3% for dose difference and distance to agreement criteria of 3%/2 mm, compared to 95.7% in the previous formulation. This difference may be of clinical importance, as the new formulation may allow the quality assurance of complex treatment plans, relying on a variety of doses and dose rates; thus, expanding the potential practical application of the dosimeter.

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Gellan gum gel tissue phantoms and gel dosimeters with tunable electrical, mechanical and dosimetric properties

Cited by 10 publications

References 21 publications

Didecyldimethylammonium Chloride- and Polyhexamethylene Guanidine-Resistant Bacteria Isolated from Fecal Sludge and Their Potential Use in Biological Products for the Detoxification of Biocide-Contaminated Wastewater Prior to Conventional Biological Treatment

Didecyldimethylammonium Chloride- and Polyhexamethylene Guanidine-Resistant Bacteria Isolated from Fecal Sludge and Their Potential Use in Biological Products for the Detoxification of Biocide-Contaminated Wastewater Prior to Conventional Biological Treatment

New directions for tetrazolium - gellan gum gel dosimeters

Optimization of the Dose Rate Effect in Tetrazolium Gellan Gel Dosimeters

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