Dr Monica Felipe-Sotelo

There is a great demand from patients requiring skin repair, as a result of poorly healed acute wounds or chronic wounds. These patients are at high risk of constant inflammation that often leads to life-threatening infections. Therefore, there is an urgent need for new materials that could rapidly stimulate the healing process and simultaneously prevent infections. Phosphate-based coacervates (PC) have been the subject of increased interest due to their great potential in tissue regeneration and as controlled delivery systems. Being bioresorbable, they dissolve over time and simultaneously release therapeutic species in a continuous manner. Of particular interest is the controlled release of metallic antibacterial ions (e.g. Ag+), a promising alternative to conventional treatments based on antibiotics, often associated with antibacterial resistance (AMR). This study investigates a series of PC gels containing a range of concentrations of the antibacterial ion Ag+ (0.1, 0.3 and 0.75 mol%). Dissolution tests have demonstrated controlled release of Ag+ over time, resulting in a significant bacterial reduction (up to 7 log), against both non-AMR and AMR strains of both Gram-positive and Gram-negative bacteria (Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa). Dissolution tests have also shown controlled release of phosphates, Ca2+, Na+ and Ag+ with most of the release occurring in the first 24 h. Biocompatibility studies, assessed using dissolution products in contact with human keratinocyte cells (HaCaT) and bacterial strains, have shown a significant increase in cell viability (p ≤ 0.001) when gels are dissolved in cell medium compared to the control. These results suggest that gel-like silver doped PCs are promising multifunctional materials for smart wound dressings, being capable of simultaneously inhibit pathogenic bacteria and maintain good cell viability.

Chemical composition analysis of açaí extracts revealed higher levels of total polyphenol content in purple açaí samples for both commercial (4.3–44.7 gallic acid equivalents mg/g) and non-commercial samples (30.2–42.0 mg/g) compared to white (8.2–11.9 mg/g) and oil samples (0.8–4.6 mg/g). The major anthocyanin compounds found in purple açaí samples were cyanidin-3-glucoside and cyanidin-3-rutinoside with total concentrations in the range of 3.6–14.3 cyanidin-3-glucoside equivalents mg/g. The oligomeric proanthocyanidins were quantified in the range of 1.5–6.1 procyanidin B1 equivalents mg/g. Moreover, açaí presented significant levels of calcium, magnesium, manganese, iron, zinc and copper, essential minor and trace elements, in comparison with other berries. All of the açaí extracts at 50 μg/mL potently inhibited the release of reactive oxygen species in lipopolysaccharide-stimulated RAW 264.7 murine macrophage cells, but none inhibited the release of nitric oxide. Furthermore, all the açaí samples demonstrated potential as wound healing agents due to the high levels of migration activity in human fibroblast cells.

Contamination of groundwater with arsenic from natural sources is endemic in the West Bengal region of India. Despite increased awareness regarding the consumption of safe water for drinking, the use of groundwater for agricultural purposes, cooking and other domestic tasks still prevails. This study investigates the accumulation of As, Mn and Fe in paddy soils irrigated with groundwater and evaluates the levels of these elements in the different parts of the rice plants. The results show that although there is a significant accumulation of As, Mn and Fe in the soils irrigated with groundwater, the uptake by the grains is not proportional to the concentrations in the soils. Arsenic is accumulated mainly in the roots, followed by straw and grains, and significant amounts of arsenic are removed by de-husking of the rice (86–88 % of As in the wholegrain). The evaluation of the effect of washing and cooking the rice with groundwater shows that there is a marked increase in the arsenic levels of cooked rice (up to 232 %). However, the accumulation is highly dependent on the type of rice, with processed commercial samples (parboiled) having a lower capacity to retain arsenic than the rice varieties utilised by the local villagers.

Banana peels were used as feedstock to produce a carbon dense hydrochar for the removal of toxic metals from wastewater. Compared to the biomass feedstock (41.3% mass C), the banana peel hydrochar possesses higher carbon (54–72% mass C) and lower ash contents. The carbonised banana peels treated between 150 and 300 °C (1−2h) demonstrated an excellent ability to remove Cd2+ (5–100 mg L−1), achieving 99% removal, in comparison with 75% for the raw peel. The liquid by-product generated in the carbonisation process was tested as feedstock in microbial electrochemical devices, showing significant reduction in the chemical oxygen demand levels (initially 10–25 103 mg L−1), associated with the production of electrical outputs; 81–85% reduction with microbial communities from compost, and 53–85% with anaerobic sludge. The results demonstrate the complete utilization of waste from mass cultivation of banana, providing a full-cycle solution for the pollution associated to this important crop. [Display omitted] •Hydrothermal carbonisation is a sustainable solution for waste in banana industry.•Hydrochars from banana peels are effective sorbents of Cd2+ ion from water.•Promising use of liquid by-product from hydrocharring for bioelectrochemical cells.

In this study, it was hypothesised that UV-absorbing disinfection byproducts (DBPs) may include compounds, such as halofuranones, prioritized as candidates for explaining the increased risk of bladder cancer associated with the consumption of chlorinated water highlighted by epidemiological studies. Hence, UV spectroscopy was used as a screening method to identify conditions forming stable UV-absorbing DBPs from 10 phenolic precursors at various pH levels, chlorine and bromide doses. Subsequently, high performance liquid chromatography coupled to high resolution mass spectrometry (OrbitrapTM) was used to elucidate the chemical formulas of 30 stable DBPs, 12 of which were tentatively identified as furan-like structures, including trichlorofuran-2-carboxylic acid, dichlorofuran-2-carboxylic acid, 3,4-dichlorofuran-2,5-dicarbaldehyde, 4-chloro-5-(dichloromethyl)furan-2,3-dione, 5-formyl-2-furancarboxylic acid, chloro-5-methyl-2-furancarboxylic acid, 2-acetylchlorofuran-5-one and bromo-2-furancarboxylic acid. Eleven of the furan-like structures are previously unknown as DBPs. A novel pathway was proposed to explain their formation, involving the opening of the oxidised phenolic ring followed by the formation of a 5-membered ring by intramolecular nucleophilic addition. Of the 12 furan-like DBPs identified, eight and three were respectively predicted to be mutagens and bladder carcinogens, using a quantitative structure-activity relationship theoretical model. The findings indicate the formation of furan-like DBPs from natural organic matter surrogates is more widespread than previously appreciated. Moreover, this class of DBPs may be toxicologically significant for the urinary bladder.

Epidemiological studies have consistently associated the consumption of chlorinated drinking water with an enhanced risk of bladder cancer. While this suggests that some disinfection byproducts (DBPs) are bladder carcinogens, causal agents are unknown. This study aims to highlight likely candidates. To achieve this, structures ofknown and hypothesised DBPs werecompared with 76 known bladder carcinogens. The latter are dominated by nitrogenous and aromatic compounds; only 10 are halogenated. Under 10% of the chlorine applied during drinking water treatment is converted into identified halogenated byproducts; most of the chlorine is likely to be consumed during the generation of unidentified non-halogenated oxidation products. Six nitrosamines are among the nine most potent bladder carcinogens, and two of them are known to be DBPs: N-nitrosodiphenylamine and nitrosodibutylamine. However, these and other nitrosamines are formed in insufficiently low concentrations in chlorinated drinking water to account for the observed bladder cancer risk. Furthermore, although not proven bladder carcinogens, certain amines, haloamides, halocyclopentenoic acids, furans and haloquinones are potential candidates. At present, most identified bladder carcinogens are nitrogenous, whereas > 90% of natural organic matter is not. Therefore, non-nitrogenous DBPs are likely to contribute to the bladder cancer risk. Given the high proportion of DBPs that remains uncharacterised, it is important that future research prioritises compounds believed to be potent toxicants.

This work describes the solubility of nickel under the alkaline conditions anticipated in the near field of a cementitious repository for intermediate level nuclear waste. The measured solubility of Ni in 95%-saturated Ca(OH)2 solution is similar to values obtained in water equilibrated with a bespoke cementitious backfill material, on the order of 5 × 10−7 M. Solubility in 0.02 M NaOH is one order of magnitude lower. For all solutions, the solubility limiting phase is Ni(OH)2; powder X-ray diffraction and scanning transmission electron microscopy indicate that differences in crystallinity are the likely cause of the lower solubility observed in NaOH. The presence of cellulose degradation products causes an increase in the solubility of Ni by approximately one order of magnitude. The organic compounds significantly increase the rate of Ni transport under advective conditions and show measurable diffusive transport through intact monoliths of the cementitious backfill material.

Organic superplasticisers improve the flow properties of cement, offering operational advantages for the disposal of radioactive wastes. However, there are concerns that they could increase the mobility of encapsulated contaminants significantly. The effect of polycarboxylate ether superplasticisers on the solubility of Ni(II), Am(III), Pu(IV) and U(VI) in two cement-equilibrated waters (ordinary Portland cement/pulverised fuel ash (OPC/PFA) and OPC/ground granulated blast-furnace slag (GGBS)) has been assessed. The study included four commercial superplasticisers, three adjuncts (a de-foaming agent, biocide and viscosity modifier) and a bespoke, synthesised superplasticiser from which residual monomer had been removed by dialysis. The commercial products (0·5% w/w dosage) had a much greater effect on metal solubility than the dialysed equivalent, increasing solubility by 2–3 orders of magnitude. As the adjuncts alone showed no effect, the difference between the commercial and synthesised superplasticisers is attributed to small molecules, primarily residual monomers, in the commercial formulations owing to incomplete polymerisation. The distribution of radionuclides in hardened cement pastes corresponds closely to the distribution of superplasticiser, as shown by 14C-labelling in combination with digital autoradiography and accounting for the bleed observed for certain slag-rich formulations.

The elemental composition of 37 bottled waters from the UK and continental Europe has been determined. Ca, K, Mg, Na, Al, As, Ba, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Sr, U, V and Zn were determined by ICP-OES and ICP-MS, in addition to inorganic and total organic carbon. The composition of all the waters analysed fell within the guideline values recommended by the World Health Organization. Na, Ca, Sr and Ba showed the widest variation in concentrations, ranging over two orders of magnitude. Levels of Fe were below the limit of detection (30 μg L−1) in all samples analysed. Waters produced in the UK generally showed lower levels of most major elements and trace metals, with the exception of Ba (up to 455 μg L−1). Italian waters showed the highest concentrations of Sr (3000–8000 μg L−1) and U (8–13 μg L−1), whereas waters produced in Slovakia and the Czech Republic showed the highest levels of Pb (0.7–4 μg L−1). The use of multivariate analysis reveals an association between high alkaline metal content and high concentrations of As and Cr. There also appears to be a correlation between high Ca and Sr content and high levels of U. Analysis of variance (ANOVA) indicates that the composition of bottled water can be distinguished primarily by the country of origin, over other factors including the geological environment of the source. This would suggest that composition reflects, and is biased towards, consumer preferences.

This work presents the study of the solubility of selenium under cementitious conditions and its diffusion, as SeO32−, through monolithic cement samples. The solubility studies were carried out under alkaline conditions similar to those anticipated in the near-field of a cement-based repository for low- and intermediate-level radioactive waste. Experiments were conducted in NaOH solution, 95%-saturated Ca(OH)2, water equilibrated with a potential backfill material (Nirex reference vault backfill, NRVB) and in solutions containing cellulose degradation products, with and without reducing agents. The highest selenium concentrations were found in NaOH solution. In the calcium-containing solutions, analysis of the precipitates suggests that the solubility controlling phase is Ca2SeO3(OH)2·2H2O, which appears as euhedral rhombic crystals. The presence of cellulose degradation products caused an increase in selenium concentration, possibly due to competitive complexation, thereby, limiting the amount of calcium available for precipitation. Iron coupons had a minor effect on selenium solubility in contrast to Na2S2O4, suggesting that effective reduction of Se(IV) occurs only at Eh values below −300 mV. Radial through-diffusion experiments on NRVB and in a fly ash cement showed no evidence of selenium breakthrough after one year. However, autoradiography of the exposed surfaces indicated that some migration had occurred and that selenium was more mobile in the higher porosity backfill than in the fly ash cement.

Radial diffusion experiments have been carried out to assess the migration of 36Cl, as chloride, through a cementitious backfill material. Further experiments in the presence of cellulose degradation products were performed to assess the effect of organic ligands on the extent and rate of chloride diffusion. Results show that breakthrough of 36Cl is dependent on chloride concentration: as the carrier concentration increases, both breakthrough time and the quantity retained by the cement matrix decreases. Experiments in the presence of cellulose degradation products also show a decrease in time to initial breakthrough. However, uptake at various carrier concentrations in the presence of organic ligands converges at 45% of the initial concentration as equilibrium is reached. The results are consistent with organic ligands blocking sites on the cement that would otherwise be available for chloride binding, though further work is required to confirm that this is the case. Post-experimental digital autoradiographs of the cement cylinders, and elemental mapping showed evidence of increased 36Cl activity associated with black ash-like particles in the matrix, believed to correspond to partially hydrated glassy calcium-silicate-sulfate-rich clinker.

Water from La Pampa, Argentina, was used for washing and cooking rice to examine the in-situ impact of using naturally-contaminated water for food preparation on the elemental dietary intake. Whilst washing with the control tap water (28 g/L As) reduced the concentration of As in rice by 23%, the use of different well waters (281-1144 g/L) increased As levels significantly (48-227%) in comparison with the original concentration in the rice (0.056 µg/g). Cooking the rice at a low water-to-rice ratio (2:1) using modern methods increased the levels of As in the cooked samples by 2-3 orders of magnitude for both pre-washed and un-washed rice. Similar trends were observed for vanadium. Although the levels of manganese, iron, copper, zinc and molybdenum in rice were reduced during washing and cooking for most water samples, the molybdenum concentration in the cooked rice doubled (2.2-2.9 µg/g) when using water containing >1 mg/L Mo.

Acai fruit is recognized for its health promoting properties. However, there is still a need to address the effects of industrial processing on this fruit. In this study, phenolic content, anti-inflammatory properties and dermal wound repair properties of 20 acai samples, before and after industrial processing, from various Amazon regions were investigated. Acai pulp was rich in total phenolics (18.9–58.8 mg g−1) and proanthocyanins (9.8–43.1 mg g−1), but contained trace anthocyanins (up to 0.1 mg g−1). Industrially processed samples lost substantial amounts of proanthocyanidins (up to 83.2%), while the anthocyanins inherently present were greatly enriched after processing (20-fold higher). Non-processed acai pulp extracts protected against early inflammation response which was correlated with proanthocyanidins, by significantly inhibiting nitric oxide production and suppressing pro-inflammatory gene expression including interleukin-1β, cyclooxygenase-2, nitric oxide synthase, and interleukin-6. The promotion of dermal wound repair of acai seed and pulp extracts was mainly contributed by anthocyanins and other bioactive compounds. The anti-inflammatory effect was diminished but wound healing effect was retained after pulp processing, suggesting the processing technology needs to be improved to maintain biological properties of acai fruit.

The solubility of uranium and thorium has been measured under the conditions anticipated in a cementitious, geological disposal facility for low and intermediate level radioactive waste. Similar solubilities were obtained for thorium in all media, comprising NaOH, Ca(OH)2 and water equilibrated with a cement designed as repository backfill (NRVB, Nirex Reference Vault Backfill). In contrast, the solubility of U(VI) was one order of magnitude higher in NaOH than in the remaining solutions. The presence of cellulose degradation products (CDP) results in a comparable solubility increase for both elements. Extended X-ray Absorption Fine Structure (EXAFS) data suggest that the solubility-limiting phase for uranium corresponds to a becquerelite-type solid whereas thermodynamic modelling predicts a poorly crystalline, hydrated calcium uranate phase. The solubility-limiting phase for thorium was ThO2 of intermediate crystallinity. No breakthrough of either uranium or thorium was observed in diffusion experiments involving NRVB after three years. Nevertheless, backscattering electron microscopy and microfocus X-ray fluorescence confirmed that uranium had penetrated about 40µm into the cement, implying active diffusion governed by slow dissolution-precipitation kinetics. Precise identification of the uranium solid proved difficult, displaying characteristics of both calcium uranate and becquerelite.

The influence of anthropogenic organic complexants (citrate, EDTA and DTPA from 0.005 to 0.1 M) on the solubility of nickel(II), thorium(IV) and uranium (U(IV) and U(VI)) has been studied. Experiments were carried out in 95%-saturated Ca(OH)2 solutions, representing the high pH conditions anticipated in the near field of a cementitious intermediate level radioactive waste repository. Results showed that Ni(II) solubility increased by 2–4 orders of magnitude in the presence of EDTA and DTPA and from 3 to 4 orders of magnitude in the case of citrate. Citrate had the greatest effect on the solubility of Th(IV) and U(IV)/(VI). XRD and SEM analyses indicate that the precipitates are largely amorphous; only in the case of Ni(II), is there some evidence of incipient crystallinity, in the form of Ni(OH)2 (theophrastite). A study of the effect of calcium suggests that U(VI) and Ni(II) may form metal-citrate-OH complexes stabilised by Ca2+. Thermodynamic modelling underestimates the concentrations in solution in the presence of the ligands for all the elements considered here. Further investigation of the behaviour of organic ligands under hyperalkaline conditions is important because of the use of the thermodynamic constants in preparing the safety case for the geological disposal of radioactive wastes.

The whereabouts of the overwhelming majority of plastic estimated to enter the environment is unknown. This study’s aim was to combine information about the environmental occurrence and physicochemical properties of widespread polymers to predict the fate of aquatic plastic litter. Polyethylene and polypropylene are common in the surface layer and shorelines; polyester and cellulosic fibres in sewage treatment works, estuarine and deep-sea sediments. Overall, non-buoyant polymers are underrepresented on the ocean surface. Three main explanations are proposed for the missing plastic. The first is accumulation of both buoyant and non-buoyant polymers in sewage treatment works, river and estuarine sediments and along shorelines. The second is settling of non-buoyant polymers into the deep-sea. The third is fragmentation of both buoyant and non-buoyant polymers into particles smaller than captured by existing experimental methods. Some isolation techniques may overrepresent larger, buoyant particles; methodological improvements are needed to capture the full size-range of plastic litter. When microplastics fragment they become neutrally-buoyant, thus nanoplastics are potentially widely dispersed in aquatic systems, both horizontally and vertically. Ultimately, over decades or longer, plastics are potentially solubilized and subsequently biodegraded. The rates at which these processes apply to plastic litter in different environmental compartments remain largely unknown.