[Effects of Biochar on Growth and Pollutant Accumulation of Lettuce in Soil Co-contaminated with Tetracycline and Copper].

Through lettuce potting experiments, the effects of different types of biochar (apple branch, corn straw, and modified sorghum straw biochar with phosphoric acid modification) on lettuce growth under tetracycline (TC) and copper (Cu) co-pollution were investigated. The results showed that compared with those under CK, the addition of biochar treatment significantly increased the plant height, root length, shoot fresh weight, and root fresh weight of lettuce (P < 0.05). The addition of different biochars significantly increased the nitrate nitrogen, chlorophyll, and soluble protein content in lettuce physiological indicators to varying degrees, while also significantly decreasing the levels of malondialdehyde, proline content, and catalase activity. The effects of biochar on lettuce physiological indicators were consistent during both the seedling and mature stages. Compared with those in CK, the addition of biochar resulted in varying degrees of reduction in the TC and Cu contents of both the aboveground and underground parts of lettuce. The aboveground TC and Cu levels decreased by 2.49%-92.32% and 12.79%-36.47%, respectively. The underground TC and Cu levels decreased by 12.53%-55.64% and 22.41%-42.29%, respectively. Correlation analysis showed that nitrate nitrogen, chlorophyll, and soluble protein content of lettuce were negatively correlated with TC content, whereas malondialdehyde, proline content, and catalase activity were positively correlated with TC content. The resistance genes of lettuce were positively correlated with TC content (P < 0.05). In general, modified biochar was found to be more effective in improving lettuce growth quality and reducing pollutant accumulation compared to unmodified biochar, with modified sorghum straw biochar showing the best remediation effect.

Study on persulfate activated by Ce-modified tea waste biochar to degrade tetracycline.

In this study, the Ce-modified tea residue biochar (Ce-TBC) was successfully generated and applied to the biochar/persulfate system (Ce-TBC/PDS), the mechanism of the removal of tetracycline (TC) using Ce-TBC/PDS was elaborated. Under the optimal experimental conditions (Ce-TBC = 0.8 g L-1, PDS = 4 mM, TC = 10 mg L-1), the removal efficiency of TC was 91.28%, and after 5 cycles, the elimination rate of Ce-TBC/PDS still reached up to 80%. The mechanism of TC removal by Ce-TBC/PDS was analyzed by scanning electron microscopy (SEM), X-ray diffractometer (XRD), Fourier infrared transform spectrometer (FT-IR), and X-ray photoelectron spectrometer (XPS) characterization, and influence factor experiments. The results showed that the introduction of CeOx increased the oxygen vacancies on the TBC surface and promoted the interconversion between Ce3+ and Ce4+ for better activation of PDS and generation of active species. Free radical quenching experiments and paramagnetic resonance spectrometry (EPR) analysis showed that the non-radical pathway 1O2 played a dominant role in the Ce-TBC/PDS system. The present work provided an efficient means of PDS activator and recycling of tea waste.

A ratiometric fluorescence sensor for tetracycline detection based on two fluorophores derived from Partridge tea.

Blue fluorescent carbon dots (PCDs) were prepared by hydrothermal method with Partridge tea. The ethanol extract of Partridge tea (PEE) was found to emit red fluorescence. Thus, a novel ratiometric sensor was constructed by simply mixing the two fluorophores derived from Partridge tea. The presence of tetracycline (TET) at lower concentrations enhanced the emission peak at 508 nm of PCDs and had a negligible effect on the emission peak at 680 nm of PEE. TET at higher concentrations led to  quenching  both the fluorescence of PCDs and PEE via inner filter effect and fluorescence resonance energy transfer, separately. Good linearities for the detection of TET were obtained in the ranges 0.67 to 15.00 µM and 33.33 to 266.67 µM, with limit of detection of 0.095 µM. The sensor was successfully applied to detect TET in lake water and milk samples with good recoveries ranging from 93.27 ± 4.04% to 107.30 ± 6.16%. This study provided a simple, selective, sensitive, rapid, and environmentally friendly method of monitoring TET residues in the environment and food.

Qualitative immunoassay for the determination of tetracycline antibiotic residues in milk samples followed by a quantitative improved HPLC-DAD method.

Environmental contaminant is one of several problems harming people and wildlife. An example of current emerging contaminants are antibiotics residues that can present in water and food. Although antibiotics are intended to treat or prevent human and animal infections, antibiotics have also been used as animal food supplements for their ability to promote growth and feed efficiency. This overuse of antibacterial has resulted in the accumulation of antibiotics residues in food products which are eventually consumed by human. The continuous unnecessary exposure of human to antibiotics through the direct animals meet or milk, or indirectly through plants or soil can increase the chance of the emergence of multi drug resistance bacteria and consequently adversely affecting human health. New regulations have been imposed regarding antibiotics utilization. Due to the scarce of data regarding antibiotics residue conditions in different types of food intended for human consumption in Saudi Arabia, this study proposed an optimized chromatographic method (HPLC-DAD) followed by an immunoassay approach for specifically detecting tetracyclines antibiotics in animal milk samples. The method was carried out using an RP-C18 column with a mobile phase consisting of 0.01 M KH2PO4: acetonitrile:methanol (70:20:10, v/v/v) adjusted to pH 4. Improvements were observed in the method in terms of resolution and sensitivity. The protein precipitation method used for extraction demonstrated high percent recoveries of 85-101%. The method was validated according to the guidelines of the International Conference for Harmonization (ICH). It is evidently clear from these findings that the presence of tetracycline and oxytetracycline antibiotics residues in milk products from the Saudi market are below the maximum residual limits (MRLs).

A novel colorimetric aptasensor for sensitive tetracycline detection based on the peroxidase-like activity of Fe3O4@Cu nanoparticles and "sandwich" oligonucleotide hybridization.

A novel colorimetric aptasensor has been developed for highly sensitive tetracycline (TC) detection based on the peroxidase-like activity of Fe3O4@Cu nanoparticles and "sandwich" oligonucleotide hybridization. The Fe3O4@Cu nanoparticles with high peroxidase-like activity were successfully synthesized under mild conditions. Then, a "sandwich" oligonucleotide hybridization probe (a short amino-modified complementary sequence of a portion of the TC aptamer (cDNA1), TC aptamers, and a long complementary to 5' terminal TC aptamer sequence (cDNA2)) was created in 96-wells plates via DNA hybridization in the absence of TC from the detection system. The unique "sandwich" oligonucleotide hybridization probe adsorbed large numbers of Fe3O4@Cu nanozymes while further enhancing its peroxidase-like activity. Based on the 3,3',5,5'-tetramethylbenzidine (TMB)-hydrogen peroxide (H2O2) reporting system, the blue color of the solution decreased linearly with the increase of TC concentration, ranging from 10-3 to 103 µg/L with an ultralow limit of detection (LOD) of 0.91 ng/L (2 pM). The proposed method was successfully applied to detect TC in spiked milk samples, with recoveries of 81.8 to 112%, demonstrating the excellent potential for highly sensitive TC detection in milk.

High mesoporosity phosphorus-containing biochar fabricated from Camellia oleifera shells: Impressive tetracycline adsorption performance and promotion of pyrophosphate-like surface functional groups (C-O-P bond).

In China, more than 3.5 million tons of Camellia oleifera discarded shells are produced every year. This work first prepared phosphorus-containing biochar (PBC) from C. oleifera shells and was successfully applied to the efficient removal of tetracycline (TC) from solutions. The prepared PBC exhibits superior TC adsorption capacity of 451.5 mg/g, and TC uptake rapidly reached 315.5 mg/g at the first 5 min (C0 = 50 mg/L). Furthermore, PBC also shows excellent applicability to the broad range pH value (1-9) and superior selective removal in the presence of various high concentration coexisting ions (1 mM). Mechanisms underlying TC adsorption were also put forward, and analysis suggested that pyrophosphate-like surface functional groups (C-O-P bond) played a critical role in this process. Notably, treating pharmaceutical wastewater with PBC can efficiently reduce chemical oxygen demand (COD) and total organic carbon (TOC) concentration below the discharge standard of China (GB21904-2008).

Computational and experimental assessment of pH and specific ions on the solute solvent interactions of clay-biochar composites towards tetracycline adsorption: Implications on wastewater treatment.

Experimental and computational investigations have been conducted in this study to assess the influence of municipal waste pyrolyzed biochar impregnated clay composites on antibiotic removal as a material for wastewater treatment and simultaneous value-addition for waste. The surface potential (zeta potential) of the pristine biochar and composite samples are found to be within the range ~10 to ~ -40 mV in the pH range 2-10. The presence of different inorganic salt solutions influences the electrophoretic mobility of the dispersed phase in a suspension, as well as its zeta potential. In addition of Na+ salt solutions, the Na+ ions undergo electrostatic interaction with the negatively charged biochar samples and form a double layer at the interface of biochar and ionic salt solution. Molecular dynamics simulations have been employed to understand experimental findings, ions adsorption and solute-solvent interactions at the molecular level of two biochar B7 (seven benzene rings, one methoxy, one aldehyde and two hydroxyls groups) and B17 (seventeen benzene rings, one methoxy, two hydroxyls and two carboxylic acid groups) in salts aqueous solutions. The results confirm that hydroxyls and carboxylate groups of biochar are responsible for solute-solvent interactions. Successful removal of tetracycline antibiotics is observed with 26 mg/g maximum adsorption capacity with montmorillonite biochar composite. This study confirms that interactions between amide and hydroxyl groups of tetracycline with hydroxyl and carboxylate groups of biochar play the key role in the adsorption process. The solution pH and presence of different background electrolytes effectively influence the process of solute-solvent interactions as well as adsorption efficacy towards tetracycline adsorption.

Removal of tetracycline with aluminum boride carbide and boehmite particles decorated biochar derived from algae.

For the first time, using aluminum-boron electrodes in the electrocoagulation cell for harvesting the cultivated Chlorella microalgae and then performing a hydrothermal process of producing biofuel, mesoporous biochar was produced with an average pore diameter of 11.62 nm, a high specific surface area of 126.4 m2/g and a total pore volume of 0.55 cm3/g. Based on the chemical characterization, aluminum boride carbide (Al3B48C2) and boehmite [Al2(OOH)2] were identified in the biochar composition so that 7.17 wt% Al and 16.67 wt% B were measured on the biochar surface by EDS analysis. As the by-product of hydrothermal converting microalgae Chlorella into biofuel, the residual biochar was innovatively used to separate tetracycline from aqueous solutions. The nonlinear form of the Freundlich model fitted theadsorption equilibrium data well with the least error function value explained by the intraparticle diffusion model. The maximum adsorption capacity of 25.94 mg/g was obtained through endothermic physical adsorption.

Toxicity of tetracycline and its transformation products to a phosphorus removing Shewanella strain.

Tetracycline (TC) as an emerging contaminant has raised serious concerns about its toxicity and removal in wastewater treatment processes. The more toxic transformation products of TC, 4-epitetracycline (ETC), anhydrotetracycline (ATC) and 4-epianhydrotetracycline (EATC) are also widely detected. This study investigated the antibacterial and bactericidal activity of TC, ETC, ATC, EATC against Shewanella sp, using Escherichia coli and Pseudomonas aeruginosa strains as quality controls. Further, batch assays were conducted to investigate the inhibition of these antibiotics on the phosphorus removal of the Shewanella strain, and removal mechanisms of TC and its transformation products (TCs). The inhibition on phosphorus removal by the Shewanella strain at 20 mg L-1 was in the order of ATC > EATC > TC > ETC. COD removal, poly-P accumulation and glycogen synthesis by the Shewanella strain were also inhibited. Biodegradation was the main removal mechanism of TC and ETC, while adsorption was the main one of ATC and EATC. This study helps to further understand the structure-activity relationship of TC.

Liquidambar styraciflua L.: A new potential source for therapeutic uses.

Liquidambar styraciflua L., ALTINGIACEAE, popularly known as sweet gum or alligator tree, is an aromatic tree with a natural distribution in North America and acclimated in Brazil. In traditional medicine, L. styraciflua L is used for the treatment of stomach disorders, wounds, and coughs. The present study was designed to investigate the biological potential and chemical profile of extracts obtained from aerial parts of L. styraciflua L. The chemical profile was established using liquid chromatography-mass spectrometry analysis and the extracts were tested for total phenolics, flavonoids, and tannins using spectrophotometric assays. The anti-inflammatory activity of L. styraciflua L was tested using an inhibition of hyaluronidase enzyme assay, and cytotoxic activities were tested by the 3-(4,5-dimethylthiazol-2 yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. The synergy between the plant extracts with ciprofloxacin and tetracycline was studied by the checkerboard assay method against eight bacterial strains.The phytochemical investigation showed that the leaves and stem are rich in phenolics compounds (1419.34-1614.02 mg GAE/g, 875.21-1557.57 mg GAE/g, respectively), mainly flavonoids and hydrolyzable tannins. The samples of the stem exhibited the best anti-inflammatory activity. The butanol fraction of the stem was better than the commercial propolis extract. The hydroalcoholic extract of the stem and the propolis did not exhibit significant differences (p < 0.05) at any of the concentrations tested. A synergistic interaction was observed against the Gram-positive bacterial Enterococcus faecalis (hydroalcoholic extract of leaves and tetracycline) and Staphylococcus aureus (hydroalcoholic extract of stem and tetracycline). The IC50 values obtained for the extracts indicate the absence of toxicity and moderate cytotoxic for the hydroalcoholic extract of the stem. On the basis of our findings, L. styaciflua may be considered as a potential therapeutic source with high anti-inflammatory activity and synergistic interactions with antibiotics against bacteria.

Evaluation of tetracycline in milk following extra-label administration of topical tetracycline for digital dermatitis in dairy cattle.

Digital dermatitis (DD) is a painful infectious foot lesion commonly treated topically with extra-label tetracycline. Our objectives were to determine the concentrations of tetracycline in milk and plasma and to calculate a withdrawal interval following topical application at various doses. Another objective was to evaluate agreement between tests for measuring tetracycline in milk. A randomized block trial was conducted on 2 farms, where 50 cows with active DD lesions on 2 feet were allocated to 1 of 5 treatment groups (n = 10 cows per group). Treatment groups consisted of topical applications of tetracycline hydrochloride, in a paste or as a powdered form under a bandage, at 3 different dosing levels (2, 5, and 25 g) on each of the 2 affected feet. Following enrollment and treatment, samples were collected from milk, teat skin, and blood every 8 to 24 h for up to 7 d postdosing. Concentrations of tetracycline were measured by liquid chromatography-mass spectrometry and milk samples were further tested using the Charm ROSA TET test (Charm Sciences Inc., Lawrence, MA). Tetracycline was present in milk, plasma, and teat skin from all treatment groups. Tetracycline concentrations varied depending on time of sampling, method of application, and dosing level. At 8 h post-treatment, 11% of cows had tetracycline present in milk higher than 100 ng/mL (ppb) but none higher than 300 ng/mL. The 25-g treatment group had the longest estimated withdrawal interval, the highest observed concentrations (210-244 ng/mL) of tetracycline present in milk, and the longest observed consecutive period of tetracycline presence (from 8 to 72 h) among all treatment groups. Compared with liquid chromatography-mass spectrometry, the Charm test had a sensitivity of 77 and 100% for measuring tetracycline in milk at ≥30 and ≥100 ng/mL, respectively. Post-treatment samples of the teat skin were taken from 15 cows on 6 occasions, and every cow had tetracycline present in at least 1 of those 6 samples. This confirms an association between topical DD treatment with tetracycline and contamination of the teat. A total of 22% of blood samples had detectable tetracycline, and the majority (63%) occurred at 8 h post-treatment. At 100 ng/mL, the estimated cow-level milk withdrawal interval ranged from 0 to 70 h. At 300 ng/mL, the estimated cow-level withdrawal interval ranged from 0 to 34 h, and was 0 h at the bulk tank level. We recommend that conservative measures be adopted after extra-label use of topical tetracycline for DD treatment, including using a low dose and strategic post-treatment testing for tetracycline-class drugs in milk.

A magnetite/PMAA nanospheres-targeting SERS aptasensor for tetracycline sensing using mercapto molecules embedded core/shell nanoparticles for signal amplification.

Surface-enhanced Raman scattering (SERS) biosensors have promising potential in the field of antibiotics detection because of their ultrahigh detection sensitivity. This paper reports a rapid and sensitive SERS-based magnetic nanospheres-targeting strategy for sensing tetracycline (TTC) using aptamer-conjugated magnetite colloid nanocrystal clusters (MCNCs)-polymethacrylic acid (PMAA) magnetic nanospheres (MNs) as the recognition and the Au/PATP/SiO2 (APS) as the labels. Initially, MNs were fabricated and conjugated with the aptamers through condensation reaction. MNs possessed high saturation magnetization (Ms) value of 71.5emu/g and excellent biocompatibility, which facilitated the rapid and easy magnetic separation. Then, complementary DNA (cDNA) were loaded on the APS nanocarrier to produce a large amplification factor of Raman signals. The MNs-targeting aptasensor was thus fabricated by immobilizing the APS to the MNs' surfaces via the hybrid reaction between cDNA and aptamers. Sequel, TTC bound successfully to the aptamer upon its addition with the subsequent release of some cDNA-APS into the bulk solution. Under magnet attraction, the nanospheres were deposited together. Consequently, a display of strong SERS signals by supernatants of the resulting mixtures with increasing TTC concentrations was observed. The proposed aptasensor showed excellent performances for TTC detection along with wide linear range of 0.001-100ng/mL, low detection limit 0.001ng/mL, high sensitivity, and good selectivity to the general coexisted interferences.

A molecularly imprinted photonic polymer sensor with high selectivity for tetracyclines analysis in food.

A molecularly imprinted photonic polymer (MIPP) sensor for respective detection of tetracycline, oxytetracycline and chlortetracycline is developed based on the combination of a colloidal crystal templating method and a molecular imprinting technique. Colloidal crystal templates are prepared from monodisperse polystyrene colloids. The molecularly imprinted polymer, which is embodied in the colloidal crystal templates, is synthesized with acrylic acid and acrylamide as monomers, N,N'-methylene bisacrylamide as a cross-linker and tetracyclines (TCs) as imprinting template molecules. After removal of the colloidal crystal template and the molecularly imprinted template, the resulted MIPP consists of a three-dimensional, highly ordered and interconnected macroporous array with a thin hydrogel wall, where nanocavities complementary to analytes in shape and binding sites are distributed. The response of MIPP to TCs stimulants in aqueous solution is detected through a readable Bragg diffraction red-shift, which is due to the lattice change of MIPP structures responding to their rebinding to the target TCs molecules. A linear relationship was found between the Δλ and the concentration of TCs in the range from 0.04 µM to 0.24 µM. With this sensory system, direct and selective detection of TCs has been achieved without using label techniques and expensive instruments. The developed method has been applied successfully to detect tetracycline in milk and honey samples.

Effects of residual antibiotics in groundwater on Salmonella typhimurium: changes in antibiotic resistance, in vivo and in vitro pathogenicity.

An outbreak-causing strain of Salmonella enterica serovar Typhimurium was exposed to groundwater with residual antibiotics for up to four weeks. Representative concentrations (0.05, 1, and 100 µg L(-1)) of amoxicillin, tetracycline, and a mixture of several other antibiotics (1 µg L(-1) each) were spiked into artificially prepared groundwater (AGW). Antibiotic susceptibility analysis and the virulence response of stressed Salmonella were determined on a weekly basis by using human epithelial cells (HEp2) and soil nematodes (C. elegans). Results have shown that Salmonella typhimurium remains viable for long periods of exposure to antibiotic-supplemented groundwater; however, they failed to cultivate as an indication of a viable but nonculturable state. Prolonged antibiotics exposure did not induce any changes in the antibiotic susceptibility profile of the S. typhimurium strain used in this study. S. typhimurium exposed to 0.05 and 1 µg L(-1) amoxicillin, and 1 µg L(-1) tetracycline showed hyper-virulent profiles in both in vitro and in vivo virulence assays with the HEp2 cells and C. elegans respectively, most evident following 2nd and 3rd weeks of exposure.

An experimental study of the use of hyperbaric oxygen to reduce the side effects of radiation treatment for malignant disease.

Hyperbaric oxygen (HBO) has been used for more than 20 years to assist wound healing in the treatment of the more severe complications associated with the side effects of therapeutic radiation treatment. A prospective study was performed in an irradiated rat model to determine whether HBO is effective in reducing the long-term side effects of therapeutic radiation treatment on normal tissue, when given 1 week after the completion of the radiation treatment. The experimental model was designed to simulate a fractionated course of therapeutic radiation that is commonly used in the treatment of cancer of the mandible. One week following completion of the radiotherapy, the animals underwent a 4-week course of HBO treatment, and two animals from each group were killed at 8-week intervals until the end of the experiment at 36 weeks. Histological sections of tissue clearly showed continued growth of teeth and maintenance of specialized tissues, such as salivary gland and bone, in the treated group compared to the non-treated group. This experimental model demonstrated that HBO is effective in reducing the long-term side effects of therapeutic radiation treatment in normal tissue, when given 1 week after the completion of the radiation treatment.

Tetracycline residues in honey after hive treatment.

Tetracyclines are used to control bacterial diseases such as European and American foulbrood, which may cause severe losses in the honey bee population and honey production. By using 24 hives randomly distributed into four groups of six hives, this study was performed to measure the occurrence of tetracycline hydrochloride (TC) residues in honey following two types of TC application. Two groups of colonies were treated three times with 0.5 g TC in 1 litre syrup (group S) or in 10 g powdered sugar (group P). Six hives of a first control group (C) fed with untreated syrup were installed at 20 and 45 m from groups S and P, respectively. A second control group (DC) was set up 3 km away. Honey was sampled at different times from all hives, and honey artificially contaminated with TC was stored in the laboratory at 4, 20 and 35 degrees C; all samples were analysed by ELISA and HPLC methods. One day after the last application, the mean TC concentration in brood chamber honey was ten times higher in group S (40.7 mg kg(-1)) than in group P (4.34 mg kg(-1)). After 8 days, TC residues were detected in all hives of group C. After 146 days, the mean TC concentration in harvested honey was 1.54, 0.35 and 0.15 mg kg(-1) for groups S, P and C, respectively. The control group C had been contaminated with TC by drifting. In all hives of group DC, no residues were detected at any time during the study. The honey collected at day 504 did not contain any detectable TC residues, except in one super from group C (0.026 mg kg(-1)). The half-life of TC in honey from supers was similar in groups C, S and P: 65 days. This duration was twice lower than in honey stored in laboratory in similar conditions: at 35 degrees C in the dark (t(1/2) = 121 days). In honey stored at 20 degrees C, TC was quite stable and its half-life was 242 days. The data from these experiments indicate levels of TC residues in honey after a treatment in hives, their persistence and diffusion into the apiary. These results show that the TC must be used with precaution in honey production.

Evaluating the vulnerability of surface waters to antibiotic contamination from varying wastewater treatment plant discharges.

Effluents from three wastewater treatment plants with varying wastewater treatment technologies and design were analyzed for six antibiotics and caffeine on three sampling occasions. Sulfamethoxazole, trimethoprim, ciprofloxacin, tetracycline, and clindamycin were detected in the effluents at concentrations ranging from 0.090 to 6.0 microg/L. Caffeine was detected in all effluents at concentrations ranging from 0.19 to 9.9 microg/L. These findings indicate that several conventional wastewater management practices are not effective in the complete removal of antibiotics, and their discharges have a large potential to affect the aquatic environment. To evaluate the persistence of antibiotics coming from the wastewater discharges on the surrounding surface waters, samples were collected from the receiving streams at 10-, 20- and 100-m intervals. Ciprofloxacin, sulfamethoxazole, and clindamycin (0.043 to 0.076 microg/L) were found as far as 100 m from the discharge point, which indicates the persistence of these drugs in surface waters.