Traces of antimicrobials in milk are of great concern for public health. The European Union has established maximum residue limits in milk; these, however, by themselves do not guarantee the absence ...of drug residues in milk and related products. Currently, very little information is available on the transfer of antibiotic residues from milk to other dairy products and their potential effect on food safety. This work evaluated the presence of antibiotic residues in pasteurized fluid milk and fresh cheeses from goat's milk containing these veterinary drugs at legal safety levels (maximum residue limits) and assessed the safety margin of these dairy products for consumers. Eight antibiotics (amoxicillin, benzylpenicillin, cloxacillin, neomycin, erythromycin, ciprofloxacin, enrofloxacin, and oxytetracycline) were selected, and three batches of fresh cheese were made from pasteurized goat's milk spiked with each of these drugs. Drug residues in milk and cheese samples were analyzed by liquid chromatography-tandem mass spectrometry. The safety margin of goat's milk products was calculated taking into account different age groups (children, teenagers, and adults). Results showed that most antibiotics present in raw milk remained in pasteurized milk and were transferred to cheese to a high extent; retention was above 50% in most cases. The minimum safety margin in pasteurized milk was obtained for enrofloxacin, ciprofloxacin, and erythromycin for the children's group. For fresh cheese, an elevated safety margin was obtained for all antibiotics and age groups considered. However, the large amounts of antibiotics retained in the cheese might contribute to the development and spread of antimicrobial resistance. Considering the differences in milk from different species and the great variety of cheeses, it would be advisable to continue the traceability study of antibiotics in order to increase the safety margin of dairy products.
Lugdunin, a novel thiazolidine cyclopeptide, exhibits micromolar activity against methicillin‐resistant Staphylococcus aureus (MRSA). For structure–activity relationship (SAR) studies, synthetic ...analogues obtained from alanine and stereo scanning as well as peptides with modified thiazolidine rings were tested for antimicrobial activity. The thiazolidine ring and the alternating d‐ and l‐amino acid backbone are essential. Notably, the non‐natural enantiomer displays equal activity, thus indicating the absence of a chiral target. The antibacterial activity strongly correlates with dissipation of the membrane potential in S. aureus. Lugdunin equalizes pH gradients in artificial membrane vesicles, thereby maintaining membrane integrity, which demonstrates that proton translocation is the mode of action (MoA). The incorporation of extra tryptophan or propargyl moieties further expands the diversity of this class of thiazolidine cyclopeptides.
Ornament clasp confers function: Synthetic analogues of lugdunin, the first antibiotic from the human nose, reveal essential motifs for conferring antimicrobial activity against methicillin‐resistant Staphylococcus aureus. In addition to an alternating d‐ and l‐configuration, the thiazolidine heterocycle—featured for the first time in a cyclopeptide—is invaluable for the proton translocation mode of action.
The aim of this study was to evaluate the transfer of the most widely used antibiotics in dairy goats from milk to cheese as well as their effect on the cheese-making process and cheese ...characteristics during ripening. Antibiotic-free milk was spiked individually with 7 veterinary drugs (amoxicillin, benzylpenicillin, cloxacillin, erythromycin, ciprofloxacin, enrofloxacin, and oxytetracycline) at an equivalent concentration of the European Union maximum residue limit. Spiked goat milk was used to make mature Tronchón cheeses, which were analyzed at 0, 30, and 60 d of maturation to determine pH, chemical composition, proteolytic and lipolytic activities, and color and textural properties. A sensory evaluation of 60-d ripened cheeses was carried out. Cheeses from raw antibiotic-free goat milk were made simultaneously to be used as reference. The cheese-making process was unaffected by the presence of most antibiotics evaluated. Only erythromycin and oxytetracycline significantly increased the time required for cheese production (122 ± 29 and 108 ± 25 min, respectively). However, variable amounts of antibiotics, ranging from 7.4 to 68%, were transferred from milk to cheese, with oxytetracycline and quinolones showing the highest retention rates. In general, antibiotic residues present in the cheeses at the beginning of maturation decrease significantly along time. Thus, β-lactams and erythromycin residues were not detectable after 30 d of ripening. However, relatively high concentrations of enrofloxacin (148 ± 12 µg/kg) and ciprofloxacin (253 ± 24 µg/kg) residues were found in the cheeses after 60 d of maturation. The quality characteristics of the Tronchón cheeses were only slightly affected by such substances, with few significant differences in the free fatty acid concentration and color and textural properties of the cheeses. Results herein indicate that the use of goat milk containing antibiotics, such as quinolones, at the European Union maximum residue limit for cheese production could adversely affect the safety of the final products because relatively high concentrations of these substances could be retained in soft and semi-mature cheeses, making it necessary to assess the risk for consumer health. Studies on the partition of the antibiotic substances during cheese-making, using specific technologies, would be convenient to guarantee the safety of cheese and related products.
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•Nanodesign of food-grade niosomes containing resveratrol (RSV) was performed.•Dodecanol was used as stabiliser of niosome membrane.•Niosomes were produced by a modified thin film ...hydration method.•Factorial design of experiments and statistical analysis of variance were applied.•A functional yoghurt was successfully prepared by adding RSV entrapped niosomes.
Nanodesign of niosomes containing resveratrol (RSV) was carried out using food-grade surfactants with dodecanol to stabilise the membrane. Niosomes were prepared using a modified thin film hydration method.
A factorial design analysis was carried out to reduce the number of experiments. The response factors were: mean size, polydispersity index (PDI) and entrapment efficiency (EE). Agitation speed and surfactant to dodecanol weight ratio were selected as key parameters for niosomes preparation. Parameter contribution was determined using a statistical analysis of variance (ANOVA).
Niosomes formulated with Span 60 or Maisine 35-1 as surfactants, and dodecanol as stabiliser, were able to incorporate RSV. These niosomes exhibited a small mean size, narrow size distribution, high RSV entrapment efficiency and good stability. RSV addition did not involve changes in the textural properties of regular yoghurt demonstrating that RSV entrapped niosomes are suitable additives in these dairy products.
The porous substrates of commercially pure titanium have been coated with a novel bilayer of bioactive glasses (BGs), 45S5 and 1393, to improve the osseointegration and solve the stress-shielding ...phenomenon of titanium partial implants. The porosity of the substrates and the scratch resistance and bioactivity of the coating have been evaluated. Results are discussed in terms of stiffness and yield strength of the substrates, as well as the chemical composition, thickness, and design of the bioglass coating (monolithic vs bilayer). The role of the pores was a crucial issue in the anchoring of the coating, both in porosity percentage (30 and 60 vol %) and in pore range size (100-200 and 355-500 μm). The study was focused on the adhesion and infiltration of a 1393 bioglass layer (in contact with a porous titanium substrate), in combination with the biofunctionality of the 45S5 bioglass layer (surrounded by the host bone tissue), as 1393 bioglass enhances the adherence, while 45S5 bioglass promotes higher bioactivity. This bioactivity of the raw powder was initially estimated by nuclear magnetic resonance, through the evaluation of the chemical environments, and confirmed by the formation of hydroxyapatite when immersed in a simulated body fluid. The results revealed that the substrate with 30 vol % of porosity and a range of 355-500 μm pore size, coated with this novel BG bilayer, presented the best combination in terms of mechanical and biofunctional properties.
In the present study, we investigated commercial dental floss coated with chitosan or chitosan + mesoporous bioactive glass nanoparticles (MBGNs) in order to determine the antimicrobial and ...mechanical properties of the newly fabricated flosses. Whereas these coatings showed notable ability to inhibit growth of both Gram (+) and Gram (−) bacteria after 24 h, the impact was negligible at 3 h. Furthermore, the tensile strength of the floss was improved by the addition of these layers, making it more durable and effective for cleaning between teeth. We therefore propose enhanced investigations of these composites since they demonstrate enormous potential in promoting oral health.
Graphical Abstract
Zeolite crystals with an embedded and interconnected macropore system are prepared by using mesoporous silica particles as a silica source and as a sacrificial macroporogen. These novel hierarchical ...zeolite crystals are expected to reduce diffusion limitations in all zeolite‐catalyzed reactions, especially in the transformation of larger molecules like in the catalytic cracking of polymers and the conversion of biomass.
In this book, Miquel Beltrán undertakes the task of comparing Puerta del Cielo with Spinoza's Ethica, in order to find the doctrines asserted both by Herrera and Spinoza concerning God's essence and ...attributes.
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•Bioactive glass 45S5 scaffolds coated with metal-loaded hydroxyapatite nanoparticles.•Dual Mg-Zn loaded hydroxyapatite led to higher bioactivity than monometal ...loading.•Mg-Zn-hydroxyapatite coatings enhance the biological performance of 45S5 scaffolds.
Bioactive glass (BG)-based scaffolds of 45S5 composition covered with hydroxyapatite nanoparticles loaded with Mg2+, Zn2+ and, both Mg2+ and Zn2+ ions, were developed and tested as materials for tissue engineering applications. The scaffolds were prepared by the foam replica technique and mono- and bi-metal loaded and unloaded hydroxyapatite nanoparticles (HA, Zn-HA, Mg-HA and Mg-Zn-HA) were obtained by an adaptation of the wet chemical deposition method. Coating of BG with these nanoparticles was performed by dip-coating to obtain HA-BG, Zn-HA-BG, Mg-HA-BG and Mg-Zn-HA-BG scaffolds.
As predictor of the bone bonding ability of the produced scaffolds, in this study we investigated the formation of an apatite layer on the scaffold surfaces in the presence of simulated body fluid. The cytotoxicity and osteogenic properties of the materials in vitro was evaluated using human osteoblast-like MG-63 cell cultures. The mineralization assay following Kokubo’s protocol indicated that bi-metal loaded Mg-Zn-HA-BG scaffolds exhibited higher/faster bioactivity than mono-metal loaded scaffolds while mineralization of HA-BG, Zn-HA-BG and Mg-HA-BG was similar to that of uncoated scaffolds. Moreover, an increase of proliferation of MG-63 cells after 48 h and 7 days was measured by BrdU assays for Mg-Zn-HA-BG scaffolds. In agreement with these results, SEM images confirmed increased interaction between these scaffolds and cells, in comparison to that observed for mono-metal-loaded HA-coated scaffolds. Altogether, the obtained results suggest that nanocrystalline Mg-Zn-HA coatings enhance the biological performance of standard scaffolds of 45S5 BG composition. Thus these novel ion doped HA coated scaffolds are attractive systems for bone tissue engineering.
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