Search

Biofilms are a constant concern in the food industry; understanding the effect of environmental conditions on biofilm formation is essential to develop effective control strategies. Therefore, this study was conducted to investigate biofilms formation by Staphylococcus epidermidis under various conditions. Biofilms were cultured in nutrient broth containing different carbon source concentrations (0–10 mg/mL) on polystyrene surfaces for 32 h of incubation at 37 °C or 55 °C, with quantification and enumeration at 8, 16, 24 and 32 h. S. epidermidis developed biofilms under all tested conditions; achieved the highest yield of biofilm biomass at 2.5 mg/mL for all carbon sources at 37 °C. The highest efficiency of extracellular polymeric substance (EPS) molecule production occurred under glucose availability in the growth environment, with a higher yield of biomass and a significantly smaller number of metabolically active cells than under other tested conditions. A condensed ball-shaped structure was observed under the lactose condition. Meanwhile, biofilms in the presence of maltose showed mainly opaque thick rich colonies, while a compact multilayered-shaped structure was exhibited under both glucose and sucrose conditions. These results contribute to a better understanding of the biofilm formation by S. epidermidis in order to reduce contamination and recontamination in the food industry.

Bacillus cereus spores are a concern to the food industry due to their high resistance to processing and their ability to germinate to vegetative cells under suitable conditions. This research aimed to elucidate the mechanisms of Bacillus cereus spore inactivation under ultrasonication (US) combined with thermal (thermosonication, TS) treatments, with pressure (manosonication, MS) treatments, and with thermal and pressure (manothermosonication, MTS) treatments. Electronic microscopy, dipicolinic acid (DPA) release, and flow cytometric assessments were used to investigate the inactivation effect and understand the inactivation mechanisms. The sporicidal effects of the US and thermal treatment were slight, and the MS and TS also showed little inactivation effect. However, ultrasonication promoted the detachment of the exosporium, thereby reducing the spore’s ability to adhere to a surface, while the thermal treatment induced a decrease in the electron density in the nucleoid of bacterium, which retained a relatively intact exosporium and coat. MS caused 92.54% DPA release, which might be due to triggering of the germinant receptors or releasing of ions and Ca2+-DPA. In addition, the morphological changes such as core hydration and cortex degradation were significant after treatment with MS. The release of DPA and the morphological changes were responsible for the reduction in thermal resistance. The MTS showed a remarkable inactivation effect of 3.12 log CFU/mL reductions after 30 min of treatment. It was the most effective treatment and exhibited a large fraction of damage. In addition, the MTS had a significant impact on the intracellular structure of the spores, with the coat destroyed and the cortex damaged. These results indicated that ultrasonication combined with thermal and pressure treatments had a significant sporicidal effect on Bacillus cereus spores and could be a promising green sterilization technology.

Recently modified pectin (MP) showed improved functional properties and bioactivities than the native one. Ultrasound, as one of the green technologies, was investigated to degrade and modify bioploymers with high efficiency and low cost. In an aqueous system with pectin, ultrasonication creates localized high temperature and pressure spots, and produces “microjets” and free radicals, which contribute to modify the structural, functional, and bioactive properties of pectin. The factors influencing pectin modification include ultrasound frequency, power intensity, temperature, treatment time and duty cycle. Precise control of these parameters is critical for ultrasound technology to produce products with consistent and predictable properties. This work summarizes recent advances in applications of power ultrasound technology in oriented degradation and modification of pectin. Different degradation processing situations and the degradation phenomena of pectin during extraction have been reviewed. Furthermore, future trends to better utilize this green technology have also been purposed.

Antimicrobial films are widely used in food and other fields. The present work established a method of preparing antimicrobial films made of calcium alginate and lysozyme. For the sake of the optimization of antimicrobial effect, sonication was applied to increase the immobilization efficiency. Different ultrasonic power and treatment duration were studied. With the assistant of sonication, lysozyme immobilization rate was speeded up and the amount of lysozyme immobilized on the supporters was increased. The catalytic activity of the antimicrobial film was measured using the turbidimetric assay and reached the maximum at 147.8 W. The antimicrobial activity determined by the inhibition zone test was also promoted by sonication. To explore the mechanism of the ultrasonic effect on the lysozyme immobilization, lysozyme structures alteration before and after ultrasonic treatment was considered. The circular dichroism and fluorescence spectra illustrated that sonication affected the secondary and tertiary structures of lysozyme. The changes in the enzyme structures may lead to the improvement of the enzymatic activity. The impact of sonication on the microstructure of the films was investigated by the scanning electron microscope. The film surface showed some cracks after sonication that increased the superficial area accordingly.

Chinese rice wine, a traditional wine widely consumed in China, is typically sterilized in light of its sublethal alcohol content and nutritional richness. Nevertheless, several foodborne pathogens have been detected in final products, of which Bacillus cereus is one of the most heat-resistant. To study the effects of the wine matrix on bacterial inactivation, simulated media were established based on the main characteristics of the wine, including glucose content (23.48 ± 0.86 g/L), alcohol content (17.0 ± 0.5%), pH (4.14 ± 0.06), and protein content. In Chinese rice wine, log counts declined to 5.79 after 1 min heat treatment at 60.0 °C, 4.99 at 70.0 °C, and 4.37 at 80.0 °C. The loss of viability was smaller in simulated media with protein and glucose than in sterile saline, implying that glucose and especially protein were protective. The inactivation kinetics of B. cereus vegetative cells were then assessed in these media, and modeled. Remarkably, thermal survival curves in Chinese rice wine and simulated media were linear and well-modeled by first-order kinetics with R2 values 0.9501–0.9992. The data demonstrated that media with acidic pH were the most adverse environment against B. cereus, with D-value 0.61 ± 0.02 min at 60.0 °C. Similar values were obtained in media with 23.48 g/L glucose at 80.0 °C. Transmission electron micrographs showed heat-induced injuries in B. cereus through “coagulation” of the cytoplasmic content in all the media. Furthermore, modifications on the cell wall in acidic pH and alcohol media, leakage of cellular content observed in Chinese rice wine and glucose media. Conclusively, the results might help optimize the sterilization parameters to ensure the safety and quality of Chinese rice wine.

Graphene oxide/polyaniline (GO/PANI) has been demonstrated to be an effective anti-corrosive nanofiller in polymer matrix, however, its hydrophobility restricts its application in waterborne polymer coatings. Here, cetyltrimethylammonium bromide (CTAB) and cationic gemini surfactant (GS) with the same constitutional unit as CTAB were adopted to fabricate CTAB modified GO/PANI (CGO/PANI) and GS modified GO/PANI (GGO/PANI). The incorporation of GS not only increased the intercalation degree of GO nanosheets but also functionalized as dopant to improve the electrochemical properties of PANI. The dispersibility and compatibility of GGO/PANI in waterborne alkyd resin (WAR) were also higher than that of CGO/PANI, resulting in the formation of more uniform nanocomposite coating. Compared with pure WAR, the coating resistance of GGO/PANI/WAR increased by 4 orders of magnitude, the corrosion density decreased by 3 orders of magnitude and the corrosion potential shifted from −0.72 V to −0.28 V. GGO/PANI/WAR also displayed enhanced long-term anti-corrosive properties in comparison with CGO/PANI/WAR.

Mo-N-co-doped mesoporous TiO 2 microspheres were synthesized via a solvothermal method, followed by nitriding treatment under ammonia gas flow. The efficiency of the samples was investigated by monitoring the degradation of Rhodamine-B under visible light irradiation. The experimental results revealed that Mo-N-co-doped mesoporous TiO 2 microspheres showed better performances than Mo-TiO 2 microspheres. It was observed that; 0.1% molar quantity of Mo doped on TiO 2 at 500 °C for 2 h under nitriding conditions gave highest photocatalytic activities. The nitridation under ammonia gas of Mo-TiO 2 samples created oxygen vacant sites and led to incorporation of substitutional and interstitial Nitrogen. The enhanced visible light photocatalytic activities of Mo-N-co-doped TiO 2 photocatalyst was attributed to the large surface areas, narrow band gap and intense light absorbance in visible region. This study may create a promising and eco-friendly method towards synthesis of metal and non-metals co-doped on semiconductor materials to improve their photocatalytic activities and applications.

Iron (III) and nitrogen co-doped mesoporous TiO 2 microspheres (Fe-N-TiO 2 ) are prepared using a self-assembly based solvothermal process followed by an ammonothermal method. Among all samples, 1 mol.% of Fe dopants and 500 °C nitridation (for 2 h) gives the highest visible light photoactivity. Results imply that the Fe 3+ /Fe 2+ dopant trap energy level introduced within the band gap in mildly Fe (∼1 at%) doped TiO 2 and the mesoporous nature of the material, both aid in the observed catalytic performance. Subjecting Fe-TiO 2 samples to ammonothermal process induces oxygen vancancies, and substitutional and interstitial N. This reduces optical band gap, and introduces local states. The lower band gap and local states together aid in the absorption of visible light and separation of charge carriers. Co-dopants are distributed uniformly in the best photocatalysts. The active species generated in the photocatalytic system is shown to be singlet molecular oxygen ( 1 O 2 ) using selective radical quenchers.

Edge- and corner-truncated octahedral Cu2O is successfully synthesized using an aqueous mixture of CuCl2, sodium dodecyl sulfate, NaOH, and NH2OH3·HCl. Cu2O1-xNx(150 °C, 30 min) samples are synthesized by nitridation of Cu2O using an ammonothermal process. Cu retains a formal valence state through and beyond the nitridation process. N concentration in this sample is 1.73 at%, out of which 1.08 at% is substitutional in nature. Photocatalytic activity of Cu2O1-xNx(150 °C, 30 min) sample is investigated and compared to that of pristine edge- and corner-truncated octahedral Cu2O. Results show that Cu2O1-xNx(150 °C, 30 min) sample with dominant {110} facets has a higher photocatalytic activity than the pristine Cu2O material. Higher surface energy and a greater density of the “Cu” dangling bonds on {110} facets of edge- and corner-truncated octahedral Cu2O1-xNx is the plausible reason for the observed optimum catalytic activity. Furthermore defect states induced by nitridation results in improved visible light adsorption. And also the band edge states changes which brought about by N doping. This is an interesting result since it bypasses the usual challenge faced by pristine Cu2O which have band edge states between which transitions are normally forbidden. Selective radical quenching experiments suggest that photocatalytic activity of Cu2O1-xNx is due to formation of hydroxyl radicals in water, subsequent to photogeneration of charge carriers in the photocatalyst.

A simple solvothermal approach with post-calcination is used to obtain (Ag, Ag2O) co-loaded TiO2 microspheres with high specific surface area (43.8 m2g-1) and desirable visible light photocatalytic degradation (64% after 2 h visible light irradiation). Generally, N-doping of TiO2 via nitridation using NH3 improves the visible light absorption property of material. However, nitridation of (Ag, Ag2O) co-loaded TiO2 results in a deleterious impact on the photocatalytic performance (around 20% after 2 h visible light irradiation). This is because nitridation of Ag-Ag2O-TiO2 results in (a) reduction of Ag2O to Ag and (b) Ag agglomeration and grain growth on TiO2 particles. These results in fact imply that in as-synthesized (Ag, Ag2O) co-loaded TiO2 systems, local surface plasmonic resonance (associated with of 5–12 nm Ag particles) aids in enhanced broad band visible light absorption; furthermore the heterojunction between TiO2 and Ag2O improves efficiency with which photogenerated carriers become available for photocatalysis. In all cases we show through selective radical quenching experiments that singlet oxygen is the primary reason for the dye degradation observed.

Nickel, nitrogen-codoped mesoporous TiO2 microspheres (Ni–N–TiO2) with high surface area, and an effective direct band gap energy of ∼2.58 eV. Nickel sulfate used as the Ni source and ammonia gas as the N source here. The efficiency of the as-prepared samples was investigated by monitoring the degradation of Rhodamine B under visible light irradiation. The experimental results indicate that Ni-doped mesoporous TiO2 microspheres show higher photocatalytic activity than mesoporous TiO2 microspheres under visible light irradiation. It mainly due to that the electron trap level (Ni2+/Ni+) promoting the separation of charge carriers and the oxygen vacancies inducing the visible light absorption. In addition, Ni–N–TiO2 shows enhanced activity compared with Ni–TiO2. Codopants and dopants are found to be uniformly distributed in TiO2 matrix. Among the all samples the 0.5% molar quantity of Ni dopant and 500 °C 2 h nitriding condition gives the highest photocatalytic activity. The treatment of ammonia gas on Ni–TiO2 sample induced oxygen vancancies, substitutional and interstitial N. A suitable treatment by ammonia gas also promote separation of charge carriers and the absorption of visible light. The active species generated in the photocatalytic system were also investigated. The strategy presented here gives a promising route towards the development of a metal and non-metal codoped semiconductor materials for applied photocatalysis and related applications.

A dual-site fluorescent probe with double bond and aldehyde as reactive sites, was designed for the selective detection of sulfite and biothiols. Sulfite reacts with conjugate bond selectively, while Cys responses with aldehyde and GSH occurs substitution reaction. Different interactions cause different absorption and fluorescence responses. Moreover, it could be further applied in imaging in living cells.

This study evaluated the inactivation effect of ultrasonic treatment combined with acidic electrolyzed water (AEW) on Bacillus cereus spores. AEW treatment reduced the spores by 1.05–1.37 log CFU/mL while the sporicidal effect of ultrasound was minor. More strikingly, simultaneous ultrasonic and AEW treatments for 30 min led to 2.29 log CFU/mL reduction and thus, considered a synergistic effect. Flow cytometry combined with SYTO/PI staining analysis revealed that ultrasound hydrolyzed the cortex while the AEW partially damaged the integrity of the inner membrane. Scanning and transmission electron microscopies were used to characterize the ultrastructural changes. The detachment of the exosporium induced by ultrasound was the most apparent difference compared with the control group, and the electron density of spores appeared to be heterogeneous after treatment with AEW. These results indicated that combining ultrasound with AEW is a promising decontamination technology with potential uses in the food industry and environmental remediation.

The extreme resistance of bacterial spores to most killing agents makes them a major concern to the food industry and consumers. This gave rise an increasing interest in developing new strategies to inactivate spores and understand the mechanisms of inactivation by various agents. In this study, ultrasound combined with heat (thermosonication, TS) was used to inactivate the spores of Bacillus subtilis and the factors that influence the resistance to TS were analyzed. The spores of wild-type B. subtilis and isogenic mutants were subjected to heat at 80 °C and ultrasound at 6.67–20 W/mL and 23 °C for 0–40 min. TS treatment has synergistically resulted in spore inactivation, and spores of wild-type B. subtilis and isogenic mutants showed different resistance to TS treatment, which was in the following order: Strains 533 (wild-type) ≈ strains PS3518 (gfp) ≈ strains PS2318 (recA−) > strains PS578 (α−β−), and spores of strains PS3328 (cotE−) were also more susceptible than those of wild-type strains. The inactivated spores lost some proteins in the spore core but initiated germination normally. The germinated inactivated spores did not swell and their plasma membrane permeability was equally altered. It was concluded that the damage to spores' inner membrane (IM) proteins or the IM itself has led to the leakage of intracellular substances and the death of a spore by TS treatment. Our results could support the development and optimization of TS treatment, which has great significance for its further utilization in food industry.

Staphylococcus epidermidis has emerged in recent years as one of the most important opportunistic pathogens owing to its ability to attach to processing surfaces in the food industry. Demands of foodstuffs maintaining microbiological safety and stability enhance the need to develop natural antimicrobial agents as food preservatives. Proanthocyanidins from Chinese bayberry leaves (BLPs) belonging to the class of polyphenols promise to be a potential antibacterial material against bacterial adhesion and biofilm formation. The aim of the present study was to investigate the effects of BLPs on S. epidermidis growth and biofilm formation. BLPs possessed antimicrobial activity with MIC and MBC of 320 and 640 μg/ml, respectively. Scanning electron microscopy, transmission electron microscopy, and flow cytometry analysis revealed a loss of the cell structure and function after treatment of BLPs, evidenced by cell membrane hyperpolarization and changes in cellular morphology. BLPs inhibited the biofilm formation by S. epidermidis on polystyrene microplates. Atomic force microscopy analysis showed that BLPs could decrease the stiffness and adhesion force of the cell envelope, which might account for the inhibition of biofilm formation. In summary, this study indicated that BLPs have potential to be developed as natural preservatives to control S. epidermidis in foods.

In recent years, power ultrasound (PU) has attracted considerable interest in food science and technology due to its promising applications in food processing and preservation. It is well known to have significant effects on the rate of various processes in the food industry, and it is recognized as innovative technology for achieving the objective of sustainable “green” chemistry and industrialization. Using ultrasound, food processes can be completed in seconds or minutes with higher reproducibility, lower processing costs, easier operation, higher product purity, elimination of post-treatment of waste water, and lower energy requirements than traditional processes. Several processes such as extraction, degradation, sterilization, and enzyme modification have been applied efficiently in the food industry. Food processes performed under ultrasound treatment will be affected by cavitation phenomena and mass transfer processes. This chapter presents the current knowledge on the applications of ultrasound in food processing.

Mesoporous anatase TiO 2 microspheres were prepared via solvothermal method. Ammonium tungstate was used as the W source, and ammonia gas flowing in an ammonothermal reactor as the N source for codoping. TiO 2 :(W,N) mesoporous microspheres, which were prepared from solvothermal treatment at 160 °C for 16 h and thermal ammonolysis at 500 °C for 2 h after calcination, have high specific surface area of 106 m 2 g −1 . XPS results indicate the presence of N O , N i and W 6+ in the codoped mesoporous TiO 2 microspheres. Monodoping with N shifts the absorption band edge of anatase TiO 2 from ultraviolet region to visible region. Although codoping with W makes the visible light absorbance decrease a little, the photocatalytic degradation of a cationic dye rhodamine B (RhB) on mesoporous TiO 2 :(W,N) microspheres is increased to 1.7 times of that on mesoporous TiO 2 :N microspheres. This may due to decreasing recombination centers by W-doping charge compensation.

The current study aimed to investigate the synergistic effect of ultrasound and pectinase on pectin hydrolysis. Effects of ultrasound on the hydrolysis rate of pectin, enzymatic kinetics parameters and pectinase structures (determined by the DNS method, Michaelis–Menten equation, chemical reaction kinetics model, fluorescence spectroscopy and circular dichroism spectroscopy) were also studied in order to illuminate the mechanisms of the synergistic effect. The hydrolysis rate of pectin achieved maximum value with ultrasound treatment at 4.5 W mL−1 intensity and ultrasound time of 10 min, increasing by 32.59 % over the control. The optimum temperature for the hydrolysis reaction was 50 °C and kept unchanged with ultrasound treatment. Besides, the value of V max increased whereas K m decreased in the sonoenzymolysis reaction compared with that in the routine enzymolysis reaction. Results indicated that under ultrasound irradiation, pectin was hydrolyzed at an elevated rate and the pectinase exhibited stronger affinity to the substrate. Fluorescence spectra revealed that ultrasound favorably decreased the amount of tryptophan on the pectinase surface; while the far-UV circular dichroism spectra showed an increased fraction of β-sheet and a reduced fraction of random coil in the secondary conformation. Changes in the pectinase structures contributed to the enhancement of pectinase activity and the consequent promotion of the hydrolysis process. Results of pectin degradation kinetics certified the synergistic effect of ultrasound and pectinase at the temperature range of 20–50 °C, which were evidenced from the positive values of the synergistic coefficients.

UNLABELLED Mature-green cherry tomato fruits (Lycopersicon esculentum cv. Jinyu) were exposed to different power densities of ultrasound (66.64, 106.19, and 145.74 W/L) at 25 °C to study ultrasound non-thermal effects on the storage properties. Among the three levels of ultrasound irradiation, 106.19 W/L ultrasound was effective in reducing the spoilage microorganisms, delaying postharvest ripening through inhibiting ethylene production and respiration rates, and consequently maintaining fruit firmness, flavor, enzyme activities, antioxidants (total phenolics, total flavonoids), and the total antioxidant capacity of cherry tomatoes. The 66.64 W/L ultrasound had similar effects but to a lesser extent. Meanwhile, although 145.74 W/L ultrasound resulted in higher content of ascorbic acid (AA), it showed many negative effects on the storage quality of fruits. These results demonstrated that ultrasound of appropriate power density had great potentials in inhibiting decay, maintaining flavor and nutritional quality of cherry tomatoes. PRACTICAL APPLICATION Recently, ultrasound has been considered as a multifunctional pretreatment method for the preservation of postharvest fruits and vegetables. Although the preservation effects were slight because of the screening of the thermal effects, its non-thermal effects presented potentials in improving storage quality of cherry tomato. Further studies are needed to explore the combinations between ultrasound with heating as well as other postharvest preservation technologies to enhance the effects of ultrasound. These explorations would facilitate the large-scale application of ultrasound in the preservation of fresh fruits and vegetables.

Because of the hydrophobicity and formation of biofilm, Bacillus cereus spores are highly resistant and widespread in food industry. The outermost layer: exosporium of Bacillus cereus spore plays an important role in its surface property. Previous work indicated that ultrasound detached the exosporium of spores, thus the surface properties were further investigated in this study. The detachment of exosporium was observed without damage to inner layers through TEM micrographs. Besides, the size of spores dropped rapidly from 2017.67 to 960.53 nm after 1 min ultrasound treatment. At the same time, the absolute zeta potential value also decreased rapidly. The ratio of hydrophobic spores (RHS) was defined as hydrophobicity, and it dropped-off with the detachment of exosporium. The SDS-PAGE results showed that the intensity of protein bands dropped especially that with higher molecular weight after ultrasound treatment. What's more, a lot of bands disappeared because of the separation of exosporium. In a word, these results indicated that ultrasound could detach exosporium and decrease the hydrophobicity of spores, which had lower adhesion to hydrophobic surface and easier to be cleaned.

Although different delivery systems have been developed to overcome the limits of Epigallocatechin-3-gallate (EGCG) and quercetin in food application, none have referred to their simultaneous encapsulation. In this study, these two polyphenols were successfully co-loaded into liposomes. Under the optimal conditions (lecithin-total polyphenols ratio 25:1, lecithin-cholesterol ratio 6:1, lecithin-Tween 80 ratio 8:1 and ultrasonic time 2 min), the mean size, polydispersity index (PDI) and zeta potential of liposomes were 111.10 ± 0.52 nm, 0.259 ± 0.006 and -19.83 ± 0.45 mV, with an encapsulation efficiency of 64.05 ± 1.56% and 61.73 ± 2.55% for EGCG and quercetin, respectively. After 30-day storage, an increase of 4.05% was observed in the mean size with no significant change (P ≥ 0.05) in the PDI and zeta potential. Moreover, 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay revealed a synergistic antioxidant effect of the two compounds in liposomal system. These results demonstrated that co-encapsulation of EGCG and quercetin enhances their effectiveness. PRACTICAL APPLICATION: EGCG and quercetin are natural polyphenols abound in the human diet with diverse biological activities. These two polyphenols were successfully co-encapsulated into a homogeneous and stable liposomal system. Interestingly, a synergistic antioxidant effect of the two polyphenols was observed due to co-encapsulation. This indicated that the simultaneous delivery of EGCG and quercetin was an attractive approach to improve their functionality for expanding their application in food, cosmetic and pharmaceutical industries.

With the extensive application of enzyme-catalyzed reactions in numerous fields, improving enzymatic efficiency has attracted wide attention for reducing operating costs and increasing output. There are three targets throughout enzymatic reactions: the enzyme, substrate, and mixed reaction system. Ultrasound has been known to accelerate enzymatic reactions by acting on different targets. It can modify both enzyme and substrate macromolecules, which is helpful for enhancing enzyme activity and product yields. The synergistic effect of ultrasound and enzymes is widely reported to increase catalytic rates. The present review discusses the positive effect induced by ultrasound throughout the enzymatic process, including ultrasonic modification of enzymes, ultrasound assisted immobilization, ultrasonic pretreatment of substrates, and ultrasound assisted enzymatic reactions.

Owing to the resistance to conventional cleaning and sanitizing agents, biofilms formed on surfaces of dairy processing equipment pose a hazard to the dairy industry. The objective of this study was to evaluate the diversity of the microflora attached to various surfaces of the processing lines of a milk powder processing factory based on 16S rRNA gene sequence analysis. The production of biofilms by the bacterial strains was evaluated on polystyrene (PS) and stainless-steel (SS) surfaces by crystal violet staining method. Especially, effects of temperatures (e.g., 37 °C and 55 °C) and growth mediums (e.g., nutrient broth, NB; tryptic soy broth, TSB) on the production of biofilms by these strains on PS surfaces were explored. Besides, the tolerance of the biofilms of the strains to CIP processes (1.5% v/v HNO3 solution or 2.0% w/v NaOH solution at 80 °C) were analyzed. Forty-five isolates from eleven interior surfaces of the facilities were identified and the distribution of strains had high species diversity, which indicated that multiple spoilage and pathogenic microorganisms remained in milk powder processing lines after CIP processes. Bacteria showed higher biofilm-forming abilities on SS compared to PS surfaces under the same condition. Moreover, effects of the incubation temperature and growth medium on biofilm formation varied between genera, species, and strains. One strain of each species with biofilm-forming abilities on SS surfaces was selected to check the resistance of their biofilms formed on SS coupons to the CIP processes. Biofilms of all of the nine strains were highly or moderately alkali and acid resistant, posing a threat to the milk powder production. These results suggested that organisms within the biofilm might withstand temperature and pH changes better than planktonic organisms. More research is needed to investigate different species isolated from different facilities of the processing lines and to improve the key controlling points in the CIP processes.

Background Spinal cord injury (SCI) is characterized by a high rate of disability and imposes a heavy burden on society and patients. SCI can activate glial cells and lead to swelling, hyperplasty, and reactive gliosis, which can severely reduce the space for nerve growth. Glial cells can secrete a large amount of extracellular inhibitory components, thus altering the microenvironment of axon growth. Both these factors seriously impede nerve regeneration. In the present study, we investigate whether curcumin (cur), a phytochemical compound with potent anti-inflammatory effect, plays a role in the repair of SCI. Materials and methods We established a rat model of SCI and treated the animals with different concentrations of cur. Using behavioral assessment, immunohistochemistry, real-time polymerase chain reaction, Western blotting, and enzyme-linked immunosorbent assay, we detected the intracellular and extracellular components of glial scar and related cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, nuclear factor (NF)-κb, transforming growth factor (TGF)-β 1 , TGF-β 2 , and sex determining region Y-box (SOX)-9. Results We found that cur inhibited the expression of proinflammatory cytokines, such as TNF-α, IL-1β, and NF-κb; reduced the expression of the intracellular components glial fibrillary acidic protein through anti-inflammation; and suppressed the reactive gliosis. Also, cur inhibited the generation of TGF-β 1 , TGF-β 2 , and SOX-9; decreased the deposition of chondroitin sulfate proteoglycan by inhibiting the transforming growth factors and transcription factor; and improved the microenvironment for nerve growth. Through the joint inhibition of the intracellular and extracellular components of glial scar, cur significantly reduced glial scar volume and improved the Basso, Beattie, and Bresnahan locomotor rating and axon growth. Conclusions Our data support a role for curcumin in promoting neural function recovery after SCI by the joint inhibition of the intracellular and extracellular components of glial scar, providing an important strategy for treating SCI.

Polygalacturonase (PG) is one of the most commonly used enzymes during fruit and vegetable processing in the food industry. Ultrasound has the potential to enhance enzyme activity, modify the PG enzyme and enlarge its application range. This study investigated the enzymatic properties of commercial PG under ultrasound treatment, including enzyme activity, kinetic and thermodynamic properties and temperature stability. These properties were investigated with the aid of a chemical reaction kinetics model, Michaelis–Menten equation, Arrhenius equation, Eyring transition state theory and biphasic inactivation kinetics model. PG structures were also studied using fluorescence spectroscopy and circular dichroism (CD) spectroscopy. The maximum activity of PG was observed at 4.5 W ml−1 intensity and ultrasound duration of 15 min, under which the enzyme activity increased by 20.98% over the control. Results of degradation kinetics and thermodynamics of hydrolysis reactions catalysed by PG certified that ultrasound treatment could make PG exhibit higher reaction ability, which was evidenced from the increased rate constants and reduced thermodynamic parameters. Meanwhile, after ultrasound treatment, the value of Vmax in the enzymatic reaction increased, whereas Km decreased as compared with the control. These results demonstrated that the substrate was converted into the product at a higher rate and efficiency, and the enzyme displayed better affinity to the substrate. Ultrasound improved the temperature stability of PG and prolonged its lifetime without affecting its optimum temperature. Fluorescence spectra and far-UV CD spectra revealed that ultrasound treatment irreversibly decreased the amount of tryptophan on the PG surface but increased the β-sheet in PG secondary conformation, possibly by the exposure of more active sites.

A kind of surface complex (triethylamine and mesoporous W-N-TiO

Complement activation plays important roles in the pathogenesis of central nervous system (CNS) diseases. Patients face neurological disorders due to the development of complement activation, which contributes to cell apoptosis, brain edema, blood-brain barrier dysfunction and inflammatory infiltration. We previously reported that induced neural stem cells (iNSCs) can promote neurological functional recovery in closed head injury (CHI) animals. Remarkably, we discovered that local iNSC grafts have the potential to modulate CNS inflammation post-CHI. In this study, we aimed to explore the role of systemically delivered iNSCs in complement activation following CNS injury. Our data showed that iNSC grafts decreased the levels of sera C3a and C5a and down-regulated the expression of C3d, C9, active Caspase-3 and Bax in the brain, kidney and lung tissues of CHI mice. Furthermore, iNSC grafts decreased the levels of C3d+/NeuN+, C5b-9+/NeuN+, C3d+/Map2+ and C5b-9+/Map2+ neurons in the injured cortices of CHI mice. Subsequently, we explored the mechanisms underlying these effects. With flow cytometry analysis, we observed a dramatic increase in complement receptor type 1-related protein y (Crry) expression in iNSCs after CHI mouse serum treatment. Moreover, both in vitro and in vivo loss-of-function studies revealed that iNSCs could modulate complement activation via Crry expression.

Manganese- and nitrogen-co-doped mesoporous TiO2 microsphere photocatalysts are prepared by a simple sol–gel method with controllable sizes in the range of 400–500 nm and high surface area of 112 m2 g−1. Manganous acetate is the Mn source, and ammonia gas is the nitrogen source used. The dopants are found to be uniformly distributed in the TiO2 matrix. Interestingly, in (Mn,N)-co-doped TiO2, we observe an effective indirect band gap of ~2.58 eV. (Mn,N)-co-doped mesoporous TiO2 microspheres show higher photocatalytic activity than Mn–TiO2 microspheres under visible light irradiation. Among the samples reported in this work, 0.2 at.% Mn doping and 500 °C 2-h nitriding condition give the highest photocatalytic activity. The observed photocatalytic activity in the (Mn,N)-co-doped TiO2 is attributed to the contribution from improved absorption due to trap levels of Mn, oxygen vacancies and N doping. Manganese- and nitrogen-co-doped mesoporous TiO2 microspheres containing substitutional N, interstitial N and O vacancies show high visible light photocatalytic activity.

The interaction between bovine serum albumin (BSA) and FeIII complexes with three binary organic acid (biorga) ligands, [FeIII(oxa)(H2O)4]+ (oxa = oxalic acid), [FeIII(pra)(H2O)4]+ (pra = propanedioic acid) and [FeIII(sua)(H2O)4]+ (sua = succinic acid), as well as the sonocatalytic damage of BSA in the presence of these three FeIII–biorga complexes under ultrasonic irradiation, were studied by UV–vis and fluorescence spectra. The experimental results show that the fluorescence quenching process of BSA caused by three FeIII–biorga complexes are all static quenching and the corresponding quenching rate constants (K q), equilibrium constants (K A) and the binding site numbers (n) were calculated. The results reveal that, under ultrasonic irradiation, the BSA molecules were obviously damaged by these FeIII–biorga complexes. In addition, the effects of several factors on the damage of BSA molecules were examined. The experimental results demonstrate that the damage degree of BSA increased with an increase of ultrasonic irradiation time, FeIII–biorga complex concentration, and ionic strength. In comparison, [FeIII(pra)(H2O)4]+ exhibited higher sonocatalytic activity than [FeIII(oxa)(H2O)4]+ and [FeIII(sua)(H2O)4]+. Finally, the extent of generation of \( \cdot {\text{O}}_{2}^{ - } \)and ·OH during sonocatalytic processes was estimated. Perhaps, the results will be significant for promoting sonodynamic treatment (SDT) of tumors at the molecular level.

In this work, the TiO2, CeO2/TiO2 and Fe2O3/TiO2 powders were irradiated, respectively, by ultrasound and visible-light, and the generation of reactive oxygen species (ROS) were estimated by the method of Oxidation-Extraction Photometry (OEP). That is, the 1,5-diphenyl carbazide (DPCI) can be oxidized by generated ROS into 1,5-diphenyl carbazone (DPCO), which can be extracted by mixed solvent of benzene and carbon tetrachloride. The DPCO extract liquor displays an obvious absorbance at 563 nm wavelength. In addition, some influencing factors, such as (ultrasonic or visible-light) irradiation time, catalyst addition amount and DPCI concentration, on the generation of ROS were also reviewed. The results indicated that the quantities of generated ROS increase with the increase of (ultrasonic or visible-light) irradiation time and catalyst addition amount. Moreover, the displayed quantities of ROS are also related with DPCI concentration. And then, several radical scavengers were used to determine the kinds of the generated ROS. At last, the researches on the sonocatalytic and photocatalytic degradation of several organic dyes have also been performed. It is wished that this paper might offer some important subjects for broadening the applications of sonocatalytic and photocatalytic technologies in future environment treatment.

We designed and synthesized a novel mutual prodrug, named BC-01 (3), by integrating ubenimex and Fluorouracil (5-FU) into one molecule based on prior research results that showed that a combination of the aminopeptidase N (CD13) inhibitor, ubenimex, and the cytotoxic antitumor agent, 5-FU, exhibited improved in vitro and in vivo antitumor efficiency. 3 showed potent inhibitory activity against CD13 enzymatic activity. Compared with ubenimex, 3 exhibited more potent anti-angiogenesis effects, and compared with the approved 5-FU prodrug, capecitabine, 3 exhibited more potent tumor growth inhibitory and anti-metastasis effects. Additionally, compared with 5-FU or 5-FU plus ubenimex, 3 also exhibited a superior antitumor efficiency even in our 5-FU-resistant mice model. Other antitumor agents could be conjugated with ubenimex using this strategy to obtain novel mutual prodrugs with promising antitumor potency.

Herein we report the homogeneous and effective substitution of O by N in the layered titanates. The resultant materials HTiNbO5-xNx (350°C, 30 min) unveiled extraordinary band-to-band excitation and increased absorption intensity (induced by oxygen vacancies). Upward shift of valence band maximum by N 2p states is confirmed by photoelectron spectroscopy and is concluded as the source of band-to-band visible light excitation. The electrons generated upon visible light excitation in the conduction band of HTiNbO5-xNx (350°C, 30 min) had strong reduction ability, reducing O2 into active O2•- radicals during photocatalysis. These findings are the clear evidence for the substantial role of doped N in achieving band-to-band visible-light photon excitation in layered titanates. The new physical insights into substitutional N in layered titanates with hydrogen bond (weak bond energy) gained here may have important implications for developing other efficient visible light photocatalysts by nonmetal doping.

In this paper, the Safranine T (ST) was used as sonosensitive compound to study the sonodynamic damage to bovine serum albumin (BSA) under ultrasonic irradiation using fluorescence and UV–vis spectroscopy. The experimental results revealed the obvious synergetic effect of Safranine T (ST) and ultrasonic irradiation during the damage of BSA molecules. In addition, some influencing factors such as ultrasonic irradiation time, Safranine T (ST) concentration, pH value and ionic strength on the sonodynamic damage of BSA molecules were also considered. Finally, the generation of reactive oxygen species (ROS) in sonodynamic process was estimated by the method of Oxidation-Extraction Photometry (OEP). Meanwhile, several radical scavengers were used to determine the kind of generated ROS. Experiments showed that under ultrasonic irradiation the Safranine T (ST) can generate several kinds of ROS at the same time, at least including singlet oxygen ( 1 O 2 ) and hydroxyl radicals ( OH).

BACKGROUND: In order to effectively degrade bovine serum albumin (BSA) under ultrasonic irradiation, biological mineral material (tooth powder) was adopted to mix with nano-sized TiO2 powder. A TiO2/tooth composite with high sonocatalytic activity and remarkable selectivity was prepared. RESULTS: TiO2/tooth composite with tooth content of 30% (w/w) heat-treated at 500 °C for 40 min was used as sonocatalyst and the catalytic degradation of BSA under ultrasonic irradiation was examined. Some influencing factors, such as ultrasonic irradiation time, TiO2/tooth catalyst amount, solution acidity and NaCl concentration, were studied by UV-vis and fluorescence spectroscopic analysis. Furthermore, the BSA attack site for the TiO2/tooth composite was identifies by synchronous fluorescence spectra. CONCLUSION: The results indicated that, under ultrasonic irradiation, the TiO2/tooth composite can promote the degradation of BSA more effectively than pure nano-sized TiO2 powder. The attack site is identified as tyrosine (Tyr) residue. These results are of great significance for the use of a sonocatalytic method to treat tumours in clinical applications. Copyright © 2011 Society of Chemical Industry

The effects of chitosan oligosaccharide on the activation of murine spleen CD11c(+) dendritic cells via Toll-like receptor 4

Highly crystalline mesoporous anatase TiO2 nanospheres with high surface area (higher than P25 and anatase TiO2) are prepared by a soft-template method. Despite the high specific surface area, these samples have three times lower equilibrium adsorption (

Mature-green cherry tomato fruits (Lycopersicon esculentum cv. Jinyu) were exposed to different power densities of ultrasound (66.64, 106.19, and 145.74 W/L) at 25 °C to study ultrasound non-thermal effects on the storage properties. Among the three levels of ultrasound irradiation, 106.19 W/L ultrasound was effective in reducing the spoilage microorganisms, delaying postharvest ripening through inhibiting ethylene production and respiration rates, and consequently maintaining fruit firmness, flavor, enzyme activities, antioxidants (total phenolics, total flavonoids), and the total antioxidant capacity of cherry tomatoes. The 66.64 W/L ultrasound had similar effects but to a lesser extent. Meanwhile, although 145.74 W/L ultrasound resulted in higher content of ascorbic acid (AA), it showed many negative effects on the storage quality of fruits. These results demonstrated that ultrasound of appropriate power density had great potentials in inhibiting decay, maintaining flavor and nutritional quality of cherry tomatoes.Recently, ultrasound has been considered as a multifunctional pretreatment method for the preservation of postharvest fruits and vegetables. Although the preservation effects were slight because of the screening of the thermal effects, its non-thermal effects presented potentials in improving storage quality of cherry tomato. Further studies are needed to explore the combinations between ultrasound with heating as well as other postharvest preservation technologies to enhance the effects of ultrasound. These explorations would facilitate the large-scale application of ultrasound in the preservation of fresh fruits and vegetables.

Background The objective of the present study was to clarify the relationship between the neuroprotective effects of curcumin and the classical wnt signaling pathway. Method Using Sprague–Dawley rats at a gestational age of 14.5 d, we isolated neural stem cells from the anterior two-thirds of the fetal rat brain. The neural stem cells were passaged three times using the half media replacement method and identified using cellular immunofluorescence. After passaging for three generations, we cultured cells in media without basic fibroblast growth factor and epidermal growth factor. Then we treated cells in five different ways, including a blank control group, a group treated with IWR1 (10 μmol/L), a group treated with curcumin (500 nmol/L), a group treated with IWR1 + curcumin, and a group treated with dimethyl sulfoxide (10 μmol/L). We then measured the protein and RNA expression levels for wnt3a and β-catenin using Western blotting and Reverse transcription-polymerase chain reaction (RT-PCR). Results Western-blotting: after the third generation of cells had been treated for 72 h, we observed that wnt3a and β-catenin expression was significantly increased in the group receiving 500 nmol/L curcumin but not in the other groups. Furthermore, cells in the IWR1-treated group showed decreased wnt3a and β-catenin expression, and wnt3a and β-catenin was also decreased in the IWR1 + 500 nmol/L curcumin group. No obvious change was observed in the dimethyl sulfoxide group. RT-PCR: RT-PCR showed similar changes to those observed with the Western blotting experiments. Conclusions Our study suggests that curcumin can activate the wnt signaling pathway, which provides evidence that curcumin exhibits a neuroprotective effect through the classical wnt signaling pathway.

The interaction between 1,2-dihydroxy-9, 10-anthraquinone-3-aminomethyl-N, N-diacetate-Ferrous(III) (Alizarin–DA–Fe(III)) and bovine serum albumin (BSA) was studied by using UV–vis and fluorescence spectra. And then, the H2O2 damage of BSA induced by Alizarin–DA–Fe(III) was examined. The results show that due to the interaction the fluorescence of BSA solution can be obviously quenched by Alizarin–DA–Fe(III) and that the quenching process belongs to the static quenching. In addition, in the presence of Alizarin–DA–Fe(III) the BSA molecules were markedly damaged by H2O2. Meanwhile, the effects of the standing time, Alizarin–DA–Fe(III) concentration and H2O2 concentration on the damage of BSA molecules were also researched. The experimental results demonstrate that the damage degree increase with the increase of standing time, Alizarin–DA–Fe(III) concentration and H2O2 concentration. Finally, the generation of reactive oxygen species (ROS) from H2O2 induced by Alizarin–DA–Fe(III) as Fenton-like reagent was estimated by some quenchers. Because the Iminodiacetic–Ferrous(III) (IDA–Fe(III)) and Nitrilotriacetic–Ferrous(III) (NTA–Fe(III)) can be thought of as the active part of Alizarin–DA–Fe(III), they were used to compare the catalytic activity with Alizarin–DA–Fe(III). Owing to the special plane structure, the experiment results showed that the Alizarin–DA–Fe(III) exhibited higher damage ability than IDA–Fe(III) and NTA–Fe(III). Perhaps, the Alizarin–DA–Fe(III) may be used as a new antitumor compound to induce peroxides in body to kill cancer cells.

The interaction of Cresol Red derivatives (Cresol Red (o-Cresolsulfonphthalein), Cresol Red-DA (3,3'-Bis [N,N-di (carboxymethyl) aminomethyl]-o-cresolsulfonphthalein) and Cresol Red-DA-Fe(III) (3,3'-Bis [N,N-di (carboxymethyl) aminomethyl]-o-cresolsulfonphthalein-Ferrous(III)) with bovine serum albumin (BSA) were studied by the combination of ultraviolet spectroscopy, circular dichroism (CD) spectroscopy, fluorescence spectroscopy and synchronous fluorescence spectroscopy. On that basis, the sonodynamic and sonocatalytic damages of Cresol Red derivatives to BSA under ultrasonic irradiation were also investigated by means of corresponding spectrum technology. Meanwhile, some influenced factors such as ultrasonic irradiation time, Cresol Red derivatives concentration and ionic strength on the damage degree of BSA molecules were also reviewed. In addition, the binding site and damage site of BSA molecules were estimated by synchronous fluorescence spectra. Finally, the results of oxidation-extraction photometry (OEP) using several reactive oxygen species (ROS) scavengers indicated that the damage of BSA molecules is mainly due to the generation of ROS. Perhaps, this paper may offer some important subjects for broadening the application of Cresol Red derivatives in sonodynamic therapy (SDT) and sonocatalytic therapy (SCT) technologies for tumor treatment.