Structure, stability, antioxidant activity, and controlled-release of selenium nanoparticles decorated with lichenan from Usnea longissima.

Selenium nanoparticles (SeNPs) have attracted widespread attention, but the poor water dispersibility restricted their applications seriously. Herein, Usnea longissima lichenan decorated selenium nanoparticles (L-SeNPs) were constructed. The formation, morphology, particle size, stability, physicochemical characteristics, and stabilization mechanism of L-SeNPs were investigated via TEM, SEM, AFM, EDX, DLS, UV-Vis, FT-IR, XPS, and XRD. The results indicated that the L-SeNPs displayed orange-red, amorphous, zero-valent, and uniform spherical nanoparticles with an average diameter of 96 nm. Due to the formation of CO⋯Se bonds or the hydrogen bonding interaction (OH⋯Se) between SeNPs and lichenan, L-SeNPs exhibited better heating and storage stability, which kept stable for more than one month at 25 °C in an aqueous solution. The decoration of the SeNPs surface with lichenan endowed the L-SeNPs with superior antioxidant capability, and their free radicals scavenging ability exhibited in a dose-dependent manner. Furthermore, L-SeNPs showed excellent selenium controlled-release performance. In simulated gastric liquids, selenium release kinetics from L-SeNPs followed the Linear superimposition model, which was governed by the polymeric network retardation of macromolecular, while in simulated intestinal liquids, it was well fitted to the Korsmeyer-Peppas model and followed a Fickian mechanism controlled by diffusion.

Study on performance of carbon source released from fruit shells and the effect on biological denitrification in the advanced treatment.

In order to solve the problem of shortage of carbon source for biological denitrification in advanced treatment of the effluent from secondary treatment of sewage, five kinds of fruit shells (pistachio shell, peanut shell, ginkgo shell, walnut shell and hazelnut shell) were preliminarily selected from eight kinds of fruit shells for experiments of static carbon release and denitrification. The carbon release performance (amount and law of carbon release and biodegradability of released carbon) and denitrification performance of different shells were investigated. Results showed that the peanut shell had the largest amount of carbon release (0.88 mg chemical oxygen demand [COD] g-1) and the highest removal rate of nitrate (NO3--N) (76.48% ± 4.06%). However, the released carbon could not be fully utilized by denitrifying bacteria, resulting in a (205.90% ± 59.49%) increase in effluent COD compared with influent. The amounts of carbon release of ginkgo nut shell, walnut shell, and hazelnut shell were low (0.45, 0.41, and 0.43 mg COD g-1, respectively). The released carbon could not be used easily by microorganisms. Meanwhile, the contents of degradable aromatic protein and protein-like in dissolved organic matter (DOM) were low. Even the fulvic acid-like with low biodegradability also appeared in the soaking solution of the hazelnut shell. The NO3--N and total nitrogen aveage removal rates were low in these three fruit shells and showed the removals within the 54.10-57.25% range and 52.21%-54.24% range, respectively. The amount of carbon release of pistachio shell was lower than that of peanut shell. However, the released carbon of the former was more biodegradable than that of the latter. Moreover, the relative molecular mass of DOM was small, and the contents of aromatic protein and protein-like were much higher than those of the four other kinds of fruit shells. The NO3--N removal rate (71.48% ± 0.98%) of pistachio shell was only slightly lower than that of peanut shell. In conclusion, pistachio shell was the best carbon source for biological denitrification in the advanced treatment.

Hard, Soft, and Hard-and-Soft Drug Delivery Carriers Based on CaCO3 and Alginate Biomaterials: Synthesis, Properties, Pharmaceutical Applications.

Because free therapeutic drug molecules often have adverse effects on normal tissues, deliver scanty drug concentrations and exhibit a potentially low efficacy at pathological sites, various drug carriers have been developed for preclinical and clinical trials. Their physicochemical and toxicological properties are the subject of extensive research. Inorganic calcium carbonate particles are promising candidates as drug delivery carriers owning to their hardness, porous internal structure, high surface area, distinctive pH-sensitivity, low degradability, etc, while soft organic alginate hydrogels are also widely used because of their special advantages such as a high hydration, bio-adhesiveness, and non-antigenicity. Here, we review these two distinct substances as well as hybrid structures encompassing both types of carriers. Methods of their synthesis, fundamental properties and mechanisms of formation, and their respective applications are described. Furthermore, we summarize and compare similarities versus differences taking into account unique advantages and disadvantages of these drug delivery carriers. Moreover, rational combination of both carrier types due to their performance complementarity (yin-&yang properties: in general, yin is referred to for definiteness as hard, and yang is broadly taken as soft) is proposed to be used in the so-called hybrid carriers endowing them with even more advanced properties envisioned to be attractive for designing new drug delivery systems.

Stability and surface properties of selenium nanoparticles coated with chitosan and sodium carboxymethyl cellulose.

The effect of polysaccharide coatings on the stability and release characteristics of selenium nanoparticles (SeNPs) was evaluated by comparing the characteristics of chitosan-coated SeNPs (CS-SeNPs) and sodium carboxymethyl cellulose-coated SeNPs (CMC-SeNPs). The release characteristics of SeNPs were investigated in storage conditions, gastrointestinal conditions, and free radical systems. CMC-SeNPs formed dimers or trimers, whereas CS-SeNPs were monodispersed but formed large aggregates in a pH range of 7.4-8.25. Upon 50 days of storage at 30 °C, both CMC-SeNPs and CS-SeNPs were converted to Se4+. SeNPs exhibited a lower release rate in simulated gastrointestinal conditions than in free radical systems. SeNPs release in ABTS and superoxide anion free radical systems followed the first-order and Korsmeyer-Peppas models, respectively, indicating that SeNP release is mainly governed by dissolution mechanisms. Additional studies are needed to examine the potential environmental effects and biological activity of the Se4+ released from SeNPs.

Selenium release kinetics and mechanism from Cordyceps sinensis exopolysaccharide-selenium composite nanoparticles in simulated gastrointestinal conditions.

This work investigated selenium (Se) release kinetics and mechanism from exopolysaccharide-selenium nanoparticles (EPS-SeNPs, Se/EPS = 1/20, 1/1 and 4/3) in simulated gastric (SGF) and intestinal fluids (SIF) using kinetics models of Zero order, First order, Higuchi, Hixson-Crowell and Korsmeyer-Peppas. EPS-SeNPs showed an increase in size from 80-125 nm to 250-320 nm and more ambiguous boundary after gastrointestinal digestion. Se/EPS ratio and pH had significant influence on Se release. Se release kinetics from EPS-SeNPs (Se/EPS = 1/1 and 4/3 in SGF) followed a classical Fickian diffusion, in contrast to an erosion governed by macromolecular chains relaxation for Se/EPS = 1/20 in SIF. Se release from EPS-SeNPs (Se/EPS = 1/1 and 4/3 in SIF) was well-fitted to Korsmeyer-Peppas model and followed a non-Fickian mechanism controlled by both diffusion and erosion. Additionally, EPS-SeNPs (Se/EPS = 1/20) showed a low Se release after SGF digestion, but a high release after SIF digestion, suggesting its application in controlled release of Se-enriched supplements for Se-deficiency treatment.

Emergent thallium exposure from uranium mill tailings.

Thallium (Tl) pollution caused by the exploitation of uranium (U) mines has long been neglected due to its low crustal abundance. However, Tl may be enriched in minerals of U ore because Tl has both sulfurophile and lithophile properties. Herein, a semi-dynamic leaching experiment combined with statistical analysis, geochemical speciation and multi-characterization provided novel insight into the distinct features and mechanisms of Tl release from uranium mill tailings (UMT). The results showed that particle size effects prevail over the pH on Tl release, and surface dissolution is the pivotal mechanism controlling Tl release based on Fick's diffusion model. The study revealed that long-term leaching and weathering can lead to the increased acid-extractable and oxidizable fractions of Tl in UMT, and that the exposure and dissolution of Tl-containing sulfides would largely enhance the flux of Tl release. The findings indicate that UMT containing (abundant) pyrite should be paid particular attention due to Tl exposure. Besides, critical concern over the potential Tl pollution in universal U mining and hydrometallurgical areas likewise may need to be seriously reconsidered.

Are the release characteristics of Erzhi pills in line with traditional Chinese medicine theory? A quantitative study.

OBJECTIVE: Traditional Chinese medicine (TCM) has been widely used throughout China to prevent and cure diseases for thousands of years, and now it is a part of the integrative medicine field that is available in Western societies. To ensure the safety and quality of the herbal medicines that are a major part of the TCM tradition, they must be held to modern pharmaceutical standards. Erzhi pill (EZP) is a Chinese Pharmacopeia-listed herbal preparation that is used in the long-term clinical management of post-menopausal symptoms, osteoporosis and menstrual disorders. Until now, whether the drug release mechanism of EZP is in line with its intended TCM usage has not been studied. METHODS: The release of specnuezhenide from three EZPs (self-made, Leiyunshang and Renhe) in simulated gastric fluid (SGF), acetate buffer (pH 4.5 buffer) and simulated intestinal fluid (SIF) was investigated in a dissolution test. The water uptake capacity and erosion extent of the three EZPs were investigated using swelling and erosion studies. The drug release mechanism was further assessed through statistical model fitting, using DDSolver software. RESULTS: The release of specnuezhenide from all three EZPs in SGF was less than 50% within a 4 h period. However, over 70% of the specnuezhenide was released from each EZP in both pH 4.5 buffer and SIF in the same time. Analysis of the swelling and erosion behaviors and the drug release mechanism of the three EZPs confirmed that the release rate from EZP followed a sustained release profile, which was an interactive combination of swelling and erosion. CONCLUSION: This study showed that the release pattern from the pills was in line with the intended TCM use of EZP. TCM had not only theoretically considered sustained release from the pills, but also formulated them to achieve this release pattern. When establishing quality control standards for pills, the theoretical TCM usage and the actual release patterns need to be considered.

Are the release characteristics of Erzhi pills in line with traditional Chinese medicine theory? A quantitative study / 中西医结合学报

OBJECTIVE@#Traditional Chinese medicine (TCM) has been widely used throughout China to prevent and cure diseases for thousands of years, and now it is a part of the integrative medicine field that is available in Western societies. To ensure the safety and quality of the herbal medicines that are a major part of the TCM tradition, they must be held to modern pharmaceutical standards. Erzhi pill (EZP) is a Chinese Pharmacopeia-listed herbal preparation that is used in the long-term clinical management of post-menopausal symptoms, osteoporosis and menstrual disorders. Until now, whether the drug release mechanism of EZP is in line with its intended TCM usage has not been studied.@*METHODS@#The release of specnuezhenide from three EZPs (self-made, Leiyunshang and Renhe) in simulated gastric fluid (SGF), acetate buffer (pH 4.5 buffer) and simulated intestinal fluid (SIF) was investigated in a dissolution test. The water uptake capacity and erosion extent of the three EZPs were investigated using swelling and erosion studies. The drug release mechanism was further assessed through statistical model fitting, using DDSolver software.@*RESULTS@#The release of specnuezhenide from all three EZPs in SGF was less than 50% within a 4 h period. However, over 70% of the specnuezhenide was released from each EZP in both pH 4.5 buffer and SIF in the same time. Analysis of the swelling and erosion behaviors and the drug release mechanism of the three EZPs confirmed that the release rate from EZP followed a sustained release profile, which was an interactive combination of swelling and erosion.@*CONCLUSION@#This study showed that the release pattern from the pills was in line with the intended TCM use of EZP. TCM had not only theoretically considered sustained release from the pills, but also formulated them to achieve this release pattern. When establishing quality control standards for pills, the theoretical TCM usage and the actual release patterns need to be considered.

[Preparation of Cangyi nanoemulsion in situ gel and drug release mechanism of nasal mucosa in vitro].

To prepare Cangyi nanoemulsion in situ gel and study its nasal mucosa release mechanism in vitro. After proper treatment of different drugs in the compound, the prescription of nanoemulsion was determined by pseudo-ternary phase diagram method. With the ratio of mixed emulsifier to oil phase [(S+COS)/O], the ratio of mixed emulsifier(K_m), the ratio of water phase to mixed emulsifier and oil phase[W/(S+COS+O)] as investigation factors and the normalized value(OD) as evaluation index, the prescription of Cangyi nanoemulsion was optimized by central composite design-response surface method. With the ratio of poloxamer 407(P407) and poloxamer 188(P188) as the investigation factors and the gelation temperature as the evaluation index, the in situ gel prescription of Cangyi nanoemulsion was optimized. The improved Franz diffusion cell was used to explore the nasal mucosa drug-release mechanism of Cangyi nanoemulsion in situ gel with oxymatrine, ferulic acid and salvianolic acid B content as indexes. The optimal prescription of Cangyi nanoemulsion in situ gel was as follows: 6.862% castor oil polyoxyl(EL), 4.262% absolute ethanol, 1.392% ethyl oleate, 7% P407 and 6% P188. The average pH was 5.55 and the average gelation temperature was 32.8 ℃. In vitro release studies showed that oxymatrine, ferulic acid and salvianolic acid B were released simultaneously and the drug release behavior was consistent with that in Higuchi model. The preparation process of Cangyi nanoemulsion in situ gel is stable, with suitable pH value, gelation temperature and viscosity. It has a certain slow-release effect, and can meet the needs of local nasal drug use.

Critical insight and indication on particle size effects towards uranium release from uranium mill tailings: Geochemical and mineralogical aspects.

Uranium (U) is both chemically toxic and radioactive. Uranium mill tailings (UMTs) are one of the most important sources of U contamination in the environment, wherein the mechanisms that control U release from UMTs with different granularities have not yet been well understood. Herein, the release behaviours and underlying release mechanisms of U from UMTs with five different particle size fractions (<0.45, 0.45-0.9, 0.9-2, 2-6 and 6-10 mm) were studied with a well-defined leaching test (ANS 16.1) combined with geochemical and mineralogical characterizations. The results showed that the most remarkable U release unexpectedly emerged from UMT2-6 mm; in contrast, the smallest particle size UMT<0.45 mm contributed to the least U release. The predominant mechanism of U release from UMT2-6 mm was the oxidative dissolution of U-bearing sulfides, while abundant gypsum present in UMT<0.45 mm inhibited U release. The study highlights the importance of combined geochemical and mineralogical investigation when performing leaching tests of mineral-containing hazardous materials such as UMTs with consideration of particle size effects. The findings also indicate that elevating the content of gypsum and avoiding the oxidation of sulfides can effectively help immobilize and minimize the residual U release from the UMTs.

Construction of self-assembled polyelectrolyte complex hydrogel based on oppositely charged polysaccharides for sustained delivery of green tea polyphenols.

In this study, we have developed a novel polyelectrolyte complex (PEC) hydrogel that could be easily prepared by self-assembly of two food-grade polysaccharides salecan and N,N,N-trimethyl chitosan (TMC). The electrostatic interactions between two polysaccharides were driving force in complexation processes and have been demonstrated by FTIR, XRD, XPS and TGA. The swelling capacity, morphology and rheological property of the hydrogels could be well tuned by controlling salecan/TMC ratio. Green tea polyphenols (GTP) was efficiently encapsulated into PEC hydrogels and liberated in a sustained pattern. The amount of GTP released in simulated intestinal fluid (SIF) was significantly higher than simulated gastric fluid (SGF). Increasing salecan/TMC ratio also markedly enhanced GTP release amount. Release exponent n obtained in SGF indicated a Fickian diffusion, while in SIF an anomalous transport occurred. The release mechanism was well-fitted with Ritger-Peppas model. Taken together, these PEC hydrogels could be suitable carriers for intestinal targeted nutrient delivery.

Water-in-oil-in-water double emulsions loaded with chlorogenic acid: release mechanisms and oxidative stability.

Chlorogenic acid (CA) is a natural compound used as an antioxidant in the preparation of food, drugs, and cosmetics. Due to their low stability and bioavailability, many researchers have studied the encapsulation of CA in various delivery colloidal systems. The aim of this study was to evaluate the stability of water-in-oil-in-water (W/O/W) double emulsions loaded with CA and its antioxidant capacity. For this purpose, CA-W/O/W double emulsions were prepared using Span 80 and lecithin as lipophilic emulsifiers, and Tween 20 as a hydrophilic emulsifier. The influence of nature of lipophilic emulsifiers, the presence of chitosan (CH) in the internal and external aqueous phases, pH, temperature and the storage time of W/O/W double emulsions were also investigated. Depending on the preparation conditions, the W/O/W double emulsions showed the droplet size in the range 9.13 ± 0.55 µm-38.21 ± 1.87 µm, the creaming index 34%-78% and the efficiency encapsulation 79.45 ± 1.5%-88.13 ± 1.9%. Zeta potential values were negative for the W/O/W double emulsion without CH (-36.8 ± 2.02mV; -27.3 ± 1.75mV) and positive for the W/O/W double emulsions with CH in the external aqueous phase (+6.5 ± 0.42mV; 28.6 ± 0.92mV). The study of the release of CA from W/O/W double emulsions has highlighted two mechanisms: one based on the coalescence between the water inner droplets or between the oil globules as well as a diffusion releasing mechanism. The oxidative stability parameters of the W/O/W double emulsions, such as the peroxide value (POV) and the conjugated diene content (CD) were measured.

Preparation and evaluation of a sustained-release buckwheat noodle.

BACKGROUND: Different carbohydrates elicit various effects on the digestibility and the glucose release rate, so it is of interest to develop a sustained-release noodle based on the combination of different carbohydrates and reveal the sustained-release mechanism. RESULTS: The data obtained suggest that xanthan and konjac gum exhibited excellent and synergistic sustained-release properties, whereas cornstarch showed the lowest average digestion rate. The sustained release was particularly evident when the noodle consisted of the following components: 50 g of 25 g kg(-1) hydrophilic colloid mixture solution composed of a 1:1 mass ratio of xanthan:konjac gum and 100 g of reconstructed flour consisting of 200 g kg(-1) buckwheat flour, 400 g kg(-1) cornstarch, and 400 g kg(-1) plain flour. The morphological structure of noodles revealed that the composite hydrophilic colloids strengthened the interaction between the gluten network and starch granules. This buried starch within the three-dimensional structure thereby releasing glucose in a slow and sustained way. The most suitable model to describe glucose release from noodles was the Ritger-Peppas equation, which revealed that matrix erosion contributed to the release mechanism. CONCLUSION: These findings indicate that the controlled use of hydrophilic colloids and starches in manufacturing noodles could modulate the glucose sustained-release. © 2015 Society of Chemical Industry.