Calcium Chloride Solution Research Articles

Effect of calcium oxide nanoparticles produced from Lavetira critica leaf extract on the freshness of fresh‐sliced fruits

AbstractThis study was piloted to assess the fusion of nanoparticles (LCCaNP) from leaf extract of Lavatera critica (LC) and calcium chloride and to observe their impact on the safety of fresh‐sliced fruits and extend their shelf life. LCCaNP were synthesized by mixing calcium chloride and LC leaf extract, followed by the addition of sodium hydroxide. The quality of the produced LCCaNP was proven by conducting different physical and chemical tests. Fresh apples, strawberries, and guavas were independently immersed in diverse concentrated LCCaNP and 2% calcium chloride solution for 5 min. These treated sliced fruits were stuffed in polypropylene plastic bags and stored at 5°C. The total soluble solid content (TSS), pH, firmness, and weight reduction rate, 2,2‐diphenylpicrylhydrazyl (DPPH), and sensory analysis were conducted for the total storage period of 25 days in a 5‐day interval. LCCaNP and calcium chloride were proficient to preserve the fruits for up to 20 days. Our findings showed that LCCaNP‐treated fresh‐sliced fruits had an improved and enhanced shelf‐life than control (nontreated) samples. In conclusion, the leaf of LC is an eventual source for the making of calcium oxide nanoparticles and could serve as an improved food conservation with proficiency to extend the fruit's shelf life for up to 20 days.Novelty impact statementFor the first time had produced the natural LCCaNP from a natural plant of LC and evaluated its impact on the safety of fresh‐sliced fruits. The natural nanosized LCCaNP is successfully produced by using the natural Ayurvedic plant of LC. LCCaNP acted as a better food preservative and had the capability to extend the shelf life of apples, strawberries, and guavas for up to 20 days without causing any side effects.

Influence of pre-harvest calcium applications on table olive characteristics during Spanish-style elaboration process

Calcium is largely used in the agri-food industry thanks to its positive effects, such as its preserving activity or its protection against pathogens. Post-harvest spraying of calcium chloride (CaCl2) solutions has demonstrated an increase in firmness and phenolic content. The aim of this research was to investigate the effects of pre-harvest applications of two CaCl2 concentrations (Ca 0.5% and Ca 1.0%) during the Spanish-style elaboration process at the beginning, middle, and end of the fermentation process. The analysis focussed on the Ca concentration in the whole fruit and in the different tissues (pulp, pit, and seed), as well as on the firmness, phenolic content, and antioxidant activity in the ‘Ascolana tenera’ table olive. An increased Ca concentration in the pulp (20.2 and 55.1%) and seed (13.4 and 36.5%) was observed during a monitoring period in which 0.5% and 1.0% CaCl2 concentrations, respectively, were compared with Ca 0% (water). No significant Ca increase was found in the pit. The fruit firmness was higher following the Ca treatments (22.8% and 68.3%, respectively), and a decrease in the contents of hydroxytyrosol, tyrosol, and verbascoside was observed during the elaboration process. The highest content of these phenols was found on the first date of monitoring for a 1.0% CaCl2 concentration. Hydroxytyrosol, oleuropein, and PB1 showed a significant difference on different monitoring dates. The antioxidant activity during the fermentation period rose between 63.3 and 87.2% compared with the Control (Ca 0%). A similar increasing trend was registered for the phenolic compounds. Our results are useful for the table olive sector to improve the handling in post-harvest processing and to increase the final quality of the olives.

Fabrication of sodium alginate-melamine@ZIF-67 composite hydrogel and its adsorption application for Pb(II) in wastewater.

A low-cost and environmental-friendly sodium alginate-melamine@zeolitic imidazolate framework-67 (SA-ME@ZIF-67) adsorbent was fabricated by chemical grafting and in situ growth for the removal of lead ions in wastewater. Firstly, melamine (ME) was grafted onto sodium alginate (SA) by amide reaction, and then SA-ME was dropped into a solution of calcium chloride to form hydrogel bead, and ZIF-67 was grown on the SA-ME hydrogel bead by the in situ growth method. The SA-ME@ZIF-67 adsorbent was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The SA-ME@ZIF-67 adsorbent was used to effectively adsorb Pb(II) from aqueous solutions. The initial concentrations of lead ions, adsorbent dose, initial pH of lead ion solution, temperature, and adsorption time for the material were optimized. The adsorption isotherms and kinetics fitted to Langmuir isotherm model (R2 = 0.9281, 0.9420, and 0.9623 at the temperatures of 288.15K, 298.15K, and 308.15K, respectively) and pseudo-second-order kinetic model (R2 = 0.9901) respectively. According to the Langmuir model at 308.15K, the maximum adsorption capacity of the adsorbent for Pb(II) was 634.99mg/g. The recycling application of the adsorbent was possible as it was easily collected and reused after five adsorption-regeneration cycles. In addition, the Pb(II) in real wastewater samples has been efficiently removed using the fabricated hydrogel. The results showed that the SA-ME@ZIF-67 adsorbent had high adsorption capacity, removal efficiency, and easy recyclability for Pb(II).

A new separation approach of amylose fraction from gelatinized high amylose corn starch

This work aimed at developing a new method to separate amylose from high amylose corn starch (HACS) with calcium chloride (CaCl 2 ) solution. The prepared amylose C was compared with the amylose N obtained with traditional sodium hydroxide (NaOH) solution. Although the extraction rate of purified amylose C (55.42 ± 0.53%) was slightly lower than that of purified amylose N (61.17 ± 0.60%), high performance size exclusion chromatography (HPSEC-MALLS-RI) patterns showed that it had higher purity. X-ray diffraction (XRD) and differential scanning calorimeter (DSC) results indicated that amylose C had more ordered and compact structure. In addition, the reagent solution consumption of amylose C was only about 30% of amylose N. • A new method of separating amylose with calcium chloride solution was established. • The purity of the amylose separated by calcium chloride solution was higher. • The method consumed smaller volume of water.

Organic Pollutant Biodegradation by an Immobilized Mixed Bacterial Culture

Pollution of organic compounds in rivers is generally contributed by wastewater discharge from human activities e.g. untreated black- & greywater, livestock farming, and industry. Without proper control of this waste generation, the river ecosystem will suffer if just rely on its self-purification and dilution by natural runoff to reduce the downstream effect. This research aimed to treat organic wastewater with an immobilized mixed bacterial culture. Immobilization was carried out using calcium alginate in a form of macrocapsule/beads, allowing the degrader microbe to be entrapped in its matrix thus preventing it from washout from the system. 3% (w/v) sodium alginate was mixed with 5 mg (dry) mixed culture and dropwise on 4% (w/v) calcium chloride solution. The results showed that immobilized microbes were still able to grow despite being entangled in a calcium alginate matrix with an initial growth of 6.1 x 105 to 7.4 x 107 colonies/grams and reduced COD content up to 68.3%. Degrader microbe immobilization offers considerable advantages compared to free/ suspended cell system due to the influence of river water flow.

Effect of Calcium Chloride on the Chemical Properties of the Refrigerated Fruits of the Apple Variety Golden Delicious

This study aims to identify the possibility of using calcium chloride solutions to maintain the best quality of the fruits of the Golden Delicious apple variety stored in cold storage and grown under the conditions of the AL-Marj region in Libya. It was conducted during the 2017 and 2018 planting seasons, and the treatments included spraying with two concentrations of calcium chloride, namely (0% and 0.06%) where the first spray was a month after the peak of flowering, and the spraying was repeated three times, one spray every 30 days, after harvesting, the fruits were immersed before storage in calcium chloride solutions at concentrations of (0%, 2%, 4%, 6%) and stored for (120 days) at a temperature of zero Celsius. The obtained results showed that the use of calcium chloride sprayed on the fruits better preserved their quality compared to the non-sprayed ones. The immersion in calcium chloride solutions also preserved the quality of the fruits by increasing its concentration within the limits of the concentrations included in this study, which makes us conclude the important role of calcium chloride in maintaining the quality of the fruits of this variety.

Synthesis of Alginate/Hydroxyapatite Beads for Acetaminophen Delivery

Conventional drug delivery systems usually involve the intake of multiple drugs, which could amplify the risk of overdosing. Acetaminophen is a widely used pain relief substance that is prone to accidental overdosing. Hence, a controlled drug delivery system is needed to ensure its efficacy. A nanocomposite hydroxyapatite/alginate system that was used as a drug carrier for acetaminophen was synthesized through the sol-gel method, and the mechanism underlying its controlled drug delivery was investigated. Spherical nanocomposite bead samples were synthesized by incorporating 5 wt%, 10 wt%, and 15 wt% hydroxyapatite into mixtures containing alginate. The mixtures were then dropped into calcium chloride solution. The phase purity of the hydroxyapatite sample was confirmed through X-ray diffraction, and the functional groups that confirmed the presence of alginate and hydroxyapatite in the nanocomposite samples were analyzed by using Fourier transform infrared spectroscopy. The release of acetaminophen can be controlled for 48 h, and the Korsmeyer–Peppas kinetics model showed the best correlation for all samples. The kinetics of Al/HAp5, Al/HAp10, and Al/HAp15 were governed by quasi-Fickian diffusion with the n values of 0.199, 0.238, and 0.225, respectively. The composite beads show potential for application as a controlled drug delivery vehicle.

SEED PRIMING EFFECTS ON MORPHOLOGICAL TRAITS OF AMARANTHUS HYPOCHONDRIACUS UNDER OPTIMAL AND LOW TEMPERATURES

The recent research evaluated the effects of growth stimulant seed treatment on the morphological traits of Amaranthus hypochondriacus L. cv. ‘Krepysh’ grown under optimal and low positive temperature conditions. The seeds were continuously soaked for 4 h in five different solutions of growth stimulants, i.e., salicylic acid (SAA - 138 mg/L), hydrogen peroxide (H2O2 - 10 and 50 mmol/L), calcium chloride (CaCl2 - 3000 mg/L), succinic acid (SUA - 500 mg/L), and control (distilled water). The stimulant-primed seeds were germinated at optimal temperature (23°C) and continued to germinate at low temperatures of 10°C (T10) and 23°C (T23). The results showed that seed germination rates viz., germination potential (GP), germination rate (GR), germination index (GI), viability index (VI), and seed vigor index (SVI), were significantly improved with seed quality potential compared with the control. Under low positive temperature, seeds treated with succinic acid, H2O2, and CaCl2 had the most significant effects on improving seed quality and induced cold resistance in the seeds. The morphological indicators of amaranth seedlings, i.e., biomass, hypocotyl, and root length, were also significantly improved with seed treatment by growth stimulants. Priming of amaranth seeds with hydrogen peroxide and succinic acid showed a greater increase in seedlings’ biomass at room (23°C) and low (10°C) temperatures. The seed treatment with SUA and SAA significantly contributed to enhancing the hypocotyl length. The amaranth roots achieved maximum length after seed treatment with SUA and CaCl2. In general, the seed treatment effects on seedling's biomass under chilling stress were associated with the potential of inducing cold tolerance in seedlings.

SEED PRIMING EFFECTS ON SEED QUALITY AND ANTIOXIDANT SYSTEM IN THE SEEDLINGS OF AMARANTHUS TRICOLOR L.

Amaranthus tricolor L. cv. ‘Valentina’ leaves are a promising source of dietary food supplements (DFS) and are used to prepare tea drinks that improve human health in Russia. Amaranth is a small-seeded crop, and the seed mass differs significantly, which leads to unfriendly shoots and a decrease in the potential productivity of the plant biomass. Pre-sowing treatment with growth stimulants can improve its seed quality. The study aimed to improve the seed quality, the morpho-physiological parameters, and the antioxidant properties of amaranth seedlings grown from seeds treated with plant growth stimulants at the Federal State Budgetary Scientific Institution, Federal Scientific Vegetable Center (FSBSI FSVC), Moscow, Russia. For seed treatments, water solutions of salicylic acid (SA - 138 mg/L), hydrogen peroxide (H2O2 - 5 mM), succinic acid (ScA - 500 mg/L), calcium chloride (CaCl2 - 3000 mg/L), and gibberellic acid (GA3 - 300 mg/L) were used. Researchers germinated the seeds first in petri dishes in natural light at a daytime temperature of 23±2°C for seven days. Determining amaranthine, chlorophyll, and carotenoid content used generally accepted methods. Pre-sowing treatment of large and small fractions of amaranth seeds with GA3, ScA, and CaCl2 improved the seed quality, whereas seed treatment of SA and H2O2 reduced the seed quality. Recording of antioxidants (amaranthine and carotenoids) and total chlorophyll content accumulation in seedlings grown from the treated seeds followed. The levels of amaranthine and photosynthetic pigments decreased in the seedlings of Amaranthus tricolor L. cv. Valentina seeds with ScA, CaCl2, and GA3 treatments, while the seedling's biomass exceeded that of control, which suggests that these chemicals act as growth regulators. The negative effect of SA on the viability of large (LF) and small (SF) amaranth seeds showed significant reductions in the morphometric indicators. It may be due to oxidative stress, enhancing amaranthine content in the cotyledonary leaves of seedlings.

Solution blowing spinning of polylactate/polyvinyl alcohol/ZnO nanocomposite toward green and sustainable preparation of wound dressing nanofibrous films.

The outstanding biodegradability, biocompatibility, affordability, and renewability of polylactic acid have made it a prominent biomaterial. Herein, an innovative, easy, and eco-friendly technique is used to prepare sodium polylactate (SP)-based nanofibers. Solution blowing spinning (SBS) was used to create fibrous mats of SP and polyvinyl alcohol (PVA). SBS's SP nanfibers were crosslinked using an aqueous solution of calcium chloride to produce moisture-resistant calcium polylactate nanofibrous spun mats. Both of UV-visible absorption spectra and transmission electron microscopy were utilized to study the produced zinc oxide (ZnO) nanoparticles (NPs) to indicate a diameter of around 15-23 nm with a high intensity absorption intensity at 370 nm. New polylactate copolymer was synthesized and characterized by infrared and NMR spectroscopic techniques. In order to prepare SP/PVA/ZnO nanocomposite nanofibers, various ZnO ratios were used. The morphologies of the composite nanofibers were investigated by infrared spectroscopy (FTIR), energy-dispersive X-ray analyzer, and scanning electron microscopy. The cytotoxicity tests of the prepared mat were studied by conducting experiments with L-929 cells at various time intervals. The prepared composite SP/PVA/ZnO nanofibers were subjected to cytotoxicity tests to determine their cytocompatibility. Results showed that those with ZnO concentrations between 0.5% and 2% were found to be less harmful than those with higher concentrations. A variety of bacterial species, including Bacillus pumilus and Staphylococcus aureus, as well as Klebseilla pneumoniae and Escherichia coli, were used to test the antibacterial properties of SP/PVA/ZnO spun mats. The ZnO NPs integrated in the SP/PVA fibrous mats were responsible for their antibacterial properties. After finding the appropriate concentration of ZnO that is least harmful while yet giving a satisfactory antibacterial activity, this biomaterial might be perfect for wound dressing applications. HIGHLIGHTS: New eco-friendly biodegradable sodium polylactate (SP) copolymer was synthesized. Zinc oxide nanoparticles (ZnO NPs) with a diameter of 15-23 nm were prepared. High antibacterial SP/PVA/ZnO fibers were prepared by solution blowing spinning. SP/PVA/ZnO nanofibers (180-220 nm) with various ratios of ZnO were presented. Cytotoxicity results showed that the cell viability decreases with increasing ZnO.

INTERPRETATION OF MORPHOLOGICAL PICTURE OBSERVED IN HISTOLOGICAL PREPARATIONS FROM THE POINT THE VIEW OF STEREOLOGY

The study of a biological microobject from the standpoint of three-dimensionality gives more correct and realistic vision. The study material included 8 preparations of the palatine and labial salivary glands of adult human individuals fixed in 4% glutaraldehyde solution in phosphate buffer (pH 7.4). Following pre-fixation, the object was cut into individual slices and fixed in a freshly prepared similar fixator adding 1% calcium chloride solution at 4 °C for 12 hours. The tissue was washed after the fixation and then processed according to the requirements for electron microscopy. Tissues enclosed in epoxy resin were used to obtain semi-thin series of histological sections for further graphic and plastic reconstruction of epithelial components (including tubular) glands. Semi-thin sections were stained with 0.1% toluidine blue in phosphate buffer with different pH (from 5.5 to 8.5). Spiral, corkscrew, tortuous, arched and other forms of biological tubular structures at the microscopic level are no exception and, as our study shows, are natural phenomena along with their rectilinear shape. It can be assumed that the interdependence between the shape of the tubular transport microchannels and the laminar motion of the fluid naturally reflects the elements of curvilinear symmetry and, in particular, its spiral property. Conclusion. Thus, we could assume that the tortuous shape of transport channels of human and animal tissues is a useful stereomorphological device, and their study and three-dimensional modelling is of great scientific interest, in particular, for understanding the mechanism of laminar fluid movement through biological tubes.

Stabilisation of a clay soil by injection of different ions

In this research study the effects of calcium and magnesium ions on stabilisation of a clay soil were studied by conducting a set of laboratory tests. A special apparatus was employed for carrying out the tests under constant voltage and time. During the tests, solutions of calcium chloride (CaCl2) or magnesium chloride (MgCl2) with different concentrations were injected into the soil samples. The electro-osmotic and electrokinetics methods were used for stabilisation of the soil and the results were compared with each other. In the electro-osmotic technique, distilled water was used as pore fluid, but in the electrokinetic method, calcium chloride or magnesium chloride solutions with various concentrations were injected into the pores of soil samples. The results revealed an increase in strength of the soil in both methods. In the electrokinetic method, the amount of increase in strength was a function of concentration of the solution that was used. The results also indicated that a solution of calcium chloride is more effective in increasing the strength, discharge flow and electro-osmotic permeability than a magnesium chloride solution at various concentrations. In addition, the variations of these properties are a function of the concentration of the given solution.

MORFOMETRIA OVARIANA APLICADA AO USO DE QUIMIOESTERILIZANTE EM CADELAS E GATAS

To achieve success in stray animals’ population control strategies, alternative methods to surgical castration, which reaches a greater number of animals, have been studied. However, considering females, it is necessary to know adequate volumes of chemosterilizer to be injected into the ovary and biological factors that influence ovarian volumetry. This study aims to determine the volume of 20% calcium chloride solution diluted in 95% ethanol to inject into the ovary of bitches and queens. Furthermore, correlations between ovarian measures (length [L], width [W], height [H], and volume) and body mass, age, and the volume of injected chemosterilizer were analyzed. For this, 64 ovaries, collected after elective ovariohysterectomy, received an injection of the solution. Ovarian measures were performed pre-injection and post-injection, and volume was calculated using Lambert's empirical formula, the formula for an ellipsoid, and the formula for spherical prolate. The mean ± standard error of the chemosterilant volume injected in the ovary was 0.09 ± 0.02 mL for bitches and 0.10 ± 0.02 mL for queens; ovaries’ width obtained a strong correlation with the injected volume; age showed a correlation to chemosterilant volume for both species and ovarian volume of queens; and body mass showed a correlation to ovarian measurements, ovarian volume e injected volume for bitches. Lambert's empirical formula and ellipsoid formula were more reliable for this assessment and respectively demonstrate an increase of 33% and 24% in ovarian volume in bitches post-injection; and 27% and 22% in queens post-injection.

Study of the Influence of Thermal Convection on Temperature Measurement in Thermal Control Boreholes during Artificial Ground Freezing

This paper considers the problem of thermal convection of a calcium chloride solution in a vertical borehole. A non-uniform temperature distribution with a given vertical gradient is set at the walls of the borehole. The non-stationary temperature distribution along the borehole axis was analyzed, and its deviations from the temperature at the walls were investigated. From a practical point of view, this problem is important for estimating the error in distributed temperature measurements over the depth of thermal control boreholes during artificial ground freezing. In this study, an area near the bottom of the borehole was identified where the fluid temperature at the borehole axis deviates significantly from the temperature at the wall. The maximum deviations of the fluid temperature from the temperature at the walls, as well as the length of the temperature deviation sections, were determined.

Curcumin encapsulated polylactic acid nanoparticles embedded in alginate/gelatin bioinks for in situ immunoregulation: Characterization and biological assessment

Curcumin is a known naturally occurring anti-inflammatory agent derived from turmeric, and it is commonly used as a herbal food supplement. Here, in order to overcome the inherent hydrophobicity of curcumin (Cur), polylactic acid (PLA) nanoparticles (NPs) were synthesised using a solvent evaporation, and an oil-in-water emulsion method used to encapsulate curcumin. Polymeric NPs also offer the ability to control rate of drug release. The newly synthesised NPs were analysed using a scanning electron microscope (SEM), where results show the NPs range from 50 to 250 nm. NPs containing graded amounts of curcumin (0 %, 0.5 %, and 2 %) were added to cultures of NIH3T3 fibroblast cells for cytotoxicity evaluation using the Alamar Blue assay. Then, the curcumin NPs were incorporated into an alginate/gelatin solution, prior to crosslinking using a calcium chloride solution (200 nM). These hydrogels were then characterised with respect to their chemical, mechanical and rheological properties. Following hydrogel optimization, hydrogels loaded with NP containing 2 % curcumin were selected as a candidate as a bioink for three-dimensional (3D) printing. The biological assessment for these bioinks/hydrogels were conducted using THP-1 cells, a human monocytic cell line. Cell viability and immunomodulation were evaluated using lactate dehydrogenase (LHD) and a tumour necrosis factor alpha (TNF-α) enzyme-linked immunosorbent (ELISA) assay, respectively. Results show that the hydrogels were cytocompatible and supressed the production of TNF-α. These bioactive hydrogels are printable, supress immune cell activation and inflammation showing immense potential for the fabrication of tissue engineering constructs.

Fabrication and characterisation of novel algin incorporated bioactive-glass 58S calcium-silicate-based root canal sealer

The usage of bioceramic-based root canal sealers has escalated over the years due to their excellent properties. The present study aimed to fabricate a novel algin incorporated bioactive glass 58S calcium-silicate (Bio-G) sealer and characterise its surface microstructure and chemical compositions in comparison to commercially available bioceramic sealers (BioRoot RCS and iRoot SP). The powder form of experimental Bio-G sealer consisted of synthesised BG 58S particle, calcium silicate, zirconia dioxide, calcium carbonate and alginic acid powder as binder. The liquid composed of 5% calcium chloride solution. Five standardised disc specimens were prepared for each sealer group according to the manufacturer's instructions. Subsequently, sealer disc-specimens were placed in an incubator at 37°C, 95% relative humidity for 72h to allow setting prior to testing under scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Experimental Bio-G sealer revealed irregular micro-sized particles ranging from 0.5μm to 105μm aggregated in clusters comparable to those of BioRoot RCS and iRoot SP. EDS microanalysis showed that Bio-G had high content of oxygen, silicon, and calcium, with the presence of aluminium and chloride similar to BioRoot RCS. Meanwhile, the FTIR and XRD findings suggested that all sealers predominantly contained calcium silicate hydrate, calcium carbonate, and zirconium dioxide, while calcium aluminium silicate oxide was detected in Bio-G. The present novel Bio-G sealer demonstrated desirable particle size distribution and acceptable degree of purity. Future studies are warranted to explore its properties and clinical application.

Abalone-Inspired Adhesive and Photo-Responsive Microparticle Delivery Systems for Periodontal Drug Therapy.

Antibiotics provide promising strategies for treating periodontitis, while their delivery and controllable release with desired oral retention remain challenging. Here, inspired by the unique suction‐cup structures of abalones, a novel adhesive and photo‐responsive microparticle (MP) delivery system is developed to treat periodontitis through microfluidic electrospray technology. Such MPs are generated by quickly ionic cross‐linking of sodium alginate together with photo‐curing of poly(ethylene glycol) diacrylate of the distorted microfluidic droplets during their high‐speed dropping into calcium chloride solution. Attributing to their unique concave structures, the abalone‐inspired MPs exhibit desired underwater adhesion ability and stability under running water. In addition, due to the loading of antibiotics minocycline hydrochloride and near‐infrared (NIR)‐responsive black phosphorus during their fabrication, the resultant MPs can not only eradicate bacteria directly, but also realize a controllable and effective drug release upon NIR irradiation. Based on these features, it is demonstrated from in vivo periodontitis that the abalone‐inspired MPs are firmly adhesive and can controlled‐release drugs on the tooth, and thus have outstanding antibacterial efficacy against Porphyromonas gingivalis. These results indicate the particular values of the abalone‐inspired MPs for oral‐related disease treatment.

PH-Sensitive Polyacrylic Acid-Gated Mesoporous Silica Nanocarrier Incorporated with Calcium Ions for Controlled Drug Release

In this work, polyacrylic acid-functionalized MCM-41 was synthesized, which was made to interact with calcium ions, in order to realize enhanced pH-responsive nanocarriers for sustained drug release. First, mesoporous silica nanoparticles (MSNs) were prepared by the sol-gel method. Afterward, a (3-trimethoxysilyl)propyl methacrylate (TMSPM) modified surface was prepared by using the post-grafting method, and then the polymerization of the acrylic acid was performed. After adding a calcium chloride solution, polyacrylic acid-functionalized MSNs with calcium-carboxyl ionic bonds in the polymeric layer, which can prevent the cargo from leaking out of the mesopore, were prepared. The structure and morphology of the modified nanoparticles (PAA-MSNs) were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), and N2 adsorption–desorption analysis, etc. The controlled release of guest molecules was studied by using 5-fluorouracil (5-FU). The drug molecule-incorporated nanoparticles showed different releasing rates under different pH conditions. It is considered that our current materials have the potential as pH-responsive nanocarriers in the field of medical treatment.

Dual Crosslinked Ion-Based Bacterial Cellulose Composite Hydrogel Containing Polyhexamethylene Biguanide.

Composite bacterial cellulose (BC) based hydrogel with alginate (A) or pectin (P) or alginate and pectin was fabricated via a physical crosslinking technique using calcium chloride (CaCl2) solution and incorporated with polyhexamethylene biguanide (PHMB) as an effective antimicrobial drug by immersion method. After that, the physicochemical properties of all hydrogel formulations were characterized. The result showed that the formulations with PHMB performed better physicochemical properties than the hydrogel without PHMB. Fourier transform infrared spectroscopy (FT-IR) showed the interaction between PHMB and the carboxylic group of alginate and pectin. BC/A-PHMB hydrogel performed suitable mechanical strength, fluid uptake ability, water retention property, drug content, high integrity value, and maximum swelling degree. Moreover, in vitro cell viability of BC/A-PHMB hydrogel revealed high biocompatibility with human keratinocyte cell line (HaCaT) and demonstrated prolong released of PHMB in Tris-HCl buffer pH 7.4, while rapid release in phosphate buffer saline pH 7.4. BC/A-PHMB hydrogel demonstrated good anti-bacterial activity against S. aureus and P. aeruginosa. In conclusion, BC/A-PHMB hydrogel could be a potential dual crosslinked ion-based hydrogel for wound dressing with anti-bacterial activity.

Analysis and Experimental Study on Water Vapor Partial Pressure in the Membrane Distillation Process.

In membrane distillation, the vapor pressure difference is the driving force of mass transfer. The vapor pressure is generally assumed by the saturation pressure and calculated by the Antoine equation. However, in the actual operation process, the feed solutions usually flow in a non-equilibrium state, which does not meet the theoretical and measurement conditions of the vapor-liquid equilibrium (VLE) state. This study tested the actual water vapor pressure of the pure water, lithium bromide (LiBr) solution, lithium chloride (LiCl) solution, and calcium chloride (CaCl2) solution under different flow conditions. The results showed that the actual water vapor pressure was lower than the saturation pressure overall, and the difference increased with temperature but decreased with the mass concentration. Therefore, in vacuum membrane distillation (VMD), air gap membrane distillation (AGMD), and sweeping gas membrane distillation (SGMD), the membrane flux calculated by water vapor saturation pressure was higher than the actual membrane flux, and the relative difference decreased and was less than 10% after 60 °C. In direct contact membrane distillation (DCMD), the water vapor pressure difference on both membrane sides was almost the same by using the saturation vapor pressure or the tested data since the pressure errors were partially offset in parallel flow or counter-flow modes.