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The use of essential oils is widespread in various fields such as pharmacy, pest control, and active packaging. However, their instability and short-term effects require methods to enhance their durability and effectiveness. Encapsulation in biopolymer matrices appears to be a promising approach due to the environmental safety and cost-effectiveness of such formulations. In this study, different oil-in-water emulsions were prepared by mixing chitosan-gelatin (C-G) or pectin-gelatin (P-G) solutions with lemongrass essential oil (LG). ZnO NPs were used as an additional active component. Encapsulation in biopolymer matrices resulted in stable emulsions with a significantly slower release of LG, and ZnO NPs further suppressed LG release, particularly in the P-G emulsion. They also contributed to the stability of the emulsions and a decrease in the average droplet size of LG. Furthermore, the presence of LG and ZnO NPs improved the smoothness of the films prepared from the emulsions and dispersions using the casting technique. SEM/EDS analysis confirmed the homogeneous distribution of ZnO NPs in both C-G and P-G films. By adjusting the type and content of the biopolymers and NPs, such emulsions could be effectively utilized in various applications where controlled release of active components is required., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Jelena Jovanovic has patent Biopolymer emulsion for active packaging, uses and method of manufacturing pending to University of Belgrade. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Slow-release fertilizers (SRFs) play an essential and necessary role in sustainable agriculture. Using slow-release and environment friendly fertilizers can increase the growth of plants and reduce the loss of nutrients. Considering the deficiency of iron (Fe) and zinc (Zn) in calcareous soils, a slow-release fertilizer was prepared based on the polymeric nanocomposite, which contains NPK, Fe, and Zn. Its potential was evaluated on tomato plant growth by conducting an experiment in a factorial completely randomized design with three replications. Two levels of salinity (2 and 5 ds m -1 , two types of soil texture) clay loam and sandy loam) and five levels of fertilizers were examined in the experiment. To this, the graphene oxide-chitosan coated-humic acid@Fe 3 O 4 nanoparticles (Fe 3 O 4 @HA@GO-Cs), and the graphene oxide-chitosan coated-ammonium zinc phosphate (AZP@GO-Cs) were used as Fe and Zn sources, respectively. Then, the optimal Fe and Zn fertilizers in the presence of urea, phosphorus, and potassium slow- release fertilizers (SRF) were investigated under greenhouse conditions. The results indicated that the best improvement in growth and nutrient uptake in plants was achieved by using the SRF. Notably, in the shoots of tomato plants, the nitrogen, phosphorus, potassium, Fe, and Zn concentration increased by 44, 66, 46, 75, and 74% compared to the control. The use of nanofertilizer can be an effective, biocompatible, and economical option to provide Fe and Zn demand in plants., (© 2024. The Author(s).)

Nanocarrier preparations could effectively improve the utilization rate of pesticides, and reduce pesticide loss. In this study, glyphosate (GLY)-loaded MgAl layered double hydroxide (GLY@LDH) was synthesized via an in-situ method. Subsequently, GLY@LDH composite samples were prepared using a layer-by-layer self-assembly approach and modified with poly-L-aspartic acid (PASP) and chitosan (CS). XRD, FT-IR, SEM, and Zeta potential characterization confirmed that GLY was successfully loaded in the interlayer of LDHs and PASP/CS were successfully encapsulated on the surface of the composite sample. The release effect in different ionic solutions and soils was studied and analyzed. The release behavior conforms to the Ritger-Peppas kinetic model, and the release mechanism was ion exchange, which was further explored by means of XRD, SEM, and molecular simulation. The results of the anti-scouring experiment and contact angle measurement indicated that the layered self-assembly material enhanced the washing resistance of the material. The practical application effect of the sample was verified through a pot experiment. This study provides new insights into the simple preparation of pesticide-controlled release formulations that reduce leaching losses., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

The exploration of novel functional packaging films is of great scientific and technological interest. Herein, a novel chitosan/hollow g-C 3 N 4 /curcumin (CS-HCNS-Cur) biocomposite films was successful fabricated with integrated functions of slow release, antimicrobial activity and food freshness preservation. CS-HCNS-Cur films take the advantages of the excellent thermal stability and slow-release ability of HCNS to curcumin. Among the characterizations including scanning electron microscopy, transmission electron microscope, atomic force microscopy, fourier transform infrared spectroscopy, mechanical properties and the rheological properties measurements confirmed the successful fabrication of CS-HCNS-Cur films. The averaged water contact angle and water vapor permeability of this film were 105.83° and 105.03 × 10 -5 g·mm (m 2 ·h·kPa) -1 , respectively. This film showed pH-responsive and slow-release ability. Moreover, this film can effectively store bananas for 10 days. Therefore, CS-HCNS-Cur films have promising potential for applications in functional food packaging., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Superabsorbent polymers fabricated via grafting polymerization of acrylic acid from chitosan (CTS) yields materials that suffer from poor mechanical strength. Hybridization of chitosan with cellulose (Cell) via chemical bonding using thiourea formaldehyde resin increases the flexibility of the produced hybrid (CTS/Cell). The hybridization process and post graft polymerization of acrylic acid was followed using Fourier transform infrared (FTIR). Also, the obtained structures were homogeneous and exhibited uniform surface as could be shown from imaging with scanning electron microscopy (SEM). Thus, the polymers derived from the grafting of polyacrylic acid from (CTS/Cell) gave rise to much more mechanically robust structures ((CTS/Cell)-g-PAA) that bear wide range of pH response due to presence of chitosan and polyacrylic acid in one homogeneous entity. Additionally, the obtained structures possessed greater water absorbency 390, 39.5g/g in distilled water and saline (0.9wt.% NaCl solution), respectively, and enhanced retention potential even at elevated temperatures as revealed by thermogravimetric analysis (TGA). This could be explained by the high grafting efficiency (GE%), 86.4%, and grafting yield (GY%), 750%. The new superabsorbent polymers proved to be very efficient devices for controlled release of fertilizers into the soil which expands their use in agriculture and horticultural applications., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Using chemical inhibitors to reduce soil nitrification decreases emissions of environmental damaging nitrate and nitrous oxide and improves nitrogen use efficiency in agricultural systems. The efficacy of nitrification inhibitors such as dicyandiamide (DCD) is limited in soil due to biodegradation. This study investigated if the persistence of DCD could be sustained in soil by slow release from a chitosan hydrogel. DCD was encapsulated in glyoxal-crosslinked chitosan beads where excess glyoxal was (i) partly removed (C beads) or (ii) allowed to dry (CG beads). The beads were tested in water and in soil. The beads contained two fractions of DCD: one which was quickly released in water, and one which was not. A large DCD fraction within C beads was readily available: 84% of total DCD bead content was released after 9h immersion in water, while between 74% and 98% was released after 7d in soil under low to high moisture conditions. A lower percentage of encapsulated DCD was readily released from CG beads: 19% after 9h in water, and 33% after 7d in soil under high rainfall conditions. Kinetic analysis indicated that the release in water occurred by quasi-Fickian diffusion. The results also suggest that DCD release was controlled by bead erosion and the leaching of glyoxal derivatives, predominantly a glyoxal-DCD adduct whose release was positively correlated with that of DCD (R(2)=0.99, p⩽0.0001). Therefore, novel chitosan/glyoxal composite beads show a promising slow-release potential in soil for agrochemicals like DCD., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Due to the rapid dissolution of urea fertilisers in water, leaching and evaporation from the soil cause approximately 70 % of the urea to be lost to the atmosphere and groundwater without being used by plants. It is known that a significant portion of urea fertiliser is released into the atmosphere as ammonia gas, and into groundwater as nitrate and nitrite, resulting in nitrogen losses. To mitigate these losses, various studies have been conducted on coating urea fertiliser with different materials. Biopolymers, in addition to providing controlled release, also act as soil conditioners by increasing the water-holding capacity of the soil and providing necessary moisture to plants during dry periods. In this study, three different types of biopolymers – chitosan, pectin, and xanthan gum – at two different concentrations (1 % and 3 %), were used to coat urea fertiliser aiming for controlled release. Biopolymer solutions and their cross-linkers were prepared, and the urea fertiliser was coated using a laboratory-scale coating drum. The chemical structure of the coated urea fertiliser was determined using Fourier-Transform Infrared Spectroscopy, and its morphology was examined with a Scanning Electron Microscope. The water-holding capacity in the soil and the ammonia released into the atmosphere were also analysed. The results indicated that the most effective biopolymer coating type for the slow-release mechanism of urea was pectin at a 1 % coating ratio on the fertiliser granules. The concentration of ammonia released from the soil and the water-holding capacity of the soil treated with biopolymer-coated urea fertiliser were tested through various experiments, and the results were analysed statistically. According to the statistical analysis, the 1 % pectin-coated urea fertiliser yielded the best results in both experiments, with an ammonia release value of 246.66 ppm and an evaporation rate of 67.84 % at the end of 30 days.

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Fertilizer has been the ever-increasing demand in agricultural production in recent years, particularly with the escalating demand for food. Simultaneously, the low efficiency of nutrient utilization and environmental risks of fertilizers have posed substantial challenges in the world. Alternatively, polymer-coated fertilizers can play a pivotal role in nutrient utilization efficiency, thus reducing the fertilizer application rates and environmental pollution risks. This study aims to improve the membrane materials of typical polymer-coated fertilizers for the high nutrient utilization efficiency in conventional fertilizers. Polyvinyl alcohol (PVA) was also employed as the membrane substrate, in order to relieve the secondary pollution and uncontrollable nutrient release rates. Three types of membranes—PVA/CS membrane, PVA/CS/GA membrane, and PVA/CS/GA/nano SiO2 membrane—were prepared using three methods: blending with chitosan (CS), crosslinking with glutaraldehyde (GA), and incorporating nano SiO2. Additionally, pure PVA membranes were prepared for comparison. The four types of membranes were characterized using scanning electron microscopy (FE-SEM), water absorption (Q), biodegradability (De), and nutrient permeability coefficient (Ps). Results indicated that there were excellent dispersion and compatibility of nano SiO2 in the PVA/CS membrane solution. Furthermore, the biodegradation rates of the four membranes also exhibited gradual increments during the initial 21 days. Subsequently, biodegradation rates escalated rapidly from the 21st to the 56th day, followed by a slower growth rate after the 56th day. The CS was incorporated to enhance the membrane biodegradation rates, while the GA crosslinking contributed to the less membrane biodegradation in soil. However, the addition of nano SiO2 had minimally impacted the membrane biodegradation rates. Overall, all four membranes displayed favorable biodegradability, with the biodegradation rates ranging from 30% to 60% within 77 days. The water absorption of PVA/CS, PVA/CS/GA, and PVA/CS/GA/nano SiO2 membranes decreased by 43.00%, 68.79%, and 82.73%, respectively, compared with the PVA membranes. Furthermore, the nutrient permeability coefficients of PVA/CS/GA and PVA/CS/GA/nano SiO2 membranes decreased by 48.51% and 57.59%, respectively, compared with the PVA/CS membranes. Therefore, the addition of CS, GA crosslinking, and nano SiO2 all contributed to the hydrophobicity of PVA membranes. Four types of coated urea (PCU) particles—PCU-PVA, PCU-PVA/CS, PCU-PVA/CS/GA, and PCU-PVA/CS/GA/nano SiO2—were prepared, where these membrane solutions were applied to the urea particles using a drum coating machine. The nitrogen release behavior was evaluated using the soil burial. The time required for the nitrogen release of the four PCUs to reach 90% varied significantly, recorded at 5, 11, 23, and 28 days, respectively. On the 5th day, the nitrogen released from PCU-PVA was the highest at 90.64%, whereas the lowest was from PCU-PVA/CS/GA/nano SiO2 at 49.32%. The CS, GA crosslinking and nano SiO2 enhanced the membrane hydrophobicity, which in turn reduced the nitrogen release rate. The nitrogen release behavior of all four PCUs followed a first-order kinetic model, with the release rate constants (k) decreasing progressively—0.3 654, 0.2 333, 0.1 127, and 0.0 926, respectively—and correlating linearly with the nutrient permeability coefficient (Ps) of the membranes. The correlation coefficient (R²) was impressively high at 0.9 991. A series of polyvinyl alcohol/chitosan coating materials were introduced with excellent biodegradability and controllable nutrient release rates, suitable for use in polymer-coated fertilizers. These materials were effectively applied in the production of coated urea particles. A first-order kinetic model of PCU nitrogen release was established with the membrane nutrient permeability coefficient as a key parameter, in order to more efficiently and effectively guide the application of PCU. [ABSTRACT FROM AUTHOR]

OBJECTIVE: With the development of society and the progress of science and technology, microspheres, as a new polymer material, have been applied to all aspects of human beings. Microspheres can play a huge role in food safety, electronic technology, sewage treatment, biomedicine, etc., and are non-toxic or harmless. There are three main types of substrates for the preparation of microspheres: natural polymers, semi-synthetic polymer materials, and synthetic polymer materials. MATERIALS AND METHODS: In this study, the inorganic material kaolin was modified by the emulsification-crosslinking method with chitosan and composite microspheres with large interlayer spacing were prepared, which were characterized by Fourier Transform Ioncyclotron Resonancel (FTIR) analysis and Scanning Electron Microscope (SEM). The prepared kaolin/chitosan microspheres were then placed in different amounts of aspirin and the optimal dose was investigated by encapsulation efficiency and drug loading rate. The drug release rate of 0.5 h, 1 h, 1.5 h, 2 h, 4 h, 6 h, and 12 h was then determined by simulating the human colon to determine the performance of the sustained-release drug. RESULTS: The experimental results showed that after the prepared composite microspheres were loaded with aspirin drug, we got the optimal dosage of 0.1 g by discussing the encapsulation efficiency and drug loading rate of the drug-loaded microspheres, and the encapsulation efficiency reached 80.80%, while the drug loading rate was 24.40%, the drug release capacity reached about 83% in about 12 hours. CONCLUSIONS: The research shows that the kaolin/chitosan drug-loaded microspheres prepared by the emulsification and cross-linking method are excellent drug-loading materials. [ABSTRACT FROM AUTHOR]

Graphene oxide（GO） was prepared by the modified Hummers method. Chitosan and graphene oxide（CS/GO） composites were prepared by solution blending method through simple non-covalent modification. The water solubility and bioavailability of BEN were improved by releasing BEN. The results showed that the GO and CS/GO dispersions were still homogeneous and stable after 45 d of placement without precipitation or stratification. Compared with GO, the lateral size of CS/GO was significantly reduced, the loading（W） of BEN was increased from 450 mg/g to 650 mg/g, and the encapsulation（E） was increased from 27.13% to 39.16%. The results of in vitro release experiments showed that the release behavior of BEN@CS/GO was pH responsive. Under acidic（pH=4） conditions, the cumulative release amount within 48 h was 53.2%, and under neutral and alkaline（pH=7 and pH=9） conditions, the cumulative release amount was 38.7% and 24.6%, respectively. The release kinetics analysis of the release data from BEN@CS/GO revealed that the in vitro release of BEN was more consistent with the first-order kinetic equation. [ABSTRACT FROM AUTHOR]

Fosthiazate is a common insecticide for root‐knot nematode control, but it has a short shelf life and is prone to decomposition. In order to improve the stability and prolong the release time, this experiment used the ionic gel method to cross‐link chitosan with sodium tripolyphosphate and added nano‐silica sol to prepare microcapsules suspensions. The optimal preparation parameters for the preparation of chitosan/sodium tripolyphosphate@nano‐silica sol microcapsulated suspensions were optimized by single factor experiments and response surface analysis, and the encapsulation efficiency reached 61.3%. The highest control effect in greenhouse pots can reach 84.1%, and the optimal concentration was 2 g/m2 mixed with soil, which increased stem length, root length and fresh weight by 81.1%, 47.7% and 62.5%. The study showed that the microcapsules of chitosan cross‐linked with sodium tripolyphosphate and added with nano‐silica sol could significantly prolong the release of Fosthiazate, which also provided a positive effect on soybean cyst nematode control. [ABSTRACT FROM AUTHOR]

Herein, we report a stimuli-responsive hydrogel with inhibitory activity against Escherichia coli prepared by chemical crosslinking of carboxymethyl chitosan (CMCs) and hydroxyethyl cellulose (HEC). The hydrogels were prepared by esterification of chitosan (Cs) with monochloroacetic acid to produce CMCs which were then chemically crosslinked to HEC using citric acid as the crosslinking agent. To impart a stimuli responsiveness property to the hydrogels, polydiacetylene-zinc oxide (PDA-ZnO) nanosheets were synthesized in situ during the crosslinking reaction followed by photopolymerization of the resultant composite. To achieve this, ZnO was anchored on carboxylic groups in 10,12-pentacosadiynoic acid (PCDA) layers to restrict the movement of the alkyl portion of PCDA during crosslinking CMCs and HEC hydrogels. This was followed by irradiating the composite with UV radiation to photopolymerize the PCDA to PDA within the hydrogel matrix so as to impart thermal and pH responsiveness to the hydrogel. From the results obtained, the prepared hydrogel had a pH-dependent swelling capacity as it absorbed more water in acidic media as compared to basic media. The incorporation of PDA-ZnO resulted in a thermochromic composite responsive to pH evidenced by a visible colour transition from pale purple to pale pink. Upon swelling, PDA-ZnO-CMCs-HEC hydrogels had significant inhibitory activity against E. coli attributed to the slow release of the ZnO nanoparticles as compared to CMCs-HEC hydrogels. In conclusion, the developed hydrogel was found to have stimuli-responsive properties and inhibitory activity against E. coli attributed to zinc nanoparticles. [ABSTRACT FROM AUTHOR]

Laterite soil is one of natural resources in East Kotawaringin regency, Central Kalimantan, Indonesia, which contains high element of Fe. Fe is one of micronutrients that is needed for plant in slight amount. This study aims to determine the effect of chitosan composition and composition of zeolite : laterite on the release of Fe activities from synthesized fertilizers result. Laterite is characterized by using XRF and XRD. Slow release iron fertilizer is synthesized by eliciting laterite to zeolite matrix. Then, It is stirred into chitosan gel with concentration of 2, 2.6, and 2.8 % for 30 minutes. After Zeolite - laterite - chitosan has been homogenized, then it is dropped into 0.4 M NaOH to form beads. Then testing the release of Fe with the batch method in distilled water. The result showed that the laterite soil is amorphous form, and Fe content reached 80.25 % . The higher the concentration of chitosan which is used , then more Fe is released from fertilizer. Whereas if the amount of zeolite is greater, the slower the release of Fe will be.

Adding fragrances to the wallpaper can optimize our living environment and office environment. However, the poor adhesion and rapid release of fragrances on wallpapers have limited their application. In this study, vanillin was encapsulated in particles based on chitosan and poly(lactic‐co‐glycolic acid), thereby achieving a slow release of the fragrance. In addition, due to the addition of chitosan, the adhesion of the fragrance on the wallpaper was enhanced, and the wallpaper was given antibacterial properties. [ABSTRACT FROM AUTHOR]

Biocomposites comprising acidified chitosan (CTS) encapsulated in partially cross-linked natural rubber (NR) matrices (CTS-e-NR) were prepared and characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FE-SEM). The results of FT-IR, TGA and FE-SEM revealed that CTS was merely encapsulated within partially cross-linked natural rubber, and no chemical interaction was observed between CTS and NR. Soil burial biodegradation studies indicated that CTS-e-NR was degraded beyond any doubt, and weight loss of 48.98% was observed within 8 months. The release behaviour of CTS-e-NR was investigated in distilled water, where the naphthols (pesticide precursors) 1-hydroxynaphthalene (1-N), 2-hydroxynaphthalene (2-N), 1,4-dihydroxynaphthalene (1,4-N) and 2,6-dihydroxynaphthalene (2,6-N) were used as model pesticides. The percentage released in the first 24 h was found to be 7.38, 4.39, 2.96 and 6.95%, while 62.69, 60.64, 22.68 and 40.985% was released at the 35th day, for 1-N, 2-N, 1,4-N and 2,6-N, respectively. The release of naphthols followed non-Fickian diffusion: the combination of both polymer erosion and diffusion release mechanisms. In addition, the release behaviour was found to be consistently controlled and prolonged over a period of 35 days. Therefore, CTS-e-NR is strongly recommended for the controlled-release application of real pesticides. [ABSTRACT FROM AUTHOR]

We synthesized chitosan and modified same by blending with starch, crosslinking the matrices with sodium tripolyphosphate (TPP) and encapsulation with the drug chlorpheniramine maleate (CPM). These microparticles were characterized by FTIR, TGA, and SEM techniques. The amounts of CPM released from the microparticles generally decreased for the TPP-crosslinked beads but increased as the starch composition increased. Their release rates were best described by zero-order kinetics while their release mechanisms followed less-Fickian diffusional release. Our findings show that both the uncrosslinked and crosslinked chitosan-starch beads are promising carriers for the slow release of CPM. [ABSTRACT FROM AUTHOR]

Cellulose–chitosan films were prepared using a physical method in which cellulose and chitosan were separately dissolved via freeze thawing in LiOH/urea and mixed in different proportions, the resulting films being cast and regenerated in water/ethanol. X-ray diffraction and Fourier transform infrared spectroscopy (FT-IR) spectroscopy verified the composition changes in the nanocomposites due to different mixing ratios between the polymers. Tensile stress–strain measurements indicated that the mechanical performance of the cellulose–chitosan nanocomposites slightly worsened with increasing chitosan content compared with that of films comprising cellulose alone. Field emission scanning electron microscopy revealed the spontaneous formation of nanofibers in the films; these nanofibers were subsequently ordered into lamellar structures. Water uptake and microscopy analysis of film thickness changes indicated that the swelling dramatically increased at lower pH and with increasing chitosan content, this being ascribed to the Gibbs–Donnan effect. Slow material loss appeared at acidic pH, as indicated by a loss of weight, and quantitative FT-IR analysis confirmed that chitosan was the main component released. A sample containing 75% chitosan reached a maximum swelling ratio and weight loss of 1500% and 55 wt%, respectively, after 12 h at pH 3. The study presents a novel way of preparing pH-responsive cellulose–chitosan nanocomposites with slow-release characteristics using an environmentally friendly procedure and without any chemical reactions. [ABSTRACT FROM AUTHOR]

Background: Recent advances in nanotechnology-based drug delivery system have been shown to improve either antibacterial efficacy or pharmacokinetics behavior.The aim of this study was to design a rifampin nanoparticle (RIF-NP) which has a high loading capacity with the slow release profile. Material and Methods: The designed chitosan/gelatin/lecithin (Chg/L) RIF-NPs were prepared by multilamellar vesicle. Thereafter, the particle size, zeta potential, morphology, and release rate were investigated. To optimize the loading capacity and release profiles, different concentrations of lecithin were used. Results: Our results showed a correlation of lecithin concentration with size, zeta potential, and loading capacity of RIF-NPs. Increases in lecithin concentration (0.2–2.0 g) could cause a significant size reduction in NPs (250–150 nm); the amount of zeta potential (from 14 to 49 mV;P < 0.05) and loading capacity increases from 8% to 20% (P < 0.05). Designed NPs had slow drug release profile which was influenced by pH and lecithin concentration. The cumulative percentage of RIF released at pH 7.4 was approximately 93% up to 12 h. In overall, release profile was better than standard drug, even in various pH conditions (pH = 1, 3.4, and 7.4). The Chg/L-RIF NPs may be considered as a promising drug nanocarrier. Conclusions: These NPs release RIF in slow and constant rate, which effectively might eliminate the bacilli and prevent the formation of RIF-resistant bacilli.

Highlights • A plasma method to produce zein-coated chitosan films as a promising delivery system. • The plasma treatment provided zein-coated films a more compact interface structure. • Chitosan/drug films coated with zein showed sustained release of water-soluble drug. • Zein-coated films with cold plasma treatment exhibited a slower release property. Abstract Chitosan-based films with zein coatings were prepared in order to modify the drug release properties. The adhesion of zein layers to the films was ensured via a cold plasma treatment. Using ciprofloxacin hydrochloride as model, the effect of cold plasma on the functional properties and structures was evaluated. The results suggest that the encapsulation efficiency, chemical composition and crystal type of ciprofloxacin hydrochloride in chitosan/drug films were not altered by cold plasma treatment, while the wettability and surface free energy displayed a notable increase. After being coated with zein, the chitosan interacted with the zein through hydrogen bonding and electrostatic interactions. The burst release phenomenon of the chitosan/drug films was prevented by the zein coating. Furthermore, the plasma treatment provided the coated film with a slower release rate within 24 h, from 72.8% to 49.3%. The enhanced coating thickness and the more compact interface structure were responsible for this improvement. [ABSTRACT FROM AUTHOR]

Background: Recent advances in nanotechnology-based drug delivery system have been shown to improve either antibacterial efficacy or pharmacokinetics behavior. The aim of this study was to design a rifampin nanoparticle (RIF-NP) which has a high loading capacity with the slow release profile. Material and Methods: The designed chitosan/gelatin/lecithin (Chg/L) RIF-NPs were prepared by multilamellar vesicle. Thereafter, the particle size, zeta potential, morphology, and release rate were investigated. To optimize the loading capacity and release profiles, different concentrations of lecithin were used. Results: Our results showed a correlation of lecithin concentration with size, zeta potential, and loading capacity of RIF-NPs. Increases in lecithin concentration (0.2-2.0 g) could cause a significant size reduction in NPs (250-150 nm); the amount of zeta potential (from 14 to 49 mV; P < 0.05) and loading capacity increases from 8% to 20% (P < 0.05). Designed NPs had slow drug release profile which was influenced by pH and lecithin concentration. The cumulative percentage of RIF released at pH 7.4 was approximately 93% up to 12 h. In overall, release profile was better than standard drug, even in various pH conditions (pH = 1, 3.4, and 7.4). The Chg/L-RIF NPs may be considered as a promising drug nanocarrier. Conclusions: These NPs release RIF in slow and constant rate, which effectively might eliminate the bacilli and prevent the formation of RIF-resistant bacilli. [ABSTRACT FROM AUTHOR]

ABSTRACT The sustained release capsules are pharmaceutical dosage form used for the treatment of chronic rather than acute diseases and are useful because of its convenience and less side effects. This work describes an attempt to formulate indomethacin sustained release capsule using indomethacin covalently linked to chitosan. Chitosan was prepared by alkaline -N-deacetylation of chitin, which was isolated from the shells of local shrimps. The yield of chitosan was found to be 80%. This polymer was found to be white crystal, odorless and the IR spectroscopy of it was similar to a standard reference. Chitosan has been covalently linked to indomethacin and the ratio of drug to polymer was found to be 5:1. The chemical interaction between the drug and the polymer was proved by IR studies. In vitro release at different pH were performed and the release of indomethacin in the prepared sustained release capsule were tested and compared with conventional indomethacin capsule INDOMIN-25mg, and a commercial sustained release capsule INDO-75-SR. The release of indomethacin in our product was completed within 12 hours, while the conventional INDOMIN capsule and commercial INDO-75-SR capsule released within 2.5 and 5 hours respectively. In conclusion a cheap, locally made chitosan can be used in formulation of sustained release capsules by covalently linked to drugs containing carboxyl group (like indomethacin) or can be modified to have a carboxyl group.

Abstract: O-naphthylacetyl chitosan (NA-chitosan) was first prepared via protecting the amino groups with phthalic anhydride, followed by reaction with 1-naphthylacetyl chloride. The intermediates were hydrolyzed with anhydrous hydrazine to obtain final product. The derivatives of each step were characterized with Fourier transform infrared spectroscopy (FT-IR) and 13C solid state nuclear magnetic resonance (NMR). Results showed NA-chitosan had both naphthylacetyl and amino groups in the main chain of the polysaccharide. Elemental analysis showed that the substitution degree of hydroxyl was 0.4. Thermogravimetric analysis (TGA, DTG) of NA-chitosan was observed with much lower decomposition peak at 283°C than that of chitosan at 300°C. The release of 1-naphthylacetic acid was dependent on both pH values and the medium temperature, and at pH 12.0, 60°C the release period could last for 55days. [Copyright &y& Elsevier]

Abstract: A double-coated slow-release NPK compound fertilizer with superabsorbent and water-retention was prepared by crosslinked poly(acrylic acid)/diatomite – containing urea (the outer coating), chitosan (the inner coating), and water-soluble granular fertilizer NPK (the core). The effects of the amount of crosslinker, initiator, degree of neutralization of acrylic acid, initial monomer and diatomite concentration on water absorbency were investigated and optimized. The water absorbency of the product was 75 times its own weight if it was allowed to swell in tap water at room temperature for 2h. Atomic absorption spectrophotometer and element analysis results showed that the product contained 8.47% potassium (shown by K2O), 8.51% phosphorus (shown by P2O5), and 15.77% nitrogen. We also investigated the water-retention property of the product and the slow release behavior of N, P and K in the product. This product with excellent slow release and water-retention capacity, being nontoxic in soil and environment-friendly, could be especially useful in agricultural and horticultural applications. [Copyright &y& Elsevier]

The impact of polymer-based slow-release urea formulations on soil microbial N dynamics in potatoes has been sparingly deciphered. The present study investigated the effect of a biodegradable nano-polymer urea formulation on soil enzymatic activities and microflora involved in the N cycling of potato (Solanum tuberosum L.). The nano-chitosan-urea composite (NCUC) treatment significantly increased the soil dehydrogenase activity, organic carbon content and available potassium compared to the conventional urea (CU) treatment. The soil ammonical nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N) contents and urease activity were significantly decreased in the NCUC-amended soil. The slow urea hydrolysis rate led to low concentrations of NH4+-N and NO3−-N in the tested potato soil. Furthermore, these results corroborate the low count of ammonia oxidizer and nitrate reducer populations. Quantitative PCR (q-PCR) studies revealed that the relative abundance of eubacterial (AOB) and archaeal ammonia-oxidizing (AOA) populations was reduced in the NCUC-treated soil compared to CU. The abundance of AOA was particularly lower than AOB, probably due to the more neutral and alkaline conditions of the tested soil. Our results suggest that the biodegradable polymer urea composite had a significant effect on the microbiota associated with soil N dynamics. Therefore, the developed NCUC could be used as a slow N-release fertilizer for enhanced growth and crop yields of potato. [ABSTRACT FROM AUTHOR]

(2-((1-(4-chlorophenyl)-1H-pyrazol-3-yl)oxy)-N-(3,4-dichlorophenyl)-propanamide) is a new oil-soluble compound with good fungicidal activity against Rhizoctonia solani. Chitosan oligosaccharide (COS) is the depolymerization product of chitosan and can be developed into biological pesticides, growth regulators, and fertilizers due to its various bioactivities. COS is an oligomer of β- (1 → 4)-linked d –glucosamine and can be taken as a polyamine. In this study, microcapsules were prepared by interfacial polymerization of oil-soluble methylene diphenyl diisocyanate and water-soluble COS. The effects of several key preparation parameters, e.g., emulsifier dosage, agitation rate during emulsification, and core/shell ratio, on properties of the microcapsules such as the encapsulation efficiency, particle size, and size distribution were investigated. The microcapsules were characterized by infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy, etc., and the encapsulation efficiency and release behaviors were investigated. The results show that the microcapsules have a smooth surface and 93.3% of encapsulation efficiency. The microcapsules showed slow-release behavior following a first-order kinetic equation, and the accumulative release rates of the microcapsules with core/shell mass ratios of 8.0/4.0, 8.0/5.0, and 8.0/6.0, were 95.5%, 91.4%, and 90.1%, respectively, on day 30. Due to many high biological activities, biodegradability, and the pure nature of COS, microcapsules formed from COS are promising for applications in controlled release of pesticides, growth regulators, and fertilizer. [ABSTRACT FROM AUTHOR]

Chitosan (CTS) film was prepared by solution casting technique and characterized by means of Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM). Besides swelling index, the CTS film was investigated as a slow-release matrix for 1- and 2-naphthol (pesticide precursors) under different pH conditions. Swelling index of the CTS film was determined in different pH conditions i.e. pH 2.59, 6.84 (distilled water) and 11.02. The swelling order was found; pH 2.59 > 6.84 > 11.02. Similarly, the slow-release study was carried out at pH 2.59, 6.84 and 11.02. Over all, the release amount was found higher in acidic medium followed by neutral and basic medium. This behaviour might be due to higher swelling and dissolution of CTS film in acidic medium whereas in neutral and basic medium CTS film swells moderately. [ABSTRACT FROM AUTHOR]