Microcapsules Research Articles

Preparation and property of epoxy resins-penetrated aligned carbon nanotube bundle hybrid microcapsules for self-healing polymers

The epoxy resins-penetrated aligned carbon nanotube bundle (ACNTsB) hybrid system (epoxy@ACNTsB) was prepared by soaking ACNTsB in the acetone solution of epoxy resins. Epoxy@ACNTsB was encapsulated in aqueous solution containing an amine curing agent to prepare hybrid microcapsules (MCs). The structure and morphology of MCs were characterized by Fourier transform infrared spectroscopy, scanning electronic microscopy, transmission electron microscopy, and laser scanning confocal microscopy. The thermal properties of MCs were carried out by differential scanning calorimetry and thermogravimetric analysis. The solvent resistance of MCs in acetone was also investigated. The results show that MCs exhibit high initial decomposition of temperatures (266°C). The content of epoxy resin in MCs is about 74% and the polymer film thickness of MCs is from 1 to 2 μm. MCs show high thermal and chemical stability below 200°C and excellent solvent resistance. MCs embedded in cyanate ester (CE) resins can significantly toughen the matrix. The fracture MCs can release the epoxy resins under heating condition, and the released epoxy resins can react with the reactive –OCN group/triazine rings in the CE matrix to rebond the crack surfaces. When the temperature schedule of 100°C/1 h + 200°C/2 h is applied, 10–15 wt% MCs can recover from 82.7% to 99.8% of the original fracture toughness of CE matrix.

Dual-responsive colloidal microcapsules based on host-guest interaction on solid templates

Colloidal microcapsules (MCs) have received considerable attention in the fields of microencapsulation, drug delivery as well as microreactors due to their unique nanoparticles-composed structure. In this study, dual-responsive colloidal MCs based on host-guest interaction were successfully fabricated via a layer-by-layer assembly method on sacrificial solid templates. Ferrocene-modified polyethylenimine (PEI-Fc) and cyclodextrin-modified polystyrene nanoparticles (PS-CD NPs) were used as building blocks for assembly. The colloidal MCs could be disassembled into nano-components upon addition of competitive adamantane (Ad) molecules or in the solution with a pH lower than 4.

AFM Investigation of Liquid-Filled Polymer Microcapsules Elasticity.

Elasticity of polymer microcapsules (MCs) filled with a liquid fluorinated core is studied by atomic force microscopy (AFM). Accurately characterized spherical tips are employed to obtain the Young's moduli of MCs having four different shell thicknesses. We show that those moduli are effective ones because the samples are composites. The strong decrease of the effective MC elasticity (from 3.0 to 0.1 GPa) as the shell thickness decreases (from 200 to 10 nm) is analyzed using a novel numerical approach. This model describes the evolution of the elasticity of a coated half-space according to the contact radius, the thickness of the film, and the elastic moduli of bulk materials. This numerical model is consistent with the experimental data and allows simulating the elastic behavior of MCs at high frequencies (5 MHz). While the quasi-static elasticity of the MCs is found to be very dependent on the shell thickness, the high frequency (5 MHz) elastic behavior of the core leads to a stable behavior of the MCs (from 2.5 to 3 GPa according to the shell thickness). Finally, the effect of thermal annealing on the MCs elasticity is investigated. The Young's modulus is found to decrease because of the reduction of the shell thickness due to the loss of the polymer.

Chemically stable polyphenylene ether microcapsules prepared using a facile method for the self‐healing of polymers

AbstractChemically stable polyphenylene ether (PPO) microcapsules (MCs) filled with epoxy resins (PPO‐EP MCs) were prepared using low‐molecular‐weight PPO with vinyl end‐groups as shell wall and epoxy resins as core material using an oil‐in‐water emulsion solvent evaporation method. This method for synthesizing MCs with PPO shell walls is simple, convenient and novel, which can avoid the influence of processing parameters on the chemical stability of the epoxy resin core material. The resulting PPO‐EP MCs exhibit good chemical stability below 255 °C mainly owing to the absence of a polymerization catalyst of the epoxy resins. The initial thermal decomposition temperature of the MCs is about 275 °C. The MCs were embedded in a 4,4′‐bismaleimidodiphenylmethane/O,O′‐diallylbisphenol A (BMI/BA) thermosetting resin system. When processed at high temperature (up to 220 °C), the microencapsulated epoxy resins could be released from the fractured MCs to matrix crack surfaces and bond the crack surfaces. An amount of 8 wt% MCs restored 91 and 112% of the original fracture toughness of the BMI/BA matrix when heated at 220 °C/2 h and 80 °C/1 h + 220 °C/2 h, respectively. The MCs only slightly decreased the thermal property of the matrix. © 2016 Society of Chemical Industry

Characterization of structure and air permeability of aromatherapic terry textile

Purpose – The purpose of this paper is to investigate the physical properties of smart aromatherapic ramie/cotton terry fabrics containing microcapsules (MC) with essential Eucalyptus oil. Design/methodology/approach – Terry fabrics are manufactured by changing the weft density. The air permeability is determined for grey and microencapsulated textile. The factorial designs are made. For informative experiment the linear type of regression is analysed. Development of physical properties of microencapsulated terry fabrics is discussed. Findings – The air permeability of aromatherapic terry fabrics is determined. All statistical analysis is performed. Appropriate conclusions about the influence of fabric’s structure and microencapsulating process on terry fabric quality are made. Originality/value – To date there are no investigations concerning terry textiles with fragrance MC. This study developed analysis and empiric mathematical equations suitable for evaluating and designing terry fabrics with the air permeability required. Assessment of the influence of fabric’s weft density and binder concentration for the air permeability of terry textile is proposed.

Biodegradation of tetrabromobisphenol-A in sludge-amended soil

This study investigated the degradation of tetrabromobisphenol-A (TBBPA) and changes in the bacterial community in sludge-amended soil. The results indicated that TBBPA degradation was enhanced by spent mushroom compost (SMC), enzyme extract (EE) and extract-containing microcapsule (MC) in soil–sludge mixtures, with SMC showing a greater TBBPA degradation rate than the other additives. The TBBPA degradation rates were enhanced with SMC at the second and third additions. The bacterial composition differed in the soil–sludge mixtures with and without SMC. Bacillus, Flavobacterium, Geobacter, Mycobacterium, Pseudomonas, Rhodococcus, Sphingomonas and Streptococcus were major bacterial communities in TBBPA degradation in the soil–sludge mixtures.

X-ray imaging of gold nanoparticle loaded alginate microcapsules

Event Abstract Back to Event X-ray imaging of gold nanoparticle loaded alginate microcapsules Fengxiang Qie1, 2, Alberto Astolfo3, Astrid Kibleur3*, Xiaojuan Hao1, Tianwei Tan2* and Timothy Hughes1 1 CSIRO, Manufacturing, Australia 2 Beijing University of Chemical Technology, Beijing Key Lab of Bioprocess, China 3 Australian Synchrotron, Australia Introduction: Cell based therapy has the potential to treat a wide range of diseases. One potential solution to enable immuno-isolation of the transplanted cells is to encapsulate the cells in alginate microcapsules (MCs). The aim of this project is to develop a non-invasive and simple technique that permits the tracking of the position and integrity of the MCs when placed in laboratory animals. Information obtained from tracking the MCs will help to guide best practice as encapsulated cells are being contemplated for clinical therapies, for example, for treatment of insulin-dependent diabetes. Materials and Methods: Gold nanoparticles (AuNPs) were prepared by the citrate reduction method [1]. Poly((2-methacryloyloxy)ethyl trimethyl ammonium chloride), a positively charged polymer, and poly (ethylene glycol), a non-charged polymer were prepared via RAFT polymerisation and coated onto the AuNPs as prepared, i.e. containing dithioester end groups. Alternatively, the RAFT end groups were cleaved off affording the corresponding thiol-capped polymers which were then coated onto AuNPs. These polymer-modified AuNPs were then encapsulated (blended) in alginate MCs (~500 μm) [2].Alternatively the polymer-modified AuNPs were coated onto preformed alginate MCs via electrostatic self-assembly [3]. The cytotoxicity and mechanical stability of the AuNPs containing MCs were assessed. The attenuation coefficients were measured for both blended and coated AuNPs MCs. Finally, both the blended and coated AuNPs containing MCs were implanted into cadaver mice and X-ray imaged in order to test their ability to track alginate MCs within the body by x-ray imaging. Results and Discussion: Both blended and coated AuNP-MC composites were found to have low cytotoxicity. In addition, they were found to be mechanically stable under shaking at 37oC for more than 1 month with no measurable loss of the contrast agent. The results of our preliminary experiments conducted at the IMBL (Australian Synchrotron, Melbourne, Australia) and at SYRMEP (Elettra, Trieste, Italy) beamlines have shown that gold nanoparticles (AuNPs) are an attractive solution for MCs tracking if combined with x-ray computed tomography (CT). The AuNPs coated MCs gave a higher X-ray attenuation than the corresponding blended AuNPs-MCs at the same gold concentration due to their higher localised Au concentration. Figure1: Preparation of both blended and coated AuNPs containing alginate MCs Conclusions: X-ray imaging of encapsulated AuNPs modified with RAFT polymers is a promising methodology to track alginate MCs in situ that may be used as drug delivery devices or to encapsulate cells for cell therapy (eg. diabetes treatment). MCs decorated with a AuNPs coating were more readily identified than AuNPs blended into MCs at the same gold concentration due to the distinctive circular contrast of the coated MCs potentially enabling them to be used for in vivo tracking experiments over multiple time points. We acknowledge the travel funding provided by the International Synchrotron Access Program (ISAP) managed by the Australian Synchrotron and funded by the Australian Government. The authors thank the Chinese Scholarship Council (CSC) and CSIRO for the financial support to Fengxiang Qie

Microencapsulated Garcinia kola and Hunteria umbellata Seeds Aqueous Extracts Part 1: Effect of microencapsulation process

Objective: This study investigates microcapsulated aqueous extracts of Garcinia kola (GK) and Hunteria umbellata (HU) seeds. Method: Extracts obtained after maceration of dried powdered seeds were prepared as microcapsules with chitosan-alginate by counterion coacervation method. Microcapsules were characterized using differential scanning calorimetry (DSC), x-ray diffractometry (XRD) and fourier transform infrared (FTIR) spectroscopy. In vitro release studies were carried out at pH 1.2 for 2 h and 6.8 for a further 10 h. Results : Between 20 and 50% extract release occurred from microcapsules after 2 h while conventional tablets released 100% after 1 h at simulated gastric pH. At pH 6.8, >80% of extract was released from microcapsules after 6 h. DSC revealed the presence of complex materials. XRD and FTIR showed stable character of the plant extracts within the microcapsules. Conclusion: Controlled release of aqueous extracts derived from these plants was achieved by microencapsulation and therefore can be developed as suitable delivery devices.

Core–shell microcapsules of solid lipid nanoparticles and mesoporous silica for enhanced oral delivery of curcumin

Newly designed microcapsules (MC) combining a core of solid lipid nanoparticle (SLN) and a mesoporous silica shell have been developed and explored as oral delivery system of curcumin (CU). CU-loaded MC (MC-CU) are 2μm sized and have a mesoporous silica shell of 0.3μm thickness with a wormlike structure as characterized by small angle X-ray scattering (SAXS), nitrogen adsorption/desorption and transmission electron microscopy (TEM) measurements. It was found that SLN acts as reservoir of curcumin while the mesoporous shell insures the protection and the controlled release of the drug. MC-CU displayed a pH-dependent in vitro release profile with marked drug retention at pH 2.8. Neutral red uptake assay together with confocal laser scanning microscopy (CLSM) showed a good cell tolerance to MC-CU at relatively high concentration of inert materials. Besides, the cell-uptake test revealed that fluorescent-MC were well internalized into Caco-2 cells, confirming the possibility to use MC for gut cells targeting. These findings suggest that organic core-silica shell microcapsules are promising drug delivery systems with enhanced bioavailability for poorly soluble drugs.

Weed Control in Cotton by Combinations of Microencapsulated Acetochlor and Various Residual Herbicides Applied Preemergence

Residual herbicides are routinely recommended to aid in control of glyphosate-resistant (GR) Palmer amaranth in cotton. Acetochlor, a chloroacetamide herbicide, applied PRE, controls Palmer amaranth. A microencapsulated (ME) formulation of acetochlor is now registered for PRE application in cotton. Field research was conducted in North Carolina to evaluate cotton tolerance and Palmer amaranth control by acetochlor ME alone and in various combinations. Treatments, applied PRE, consisted of acetochlor ME, pendimethalin, or no herbicide arranged factorially with diuron, fluometuron, fomesafen, diuron plus fomesafen, and no herbicide. The PRE herbicides were followed by glufosinate applied twice POST and diuron plus MSMA directed at layby. Acetochlor ME was less injurious to cotton than pendimethalin. Acetochlor ME alone or in combination with other herbicides reduced early season cotton growth 5 to 8%, whereas pendimethalin alone or in combinations injured cotton 11 to 13%. Early season injury was transitory, and by 65 to 84 d after PRE treatment, injury was no longer noticeable. Before the first POST application of glufosinate, acetochlor ME and pendimethalin controlled Palmer amaranth 84 and 64%, respectively. Control by acetochlor ME was similar to control by diuron plus fomesafen and greater than control by diuron, fluometuron, or fomesafen alone. Greater than 90% control was obtained with acetochlor ME mixed with diuron or fomesafen. Palmer amaranth control was similar with acetochlor ME plus a full or reduced rate of fomesafen. Acetochlor ME controlled large crabgrass and goosegrass at 91 and 100% compared with control at 83 and 91%, respectively, by pendimethalin. Following glufosinate, applied twice POST, and diuron plus MSMA, at layby, 96 to 99% control was obtained late in the season by all treatments, and no differences among herbicide treatments were noted for cotton yield. This research demonstrated that acetochlor ME can be safely and effectively used in cotton weed management programs.

Mechanical behaviour of micro-capsules and their rupture under compression

Understanding the deformation of micro-capsules (MCs) and especially the mechanism of their rupture is of crucial importance for their performance in various applications. Mechanical instability can on the one hand be a failure mechanism, resulting in undesired release, but can on the other hand be used as a release trigger. In this work, finite element analysis together with nano-indentation experiments is applied to characterize the deformation of single filled MCs made of melamin–formaldehyde. The simulations reveal that the capsules undergo different deformation regimes: starting from linear elastic deformation, upon further compression the MCs yield and are plastically deformed. The final step is a strain hardening regime, where the maximum stress rapidly increases till the MCs rupture. Finally, we describe the MCs rupture mechanism obtained from numerical simulation and experimental results. We show that the axial and radial stresses cause significant thinning of the shell at the MC׳s equator, and that the circumferential stress leads to rupture along the meridians of the MC.

Microencapsulation of single-cell protein from various microalgae species

<p class="BasicParagraph" align="center"><strong>ABSTRACT</strong></p><p class="BasicParagraph" align="center"><strong> </strong></p><p class="Pa2">The objective of the research was to evaluate nutritional values of microencapsulated diet made from single cell protein of microalgae. Complete randomized design was applied using three different types of microalgae for inclusion trials i.e. (A) <em>Nannochloropsis </em>sp., (B) <em>Chlorella </em>sp., and (C) <em>Spirulina </em>sp. with five replications respectively. Microencapsulated diet was produced by a modification method based on thermal cross-linking with stable temperature. Phytoplankton was cultured in sea water for which fertilized by a modification of Walne and Guillard fertilizer. The results showed that the highest value of nutrition content was <em>Spirulina </em>sp. and the average composition of protein, crude lipid, carbohydrate, ash, nitrogen free extract, and water content was 34.80%, 0.30%, 18.53%, 20.09%, 26.29%, and 13.32%, respectively. Organoleptically, microcapsule showed that the color of capsule was dark green and smell fresh phytoplankton.</p><p class="Default"> </p>Keywords: microcapsule, single-cell protein, thermal cross-linking, microalgae, phytoplankton<br /><p class="BasicParagraph"> </p><p class="BasicParagraph"> </p><p class="BasicParagraph" align="center"><strong>ABSTRAK</strong></p><p class="BasicParagraph"><strong> </strong></p><p class="Pa2">Tujuan penelitian adalah mengevaluasi kandungan nutrisi pakan mikrokapsul protein sel tunggal (<em>single cell protein</em>) yang berasal dari berbagai jenis mikroalga (fitoplankton). Rancangan percobaan yang digunakan adalah rancangan acak lengkap, dengan perlakuan inklusi mikrokapsul dari jenis fitoplankton (A) <em>Nannochloropsis </em>sp., (B) <em>Chlorella </em>sp., dan (C) <em>Spirulina </em>sp., masing-masing diulang lima kali. Pembuatan mikrokapsul dilakukan dengan menggunakan modifikasi metode dasar <em>thermal cross-linking</em>, serta menerapkan teknik pengeringan suhu konstan. Proses pembuatan mikrokapsul protein diawali dengan kultur fitoplankton jenis <em>Nannochloropsis </em>sp., <em>Chlorella </em>sp., dan <em>Spirulina </em>sp. Kultur dilakukan di dalam laboratorium menggunakan media air laut dan modifikasi pupuk Walne dan Guillard. Hasil penelitian menunjukkan bahwa kandungan nutrisi tertinggi terdapat pada jenis mikrokapsul protein sel tunggal yang berasal dari <em>Spirulina </em>sp., dengan rata-rata komposisi kandungan protein 34,80%, lemak 0,30%, karbohidrat 18,53%, abu 20,09%, dan BETN 26,29%. Mikrokapsul berwarna hijau tua dan aroma fitoplankton segar.</p><p class="Default"> </p>Kata kunci: mikrokapsul, protein sel tunggal, <em>thermal cross-linking</em>, mikroalga, fitoplankton

Growth of Lactobacillus reuteri NCIMB 30242 during yogurt fermentation and bile salt hydrolysis activity in the product

The synthesis of bile salt hydrolase has been linked to the health benefit of Lactobacillus reuteri toward lowering blood cholesterol. The aim of this study was to examine the growth and bile salt hydrolysis activity (BSHA) of L. reuteri NCIMB 30242 during milk fermentation with a yogurt starter. There was little growth of L. reuteri during a 4-h co-fermentation with a yogurt culture, and an inoculation of 4.5 × 107 CFU.mL−1 was needed to obtain the 108 CFU.mL−1 target in the product. Enrichment of milk with sugars, minerals, or peptone-based ingredients did not improve growth of L. reuteri. Viable counts of L. reuteri above 1.5 × 108 CFU.mL−1 generated texture defects. Free and microencapsulated (ME) cultures were tested for BSHA in the yogurt drinks. L. reuteri cells which grew during the 4-h lactic fermentation had 40% less BSHA than L. reuteri added directly via the commercial culture. The BSHA of free cells was apparently three times higher than in the ME culture. This study adds data showing that the yogurt production process could affect the functionality of probiotic bacteria.

تخمین و ارزیابی ضریب نفوذ میکروکپسول های آلژینات-پروتئین آب پنیر حامل دی استیل و ارزیابی آن در شرایط مختلف دهانی

در این پژوهش میکروکپسول جدیدی تحت عنوان میکروکپسول آلژینات- پروتئین آب پنیر حامل دی استیل تهیه و خصوصیات آن تعیین گردید. رهایش دی استیل در شرایط شبیه سازی شده دهانی در سطوح مختلف بزاق به میکروکپسول (0:1، 1:4 و 1:8) و نیروهای برشی متفاوت (0، 50 و 100 معکوس ثانیه) مورد بررسی قرار گرفت و ضریب نفوذ با کمک معادله فیک تخمین زده شد. هدف اصلی این پژوهش توسعه مدلی به منظور پیش بینی فرآیند رهایش و نیز تخمین ضریب نفوذ از میکروکپسول جدید ابداعی بوده تا بتوان به کمک آن رهایش کنترل شده عطر و طعم در شرایط دهانی ایجاد نمود. نتایج این تحقیق نشان داد که مدل حاصله می تواند با ضریب همبستگی بالای 95 درصد رفتار رهایش را پیش بینی نموده و علاوه بر این مدل مذکور به خوبی قادر به تخمین میزان ضریب نفوذ می باشد. نتایج همچنین نشان داد که اعمال نیروی برشی بطور معناداری سبب افزایش ضریب نفوذ شده درحالیکه تغییر میزان بزاق تاثیر معناداری بر آن ندارد.

Uniform PEGylated PLGA Microcapsules with Embedded Fe3O4 Nanoparticles for US/MR Dual-Modality Imaging.

Well-designed agents for enhanced multimodal imaging have attracted great interests in recent years. In this work, we adopted a premix membrane emulsification (PME) method to prepare uniform PEGylated poly(lactic-co-glycolic acid) (PLGA) microcapsules (MCs) with superparamagnetic Fe3O4 nanoparticles (NPs) embedded in the shell (Fe3O4@PEG-PLGA MCs) for ultrasound (US)/magnetic resonance (MR) bimodal imaging. Compared to Fe3O4@PLGA MCs without PEGylation, Fe3O4@PEG-PLGA MCs could more stably and homogeneously disperse in physiological solutions. In vitro and in vivo trials demonstrated that Fe3O4@PEG-PLGA MCs (∼3.7 μm) with very narrow size distribution (PDI=0.03) could function as efficient dual-modality contrast agents to simultaneously enhance US and MR imaging performance greatly. In vitro cell toxicity and careful histological examinations illustrated no appreciable cytotoxicity and embolism of Fe3O4@PEG-PLGA MCs to mice even at high dose. The uniform composite MCs developed here can act as clinical bimodal contrast agents to improve hybrid US/MR imaging contrast, which is promising for accurate diagnosis and real-time monitoring of difficult and complicated diseases.

Osteogenic/angiogenic dual growth factor delivery microcapsules for regeneration of vascularized bone tissue.

Growth factors (GFs) are major biochemical cues for tissue regeneration. Herein, a novel dual GF delivery system is designed composed of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) and alginate microcapsules (MCs) via an electrodropping method. While bone morphogenetic protein (BMP)-2 is encapsulated in the PLGA NPs, vascular endothelial growth factor (VEGF) is included in the alginate MCs, where BMP-2-loaded PLGA NPs are entrapped together in the fabrication process. The initial loading efficiencies of BMP-2 and VEGF are 78% ± 3.6% and 43% ± 1.7%, respectively. When our dual GF-loaded MCs are assessed for in vitro osteogenesis of umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) on 2D and 3D environment, MCs contribute to much better UCB-MSCs osteogenesis as confirmed by von Kossa staining, immunofluorescence (osteocalcin, collagen 1), calcium content measurement, and osteogenic markers expression. In addition, when dual GF-encapsulated MCs are combined with collagen and then applied to 8 mm diameter rat calvarial defect model, the positive effects on vascularized bone regeneration are much more pronounced; micro computed tomography (CT) and histology analyses exhibit 82.3% bone healing coupled with 12.6% vessel occupied area. Put together, current study indicates a synergistic effect of BMP-2/VEGF and highlights the great potential of dual GF delivery modality (PLGA NPs-in-MC) for regeneration of vascularized bone.

Extraction of lanthanides by polysulfone microcapsules containing EHPNA. II. Coaxial microfluidic method

Controllable preparation of small-size polysulfone microcapsules (MC) containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA) by coaxial microfluidic method was focused on. N2 gas was used as continuous phase to disperse the polymer solution. The influence of polysulfone (PSF) content in the polymer solution and N2 gas flow rate on the structural properties and loading ratio of microcapsules was investigated. The mean diameter of prepared microcapsules was between 0.90 and 1.60 mm. Ultrasound method was adopted to import EHPNA into microcapsules. A very high extractant loading ratio of 6.21 g-EHPNA/g-PSF was achieved when the pore volume was 6.89 mL/g. The extraction performance was determined with lanthanides as the recovered components and with the prepared microcapsules as the separation agent. Close-packed microcapsules enjoyed a fast extraction kinetics. The maximum uptakes of La3+, Sm3+ and Er3+ were 3.02×10−4 mol/g, 8.05×10−4 mol/g and 5.58×10−4 mol/g, respectively. Microcapsules were reused seven times and showed very good stability. It is promising to apply the microcapsules into the extraction column and realize continuous operation.

The in vivo fate of nanoparticles and nanoparticle-loaded microcapsules after oral administration in mice: Evaluation of their potential for colon-specific delivery

Anti-cancer drug loaded-nanoparticles (NPs) or encapsulation of NPs in colon-targeted delivery systems shows potential for increasing the local drug concentration in the colon leading to improved treatment of colorectal cancer. To investigate the potential of the NP-based strategies for colon-specific delivery, two formulations, free Eudragit® NPs and enteric-coated NP-loaded chitosan–hypromellose microcapsules (MCs) were fluorescently-labelled and their tissue distribution in mice after oral administration was monitored by multispectral small animal imaging. The free NPs showed a shorter transit time throughout the mouse digestive tract than the MCs, with extensive excretion of NPs in faeces at 5h. Conversely, the MCs showed complete NP release in the lower region of the mouse small intestine at 8h post-administration. Overall, the encapsulation of NPs in MCs resulted in a higher colonic NP intensity from 8h to 24h post-administration compared to the free NPs, due to a NP ‘guarding’ effect of MCs during their transit along mouse gastrointestinal tract which decreased NP excretion in faeces. These imaging data revealed that this widely-utilised colon-targeting MC formulation lacked site-precision for releasing its NP load in the colon, but the increased residence time of the NPs in the lower gastrointestinal tract suggests that it is still useful for localised release of chemotherapeutics, compared to NP administration alone. In addition, both formulations resided in the stomach of mice at considerable concentrations over 24h. Thus, adhesion of NP- or MC-based oral delivery systems to gastric mucosa may be problematic for colon-specific delivery of the cargo to the colon and should be carefully investigated for a full evaluation of particulate delivery systems.

Leaching Behavior of Two Pendimethalin Formulations in a Soilless Growing Medium

Pendimethalin is commonly applied for PRE weed control in container nursery production. Field and laboratory trials were conducted to determine herbicide effectiveness and leaching of two pendimethalin formulations in pine bark, the primary component used in the growing medium of container-grown plants in the South. The microencapsulated (ME) formulation of pendimethalin gave lower control of southern crabgrass and leached deeper than the emulsifiable concentrate (EC) formulation in pine bark. The EC formulation controlled southern crabgrass 93% compared with only 70% with the ME formulation at 4.48 kg ai ha−1. After applying 3.4 kg ai ha−1pendimethalin and 17.8 cm of irrigation water, the ME formulation showed greater leaching into the 3- to 6- and 6- to 9-cm depths than the EC formulation on the basis of a southern crabgrass bioassay. Using a microwave extraction method, only 0.91 mg kg−1pendimethalin was found in the 3- to 6-cm pine bark depth compared with 4.0 mg kg−1for the ME formulation. Below the 6-cm depth, no pendimethalin was detected when the EC formulation was applied, but 0.5 ppm was found for the ME formulation. No pendimethalin was detected in effluent collected from irrigation water for the EC; however, 3.0 mg kg−1was collected from leachate for the ME formulation. Pendimethalin ME is leaching much deeper than the EC formulation in the pine bark profile, which results in lower weed control. This extensive leaching of ME formulation may be due to capsule movement with the irrigation water, combined with a delayed release of pendimethalin, which then binds to the pine bark much lower in the container profile.

Extraction of lanthanides by polysulfone microcapsules containing EHPNA. I. Piercing method

Since the conventional liquid-liquid extraction method suffered from a series of problems such as inefficiency of one stage extraction, vast device occupation and severe emulsification, we adopted microcapsule (MC) technique to change the former liquid-liquid extraction to liquid-solid extraction. Firstly, the piercing method was performed to prepare the empty polysulfone (PSF) microcapsules, which was easy to implement and control. Secondly, the ultrasonic approach was utilized to prepare the functional microcapsules containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (EHPNA). We focused on a key factor of the molar ratio of PSF over 1-Methyl-2-pyrrolidinone (NMP), attaining a loading ratio as high as 7.21 g-EHPNA/g-PSF. Thirdly, we examined the kinetics and thermodynamics of extraction. Kinetic results demonstrated that equilibrium was reached within two hours, with an extraction rate of Sm3+≈Er3+>La3+; Thermodynamic results showed that the extraction of lanthanides complied with the Langmuir law, with an extraction capacity of 0.25–0.30 mmol/g-microcapsule. Fourthly, stripping experiment indicated that three hours were required to accomplish equilibrium for La3+ and Sm3+ while longer hours for Er3+. Finally, seven extraction-stripping cyclic experiments were performed for three mixed elements, the results of which revealed that Sm3+ and Er3+ maintained constantly high extraction amount whilst La3+ leveled off at approximately 50%. This proposed polysulfone microcapsule containing EHPNA is suitable to be applied to extraction and concentration of rare earth metals.