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Controlled release formulations of Ruta essential oil obtained by ionic gelation were developed. The presence of rue essential oil in the alginate and chitosan capsules was evidenced by Fourier transform infrared spectroscopy and differential scanning calorimetry. Release studies revealed that in acidic conditions (pH 4.2), the CHS-REO particles reached a Sw of 240% (w/w) in 30 days and 101% (w/w) for ALG-REO particles, generating a RR of 23.7% for CHS-REO and 20.4% for ALG-REO. On the other hand, at pH 6.8 it favored the Sw for ALG-REO 840% (w/w) and therefore the RR (45.6%) and disfavored the Sw of CHS-REO generating low RR (16.9%). Encapsulated rue essential oil showed equal or superior nematicidal activity against the nematode Melodogyne ssp., compared to free oil and a synthetic nematicide such as Carbofuran, without having a phytotoxic effect on the plant. This study revealed that REO encapsulated in biopolymeric matrices can be used as new nematicide formulations. [ABSTRACT FROM AUTHOR]

Gonadotropin-releasing hormone (GnRH) agonists are peptides consisting of nine or ten amino acid residues. GnRH agonists have been applied in the therapy of sexual hormone disorders like prostate cancer, endometriosis, uterine myoma, central precious puberty, and in-vitro fertility. Treatment is achieved by continuous hormone intake and long-term agonists administration, which is usually associated with poor patient compliance. Because GnRH agonists that are administered with the parenteral route are broken down by peptidase, their half-life is short. As a result, developing sustained release for the drug delivery system is significant. Even though some drugs have been successfully delivered with long-acting release microspheres and approved by the Food and Drug Administration (FDA), some challenges remain. This review highlighted current approaches to encapsulate GnRH agonists into delivery systems and strategies encountered during the loading process. Moreover, the following sections provide strategies to improve the release profile, and animal and human studies were summarised. [ABSTRACT FROM AUTHOR]

Here, we have reported the influence of MMT and genipin in releasing curcumin from the Genipin crosslinked Chitosan/MMT nanoparticles, prepared by ionic gelation method. The nanoparticles were characterised using Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffractometry (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). Zeta potential and average diameter of the nanoparticles were found in the range 32-47 mV and 430-560 nm. Swelling and release of curcumin from the nanoparticles increased with the decrease in pH of the medium, MMT, and genipin content. Curcumin released from the nanoparticles reduced the viability of MCF-7 and Hep G2 cells as compared to untreated cells. The nanoparticles increased the level of reduced glutathione (GSH), superoxide dismutase (SOD), and catalase level in human PBMCs and decreased the level of Lipid peroxidation suggesting an enhanced protection against cellular damage. Lower pH and higher MMT concentration in the nanoparticles improved the mucoadhesive properties. [ABSTRACT FROM AUTHOR]

Purpose: To optimise the Eudragit/Surelease®-coated pH-sensitive pellets for controlled and target drug delivery to the colon tissue and to avoid frequent high dosing and associated side effects which restrict its use in the colorectal-cancer therapy. Methods: The pellets were prepared using extrusion-spheronisation technique. Box-Behnken and 32 full factorial designs were applied to optimise the process parameters [extruder sieve size, spheroniser-speed, and spheroniser-time] and the coating levels [%w/v of Eudragit S100/Eudragit-L100 and Surelease®], respectively, to achieve the smooth optimised size pellets with sustained drug delivery without prior drug release in upper gastrointestinal tract (GIT). Results: The design proposed the optimised batch by selecting independent variables at; extruder sieve size (X1 = 1 mm), spheroniser speed (X2 = 900 revolutions per minute, rpm), and spheroniser time (X3 = 15 min) to achieve pellet size of 0.96 mm, aspect ratio of 0.98, and roundness 97.42%. The 16%w/v coating strength of Surelease® and 13%w/v coating strength of Eudragit showed pH-dependent sustained release up to 22.35 h (t99%). The organ distribution study showed the absence of the drug in the upper part of GIT tissue and the presence of high level of capecitabine in the caecum and colon tissue. Thus, the presence of Eudragit coat prevent the release of drug in stomach and the inner Surelease® coat showed sustained drug release in the colon tissue. Conclusion: The study demonstrates the potential of optimised Eudragit/Surelease®-coated capecitabine-pellets for effective colon-targeted delivery system to avoid frequent high dosing and associated systemic side effects of drug. [ABSTRACT FROM AUTHOR]

A novel sequential processing approach to fabricate versatile fibres containing encapsulated materials is presented. It is based on developing highly porous fibres, to be filled with functional materials and coated with protective layers. Applicability of the approach to develop porous poly(methyl methacrylate) (PMMA) fibres with encapsulated antibacterial salts within a coating is demonstrated. The salt was introduced to the fibre via a sacrificial solvent. Desired solvent properties to ensure successful filling was discussed. The salt was encapsulated via spray coating. The coating characteristics were tuned via vapour treatment to facilitate controllable radial salt release. Large volume axial release was also achieved due to the axial pore connectivity. Compared to state-of-the-art methods to produce fibres with functional material inclusions such as emulsion electrospinning, the method presented herein, due to its sequential processing nature, offers greater freedom in material selection and thus broad applications of the fibres. [ABSTRACT FROM AUTHOR]

In this study, we describe the synthesis of an amine-modified acetalated dextran polymer, which is combined with heparin (HP) as the basis for a novel controlled release system. Dextran-amine (DEXAM) conjugates, synthesised using reductive amination, were incorporated into DEXAM/HP microspheres. HP binds to positively charged ammonium ions of the DEXAM conjugates, contributing to the structural integrity of the microspheres. Crystal violet (CV) was encapsulated inside DEXAM/HP microspheres as a model drug to test the system. Protamine with a high affinity for HP functioned as a trigger to release CV. DEXAM/HP microspheres were characterised by particle size, encapsulation efficiency, scanning electron microscope images, andin vitrorelease profile. Release of CV from microspheres varied with primary amine content of DEXAM conjugates, amount of HP, and concentration of protamine added. The system is considered for controlled delivery of agents without the necessity of chemical modification. [ABSTRACT FROM AUTHOR]

Chitosan films were loaded with NE nettle (Urtica dioica L.) extract (NE) at concentrations of 0, 0.5, 1 and 1.5%w/w in the free or nanoliposomal form to obtain active and nanoactive films, respectively. The antioxidant potential of the films containing NE-loaded nanoliposomes was decreased in comparison of free NE incorporated films. Diffusion of NE to soybean oil was enough to delay the induction of the oxidation of soybean oil stored for 60 days in contact with chitosan based films. Release studies indicated that the release rate of NE in 95% ethanol simulant significantly decreased by the nanoencapsulation of NE. The diffusion coefficient (D) for chitosan films containing 1.5%w/w of free and encapsulated NE at 25 °C was 18.80 and 3.68 × 10−7cm2 s−1, respectively. Moreover, the formation of nanoliposomes diminished the increasing effect of temperature on the release rate as when storage temperature increased from 4 °C to 40 °C. [ABSTRACT FROM AUTHOR]

In this study, a micellar delivery system with an amphiphilic diblock copolymer of poly (ethylene glycol) and poly (ɛ-caprolactone) was synthesised and used to incorporate hydrophobic clove essential oil (CEO). To determine an optimal delivery system, the effects of the copolymer’s hydrophobic block length and the CEO-loading content on the encapsulation of CEO were investigated. Percentages of entrapment efficiency (%EE), CEO loading (%CEO), andin vitrorelease profiles were determined. The size, size distribution, zeta potential, and morphology of the obtained micelles were determined by DLS, FE-SEM, and TEM. The %EE, %CEO, andin vitrorelease profiles of CEO incorporated in micelles were analysed by HPLC. The study revealed a sustained release profile of CEO from CEO-loaded micelles. The results indicate the successful formulation of CEO-loaded PEG-b-PCL micelle nanoparticles. It is suggested that this micelle system has considerably potential applications in the sustained release of CEO in intravascular drug delivery. [ABSTRACT FROM PUBLISHER]

Liposomes are biocompatible, biodegradable, controlled delivery systems with the ability to encapsulate both lipophilic and hydrophilic compounds, including metal ions. Liposome encapsulated Ag+(lipo-Ag+), prepared by reverse-phase evaporation, was used as a controlled delivery system againstCandida albicans. Characterisation of the lipo-Ag+indicated that the multilamellar vesicles with diameters ranging between ≈ 0.5 and 5.0 μm showed potential as a controlled delivery system to consistently deliver Ag+toC. albicans. Results from inductively coupled plasma (ICP) analysis showed higher association of cell bound Ag+at 15 mins post exposure when compared to unencapsulated Ag+. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicate detrimental effects of Ag+onC. albicanscell structure. These effects along with the ICP results also correlate with previously reported time kill experiment observations. [ABSTRACT FROM AUTHOR]

Melatonin loaded poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles and microparticles in the diameter of ∼200 nm and 3.5 μm, respectively, were prepared by emulsion–diffusion–evaporation method. Melatonin entrapment into the particles was significantly improved with the addition of 0.2% (w/v) melatonin into the aqueous phase and encapsulation efficiencies were found as 14 and 27% for nanoparticles and microparticles, respectively. At the end of 40 days, ∼70% of melatonin was released from both of particles, with high burst release. Both blank and melatonin loaded PLGA nanoparticles caused toxic effect on the MG-63 cells due to their uptake by the cells. However, when 0.05 mg microparticle that is carrying ∼1.7 μg melatonin was added to the cm2of culture, inhibitory effect of melatonin on the cells were obviously observed. The results would provide an expectation about the usage of melatonin as an adjunct to the routine chemotherapy of osteosarcoma by encapsulating it into a polymeric carrier system. [ABSTRACT FROM PUBLISHER]

Microencapsulation is finding increasing applications in cosmetics and personal care markets. This article provides an overall discussion on encapsulation of cosmetically active ingredients and encapsulation techniques for cosmetic and personal care products for topical applications. Some of the challenges are identified and critical aspects and future perspectives are addressed. Many cosmetics and personal care products contain biologically active substances that require encapsulation for increased stability of the active materials. The topical and transdermal delivery of active cosmetic ingredients requires effective, controlled and safe means of reaching the target site within the skin. Preservation of the active ingredients is also essential during formulation, storage and application of the final cosmetic product. Microencapsulation offers an ideal and unique carrier system for cosmetic active ingredients, as it has the potential to respond to all these requirements. The encapsulated agent can be released by several mechanisms, such as mechanical action, heat, diffusion, pH, biodegradation and dissolution. The selection of the encapsulation technique and shell material depends on the final application of the product, considering physical and chemical stability, concentration, required particle size, release mechanism and manufacturing costs. [ABSTRACT FROM PUBLISHER]

The aim of this research was to evaluate the potential of water-in-oil-in-water (w/o/w) and solid-in-oil-in-water (s/o/w) emulsification techniques to prepare the altered collagen type II peptide AP268-270 (ACTP)-loaded poly(lactic-co-glycolic acid) (PLGA) microspheres to make ACTP more convenient as an rheumatoid arthritis treatment. Microspheres produced by the s/o/w method had higher drug encapsulation efficiency (69.7–79.8%) than those prepared by the w/o/w method (21.8–39.3%).In vitrodrug release was influenced by the microencapsulation technique, molecular weight, and composition of the polymer. After intramuscular injection of the optimal formulation to Lewis rats, the concentration of ACTP peptide in serum reached its maximum level on day 3 and then remained nearly stable for approximately 4 weeks. In a collagen-induced arthritis rat model, a single intramuscular injection of ACTP-loaded PLGA microspheres had comparable efficacy to the intravenous injection of ACTP peptide solution once every other day. [ABSTRACT FROM PUBLISHER]

Growth factor-loaded fluorescent alginate microspheres, which can realise sustained growth factor release and fluorescence imaging, were synthesised by in situ formation of ZnO quantum dots (QDs) and covalent graft of 4-(1-pyrenyl) butyric acid (PBA). BSA was chosen as a growth factor model protein to study the release kinetic of growth factors from alginate microspheres. The microsphere size and fluorescent properties were also investigated. Investigations of cell culture were used for evaluating biocompatibility of BSA-loaded fluorescent microspheres and fluorescence imaging property of ZnO QDs and PBA-grafted sodium alginate from the microspheres. The results show that they have good fluorescent property either to microspheres or to cells and fluorescent microspheres have good biocompatibility and property in sustained release of growth factors. The obtained microspheres will be expected to realise the imaging of cells and materials and also the release of growth factor in tissue engineering or in cell culture. [ABSTRACT FROM AUTHOR]

This study evaluated the feasibility of mizolastine-loaded microparticles as therapy for atopic dermatitis. Microparticles have been researched for decades as a controlled-release drug delivery system, but seldom been used as treatment for skin disease. In this research, we induced dermatitis in BALB/c mice model by repeated topical application of dinitrofluorobenzene and compared the mizolastine microparticles injection and daily mizolastine injection treatment. The results showed that the mizolastine microparticles treatments significantly inhibited ear thickness and dermatitis index in dermatitis model compared with the dermatitis mice without treatment, showing a similar curative effect compared with daily mizolastine injection treatment, and the improvement continued for several days. Inflammatory cells infiltration into the ears and the plasma level of immunoglobulin E were also suppressed by mizolastine microparticles according to the histopathology analysis. In conclusion, the results suggested that drug-loaded microparticles could be a proper candidate for the treatment of skin diseases. [ABSTRACT FROM AUTHOR]

Calcium alginate nanoparticles (NPs) suffer from sub-optimal stability in bio-relevant media leading to low drug encapsulation efficiency and uncontrolled release profiles. To sort out these drawbacks, a novel approach is proposed herein based on introducing tannic acid into these NPs to act as a bridging cross-linking aid agent. Calcium-alginate NPs were prepared by the ionotropic gelation method and loaded with diltiazem hydrochloride as a model drug. These NPs were characterized in terms of particle size, zeta potential, and morphology, and results were explained in accordance with Fourier-transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The incorporation of tannic acid led to more than four folds increase in drug encapsulation efficiency (i.e. from 15.3% to 69.5%) and reduced burst drug release from 44% to around 10% within the first 30 min. These findings suggest the possibility of improving the properties of Ca-alginate NPs by incorporating cross-linking aid agents under mild conditions. [ABSTRACT FROM AUTHOR]

l-ascorbic acid is an abundant water-soluble nutrient found in vegetables and fruits. It enhances the cell proliferation, which is helpful in wound healing process. However, it is relatively unstable and easily degraded under external environments including acidity, alkalinity, evaporation, heat, oxidization, light or moisture. Its storage remains challenged. This study reported the development of l-ascorbic acid microcapsules using the natural protein, gelatin, and the natural polysaccharide, agar, as the wall protection carrier. The physical properties including entrapment efficiency, particle size, surface morphology, chemical compositions and release profile were identified. The cell proliferation of l-ascorbic acid microcapsules was stronger than the free drug. Significant cell growth in microencapsulated l-ascorbic acid-treated human epithelial HaCaT cells was observed when compared with untreated control. Since cell proliferation and wound repair are closely related, it is believed that l-ascorbic acid microcapsules would effectively increase the potential effect of wound healing activity in human skin. [ABSTRACT FROM AUTHOR]

This study demonstrates the feasibility of using a single-capillary electrospray (ES) system to generate novel alpha-lipoic acid encapsulated poly(ethylene oxide)-chitosan (ALA/PEO/CS) particles with a monodispersed diameter. Scanning electron microscopic images (SEM) and dynamic light scattering (DLS) results indicate that the ES system can generate either a dry powder or a homogeneous water-based suspension of ALA/PEO/CS particles. The SEM images revealed that the ALA/PEO/CS particles have a spherical shape with a diameter of approximately 707 ± 66.68 nm, and DLS showed that the ALA/PEO/CS particles suspended in deionised water have a diameter of 734.5 nm. In addition, zeta potential studies were performed using a zetasizer instrument and showed positively electric surface potential of 57.7 ± 0.5 mV, which was attributed to chitosan. Based on the DLS and zeta potential studies, we concluded that the excellent dispersity and stability of the ALA/PEO/CS suspension is attributed to the reduction in particle size and electrostatic repulsion between these tiny particles. Finally, we used lipopolysaccharide (LPS)-induced nitrite formation in Raw 264.7 macrophages as a model for in vitro anti-inflammation evaluation. We find that the anti-inflammatory ability of the ALA/PEO/CS particles is superior to that of free ALA solution in macrophage cells, which is attributed to the more efficiently intracellular delivery. The confocal image results prove that the uptake of ALA/PEO/CS particles by the LPS-treated Raw 264.7 macrophages is possibly initiated by the interaction with cell-surface molecules through electrostatic interactions, followed by endocytosis of the attached particles. [ABSTRACT FROM AUTHOR]

Polysulfenamides (PSN), with a SN linkage (RSNR2) along the polymer backbone, are a new class of biodegradable and biocompatible polymers. These polymers were unknown prior to 2012 when their synthesis and medicinally relevant properties were reported. The aim of this study was to develop microparticles as a controlled drug delivery system using polysulfenamide as the matrix material. The microparticles were prepared by a water-in-oil-in-water double-emulsion solvent-evaporation method. For producing drug-loaded particles, FITC-dextran was used as a model hydrophilic compound. At the optimal formulation conditions, the external morphology of the PSN microparticles was examined by scanning electron microscopy to show the formation of smooth-surfaced spherical particles with low polydispersity. The microparticles had a net negative surface charge (-23 mV) as analyzed by the zetasizer. The drug encapsulation efficiency of the particles and the drug loading were found to be dependent on the drug molecular weight, amount of FITC-dextran used in fabricating FITC-dextran-loaded microparticles, concentration of PSN and surfactant, and volume of the internal and external water phases. FITC-dextran was found to be distributed throughout the PSN microparticles and was released in an initial burst followed by more continuous release over time. Confocal laser scanning microscopy was used to qualitatively observe the cellular uptake of PSN microparticles and indicated localization of the particles in both the cytoplasm and the nucleus. [ABSTRACT FROM AUTHOR]

There is a growing interest in using proteins as therapeutics agents. Unfortunately, they suffer from limited stability and bioavailability. We aimed to develop a new delivery system for proteins. ALP, a model protein, was successfully encapsulated in the physically cross-linked sodium alginate/hydroxypropylcellulose (ALG-HPC) hydrogel microparticles. The obtained objects had regular, spherical shape and a diameter of ∼4 µm, as confirmed by optical microscopy and SEM analysis. The properties of the obtained microbeads could be controlled by temperature and additional coating or crosslinking procedures. The slow, sustained release of ALP in its active form with no initial burst effect was observed for chitosan-coated microspheres at pH = 7.4 and 37 °C. Activity of ALP released from ALG/HPC microspheres was confirmed by the occurance of effectively induced mineralization. SEM and AFM images revealed formation of the interpenetrated three-dimensional network of mineral, originating from the microbeads' surfaces. FTIR and XRD analyses confirmed formation of hydroxyapatite. [ABSTRACT FROM AUTHOR]

A set of chitosan-polyvinylpyrrolidone (CH-PVP) microspheres were prepared as semi-inter penetrating networks (semi-IPN) and loaded with 5-fluorouracil. In vitro release studies showed faster release for semi-IPN microspheres compared to pure CH samples, and the total release was achieved in about 20-30 days, depending on the composition. In vitro cell studies were achieved against human breast adenocarcinoma cell line cells where adsorption of cells on microspheres with a significant decrease in their number was obtained. Meanwhile, the CH-PVP films, which were prepared with the same compositions as in the microspheres, demonstrated an increase in strength from 66 to 118 MPa as the PVP content was decreased. It can be concluded that the prepared CH-PVP semi-IPN microspheres are novel promising carriers compared to pure CH microspheres since it becomes possible to adjust stability and hydrophilicity of the microspheres as well as the release rates of the drugs from the microspheres by changing the ratio of CH/PVP composition. [ABSTRACT FROM AUTHOR]

Context: The release of an encapsulated drug is dependent on diffusion and/or degradation/erosion processes. Objective: This work aimed to better understand the degradation mechanism of clonidine-loaded microparticles. Methods: Gel permeation chromatography was used to evaluate the degradation of the polymer. The water-uptake and the weight loss were determined gravimetrically. The swelling behaviour and the morphological changes of the formulations were observed by microscopy. The glass transition temperature and the crystallinity were also determined by differential scanning calorimetry and X-ray diffraction, respectively. The pH of the medium and inside the microspheres was assessed. Results: The microspheres captured a large amount of water, allowing a decrease in the molecular weight of the polymer. The pH of the medium decreased after release of the degradation products and the pH inside the microparticles remained constant due to the neutralization of these acidic products. Conclusion: Clonidine and buffers both had an action on the degradation. [ABSTRACT FROM AUTHOR]

Biodegradable poly (lactic-co-glycolic acid) (PLGA) microparticles are an effective way to achieve sustained drug release. In this study, we investigated a sustained release model of PLGA microparticles with incorporated protein via either emulsion or coaxial electrospray techniques. PLGA (75:25) was used as the carrier, and bovine serum albumin as a model protein. Coaxial electrospray resulted in a type of core-shell structure with mean diameters of 2.41 ± 0.60 µm and a centralised protein distribution within the core. Emulsion electrospray formed bigger microparticles with mean diameters of 22.75 ± 8.05 µm and a heterogeneous protein distribution throughout the microparticles. The coaxial electrospray microparticles presented a much slighter burst release than the emulsion electrospray microparticles. Loading efficiency was significantly higher ( p < 0.05) in the coaxial group than emulsion group. This indicated that both emulsion and coaxial electrospray could produce protein-loaded microparticles with sustained release behaviour, but the former revealed a superior approach for drug delivery. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop poly( D, L-lactide-co-glycolide)/montmorillonite (PLGA/MMT) nanoparticles formulations for improved oral delivery of exemestane. Exemestane-loaded PLGA nanoparticles and PLGA/MMT nanoparticles were prepared by a modified solvent extraction/evaporation technology with vitamin E succinated polyethylene glycol 1000 (TPGS) as emulsifier. The content of MMT was estimated by thermal gravimetric analysis. The drug encapsulation efficiency and in vitro drug release kinetics were measured by high-performance liquid chromatography. The size, size distribution, surface charge and morphology of the exemestane-loaded nanoparticles were characterized using a Zetasizer Nano ZS and field emission scanning electron microscopy. The physical status of exemestane in the nanoparticles was characterized by differential scanning calorimetry. In vitro cellular uptake of coumarin-6-loaded nanoparticles was investigated by confocal laser scanning microscope, demonstrating that the fluorescence nanoparticles were internalized by Caco-2 cells (as an in vitro gastrointestinal model). The results of in vitro cytotoxicity experiment on MCF-7 cells (as a model of breast cancer cells) showed the exemestane-loaded nanoparticles resulted in lower cell viability versus the pure exemestane solution. The cytotoxicity against MCF-7 cells for exemestane-loaded nanoparticles and pure exemestane solution was dependent on the drug concentration and incubation time. In conclusion, this study indicates the capability of PLGA nanoparticles and PLGA/MMT nanoparticles in enhancing the oral delivery of exemestane. [ABSTRACT FROM AUTHOR]

Chitosan-encapsulated menthol microcapsules were successfully prepared in an oil-in-water (o/w) emulsion using the Shirasu Porous Glass (SPG) membrane emulsification technique and high-speed dispersion technique for preparing a mixed o/w emulsion. The size of the menthol-loaded chitosan microcapsules was strongly depended on the average pore size of the SPG membrane and the amount of menthol loading in the dispersed phase. The membrane pore size of 5.2 µm was suitable for a viscous dispersed phase containing light mineral oil. The average diameter of emulsion droplets of 28.3 µm was obtained. Increasing the menthol loading in the dispersion phase from 5% to 10% w/w of chitosan decreased the emulsion droplet size with a broad size distribution. The crosslinked microcapsule size and size distribution of mixed emulsion droplets decreased with the increasing crosslinking time. The menthol release was a diffusion control which depended on the proportion of amino group in chitosan-to-tripolyphosphate molar ratio and crosslinking time. This work also demonstrated that hydrophilicity/hydrophobicity of the continuous phase and dispersion phase controlled SPG membrane emulsification efficiency and quality of the resulting emulsion droplets. [ABSTRACT FROM AUTHOR]

Tuberculosis remains the leading cause of preventable deaths worldwide and unsuccessful therapy is mainly due to non-compliance with very prolonged treatments, often associated with severe side-effects. Overcoming this problem demands the introduction of drug carriers releasing the antimicrobial agents in a targeted and sustained manner, allowing reduction in frequency and dosing numbers. Nano- and microparticles have taken the forefront of this approach, providing the means for the desired improvement of therapeutic schedules. Natural polymers are strong candidates as matrix-forming materials, usually exhibiting biocompatibility, biodegradability, low cost and some technological advantages as compared with synthetic counterparts. In this review, natural particulate carriers developed for tuberculosis therapy are presented, mainly focusing on the use of polysaccharides and lipids. Their effectiveness is discussed taking into account their composition. Finally, considerations on the general potential of natural materials for this application, as well as key factors still to be addressed, are discussed. [ABSTRACT FROM AUTHOR]

The therapeutic efficiency and topical performance of drug-containing microcapsules varied when the drugs existed in an internal oil phase or an internal aqueous phase within the wall shell or wall matrix of microcapsules. In this study, chitosan-based (oil-in-water) and agar-gelatin-based (water-in-oil) microencapsulation systems containing berberine were applied to cotton fabrics to provide an anti- Staphylococcus aureus activity for textile materials. The berberine microcapsule-treated cotton samples were subjected to various washing cycles and their surface morphology, chemical compositions and antibacterial property were investigated after washing. The SEM images and Fourier transform infrared analysis showed that the amount of microcapsules on cotton samples decreased gradually with an increase in washing cycles. After 20 washing cycles, the cotton fabrics with agar-gelatin (water-in-oil) microcapsules containing berberine still exhibited the anti- S. aureus activity. However, the chitosan-based (oil-in-water) system did not show any growth inhibition towards S. aureus but only in the contact areas. [ABSTRACT FROM AUTHOR]

The copolymers of N-isopropylacrylamide and sodium vinylsulphonate were synthesised by free radical polymerisation. The layer-by-layer self-assembly of the copolymers with poly(allylamine) hydrochloride was performed through assembling onto silicon wafer to form multilayer films and onto CaCO3 microparticles doped with poly(styrene sulphonate) as well as deltamethrin microcrystals to form microcapsules. The multilayer films and microcapsules were characterised by atomic force microscopy, transmission electron microscopy and scanning electron microscopy. The release behaviour of deltamethrin in the microcapsules under different conditions was also investigated by high performance liquid chromatography. Results show that these deltamethrin microcapsules have good thermo-sensitive properties and deltamethrin release can be controlled via changing temperature or self-assembly layers. [ABSTRACT FROM AUTHOR]

Particulates for pharmaceutical applications require stringent control over their characteristics to realize the optimal therapeutic performance. By generating uniform spray-dried silica particles encapsulating different model drugs via a microfluidic jet spray drying technique, we demonstrated how the effects of formulation and process parameters on the investigated properties could be directly quantified without the complications of wide particle distributions typical of conventional spray drying. The implemented strategies included incorporating lactose to modify the internal microstructures to regulate release, and increasing drying temperature during synthesis to modify the surface features of particles. The physicochemical properties of encapsulated drugs were shown to influence particle morphologies and release profiles, while the pH of initial precursors influenced the particle morphologies with slight effects on the initial release rates. The outcomes would be useful to indentify appropriate formulations and manufacturing parameters in designing spray-dried silica-based microencapsulates with tailor-made controlled release functionalities. [ABSTRACT FROM AUTHOR]

Objective: The aim of the present investigation was to design and formulate appropriate form of glabridin, using microsponge drug delivery system. Method: Microsponges were prepared by emulsion solvent evaporation method and characterized by drug loading, infrared spectroscopy and scanning electron microscopy. In vitro diffusion studies of gel formulation were performed using ethanol: phosphate buffer (1:1) mixture as receptor medium. Animal studies were carried out using brownish guinea pigs with UV-induced pigmentation model. Results: Prepared microsponges were predominantly yellowish, free-flowing and spherical in shape. The infrared spectra revealed the absence of drug polymer interaction. Scanning electron microscopy (SEM) and porosity studies confirmed spherical and porous nature. In vitro release studies data depicted highest correlation with Higuchi treatment. Animal studies also supported the better depigmenting activity as compared to plain gel. Conclusion: Glabridin microsponge-loaded gel could be efficacious in treating various hyperpigmentation disorders. [ABSTRACT FROM AUTHOR]

In this article, we report the development of chitosan/miconazole nitrate microcapsules. Four miconazole nitrate ratios including 12.5, 25, 50 and 100 mg were performed in the chitosan-based microencapsulation system. Chitosan microcapsules with the drug input of 25 mg showed the highest encapsulation efficiency (52.47%) and acceptable mean particle size (5.65 µm) when compared with those of 12.5, 50 and 100 mg. Fourier transform infrared spectroscopic spectrum proved the entrapment of miconazole nitrate into chitosan microcapsules. The antifungal result demonstrated that microcapsules containing 75 µg miconazole nitrate possessed comparable anti- Aspergillus niger activity as the commercial ointment. The growth inhibition of miconazole nitrate containing chitosan microcapsules towards human skin keratinocytes was found to be dose dependent. A total of 75 µg of miconazole nitrate containing microcapsules revealed about 25% of growth inhibition while that of 150 µg showed approximately 70% of growth inhibition. Special monitoring should be taken if a higher dose of miconazole nitrate was used to develop the microcapsules. [ABSTRACT FROM AUTHOR]

We studied a model system of controlled drug release using beta-carotene and κ-carrageenan/NaCMC hydrogel as a drug and a device, respectively. Different concentrations of genipin were added to crosslink the beta-carotene loaded beads by using the dripping method. Results have shown that the cross-linked beads possess lower swelling ability in all pH conditions (pH 1.2 and 7.4), and swelling ratio decreases with increasing genipin concentration. Microstructure study shows that cross-linking has enhanced the stability and structure of the beads network. Determination of diffusion coefficient for the release of encapsulated beta-carotene indicates less diffusivity when beads are cross-linked. Swelling models using adaptive neuro fuzzy show that using genipin as a cross-linker in the kC/NaCMC hydrogels affects the transport mechanism. The model shows very good agreement with the experimental data that indicates that applying ANFIS modelling is an accurate, rapid and simple way to model in such a case for controlled release applications. [ABSTRACT FROM AUTHOR]

In this article, an amphiphilic graft copolymer composed of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) as the hydrophilic backbone, poly( L-lactic acid) (PLA) as the hydrophobic side-chains and polyethylene glycol (PEG) as the spacer was synthesized. Transmission electron microscopy revealed that the graft copolymer could self-assemble into hollow microcapsules when dialyzed in aqueous solution and particle sizes ranged from 200 to 300 nm, while the graft copolymer formed core-shell microspheres with the absence of PEG spacer. X-ray photoelectron microscope showed that MPC polymers were located at the surface of the microcapsules. The amounts of adsorbed bovine serum albumin and Fg on the microcapsules were significantly decreased than that on the conventional PLA particles (74%% and 60%%, respectively), well indicating the anti-adhesive property of the microcapsules. Paclitaxel was chosen as a prototype anticancer drug for the encapsulation and release studies, the results showed that the drug encapsulation efficiency was 89.3 ± 1.2%% and the microcapsules exhibited controlled release behaviour. [ABSTRACT FROM AUTHOR]

Microencapsulation of biomolecules, cells and chemicals is widely used in the food and pharmaceutical industries to improve stability, delivery and to control the release of encapsulated moieties. Among encapsulation matrices, alginate is preferred due to its low cost, biodegradability and biocompatibility. Current methods for producing stable alginate gels involve dropping alginate suspensions into divalent cation solutions. This procedure is difficult to scale-up and produces undesirably large alginate beads. In our novel encapsulation method, alginate gelation occurs during spray drying upon volatilisation of a base and rapid release of otherwise unavailable calcium ions. The resulting particles, with median particle sizes in the range 15-120 µm, are insoluble in solution. Cellulase and hemicellulase activities encapsulated by this method were not compromised during spray drying and remained stable over prolonged storage. The procedure described here offers a one-step alternative to other encapsulation methods that are costly and difficult to scale-up. [ABSTRACT FROM AUTHOR]

Liquid-filled pectinate capsules have a large potential for the controlled and site-specific delivery of liquid drugs. Earlier studies have shown that pure pectinate capsules can store drugs only for a few minutes. Here, we show that the retention time can be extended to several hours by coating the capsules with the natural resin shellac. A bilberry extract containing anthocyanins with promising therapeutic properties was used as model drug to characterize the permeability of the capsules by in vitro drug release measurements. Characterizing the structure of the double-layered capsule membranes by NMR microscopy, we optimized the capsule production by adjusting the pH-value in the coating process and the gelation time of the pectinate hydrogel layer. A comparison of the layer thicknesses with drug release measurements reveals that capsules with the thinnest shellac layers provide the best entrapment. Additional squeezing experiments show that the shellac layer makes the capsules also mechanically more stable. [ABSTRACT FROM AUTHOR]

Many strategies have been proposed to explore the possibility of exploiting gastroretention for drug delivery. Such systems would be useful for local delivery, for drugs that are poorly soluble at higher pH or primarily absorbed from the proximal small intestine. Generally, the requirements of such strategies are that the vehicle maintains controlled drug release and exhibits prolonged residence time in the stomach. Despite widespread reporting of technologies, many have an inherent drawback of variability in transit times. Microparticulate systems, capable of distributing widely through the gastrointestinal tract, can potentially minimise this variation. While being retained in the stomach, the drug content is released slowly at a desired rate, resulting in reduced fluctuations in drug levels. This review summarises the promising role of microencapsulation in this field, exploring both floating and mucoadhesive microparticles and their application in the treatment of Helicobacter pylori, highlighting the clinical potential of eradication of this widespread infection. [ABSTRACT FROM AUTHOR]

Chitosan-coated nanoliposomes containing etofenprox or alpha-cypermethrin prepared by ultrasonic homogenization maintained a size distribution in the nanometre range. Nanoliposomes were constructed using different types and concentrations of chitosan to regulate the mean size and surface charge. As the chitosan concentration (0.1-0.5%%, w/v) and the degree of deacetylation increased, surface charge also increased. The encapsulation efficiency and release profile were measured by gas chromatography. Encapsulation efficiency decreased slightly as chitosan concentration increased (0.1-0.5%%, w/v). As the intrinsic surface charge or concentration of the coating material increased, the release period of the entrapped core material was extended (chitosans A and B; 0.1 and 0.3%%, w/v). The results indicate that diverse preparation conditions could affect the physicochemical properties and release profile of the resulting nanocarrier systems. [ABSTRACT FROM AUTHOR]

Paclitaxel (PTX), an antimicrotubular agent used in the treatment of ovarian and breast cancer, was encapsulated in nanoparticles (NPs) of poly(lactide-co-glycolide) (PLGA) and poly(ℇε-caprolactone) (PCL) polymers using the spray-drying technique. Morphology, size distribution, drug encapsulation efficiency, thermal degradation and drug release were characterized. MCF7 cells were employed to evaluate the efficacy of the systems on cell cycle and cytotoxicity. The particle size was in the range 0.8--1 µµm. The incorporation efficiency of PTX was more than 80%% in all NPs obtained. In  vitro drug release took place during 35 days, and drug release rates were in the order PCL > PLGA 50:50 > PLGA 75:25. Unloaded NPs showed to be cytocompatible at MCF7 cells. PTX-loaded NPs demonstrated the release of the drug block cells in the G2/M phase. All PTX-loaded formulations showed their efficacy in killing MCF7 cells, mainly PTX-loaded PLGA 50:50 and PLGA 75:25 that cause a decrease in cell viability lower than 20%%. [ABSTRACT FROM AUTHOR]

The treatment of osteomyelitis remains a challenge for orthopaedic surgeons. Controlled release of vancomycin from biodegradable microspheres is a promising method for eliminating infection. However, the large initial burst release may make it difficult to maintain the local vancomycin concentration superior to minimum inhibitory concentration for several weeks. The aims of this study were to explore applications of the silk fibroin (SF) as an aqueous coating material for vancomycin-loaded poly( ℇε-caprolactone) (PCL) microspheres, and investigate the effects of silk coating on in  vitro drug release. Examinations of particle size analyses, vancomycin content, Fourier transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy and in  vitro drug release were performed. The results showed that silk coating could reduce the large initial burst release and retard the vancomycin release. Therefore, we suggest that the SF could be used as an aqueous coating material for vancomycin-loaded PCL microspheres and prolonged the drug release. SF coating on vancomycin-loaded PCL microspheres may be considered as an effective approach to prolong the drug release and improve the anti-infection effects. [ABSTRACT FROM AUTHOR]

Spray dried microparticles containing mupirocin calcium were designed as acrylic matrix carriers with modulated drug release for efficient local drug delivery at minimum daily dose. Particle generation in spray drying and its effect on release performance were assessed by varying drug : polymer ratios with consequently altered initial saturations. Narrow-sized microparticles with mean diameters of 1.7--2.5 µµm were obtained. Properties of the generated solid dispersions were examined by X-ray, thermal (thermogravimetric analysis, modulated differential scanning calorimetry) and spectroscopic (Fourier transformed infrared, Fourier transformed Raman) methods and correlated with drug loading and in  vitro release. The best control over mupirocin release was achieved for 2 : 1 (w/w) drug : polymer ratio and found to be strongly process-dependent. For a particular ratio, increased feed concentration (>4%%) boosted while increased inlet temperature (≥≥100°°C) reduced drug release. Antimicrobial activity testing confirmed that encapsulated drug preserved its antibacterial effectiveness. Conclusively, spray drying was proven as a suitable method for preparing structured microparticles which can control drug release even at exceptionally high drug loadings. [ABSTRACT FROM AUTHOR]

Biodegradable Poly(lactic-co-glycolic acid; PLGA), microspheres encapsulating the angiogenic protein recombinant human vascular endothelial growth factor (rhVEGF) were formed to achieve VEGF release in a sustained manner. These microspheres are a promising delivery system which can be used for therapeutic angiogenesis. The PLGA microspheres incorporating two different initial loading amounts of rhVEGF have been prepared by a modified water-in-oil-in-water (w/o/w) double emulsion/solvent evaporation technique. The microspheres have been characterized by particle size distribution, environmental scanning electron microscopy (ESEM), light microscopy, encapsulation efficiency and their degradation was studied in vitro. The rhVEGF released from microspheres was quantified by the competitive enzyme-linked immunosorbent assay (ELISA) and human umbilical vein endothelial cell (HUVEC) proliferation assay was used to assess biological activity of the released VEGF. The microspheres were spherical with diameters of 10-60 µm and the encapsulation efficiency was between 46% and 60%. The release kinetics of rhVEGF was studied for two different amounts: 5 µg VEGF (V5) and 50 µg VEGF (V50) per 500 mg starting polymer. The total protein (VEGF:BSA) release increased up to 4 weeks for two rhVEGF concentrations. The ELISA results showed that the burst release for V5 and V50 microspheres were 4 and 27 ng/mL, respectively. For V5, the microspheres showed an initial burst release, followed by a higher steady-state release until 14 days. VEGF release increased up to 2 weeks for V50 microsphere. HUVEC proliferation assay showed that endothelial cells responded to bioactive VEGF by proliferating and migrating. [ABSTRACT FROM AUTHOR]

Matrix-type pellets with controlled-release properties may be prepared by hot-melt extrusion applying a single-step, continuous process. However, the manufacture of gastric-resistant pellets is challenging due to the high glass transition temperature of most enteric polymers and an unacceptably high, diffusion-controlled drug release from the matrix during the acidic phase. The objective was to investigate the influence of three plasticizers (triethyl citrate, methylparaben and polyethylene glycol 8000) at two levels (10% or 20%) on the properties of hot-melt extruded Eudragit® S100 matrix pellets. Extrusion experiments showed that all plasticizers produced similar reductions in polymer melt viscosity. Differential scanning calorimetry and powder X-ray diffraction demonstrated that the solid state plasticizers were present in the amorphous state. The drug release in acidic medium was influenced by the aqueous solubility of the plasticizer. Less than 10% drug was released after 2 h at pH 1.2 when triethyl citrate or methylparaben was used, independent of the plasticizer level. Drug release at pH 7.4 resulted from polymer dissolution and was not influenced by low levels of plasticizer, but increased significantly at the 20% level. Mechanical testing by diametral compression demonstrated the high tensile strength of the hot-melt extruded pellets that decreased when plasticizers were present. [ABSTRACT FROM AUTHOR]

Bleomycin sulphate-loaded porous microspheres were prepared using modified solvent evaporation method (w/o/w) using PLGA50:50 as a polymeric system. The prepared microspheres were incorporated in pluronic® (F127) based thermoreversible gel to develop a depot formulation. Various process parameters as solvent evaporation temperature and formulation parameters such as surfactant concentration, volume of internal and external phase and drug-to-polymer ratio were optimized for enhancing percentage drug entrapment, percentage drug loading and desired release profile by controlling size and porosity of the microspheres. Microspheres were characterized for particle size, zeta potential, surface morphology, percentage drug loading and in vitro drug release study after incorporated in gel. The formulated microspheres were porous in nature and showed biphasic in vitro drug release profile. The microspheres incorporated in pluronic® (F127) gel showed sustained release up to 1 week and may be useful for treatment of squamous cell carcinoma with better therapeutic effect. [ABSTRACT FROM AUTHOR]

Microparticle protein delivery systems based on calcium alginate were fabricated using a very convenient method, i.e. directly shredding the protein-loaded calcium alginate beads into microparticles in a commercial food processor for 3 min. Bovine serum albumin (BSA) as a model protein was encapsulated in the calcium alginate microparticles. The obtained protein-loaded microparticles were then coated with chitosan. This fabrication method offered high encapsulation efficiency and a high particle yield. Compared with beads, the microparticles exhibited a faster release rate in the initial release stage. By comparing the release profiles of uncoated beads/microparticles and chitosan-coated beads/microparticles, it was found that the releases from chitosan-coated beads/microparticles were slower. To examine whether the loaded protein denatured during the microparticle fabrication, trypsin was encapsulated in the calcium alginate microparticles and the bioactivity of trypsin released from the microparticles was measured. [ABSTRACT FROM AUTHOR]

Cysteine modified amphiphilic block copolymer acetate-polylactide-block-poly(ethylene glycol)-Cysteine (APLA- b-PEG-Cys) was synthesized and characterized. The polymer could self-assemble to form micelles with nano-size and regularly spherical in shape in aqueous solution. Folic acid (FA) was then used as a model drug to incorporate into APLA- b-PEG-Cys micelles. To enhance the stabilization of APLA- b-PEG-Cys micelle and control the drug release, the shell of APLA- b-PEG-Cys micelle was cross-linked by the in situ polycondensation of amino acid moieties on its surface. The effects of shell-cross-linking on the micelle physical chemistry properties were investigated in detail. It was found that, after cross-linking, the CMC of the APLA- b-PEG-Cys micelle was decreased, indicating that the shell-cross-linked micelle is more stable as compared to the uncross-linked one. In addition, the shell-cross-linking also changed the surface potential, micelle size and model drug (FA) release behaviour, but it did not significantly affect the micelle morphology and drug encapsulation efficiency of APLA- b-PEG-Cys micelles. [ABSTRACT FROM AUTHOR]

The aim of this study was to design and develop microspheres of indomethacin with pH and transit time dependent release properties for achieving targeted delivery to the colon. Microspheres containing varying proportions of ethyl cellulose and Eudragit (L100 or S100) either alone or in combination were prepared using an oil-in-oil emulsion-based solvent evaporation technique. System comprising of acetone (internal phase) and liquid paraffin (external phase) in the ratio of 1 : 1 and 1 : 9 yielded microspheres with good physical properties (spherical and discrete), high drug loading (70–80%) and entrapment efficiency (70–85%). The lag time in the initial release depended on the proportion of pH-sensitive polymer Eudragit, while the duration of indomethacin release from microspheres was found to be directly proportional to proportion of the total polymer. Thus, a pH- and time-modulated sigmoidal release pattern could be observed in optimized formulations with less than 10% drug release in 4–6 h followed by controlled release extending up to 14–16 h. [ABSTRACT FROM AUTHOR]

The localized and temporally controlled release of growth factors is key to achieving optimal clinical efficacy. To achieve sustained delivery of a novel bone-induced growth factor, chitosan microspheres loaded with synthetic oligopeptide (S[PO4]KIPKASSVPTELSAISTLYLDDD, P24) were prepared by an emulsion-ionic cross-linking method in the presence of tripolyphosphate, with bovine serum albumin (BSA) as a control. Both microspheres containing oligopeptide or BSA were of spherical shape with size ranging from 10–60 µm. The encapsulation efficiency was usually higher than 80% and the loading capacity was affected by initial protein dosage. From the release experiments, it was found that both proteins were slowly released from the microspheres over 7 days in a PBS solution (pH 7.4), in which the release rate of oligopeptide was much lower than that of BSA. Released oligopeptide was demonstrated to possess biological activity as evidenced by stimulation of rabbit marrow mesenchymal stem cells (MSCs) alkaline phosphatase (ALP) activity in vitro. These results indicate that the TPP-chitosan microspheres loaded with synthetic oligopeptide may possess potential application in bone tissue engineering. [ABSTRACT FROM AUTHOR]

Samples of mesoporous base-catalysed silica xerogel materials made by the sol-gel process were impregnated with an anticancer drug - doxorubicin, followed by different times of ageing at room temperature. The effect of ageing time on the physical and structural properties as well as sorption-desorption of the drug was investigated. The obtained results suggest an inverse relationship with a solid density and surface area increasing as the pore size and volume decrease during ageing time. These results also revealed the effect of ageing time on the efficiency of sorption-desorption of the drug. An increase in ageing time results in an increase of the efficiency of drug sorption and a decrease in the rate of drug release. [ABSTRACT FROM AUTHOR]