Hypoxia-induced angiogenesis is increased by the controlled release of deferoxiamine from gelatin hydrogels

The objective of this study is to design biodegradable hydrogels for the controlled release of deferoxiamine (DFO) and evaluate their biological activity. When the DFO was added to human umbilical vein endothelial cells cultured in 5.0% O2, the level of hypoxia-inducible factor-1α and vascular endothelial growth factor significantly increased compared with that without DFO. The expression of angiogenesis-related genes was accordingly increased by the DFO addition. An aqueous solution of mixed gelatin and DFO was freeze-dried, and dehydrothermally treated at 140°C for 24h to prepare a gelatin hydrogel incorporating DFO. In the release test with phosphate-buffered saline solution (PBS) at 37°C, an initial DFO release of 60% was observed, followed by no release. When placed in PBS containing collagenase, the hydrogel was enzymatically degraded with time, and consequently released DFO in a degradation-dependent manner. After the hydrogel incorporating DFO was injected intramuscularly into a mouse model of hind limb ischemia, the number of new blood vessels formed was significantly higher than that with free DFO and DFO-free hydrogel. It is concluded that the DFO-containing hydrogel shows promising for inducing angiogenesis locally.

Mineralization and drug release of hydroxyapatite/poly(l-lactic acid) nanocomposite scaffolds prepared by Pickering emulsion templating

Biodegradable and bioactive nanocomposite (NC) biomaterials with controlled microstructures and able to deliver special drugs have gained increasing attention in bone tissue engineering. In this study, the hydroxyapatite (HAp)/poly(l-lactic acid) (PLLA) NC scaffolds were facilely prepared using solvent evaporation from templating Pickering emulsions stabilized with PLLA-modified HAp (g-HAp) nanoparticles. Then, in vitro mineralization experiments were performed in a simulated body fluid (SBF) to evaluate the bioactivity of the NC scaffolds. Moreover, in vitro drug release of the NC scaffolds using anti-inflammatory drug (ibuprofen, IBU) as the model drug was also investigated. The results showed that the NC scaffolds possessed interconnected pore structures, which could be modulated by varying the g-HAp nanoparticle concentration. The NC scaffolds exhibited excellent bioactivity, since they induced the formation of calcium-sufficient, carbonated apatite nanoparticles on the scaffolds after mineralization in SBF for 3 days. The IBU loaded in the NC scaffolds showed a sustained release profile, and the release kinetic followed the Higuchi model with diffusion process. Thus, solvent evaporation based on Pickering emulsion droplets is a simple and effective method to prepare biodegradable and bioactive porous NC scaffolds for bone repair and replacement applications.

Antimicrobial packaging of chicken fillets based on the release of carvacrol from chitosan/cyclodextrin films

Chitosan/cyclodextrin films (CS:CD) incorporating carvacrol were obtained by casting, and conditioned at 23°C and 75% relative humidity prior to being immersed in liquid carvacrol until they reached sorption equilibrium. In a previous work, the in vitro antimicrobial activity of these films was studied. In this work, active films were used to inhibit microbial growth in packaged chicken breast fillets. Samples of CS:CD films loaded with carvacrol, of different sizes and thus with different quantities of antimicrobial agent, were stuck to the aluminium lid used to seal PP/EVOH/PP cups containing 25g of chicken fillets. These samples were stored for 9days at 4°C. The packages were hermetically sealed and it was confirmed that they provided an infinite barrier to carvacrol. The partition of the antimicrobial agent within the food/packaging system was analysed. The antimicrobial devices rapidly released a large percentage of the agent load, amounts that were gained by the adhesive coating of the lid and especially by the chicken fillets. The latter were the main sorbent phase, with average concentrations ranging between 200 and 5000mg/Kg during the period of storage. The microbiota of the packaged fresh chicken fillets - mesophiles, psychrophiles, Pseudomonas spp., enterobacteria, lactic acid bacteria and yeasts and fungi - were analysed and monitored during storage. A general microbial inhibition was observed, increasing with the size of the active device. Inhibition with a 24cm(2) device ranged from 0.3 log reductions against lactic acid bacteria to 1.8logs against yeasts and fungi. However, the large amount of antimicrobial that was sorbed or that reacted with the fillet caused an unacceptable sensory deterioration. These high sorption values are probably due to a great chemical compatibility between chicken proteins and carvacrol.

Cyclic RGD-modified chitosan/graphene oxide polymers for drug delivery and cellular imaging

Polymers based on cyclic RGD-modified chitosan/graphene oxide are investigated in this paper as an innovative type of drug delivery system for hepatocellular carcinoma-targeted therapy and imaging. The system was prepared using a simple noncovalent method by coating drug-loaded graphene oxide (GO) with cyclic RGD-modified chitosan (RC). The results show that an efficient loading of doxorubicin (DOX) on GO (1.00mg/mg) was obtained. The system exhibits a pH-responsive behavior because of the hydrogen bonding interaction between GO and RC, and may be very stable under physiological conditions but with release at a lower pH (tumor environment). In addition, cellular uptake and proliferation studies using hepatoma cells (Bel-7402, SMMC-7721, HepG2) indicated that the cRGD-modified chitosan/graphene oxide polymer could recognize hepatoma cells and promote drug uptake by the cells, especially for cells overexpressing integrins. Together, these results demonstrate that the RC/GO polymers provide a multifunctional drug delivery system with the ability to target hepatocarcinoma cells, and are pH-responsive and can be efficiently loaded with a number of therapeutic agents for biomedical applications.

Chitosan/fucoidan multilayer nanocapsules as a vehicle for controlled release of bioactive compounds

Hollow multilayer nanocapsules were successfully prepared through layer-by-layer assembly of two bioactive polysaccharides, chitosan and fucoidan. The stepwise adsorption of 10 chitosan/fucoidan layers and the consequent formation of a multilayer film on polystyrene nanoparticles (used as templates) were followed through ζ-potential measurement and the removal of the polystyrene core was confirmed by FTIR analysis. The chitosan/fucoidan nanocapsules morphology and size were evaluated by SEM and TEM, which showed that after the core removal, the nanocapsules maintained their spherical shape and a decrease of size occurred. A cationic bioactive compound, poly-L-lysine (PLL), was chosen to evaluate the loading and release behaviour of the nanocapsules. The chitosan/fucoidan nanocapsules showed a good capacity for the encapsulation and loading of PLL, which shows to be influenced by the initial PLL concentration and the method of encapsulation used. The results of fitting the linear superimposition model to the experimental data of PLL release suggest an anomalous behaviour, with one main polymer relaxation. The PLL release was found to be pH-dependent: at pH 2 relaxation is the governing phenomenon and at pH 7 Fick's diffusion is the main mechanism of PLL release. Chitosan/fucoidan nanocapsules is a promising delivery system for water soluble bioactive compounds, such as PLL, showing a great potential of application in food and pharmaceutical industries.

Bovine serum albumin nanoparticles as controlled release carrier for local drug delivery to the inner ear

Nanoparticles have attracted increasing attention for local drug delivery to the inner ear recently. Bovine serum albumin (BSA) nanoparticles were prepared by desolvation method followed by glutaraldehyde fixation or heat denaturation. The nanoparticles were spherical in shape with an average diameter of 492 nm. The heat-denatured nanoparticles had good cytocompatibility. The nanoparticles could adhere on and penetrate through the round window membrane of guinea pigs. The nanoparticles were analyzed as drug carriers to investigate the loading capacity and release behaviors. Rhodamine B was used as a model drug in this paper. Rhodamine B-loaded nanoparticles showed a controlled release profile and could be deposited on the osseous spiral lamina. We considered that the bovine serum albumin nanoparticles may have potential applications in the field of local drug delivery in the treatment of inner ear disorders.

Ocular delivery of macromolecules

Biopharmaceuticals are making increasing impact on medicine, including treatment of indications in the eye. Macromolecular drugs are typically given by physician-administered invasive delivery methods, because non-invasive ocular delivery methods, such as eye drops, and systemic delivery, have low bioavailability and/or poor ocular targeting. There is a need to improve delivery of biopharmaceuticals to enable less-invasive delivery routes, less-frequent dosing through controlled-release drug delivery and improved drug targeting within the eye to increase efficacy and reduce side effects. This review discusses the barriers to drug delivery via various ophthalmic routes of administration in the context of macromolecule delivery and discusses efforts to develop controlled-release systems for delivery of biopharmaceuticals to the eye. The growing number of macromolecular therapies in the eye needs improved drug delivery methods that increase drug efficacy, safety and patient compliance.

Bioactive factor delivery strategies from engineered polymer hydrogels for therapeutic medicine

Polymer hydrogels have been widely explored as therapeutic delivery matrices because of their ability to present sustained, localized and controlled release of bioactive factors. Bioactive factor delivery from injectable biopolymer hydrogels provides a versatile approach to treat a wide variety of diseases, to direct cell function and to enhance tissue regeneration. The innovative development and modification of both natural-(e.g., alginate (ALG), chitosan, hyaluronic acid (HA), gelatin, heparin (HEP), etc.) and synthetic-(e.g., polyesters, polyethyleneimine (PEI), etc.) based polymers has resulted in a variety of approaches to design drug delivery hydrogel systems from which loaded therapeutics are released. This review presents the state-of-the-art in a wide range of hydrogels that are formed though self-assembly of polymers and peptides, chemical crosslinking, ionic crosslinking and biomolecule recognition. Hydrogel design for bioactive factor delivery is the focus of the first section. The second section then thoroughly discusses release strategies of payloads from hydrogels for therapeutic medicine, such as physical incorporation, covalent tethering, affinity interactions, on demand release and/or use of hybrid polymer scaffolds, with an emphasis on the last 5 years.

Thermoresponsive polymers: insights into decisive hydrogel characteristics, mechanisms of gelation, and promising biomedical applications

Thermally induced gelling systems have gained enormous attention over the last decade. They consist of hydrophilic homopolymers or block copolymers in water that present a sol at room temperature and form a gel after administration into the body. This article reviews the main types of thermoresponsive polymers, with special focus on decisive hydrogel characteristics, mechanisms of gelation, and biocompatibility. Promising biomedical applications are described with a focus on injectable formulations, which include solubilization of small hydrophobic drugs, controlled release, delivery of labile biopharmaceutics, such as proteins and genes, cell encapsulation, and tissue regeneration. Furthermore, combinations of thermoresponsive hydrogels and various nanocarriers as promising systems for sustained drug delivery are discussed through selected examples from the literature. Finally, there is a brief overview of current progress in nano-sized systems incorporating thermoresponsive properties.

IGF-1 release kinetics from chitosan microparticles fabricated using environmentally benign conditions

The main objective of this study is to maximize growth factor encapsulation efficiency into microparticles. The novelty of this study is to maximize the encapsulated growth factors into microparticles by minimizing the use of organic solvents and using relatively low temperatures. The microparticles were fabricated using chitosan biopolymer as a base polymer and cross-linked with tripolyphosphate (TPP). Insulin like-growth factor-1 (IGF-1) was encapsulated into microparticles to study release kinetics and bioactivity. In order to authenticate the harms of using organic solvents like hexane and acetone during microparticle preparation, IGF-1 encapsulated microparticles prepared by the emulsification and coacervation methods were compared. The microparticles fabricated by emulsification method have shown a significant decrease (p<0.05) in IGF-1 encapsulation efficiency, and cumulative release during the two-week period. The biocompatibility of chitosan microparticles and the bioactivity of the released IGF-1 were determined in vitro by live/dead viability assay. The mineralization data observed with von Kossa assay, was supported by mRNA expression levels of osterix and runx2, which are transcription factors necessary for osteoblasts differentiation. Real time RT-PCR data showed an increased expression of runx2 and a decreased expression of osterix over time, indicating differentiating osteoblasts. Chitosan microparticles prepared in optimum environmental conditions are a promising controlled delivery system for cells to attach, proliferate, differentiate and mineralize, thereby acting as a suitable bone repairing material.

Smart microneedle coatings for controlled delivery and biomedical analysis

The work presented demonstrates an unconventional approach in the preparation of smart microneedle (MN) coatings utilising electrohydrodynamic atomisation (EHDA) principles. Stainless steel (600-900 µm in height) MNs were coupled to a ground electrode (in the EHDA coating set-up) with the deposition distance and collecting methodology varied for an ethanol:methanol (50:50) vehicle system. The preparation of nano- and micrometre-scaled pharmaceutical coatings was achieved. Fluorescein dye (serving as potential drug, sensory materials or disease state markers) and polyvinylpyrrolidone (PVP, polymer matrix system) formed the remaining components of the coating formulation. Based on these excipients and by varying the coating process, particles (100 nm to 3 µm) and fibres (400 nm to 1 µm) were deposited directly on MNs in controlled and selectable fashion (flow rates variable ∼ 5-50 µL/min, applied voltage variable 6-19 kV). These demonstrated options for multiple targeting and analysis applications. The underlying EHDA process permits room temperature fabrication, controlled output and scale-up potential for emerging MN devices as drug systems or lab-chip testing devices.

Nanotherapy for posterior eye diseases

It is assumed that more than 50% of the most enfeebling ocular diseases have their origin in the posterior segment. Furthermore, most of these diseases lead to partial or complete blindness, if left untreated. After cancer, blindness is the second most dreaded disease world over. However, treatment of posterior eye diseases is more challenging than the anterior segment ailments due to a series of anatomical barriers and physiological constraints confronted for delivery to this segment. In this regard, nanostructured drug delivery systems are proposed to defy ocular barriers, target retina, and act as permeation enhancers in addition to providing a controlled release. Since an important step towards developing effective treatment strategies is to understand the course or a route a drug molecule needs to follow to reach the target site, the first part of the present review discusses various pathways available for effective delivery to and clearance from the posterior eye. Promise held by nanocarrier systems, viz. liposomes, nanoparticles, and nanoemulsion, for effective delivery and selective targeting is also discussed with illustrative examples, tables, and flowcharts. However, the applicability of these nanocarrier systems as self-administration ocular drops is still an unrealized dream which is in itself a huge technological challenge.

Polymer multilayers loaded with antifungal β-peptides kill planktonic Candida albicans and reduce formation of fungal biofilms on the surfaces of flexible catheter tubes

Candida albicans is the most common fungal pathogen responsible for hospital-acquired infections. Most C. albicans infections are associated with the implantation of medical devices that act as points of entry for the pathogen and as substrates for the growth of fungal biofilms that are notoriously difficult to eliminate by systemic administration of conventional antifungal agents. In this study, we report a fill-and-purge approach to the layer-by-layer fabrication of biocompatible, nanoscale 'polyelectrolyte multilayers' (PEMs) on the luminal surfaces of flexible catheters, and an investigation of this platform for the localized, intraluminal release of a cationic β-peptide-based antifungal agent. We demonstrate that polyethylene catheter tubes with luminal surfaces coated with multilayers ~700nm thick fabricated from poly-l-glutamic acid (PGA) and poly-l-lysine (PLL) can be loaded, post-fabrication, by infusion with β-peptide, and that this approach promotes extended intraluminal release of this agent (over ~4months) when incubated in physiological media. The β-peptide remained potent against intraluminal inoculation of the catheters with C. albicans and substantially reduced the formation of C. albicans biofilms on the inner surfaces of film-coated catheters. Finally, we report that these β-peptide-loaded coatings exhibit antifungal activity under conditions that simulate intermittent catheter use and microbial challenge for at least three weeks. We conclude that β-peptide-loaded PEMs offer a novel and promising approach to kill C. albicans and prevent fungal biofilm formation on surfaces, with the potential to substantially reduce the incidence of device-associated infections in indwelling catheters. β-Peptides comprise a promising new class of antifungal agents that could help address problems associated with the use of conventional antifungal agents. The versatility of the layer-by-layer approach used here thus suggests additional opportunities to exploit these new agents in other biomedical and personal care applications in which fungal infections are endemic.

Transdermal drug delivery: 30+ years of war and still fighting!

By any measure, transdermal drug delivery (TDD) is a successful controlled release technology. Over the last 30+ years, a steady flux of transdermal products have received regulatory approval and reached the market. For the right compounds, TDD is an effective and preferred route of administration; for others, delivery across the skin makes no sense at all. Currently, the "rules" that govern (passive) TDD feasibility are clearly understood, and research activity is focused on novel approaches that strive to subvert skin's excellent barrier function, and broaden the range of active species amenable to percutaneous administration.

Bioresponsive nanohydrogels based on HEAA and NIPA for poorly soluble drugs delivery

Environmentally sensitive hydrogels have gained considerable attention in recent years as one of the most promising drug delivery systems. In the present study, two new formulations of pH and temperature stimuli-responsive nanogels (NGs) based on poly-N-isopropylacrylamide (NIPA), N-hydroxyethyl acrylamide (HEAA) and tert-butyl 2-acrylamidoethyl carbamate (2AAECM) were synthesized and evaluated for passive targeting of paclitaxel (PTX). Nanogels were prepared by microemulsion polymerization method using N-methylenebis(acrylamide) (NMBA) as crosslinking agent. TEM images and DLS results showed nanosized spherical hydrogels. FTIR spectra confirmed the synthesis of nanogels by radical polymerization among vinyl groups of monomers. The PTX loading capacity, encapsulation efficiency and in vitro release were analyzed by HPLC. The cumulative release profile of the PTX-loaded nanohydrogels within 144h showed a faster drug release at acid pH (pH 5), similar to those observed at lysosome compartment, whereas a fewer PTX amount was released from NGs at pH similar to plasma levels. Cellular uptake assays revealed rapid penetration and intracellular accumulation of those nanogels in MCF7, HeLa and T47D cells after 48h incubation. MTT assays showed cell viability dependence on concentration and time incubation. Finally, the PTX effect on cell viability showed a G2/M cell arrest after using PTX-loaded NGs and pure PTX.

Controlled release for local delivery of drugs: barriers and models

Controlled release systems are an effective means for local drug delivery. In local drug delivery, the major goal is to supply therapeutic levels of a drug agent at a physical site in the body for a prolonged period. A second goal is to reduce systemic toxicities, by avoiding the delivery of agents to non-target tissues remote from the site. Understanding the dynamics of drug transport in the vicinity of a local drug delivery device is helpful in achieving both of these goals. Here, we provide an overview of controlled release systems for local delivery and we review mathematical models of drug transport in tissue, which describe the local penetration of drugs into tissue and illustrate the factors - such as diffusion, convection, and elimination - that control drug dispersion and its ultimate fate. This review highlights the important role of controlled release science in development of reliable methods for local delivery, as well as the barriers to accomplishing effective delivery in the brain, blood vessels, mucosal epithelia, and the skin.

Recent advances in liposomal nanohybrid cerasomes as promising drug nanocarriers

Liposomes have been extensively investigated as possible carriers for diagnostic or therapeutic agents due to their unique properties. However, liposomes still have not attained their full potential as drug and gene delivery vehicles because of their insufficient morphological stability. Recently, a super-stable and freestanding hybrid liposomal cerasome (partially ceramic- or silica-coated liposome) has drawn much attention as a novel drug delivery system because its atomic layer of polyorganosiloxane surface imparts higher morphological stability than conventional liposomes and its liposomal bilayer structure reduces the overall rigidity and density greatly compared to silica nanoparticles. Cerasomes are more biocompatible than silica nanoparticles due to the incorporation of the liposomal architecture into cerasomes. Cerasomes combine the advantages of both liposomes and silica nanoparticles but overcome their disadvantages so cerasomes are ideal drug delivery systems. The present review will first highlights some of the key advances of the past decade in the technology of cerasome production and then review current biomedical applications of cerasomes, with a view to stimulating further research in this area of study.

Gelatin carriers for drug and cell delivery in tissue engineering

The ability of gelatin to form complexes with different drugs has been investigated for controlled release applications. Gelatin parameters, such as crosslinking density and isoelectric point, have been tuned in order to optimize gelatin degradation and drug delivery kinetics. In recent years, focus has shifted away from the use of gelatin in isolation toward the modification of gelatin with functional groups and the fabrication of material composites with embedded gelatin carriers. In this review, we highlight some of the latest work being performed in these areas and comment on trends in the field. Specifically, we discuss gelatin modifications for immune system evasion, drug stabilization, and targeted delivery, as well as gelatin composite systems based on ceramics, naturally-occurring polymers, and synthetic polymers.

The effect of polymer properties on direct compression and drug release from water-insoluble controlled release matrix tablets

The objective of this study was to identify and evaluate key polymer properties affecting direct compression and drug release from water-insoluble matrices. Commonly used polymers, such as Kollidon(®) SR, Eudragit(®) RS and ethyl cellulose, were characterized, formulated into tablets and compared with regard to their properties in dry and wet state. A similar site percolation threshold of 65% v/v was found for all polymers in dry state. Key parameters influencing polymer compactibility were the surface properties and the glass transition temperature (T(g)), affecting polymer elasticity and particle size-dependent binding. The important properties observed in dry state also governed matrix characteristics and therefore drug release in wet state. A low T(g) (Kollidon(®) SR<Eudragit(®) RS) decreased the percolation threshold, particle size effect and tortuosity, but increased permeability and sensitivity to heat/humidity treatment. Hence, lower permeability and higher stability are benefits of a high-T(g) polymer (ethyl cellulose). However, release retardation was observed in the same order as matrix integrity (Eudragit(®) RS<ethyl cellulose<Kollidon(®) SR), as the high permeability was counteracted by PVP in case of Kollidon(®) SR. Therefore, the Tg and composition of a polymer need to be considered in polymer design and formulation of controlled-release matrix systems.

Stimulation of bone regeneration following the controlled release of water-insoluble oxysterol from biodegradable hydrogel

Recently bone graft substitutes using bone morphogenetic proteins (BMPs) have been heralded as potential alternatives to traditional bone reconstruction procedures. BMP-based products, however, are associated with significant and potentially life-threatening side effects when used in the head and neck region and furthermore, are exorbitantly priced. Oxysterols, products of cholesterol oxidation, represent a class of molecules that are favorable alternatives or adjuncts to BMP therapy due to their low side effect profile and cost. In order to establish the optimal clinical utility of oxysterol, an optimal scaffold must be developed, one that allows the release of oxysterol in a sustained and efficient manner. In this study, we prepare a clinically applicable bone graft substitute engineered for the optimal release of oxysterol. We first solubilized oxysterol in water by making use of polymeric micelles using l-lactic acid oligomer (LAo) grafted gelatin. Then, the water-solubilized oxysterol was incorporated into a biodegradable hydrogel that was enzymatically degraded intracorporeally. In this manner, oxysterol could be released from the hydrogel in a degradation-driven manner. The water-solubilized oxysterol incorporated biodegradable hydrogel was implanted into rat calvarial defects and induced successful bone regeneration. The innovative significance of this study lies in the development of a bone graft substitute that couples the osteogenic activity of oxysterol with a scaffold designed for optimized oxysterol release kinetics, all of which lead to better repair of bone defects.

Quantifying the release of lactose from polymer matrix tablets with an amperometric biosensor utilizing cellobiose dehydrogenase

The release of lactose (hydrophilic) from polymer tablets made with hydrophobically modified poly(acrylic acid) (HMPAA) have been studied and compared to the release of ibuprofen, a hydrophobic active substance. Lactose is one of the most used excipients for tablets, but lactose release has not been widely studied. One reason could be a lack of good analytical tools. A novel biosensor with cellobiose dehydrogenase (CDH) was used to detect the lactose release, which has a polydiallyldimethylammonium chloride (PDADMAC) layer that increases the response. A sample treatment using polyethylenimine (PEI) was developed to eliminate possible denaturants. The developed methodology provided a good approach to detect and quantify the released lactose. The release was studied with or without the presence of a model amphiphilic substance, sodium dodecyl sulphate (SDS), in the release medium. Ibuprofen showed very different release rates in the different media, which was attributed to hydrophobic interactions between the drug, the HMPAA and the SDS in the release medium. The release of hydrophilic lactose, which did not associate to any of the other components, was rapid and showed only minor differences. The new methodology provides a useful tool to further evaluate tablet formulations by a relatively simple set of experiments.

NMR cryoporometry characterisation studies of the relation between drug release profile and pore structural evolution of polymeric nanoparticles

PLGA/PLA polymeric nanoparticles could potentially enhance the effectiveness of convective delivery of drugs, such as carboplatin, to the brain, by enabling a more sustained dosage over a longer time than otherwise possible. However, the link between the controlled release nanoparticle synthesis route, and the subsequent drug release profile obtained, is not well-understood, which hinders design of synthesis routes and availability of suitable nanoparticles. In particular, despite pore structure evolution often forming a key aspect of past theories of the physical mechanism by which a particular drug release profile is obtained, these theories have not been independently tested and validated against pore structural information. Such validation is required for intelligent synthesis design, and NMR cryoporometry can supply the requisite information. Unlike conventional pore characterisation techniques, NMR cryoporometry permits the investigation of porous particles in the wet state. NMR cryoporometry has thus enabled the detailed study of the evolving, nanoscale structure of nanoparticles during drug release, and thus related pore structure to drug release profile in a way not done previously for nanoparticles. Nanoparticles with different types of carboplatin drug release profiles were compared, including burst release, and various forms of delayed release. ESEM and TEM images of these nanoparticles also provided supporting data showing the rapid initial evolution of some nanoparticles. Different stages, within a complex, varying drug release profile, were found to be associated with particular types of changes in the nanostructure which could be distinguished by NMR. For a core-coat nanoparticle formulation, the development of smaller nanopores, following an extended induction period with no structural change, was associated with the onset of substantial drug release. This information could be used to independently validate the rationale for a particular synthesis method. Hence, the specific reasons for the effectiveness of the synthesis route, for obtaining core-coat nanoparticles with delayed release, have been elucidated.

Camptothecin-Loaded Liposomes with α-Melanocyte-Stimulating Hormone Enhance Cytotoxicity Toward and Cellular Uptake by Melanomas: An Application of Nanomedicine on Natural Product

In this study, we attempted to develop functional liposomes loaded with camptothecin and attached to α-melanocyte-stimulating hormone (α-MSH) to target melanoma cells. The liposomes were mainly composed of phosphatidylcholine, cholesterol, and stearylamine, and were characterized by the vesicle size, zeta potential, camptothecin encapsulation efficiency, and release behavior. Results revealed that α-MSH liposomes possessed an average size of approximately 250 nm with a surface charge of 60 mV. Camptothecin was successfully entrapped by the targeted liposomes with an encapsulation percentage of nearly 95%. The liposomes provided sustained and controlled camptothecin release. Non-targeted liposomes with the drug exerted superior cytotoxicity against melanomas compared to the free control. Cell viability was reduced from 48% to 32% compared to conventional liposomes. Peptide ligand conjugation further promoted cytotoxicity to 18% viability, which was a 2.7-fold decrease versus the free control. According to the images of fluorescence microscopy, α-MSH liposomes exhibited greater cell endocytosis than did non-targeted liposomes and the free control. α-MSH liposomes were predominantly internalized in the cytoplasm. These findings demonstrate that α-MSH liposomes could enhance the anti-melanoma activity of camptothecin owing to their targeting ability and controlled drug delivery.

Molecular engineering of glycosaminoglycan chemistry for biomolecule delivery

Glycosaminoglycans (GAGs) are linear, negatively charged polysaccharides that interact with a variety of positively charged growth factors. In this review article the effects of engineering GAG chemistry for molecular delivery applications in regenerative medicine are presented. Three major areas of focus at the structure-function-property interface are discussed: (1) macromolecular properties of GAGs; (2) effects of chemical modifications on protein binding; (3) degradation mechanisms of GAGs. GAG-protein interactions can be based on: (1) GAG sulfation pattern; (2) GAG carbohydrate conformation; (3) GAG polyelectrolyte behavior. Chemical modifications of GAGs, which are commonly performed to engineer molecular delivery systems, affect protein binding and are highly dependent on the site of modification on the GAG molecules. The rate and mode of degradation can determine the release of molecules as well as the length of GAG fragments to which the cargo is electrostatically coupled and eventually released from the delivery system. Overall, GAG-based polymers are a versatile biomaterial platform offering novel means to engineer molecular delivery systems with a high degree of control in order to better treat a range of degenerated or injured tissues.

Preparation, characterization and in vitro antiviral activity evaluation of foscarnet-chitosan nanoparticles

A new nanoparticulate system for foscarnet delivery was prepared and evaluated. Nanoparticles were obtained by ionotropic gelation of chitosan induced by foscarnet itself, acting as an ionotropic agent in a manner similar to tripolyphosphate anion. A Doehlert design allowed finding the suitable experimental conditions. Nanoparticles were between 200 and 300nm in diameter (around 450nm after redispersion). Nanoparticle size increased after 5h, but no size increase was observed after 48h when nanoparticles were crosslinked with glutaraldehyde. Zeta potential values of noncrosslinked and crosslinked nanoparticles were between 20 and 25mV, while drug loading of noncrosslinked nanoparticles was about 40% w/w (55% w/w for crosslinked nanoparticles). Nanoparticle yield was around 25% w/w. Crosslinked nanoparticles showed a controlled drug release. Foscarnet released from nanoparticles maintained the antiviral activity of the free drug when tested in vitro against lung fibroblasts (HELF) cells infected with HCMV strain AD-169. Moreover, nanoparticles showed no toxicity on non-infected HELF cells. These nanoparticles may represent a delivery system that could improve the therapeutic effect of foscarnet.

pH-responsive unimolecular micelles self-assembled from amphiphilic hyperbranched block copolymer for efficient intracellular release of poorly water-soluble anticancer drugs

Novel unimolecular micelles from amphiphilic hyperbranched block copolymer H40-poly(ε-caprolactone)-b-poly(acrylic acid)-b'-methoxy poly(ethylene glycol)/poly(ethylene glycol)-folate (i.e., H40-PCL-b-PAA-b'-MPEG/PEG-FA (HCAE-FA)) as new multifunctional nanocarriers to pH-induced accelerated release and tumor-targeted delivery of poorly water-soluble anticancer drugs were developed. The hydrophobic core of the unimolecular micelle was hyperbranched polyester (H40-poly(ε-caprolactone) (H40-PCL)). The inner hydrophilic layer was composed of PAA segments, while the outer hydrophilic shell was composed of PEG segments. This copolymer formed unimolecular micelles in the aqueous solution with a mean particle size of 33 nm, as determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM). To study the feasibility of micelles as a potential nanocarrier for targeted drug delivery, we encapsulated a hydrophobic anticancer drug, paclitaxel (PTX), in the hydrophobic core, and the loading content was determined by UV-vis analysis to be 10.35 wt.%. In vitro release studies demonstrated that the drug-loaded delivery system is relatively stable at physiologic conditions but susceptible to acidic environments which would trigger the release of encapsulated drugs. Flow cytometry and fluorescent microscope studies revealed that the cellular binding of the FA-conjugated micelles against HeLa cells was higher than that of the neat micelles (without FA). The in vitro cytotoxicity studies showed that the PTX transported by these micelles was higher than that by the commercial PTX formulation Tarvexol®. All of these results show that these unique unimolecular micelles may offer a very promising approach for targeted cancer therapy.

pH-responsive controlled release of epirubicin from Fe@Si-PW hybrid nanoparticles

An efficient drug delivery system has been fabricated through an electrostatic interaction between epirubicin and H3PW12O40-functionalized silica encapsulated maghemite nanoparticles. The obtained nanoparticles were characterized for morphology, size distribution, drug loading efficiency, drug content and drug release behavior. Our results indicate that the hybrid nanoparticles possess high adsorption capacity for epirubicin (20.6wt.%) and high drug loading efficiency (82.6%). The drug release is greater in acetate buffer (95.8%) as compared to phosphate buffered saline (47.5%). The pH-responsive release of the hybrid drug carrier and high drug loading efficiency are its advantages as a promising carrier.

Predicting release and transport of pesticides from a granular formulation during unsaturated diffusion in porous media

The release and transport of active ingredients (AIs) from controlled-release formulations (CRFs) have potential to reduce groundwater pesticide pollution. These formulations have a major effect on the release rate and subsequent transport to groundwater. Therefore the influence of CRFs should be included in modeling non-point source pollution by pesticides. We propose a simplified approach that uses a phase transition equation coupled to the diffusion equation that describes the release rate of AIs from commercial CRFs in porous media; the parameters are as follows: a release coefficient, the solubility of the AI, and diffusion transport with decay. The model gives acceptable predictions of the pesticides release from commercial CRFs in diffusion cells filled with quartz sand. This approach can be used to study the dynamics of the CRF-porous media interaction. It also could be implemented in fate of agricultural chemical models to include the effect of CRFs.

Controlled release of nerve growth factor from heparin-conjugated fibrin gel within the nerve growth factor-delivering implant

Objectives

Although nerve growth factor (NGF) could promote the functional regeneration of an injured peripheral nerve, it is very difficult for NGF to sustain the therapeutic dose in the defect due to its short half-life. In this study, we loaded the NGF-bound heparin-conjugated fibrin (HCF) gel in the NGF-delivering implants and analyzed the time-dependent release of NGF and its bioactivity to evaluate the clinical effectiveness.

Materials and Methods

NGF solution was made of 1.0 mg of NGF and 1.0 mL of phosphate buffered saline (PBS). Experimental group A consisted of three implants, in which 0.25 µL of NGF solution, 0.75 µL of HCF, 1.0 µL of fibrinogen and 2.0 µL of thrombin was injected via apex hole with micropipette and gelated, were put into the centrifuge tube. Three implants of experimental group B were prepared with the mixture of 0.5 µL of NGF solution, 0.5 µL HCF, 1.0 µL of fibrinogen and 2.0 µL of thrombin. These six centrifuge tubes were filled with 1.0 mL of PBS and stirred in the water-filled beaker at 50 rpm. At 1, 3, 5, 7, 10, and 14 days, 1.0 mL of solution in each tubes was collected and preserved at -20℃ with adding same amount of fresh PBS. Enzyme-linked immunosorbent assay (ELISA) was done to determine in vitro release profile of NGF and its bioactivity was evaluated with neural differentiation of pheochromocytoma (PC12) cells.

Results

The average concentration of released NGF in the group A and B increased for the first 5 days and then gradually decreased. Almost all of NGF was released during 10 days. Released NGF from two groups could promote neural differentiation and neurite outgrowth of PC12 cells and these bioactivity was maintained over 14 days.

Conclusion

Controlled release system using NGF-HCF gel via NGF-delivering implant could be an another vehicle of delivering NGF to promote the nerve regeneration of dental implant related nerve damage.

In vitro controlled release of vitamin C from Ca/Al layered double hydroxide drug delivery system

A new drug delivery system for vitamin C (VC), Ca/Al layered double hydroxide (LDH), is demonstrated in this work. VC anions were intercalated successfully in the Ca/Al LDH gallery by a coprecipitation method. The interlayer space of 9.8Å suggests that VC anions are vertical to the LDH layers in the form of interdigitated bilayer. The loading of VC in LDH is 36.4wt.%. The thermal stability of VC is significantly enhanced after intercalation. In vitro VC release results show that the release time of VC in a phosphate buffer at pH7.4 was significantly extended, and the maximal percentage of VC released is 80% of the total. The Avrami-Erofe'ev equation most satisfactorily explains the release kinetics of VC, which is that the release of VC is mainly dominated by the ion-exchange reaction.

Formulation of porous poly(lactic-co-glycolic acid) microparticles by electrospray deposition method for controlled drug release

In the present study, the electrospray deposition was successfully applied to prepare the porous poly(lactic-co-glycolic acid) (PLGA) microparticles by one-step processing. Metronidazole was selected as the model drug. The porous PLGA microparticles had high drug loading and low density, and the porous structure can be observed by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The production time has been shortened considerably compared with that of the traditional multi-emulsion method. In addition, no chemical reaction occurred between the drug and polymer in the preparation of porous microparticles, and the crystal structure of drug did not change after entrapment into the porous microparticles. The porous microparticles showed a sustained release in the simulated gastric fluid, and the release followed non-Fickian or case II transport. Furthermore, porous microparticles showed a slight cytotoxicity in vitro. The results indicated that electrospray deposition is a good technique for preparation of porous microparticles, and the low-density porous PLGA microparticles has a potential for the development of gastroretentive systems or for pulmonary drug delivery.

Biosurfactant stabilized anticancer biomolecule-loaded poly (D,L-lactide) nanoparticles

PLA nanoparticles (NPs) were prepared via green route using turmeric (Curcuma longa) extract (TE) as biostabiliser/biosurfactant. Of the 29 formulations, two formulations of TE synthesized PLA NPs were evaluated for encapsulation and controlled release of well known antioxidant and less bioavailable molecules curcumin and quercetin. Size of curcumin loaded PLA NPs synthesized using 0.8 mg/ml PLA (C-En-D) and 0.1 mg/ml PLA (C-En-P) were 203±77 and 110±44 nm, respectively. However, quercetin loaded PLA NPs synthesized at 0.8 mg/ml (Q-En-D) and 0.1mg/ml (Q-En-P) PLA concentrations were 170±95 and 102±31 nm, respectively. The encapsulation efficiency of curcumin loaded PLA (C-En-D and C-En-P) NPs as well as quercetin loaded PLA (Q-En-D and Q-En-P) NPs was found ∼95%. In vitro release study of C-En-D, C-En-P, Q-En-D and Q-En-P NPs showed initial burst release followed by slow and sustained release. C-En-D NPs and Q-En-D NPs showing maximum in vitro release (∼100%) were evaluated for cytotoxicity. Blank PLA NPs, C-En-D and Q-En-D NPs were found to be safe against normal human leukocytes up to 2 mg/ml dose. Both C-En-D and Q-En-D NPs showed anticancer activity against A549 cell line. But Q-En-D NPs showed better anticancer activity than C-En-D NPS on A549 cells. While blank PLA NPs did not possess anticancer activity. TE extract stabilized PLA NPs were non-toxic, biocompatible and safe to normal human leukocytes. Such technology will be better, effective and safer in use for anticancer as well as other biological application.

Injectable, self-gelling, biodegradable, and immunomodulatory DNA hydrogel for antigen delivery

DNA nanotechnology-based nanosystems and macrosystems have attracted much attention in the biomedical research field. The nature of DNA endows these systems with biodegradable, biocompatible, and immunomodulatory properties. Here, we present an injectable hydrogel system that consists only of chemically synthesized short DNA strands, water, and salts. Several preparations of polypod-like structured DNA, or polypodna, were designed, including tri-, tetra-, penta- and hexapodna, as the building blocks of self-gelling DNA hydrogel. Under physiological conditions, properly designed polypodna preparations formed a hydrogel. The analysis of the modulus data of the hydrogel consisting of two sets of hexapodna preparations showed that this injectable hydrogel was reorganized at a time scale of 0.25s. Then, DNA hydrogel containing unmethylated cytosine-phosphate-guanine (CpG) dinucleotides was used to stimulate innate immunity through Toll-like receptor 9, the receptor for CpG DNA. Gel formation significantly increased the activity of immunostimulatory CpG DNA, retarded the clearance after intradermal injection into mice, and increased the immune responses to ovalbumin (OVA) incorporated into the hydrogel as a model antigen. OVA/CpG DNA hydrogel induced much less local or systemic adverse reactions than OVA injected with complete Freund's adjuvant or alum. GpC DNA hydrogel containing no CpG sequences was less effective, indicating the importance of immunomodulation by CpG DNA hydrogel. Thus, we have created an efficient system for sustained delivery of antigens or other bioactive compounds.

The controlled release of bioactive compounds from lignin and lignin-based biopolymer matrices

This article presents the perspectives on the lignin-based controlled release (CR) of bioactive materials which are based on the researches that took place over the last three decades. It encompasses three broad spectra of observations: CR formulations with mixed-matrix of lignin; CR formulations with modified lignin; and the lignin-based CR formulation modelling. The article covers a range of bioactive materials aimed for agricultural utilisations viz. herbicides, pesticides, insecticides and fertilisers for their controlled release studies, which were formulated either with lignin or lignin-based biopolymers. The inherent complexities, structural heterogeneities, and the presence of myriad range of functionalities in the lignin structure make it difficult to understand and explaining the underlying CR behaviour and process. In conjunction to this issue, the fundamental aspects of the synthetic and biocompatible polymer-based drug controlled release process are presented, and correlated with the lignin-based CR research. The articulation of this correlation and the overview presented in this article may be complemented of the future lignin-based CR research gaining better insights, reflections, and understanding. A recommended approach on the lignin depolymerisation is suggested to fragmenting the lignin, which may be tailored further using the re-polymerisation or other synthetic approaches. Thus it may allow more control with flexibilities and improved properties of the modified lignin materials, and help achieve the desired CR outcomes.

Encapsulation and controlled release of hydrophilic pesticide in shell cross-linked nanocapsules containing aqueous core

In this study, amphiphilic biocopolymers, synthesized by mixing azidobenzaldehyde (Az) and an aqueous solution of carboxymethyl chitosan (CMCS), which self-assemble into nanocapsules with a aqueous core (ACN) in aqueous media followed by photo-cross-linking to obtain shell cross-linked nanocapsules, were used to develop a controlled release pesticide system. The system was characterized by TEM and DLS. Its encapsulation efficiency was determined. The obtained result showed that it is efficient to encapsulate methomyl reaching encapsulation efficiency as high as 90% in an aqueous medium at pH 4.0, which is mainly attributed to the hydrogen bonding adsorption between methomyl molecules and the inner surface of nanocapsules. Release profiles of methomyl from methomyl-loaded nanocapsules in an aqueous solution at pH 6.0 were shown to be diffusion controlled with a half-release time (t(½)) of 36.3-69.5h from different samples. The shell cross-linking and its degree of cross-linking are assumed to be responsible for this diffusion behavior. The insecticidal activity test in laboratory showed that the control efficacy of methomyl-loaded nanocapsules against the armyworm larvae was significantly superior to the original. The relative control efficacy still maintained 100% over 7 days.

An emerging platform for drug delivery: aerogel based systems

Over the past few decades, advances in "aerogel science" have provoked an increasing interest for these materials in pharmaceutical sciences for drug delivery applications. Because of their high surface areas, high porosities and open pore structures which can be tuned and controlled by manipulation of synthesis conditions, nanostructured aerogels represent a promising class of materials for delivery of various drugs as well as enzymes and proteins. Along with biocompatible inorganic aerogels and biodegradable organic aerogels, more complex systems such as surface functionalized aerogels, composite aerogels and layered aerogels have also been under development and possess huge potential. Emphasis is given to the details of the aerogel synthesis and drug loading methods as well as the influence of synthesis parameters and loading methods on the adsorption and release of the drugs. Owing to their ability to increase the bioavailability of low solubility drugs, to improve both their stability and their release kinetics, there are an increasing number of research articles concerning aerogels in different drug delivery applications. This review presents an up to date overview of the advances in all kinds of aerogel based drug delivery systems which are currently under investigation.

Evaluation of Calendula mucilage as a mucoadhesive and controlled release component in buccal tablets

Mucoadhesive drug delivery systems were developed to sustain drug delivery via various mucus membranes for either local or systemic delivery of poorly absorbed drugs such as peptides and proteins as well as drugs that are subjected to high first-pass metabolism. The present study was undertaken to use isolated Calendula mucilage as a mucoadhesive agent and to formulate controlled release buccoadhesive tablets with an intention to avoid hepatic first-pass metabolism as well as to enhance residence time of drug in the buccal cavity. The mucilage was isolated from the Calendula petals by aqueous extraction method and characterized for various physiochemical parameters as well as for its adhesive properties. By using direct compression technique, tablets were prepared containing dried mucilage and chlorpheniramine maleate (CPM) as a model drug. Three batches of tablets were prepared and evaluated containing three mucoadhesive components namely Methocel K4M, Carbopol 974P and isolated Calendula mucilage in 16.66%, 33.33 % and 50 % (1:2:3 ratio) resulting in 9 different formulations. FTIR studies between mucilage and CPM suggested the absence of a chemical interaction between CPM and Calendula mucilage. The results of the study showed that the isolated mucilage had good physicochemical and morphological characteristics and tablets conformed to the pharmacopoeial specifications. Also in vitro release studies showed controlled action of drug with increasing the concentration of the isolated Calendula mucilage as a mucoadhesive agent in the formulations. Permeability studies indicated that permeability behavior was not statistically different (P>0.05) by changing the mucoadhesive component. The formulated mucoadhesive tablets for buccal administration containing 75 mg Calendula mucilage showed controlled drug release. Thus, mucoadhesive natural Calendula mucilage based buccal tablets for controlled release were successfully formulated.

Single-step assembly of polymer-lipid hybrid nanoparticles for mitomycin C delivery

Mitomycin C is one of the most effective chemotherapeutic agents for a wide spectrum of cancers, but its clinical use is still hindered by the mitomycin C (MMC) delivery systems. In this study, the MMC-loaded polymer-lipid hybrid nanoparticles (NPs) were prepared by a single-step assembly (ACS Nano 2012, 6:4955 to 4965) of MMC-soybean phosphatidyhlcholine (SPC) complex (Mol. Pharmaceutics 2013, 10:90 to 101) and biodegradable polylactic acid (PLA) polymers for intravenous MMC delivery. The advantage of the MMC-SPC complex on the polymer-lipid hybrid NPs was that MMC-SPC was used as a structural element to offer the integrity of the hybrid NPs, served as a drug preparation to increase the effectiveness and safety and control the release of MMC, and acted as an emulsifier to facilitate and stabilize the formation. Compared to the PLA NPs/MMC, the PLA NPs/MMC-SPC showed a significant accumulation of MMC in the nuclei as the action site of MMC. The PLA NPs/MMC-SPC also exhibited a significantly higher anticancer effect compared to the PLA NPs/MMC or free MMC injection in vitro and in vivo. These results suggested that the MMC-loaded polymer-lipid hybrid NPs might be useful and efficient drug delivery systems for widening the therapeutic window of MMC and bringing the clinical use of MMC one step closer to reality.

In vitro characterization of a controlled-release ocular insert for delivery of brimonidine tartrate

Glaucoma is the second leading cause of blindness in the US. Brimonidine tartrate (BT) is a modern anti-glaucoma agent that is currently administered as frequently as a thrice-daily topical eye drop medication. Accordingly, compliance with BT regimens is low, limiting overall effectiveness. One attempt that has previously proved effective in addressing non-adherence is the formation of ocular inserts, such as the Ocusert(®), whose diffusion-based control released an older drug (pilocarpine) for a week-long period. Modern controlled drug-release technology provides an avenue for extending the release of practically any drug (including new drugs such as BT) for as long as 1 month from a singular insert. Currently, no controlled-release formulations for BT exist. This work outlines the development and characterization of a BT-releasing ocular insert designed from poly(lactic co-glycolic) acid/polyethylene glycol (PEG). It was found that a formulation containing 15% PEG can be created that produces a linear BT-release profile corresponding to BT eye drop delivery estimates. Additionally, these inserts were shown, through the use of atomic force microscopy and scanning electron microscopy, to have smooth surfaces and physical properties suitable for ophthalmic use.

Development and optimization of buspirone oral osmotic pump tablet

The aim of the current study was to design a porous osmotic pump-based drug delivery system for controlling the release of buspirone from the delivery system. The osmotic pump was successfully developed using symmetric membrane coating. The core of the tablets was prepared by direct compression technique and coated using dip-coating technique. Drug release from the osmotic system was studied using USP paddle type apparatus. The effect of various processing variables such as the amount of osmotic agent, the amount of swellable polymer, concentration of the core former, concentration of the plasticizer, membrane thickness, quantum of orifice on drug release from osmotic pump were evaluated. Different kinetic models (zero order, first order and Higuchi model) were applied to drug release data in order to establish the kinetics of drug release. It was found that the drug release was mostly affected by the amount of NaCl as osmotic agent, the swellable polymer; hydroxy propyl methyl cellulose (HPMC), the amount of PEG-400 and cellulose acetate in the coating solution and thickness of the semipermeable membrane. The optimized formulation released buspirone independent of pH and orifice quantum at the osmogen amount of 42%, hydrophilic polymer of 13% and pore size of 0.8 mm on the tablet surface. The drug release of osmotic formulation during 24 h showed zero order kinetics and could be suggested that this formulation as a once-daily regimen improves pharmacokinetic parameters of the drug and enhances patient compliance.

Lysine-based polycation:heparin coacervate for controlled protein delivery

Polycations have good potential as carriers of proteins and genetic material. However, poor control over the release rate and safety issues currently limit their use as delivery vehicles. Here we introduce a new lysine-based polycation, poly(ethylene lysinylaspartate diglyceride) (PELD), which exhibits high cytocompatibility. PELD self-assembles with the biological polyanion heparin into a coacervate that incorporates proteins with high loading efficiency. Coacervates of varying surface charge were obtained by simple alteration of the PELD:heparin ratio and resulted in diverse release profiles of the model protein bovine serum albumin. Therefore, coacervate charge represents a direct means of control over release rate and duration. The PELD coacervate also rapidly adsorbed onto a porous polymeric scaffold, demonstrating potential use in tissue engineering applications. This coacervate represents a safe and tunable protein delivery system for biomedical applications.

Effect of nanostructured lipid vehicles on percutaneous absorption of curcumin

The present study describes the production and characterization of monoolein aqueous dispersions (MAD) and lecithin organogels (ORG) as percutaneous delivery systems for curcumin (CUR). In particular, MAD stabilized by sodium cholate/poloxamer and w0 3 ORG lipid carriers, both in the presence and absence of CUR, have been considered: MAD morphology and dimensional distribution have been investigated by Cryogenic Transmission Electron Microscopy (cryo-TEM) and Photon Correlation Spectroscopy (PCS), while the inner structure of MAD and ORG has been studied by X-ray scattering techniques. As a general result, CUR chemical stability has been found to be better controlled by MAD, probably because CUR is more protected in the case of CUR-MAD with respect to CUR-ORG. To investigate the performance of differently composed lipid formulations as CUR delivery system, in vitro studies, based on Franz cell and stratum corneum-epidermis (SCE) membranes, and in vivo studies, based on skin reflectance spectrophotometry and tape stripping, were then performed. The results indicated that ORG induces a rapid and intense initial penetration of CUR probably due to a strong interaction between the peculiar supramolecular aggregation structure of phospholipids in the vehicle and the lipids present in the stratum corneum. Conversely, CUR incorporated into MAD can be released in a controlled fashion possibly because of the formation of a CUR depot in the stratum corneum. In this respect ORG could be employed in pathologies requiring rapid CUR action, while MAD could be proposed for assuring a prolonged CUR activity.

Microparticles produced by the hydrogel template method for sustained drug delivery

Polymeric microparticles have been used widely for sustained drug delivery. Current methods of microparticle production can be improved by making homogeneous particles in size and shape, increasing the drug loading, and controlling the initial burst release. In the current study, the hydrogel template method was used to produce homogeneous poly(lactide-co-glycolide) (PLGA) microparticles and to examine formulation and process-related parameters. Poly(vinyl alcohol) (PVA) was used to make hydrogel templates. The parameters examined include PVA molecular weight, type of PLGA (as characterized by lactide content, inherent viscosity), polymer concentration, drug concentration and composition of solvent system. Three model compounds studied were risperidone, methylprednisolone acetate and paclitaxel. The ability of the hydrogel template method to produce microparticles with good conformity to template was dependent on molecular weight of PVA and viscosity of the PLGA solution. Drug loading and encapsulation efficiency were found to be influenced by PLGA lactide content, polymer concentration and composition of the solvent system. The drug loading and encapsulation efficiency were 28.7% and 82% for risperidone, 31.5% and 90% for methylprednisolone acetate, and 32.2% and 92% for paclitaxel, respectively. For all three drugs, release was sustained for weeks, and the in vitro release profile of risperidone was comparable to that of microparticles prepared using the conventional emulsion method. The hydrogel template method provides a new approach of manipulating microparticles.

Thermosensitive hydrogels of poly(methyl vinyl ether-co-maleic anhydride) - Pluronic(®) F127 copolymers for controlled protein release

Thermosensitive hydrogels are of a great interest due to their many biomedical and pharmaceutical applications. In this study, we synthesized a new series of random poly (methyl vinyl ether-co-maleic anhydride) (Gantrez(®) AN, GZ) and Pluronic(®) F127 (PF127) copolymers (GZ-PF127), that formed thermosensitive hydrogels whose gelation temperature and mechanical properties could be controlled by the molar ratio of GZ and PF127 polymers and the copolymer concentration in water. Gelation temperatures tended to decrease when the GZm/PF127 ratio increased. Thus, at a fixed GZm/PF127 value, sol-gel temperatures decreased at higher copolymer concentrations. Moreover, these hydrogels controlled the release of proteins such as bovine serum albumin (BSA) and recombinant recombinant kinetoplastid membrane protein of Leishmania (rKMP-11) more than the PF127 system. Toxicity studies carried out in J774.2 macrophages showed that cell viability was higher than 80%. Finally, histopathological analysis revealed that subcutaneous administration of low volumes of these hydrogels elicited a tolerable inflammatory response that could be useful to induce immune responses against the protein cargo in the development of vaccine adjuvants.

In vivo inhibition of hypertrophic scars by implantable ginsenoside-Rg3-loaded electrospun fibrous membranes

Clinically, hypertrophic scarring (HS) is a major concern for patients and has been a challenge for surgeons, as there is a lack of treatments that can intervene early in the formation of HS. This study reports on a Chinese drug, 20(R)-ginsenoside Rg3 (GS-Rg3), which can inhibit in vivo the early formation of HS and later HS hyperplasia by inducing the apoptosis of fibroblasts, inhibiting inflammation and down-regulating VEGF expression. Implantable biodegradable GS-Rg3-loaded poly(l-lactide) (PLA) fibrous membranes were successfully fabricated using co-electrospinning technology to control drug release and improve drug utilization. The in vivo releasing time of GS-Rg3 lasts for 3 months, and the drug concentration released in rabbits can be controlled by varying the drug content of the electrospun fibers. Histological observations of HE staining indicate that GS-Rg3/PLA significantly inhibits the HS formation, with obvious improvements in terms of dermis layer thickness, epidermis layer thickness and fibroblast proliferation. The results of immunohistochemistry staining and Masson's trichrome staining demonstrate that GS-Rg3/PLA electrospun fibrous membranes significantly inhibit HS formation, with decreased expression of collagen fibers and microvessels. VEGF protein levels are much lower in the group treated with GS-Rg3/PLA eletrospun membranes compared with other groups. These results demonstrate that GS-Rg3 is a novel drug, capable of inhibiting the early formation of HS and later HS hyperplasia. GS-Rg3/PLA electrospun membrane is a very promising new treatment for early and long-term treatment of HS.

Combining self-assembling peptide gels with three-dimensional elastomer scaffolds

Some of the problems raised by the combination of porous scaffolds and self-assembling peptide (SAP) gels as constructs for tissue engineering applications are addressed for the first time. Scaffolds of poly(ethyl acrylate) and the SAP gel RAD16-I were employed. The in situ gelation of the SAP gel inside the pores of the scaffolds was studied. The scaffold-cum-gel constructs were characterized morphologically, physicochemically and mechanically. The possibility of incorporating an active molecule (bovine serum albumin, taken here as a model molecule for others) in the gel within the scaffold's pores was assessed, and the kinetics of its release in phosphate-buffered saline was followed. Cell seeding and colonization of these constructs were preliminarily studied with L929 fibroblasts and subsequently checked with sheep adipose-tissue-derived stem cells intended for further preclinical studies. Static (conventional) and dynamically assisted seedings were compared for bare scaffolds and the scaffold-cum-gel constructs. The SAP gel inside the pores of the scaffold significantly improved the uniformity and density of cell colonization of the three-dimensional (3-D) structure. These constructs could be of use in different advanced tissue engineering applications, where, apart from a cell-friendly extracellular matrix -like aqueous environment, a larger-scale 3-D structure able to keep the cells in a specific place, give mechanical support and/or conduct spatially the tissue growth could be required.

Desktop 3D printing of controlled release pharmaceutical bilayer tablets

Three dimensional (3D) printing was used as a novel medicine formulation technique for production of viable tablets capable of satisfying regulatory tests and matching the release of standard commercial tablets. Hydroxypropyl methylcellulose (HPMC 2208) (Methocel™ K100M Premium) and poly(acrylic acid) (PAA) (Carbopol(®) 974P NF) were used as a hydrophilic matrix for a sustained release (SR) layer. Hypromellose(®) (HPMC 2910) was used as a binder while microcrystalline cellulose (MCC) (Pharmacel(®) 102) and sodium starch glycolate (SSG) (Primojel(®)) were used as disintegrants for an immediate release (IR) layer. Commercial guaifenesin bi-layer tablets (GBT) were used as a model drug (Mucinex(®)) for this study. There was a favourable comparison of release of the active guaifenesin from the printed hydrophilic matrix compared with the commercially available GBT. The printed formulations were also evaluated for physical and mechanical properties such as weight variation, friability, hardness and thickness as a comparison to the commercial tablet and were within acceptable range as defined by the international standards stated in the United States Pharmacopoeia (USP). All formulations (standard tablets and 3D printed tablets) showed Korsmeyer-Peppas n values between 0.27 and 0.44 which indicates Fickian diffusion drug release through a hydrated HPMC gel layer.

Rapid and sensitive controlled release monitoring method of biomedical combined products with IDM for pain management and cancer treatment

New designed combined products and its determination for pain management and cancer treatment were studied. A rapid and sensitive stability indicating HPLC method had been developed and validated for the determination of Indomethacin(IDM) in a transdermal patch. This analytical method was successfully applied to the determination of Indomethacin in a transdermal patch and can be used for routine quality control analysis. Chromatographic separation was achieved isocratically on an Inertsil® C8-3 column utilizing a mobile phase of acetonitrile / 0.01 M monobasic sodium phosphate and 0.01 M dibasic sodium phosphate buffer (pH 3) (65:35, v/v) at the flow rate of 1 mL/min with UV detection at the wavelength of 210 nm. The system suitability was performed, and the result showed that Indomethacin(IDM) and its impurity were separated. The calibration curve of Indomethacin(IDM) was linear in the range of 0.1~15 ppm (r = 0.9989, n = 3).

Non-covalent hydrogels of cyclodextrins and poloxamines for the controlled release of proteins

Different types of gels were prepared by combining poloxamines (Tetronic), i.e. poly(ethylene oxide)/poly(propylene oxide) (PEO/PPO) octablock star copolymers, and cyclodextrins (CD). Two different poloxamines with the same molecular weight (ca. 7000) but different molecular architectures were used. For each of their four diblock arms, direct Tetronic 904 presents PEO outer blocks while in reverse Tetronic 90R4 the hydrophilic PEO blocks are the inner ones. These gels were prepared by combining α-CD and poloxamine aqueous solutions. The physicochemical properties of these systems depend on several factors such as the structure of the block copolymers and the Tetronic/α-CD ratio. These gels were characterized using differential scanning calorimetry (DSC), viscometry and X-ray diffraction measurements. The 90R4 gels present a consistency that makes them suitable for sustained drug delivery. The resulting gels were easily eroded: these complexes were dismantled when placed in a large amount of water, so controlled release of entrapped large molecules such as proteins (Bovine Serum Albumin, BSA) is feasible and can be tuned by varying the copolymer/CD ratio.

Facile preparation of magnetic 2-hydroxypropyltrimethyl ammonium chloride chitosan/Fe3O4/halloysite nanotubes microspheres for the controlled release of ofloxacin

Magnetic microspheres, 2-hydroxypropyltrimethyl ammonium chloride chitosan/Fe3O4/halloysite nanotubes/ofloxacin (HACC/Fe3O4/HNTs/OFL), for the controlled release of OFL were prepared by in situ crosslinking with glutaraldehyde in the spray-drying process. The magnetic microspheres were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis and a magnetometer. Various parameters influencing the encapsulation efficiency, drug loading and in vitro controlled release properties of the magnetic microspheres for OFL were also studied. Many stripes were formed and some tubular HNTs could be seen at higher magnification on the surface of the HACC/Fe3O4/HNTs/OFL magnetic microspheres. The magnetic microspheres show superparamagnetic property and fast magnetic response. The encapsulation efficiency and the cumulative release of OFL are closely related to HACC concentration, HNTs contents and crosslinking density. The release of OFL follows the first-order kinetics.