Characterization of alginate/poly-L-lysine particles as antisense oligonucleotide carriers

Exploring delivery systems for targeted nanotechnology-based gene therapy in the inner ear

Hearing loss places a significant burden on our aging population. However, there has only been limited progress in developing therapeutic techniques to effectively mediate this condition. This review will outline several of the most commonly utilized practices for the treatment of sensorineural hearing loss before exploring more novel techniques currently being investigated via both in vitro and in vivo research. This review will place particular emphasis on novel gene-delivery technologies. Primarily, it will focus on techniques used to deliver genes that have been shown to encourage the proliferation and differentiation of sensory cells within the inner ear and how these technologies may be translated into providing clinically useful results for patients.

Encapsulation and immune protection for type 1 diabetes cell therapy

Type 1 Diabetes (T1D) involves the autoimmune destruction of insulin-producing β-cells in the pancreas. Exogenous insulin injections are the current therapy but are user-dependent and cannot fully recapitulate physiological insulin secretion dynamics. Since the emergence of allogeneic cell therapy for T1D, the Edmonton Protocol has been the most promising immunosuppression protocol for cadaveric islet transplantation, but the lack of donor islets, poor cell engraftment, and required chronic immunosuppression have limited its application as a therapy for T1D. Encapsulation in biomaterials on the nano-, micro-, and macro-scale offers the potential to integrate islets with the host and protect them from immune responses. This method can be applied to different cell types, including cadaveric, porcine, and stem cell-derived islets, mitigating the issue of a lack of donor cells. This review covers progress in the efforts to integrate insulin-producing cells from multiple sources to T1D patients as a form of cell therapy.

Synthesis and evaluation of modified lens using plasma treatment containing timolol-maleate loaded lauric acid-decorated chitosan-alginate nanoparticles for glaucoma

Reducing intraocular pressure (IOP) with eye drops is one of the most common ways to control glaucoma. Low bioavailability and high frequency of administration in eye drops are major challenges in ocular pharmacotherapy. Contact lenses have attracted the attention of scientists in recent decades as an alternative method. In this study, with the aim of long-term drug delivery and better patient compatibility, contact lenses with surface modification and nanoparticles were used. In this study, timolol-maleate was loaded into polymeric nanoparticles made of chitosan conjugate with lauric acid and sodium alginate. Then silicon matrix was mixed with a curing agent (10:1), and the suspension of nanoparticles was added to the precursor and cured. Finally, for surface modification, the lenses were irradiated with oxygen plasma at different exposure times (30, 60, and 150 s) and soaked in different BSA concentrations (1, 3, and 5% w/v). The results showed nanoparticles with a size of 50 nm and a spherical shape were synthesized. The best surface modification of the lenses was for 5 (% w/v) albumin concentration and 150 s exposure time, which had the highest increase in hydrophilicity. Drug release from nanoparticles continued for 3 days and this amount increased to 6 days after dispersion in the modified lens matrix. The drug model and kinetic study show the Higuchi model completely supported the release profile. This study represents the novel drug delivery system to control intra-ocular pressure as a candidate platform for glaucoma treatment. Improved compatibility and drug release from the designed contact lenses would prepare new insight into the mentioned disease treatment.

Poly-L-lysine as a crosslinker in bile acid and alginate nanoaggregates for gene delivery in auditory cells

Background: Hearing loss is a condition that may affect a wide array of patients from various backgrounds. There are no cures for sensorineural hearing loss. Gene therapy is one possible method of improving hearing status; however, gene delivery remains challenging. Materials & methods: Polymer nanoaggregates of alginate and poly-L-lysine were prepared with and without bile acid. The nanoaggregates had physical properties, cytotoxicity, gene release and gene expression analyzed. Results & discussion: The nanoparticles produced had appropriate size and charge, low cytotoxicity between 0.5 and 1.0 mg/ml and linear gene release but poor transfection efficiency. Conclusion: The present study provides preliminary evidence for the efficacy of polymer nanotechnology with bile acids for inner ear gene delivery; optimization is required to improve transfection efficiency.

Polymer nanocarriers for targeted local delivery of agents in treating brain tumors

Glioblastoma (GBM), the deadliest brain cancer, presents a multitude of challenges to the development of new therapies. The standard of care has only changed marginally in the past 17 years, and few new chemotherapies have emerged to supplant or effectively combine with temozolomide. Concurrently, new technologies and techniques are being investigated to overcome the pharmacokinetic challenges associated with brain delivery, such as the blood brain barrier (BBB), tissue penetration, diffusion, and clearance in order to allow for potent agents to successful engage in tumor killing. Alternative delivery modalities such as focused ultrasound and convection enhanced delivery allow for the local disruption of the BBB, and the latter in particular has shown promise in achieving broad distribution of agents in the brain. Furthermore, the development of polymeric nanocarriers to encapsulate a variety of cargo, including small molecules, proteins, and nucleic acids, have allowed for formulations that protect and control the release of said cargo to extend its half-life. The combination of local delivery and nanocarriers presents an exciting opportunity to address the limitations of current chemotherapies for GBM toward the goal of improving safety and efficacy of treatment. However, much work remains to establish standard criteria for selection and implementation of these modalities before they can be widely implemented in the clinic. Ultimately, engineering principles and nanotechnology have opened the door to a new wave of research that may soon advance the stagnant state of GBM treatment development.

Investigating preparation and characterisation of diphtheria toxoid-loaded on sodium alginate nanoparticles

This paper aims to investigate the preparation and characterisation of the alginate nanoparticles (NPs) as antigen delivery system loaded by diphtheria toxoid (DT). For this purpose, both the loading capacity (LC) and Loading efficiency (LE) of the alginate NPs burdened by DT are evaluated. Moreover, the effects of different concentrations of sodium alginate and calcium chloride on the NPs physicochemical characteristics are surveyed in addition to other physical conditions such as homogenization time and rate. To do so, the NPs are characterised using particle size and distribution, zeta potential, scanning electron microscopy, encapsulation efficiency, in vitro release study and FT‐IR spectroscopy. Subsequently, the effects of homogenization time and rate on the NPs are assessed. At the meantime, the NPs LC and efficiency in several DT concentrations are estimated. The average size of the NPs was 400.7 and 276.6 nm for unloaded and DT loaded, respectively. According to the obtained results, the zeta potential of the blank and DT loaded NPs are estimated as −23.7 mV and −21.2 mV, respectively. Whereas, the LC and LE were >80% and >90%, in that order. Furthermore, 95% of the releasing DT loaded NPs occurs at 140 h in the sustained mode without any bursting release. It can be concluded that the features of NPs such as morphology and particle size are strongly depended on the calcium chloride, sodium alginate concentrations and physicochemical conditions in the NPs formation process. In addition, appropriate concentrations of the sodium alginate and calcium ions would lead to obtaining the desirable NPs formation associated with the advantageous LE, LC (over 80%) and sustained in vitro release profile. Ultimately, the proposed NPs can be employed in vaccine formulation for the targeted delivery, controlled and slow antigen release associated with the improved antigen stability.

Nano-antimicrobials: A New Paradigm for Combating Mycobacterial Resistance

BACKGROUND

Mycobacterium group contains several pathogenic bacteria including M. tuberculosis where the emergence of multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) is alarming for human and animal health around the world. The condition has further aggravated due to the speed of discovery of the newer drugs has been outpaced by the rate of resistance developed in microorganisms, thus requiring alternative combat strategies. For this purpose, nano-antimicrobials have emerged as a potential option.

OBJECTIVE

The current review is focused on providing a detailed account of nanocarriers like liposome, micelles, dendrimers, solid lipid NPs, niosomes, polymeric nanoparticles, nano-suspensions, nano-emulsion, mesoporous silica and alginate-based drug delivery systems along with the recent updates on developments regarding nanoparticle-based therapeutics, vaccines and diagnostic methods developed or under pipeline with their potential benefits and limitations to combat mycobacterial diseases for their successful eradication from the world in future.

RESULTS

Distinct morphology and the underlying mechanism of pathogenesis and resistance development in this group of organisms urge improved and novel methods for the early and efficient diagnosis, treatment and vaccination to eradicate the disease. Recent developments in nanotechnology have the potential to meet both the aspects: nano-materials are proven components of several efficient targeted drug delivery systems and the typical physicochemical properties of several nano-formulations have shown to possess distinct bacteriocidal properties. Along with the therapeutic aspects, nano-vaccines and theranostic applications of nano-formulations have grown in popularity in recent times as an effective alternative means to combat different microbial superbugs.

CONCLUSION

Nanomedicine holds a bright prospect to perform a key role in global tuberculosis elimination program.

Multivariate analysis for the optimization of polysaccharide-based nanoparticles prepared by self-assembly

Polysaccharide-based nanoparticles are promising carriers for drug delivery applications. The particle size influences the biodistribution of the nanoparticles; hence size distributions and polydispersity index (PDI) are critical characteristics. However, the preparation of stable particles with a low PDI is a challenging task and is usually based on empirical trials. In this study, we report the use of multivariate evaluation to optimize the formulation factors for the preparation of alginate-zinc nanoparticles by ionotropic gelation. The PDI was selected as the response variable. Particle size, size distributions, zeta potential and pH of the samples were also recorded. Two full factorial (mixed-level) designs were analyzed by partial least squares regression (PLS). In the first design, the influence of the polysaccharide and the crosslinker concentrations were studied. The results revealed that size distributions with a low PDI were obtained by using a low polysaccharide concentrations (0.03-0.05%) and a zinc concentration of 0.03% (w/w). However, a high polysaccharide concentration can be advantageous for drug delivery systems. Therefore, in the second design, a high alginate concentration was used (0.09%) and a reduction in the PDI was obtained by simultaneously increasing the ionic strength of the solvent and the zinc concentration. The multivariate analysis also revealed the interaction between the factors in terms of their effects on the PDI; hence, compared to traditional univariate analyses, the multivariate analysis allowed us to obtain a more complete understanding of the effects of the factors scrutinized. In addition, the results are considered useful in order to avoid extensive empirical tests for future formulation studies.

What's Next for Gastrointestinal Disorders: No Needles?

A myriad of pathologies affect the gastrointestinal tract, citing this affected area as a significant target for therapeutic intervention. One group of therapeutic agents, antisense and oligonucleotides and small interfering RNAs, offer a promising platform for treating a wide variety of diseases ranging from cancer to auto-immune diseases. Current delivery methods are carried out either systemically or locally into diseased areas, both of which involve needles. The challenge in orally administering this type of treatment lies in the complications that arise due to the vast environmental extremes found within the gastrointestinal tract, owing to the fact that, as the drug travels down the gastrointestinal tract, it is subjected to pH changes and interactions with bacteria and a variety of digestive and protective enzymes including proteases, DNAses, and RNAses. Overcoming these challenges to allow the practical application of these drugs is a priority that has invoked a multitude of research in the chemical, biological, and material sciences. In this review, we will address common gastrointestinal pathologies, the barriers to oral-based therapies and antisense-interfering technologies, the approaches that have already been applied for their delivery, and the current status of antisense drug therapy clinical trials for gastrointestinal-related disorders.

Silica nanowire conjugated with loop-shaped oligonucleotides: A new structure to silence cysteine proteinase gene in Leishmania tropica

The main aim of this study was to evaluate the capability of silica nanowire conjugated with loop-shaped oligonucleotides (SNWCLSOs) to silence cysteine proteinase b (Cpb) gene in Leishmania (L) tropica. On the other hand, its toxicity on amastigotes and mouse peritoneal macrophages was evaluated by 5-diphenyl-tetrazolium bromide (MTT) assay. For control, two loop-shaped oligonucleotides (LSO) were considered. LSO1 and LSO2 were 5'-NH2-cccccaaaaaaaaaaaaaaaaaaaaaaaaaggggg-COOH-3' and LSO2: 5'-NH2-cccccttttttttttttttttttttttttttttttttttttttggggg-COOH-3', respectively. After 72 h incubation at 37 °C, AMSNW, LSO1, and LSO2 had no remarkable toxicity on L. tropica amastigote (2 × 10(5)/mL) and mouse peritoneal macrophages (2 × 10(5)/mL). In case of SNWCLSOs, they had high toxicity on L. tropica amastigote, but they had no effect on mouse peritoneal macrophages. At concentrations of 1, 10, and 25 μg/mL, AMSNW, LSO1 and LSO2 had no effect on the gene expression. But, at concentration of 50 and 100 μg/mL, decrease of gene expression was observed. In case of SNWCLSOs, they could dramatically decrease the gene expression. It could be concluded that since SNWCLSOs could silence Cpb gene with no remarkable toxicity, they are good choice for treat cutaneous leishmaniasis in future. As a new agent, it must be checked in vivo.

Preparation and application of micro/nanoparticles based on natural polysaccharides

Polysaccharides have attracted more and more attentions and been recognized to be the most promising materials in recent years because of their outstanding merits such as easily available, non-toxic, biocompatible, biodegradable, and easily modified. Considerable research efforts have been directed toward developing polysaccharides-based micro/nanoparticles (PM/NPs). The new major studies of PM/NPs over the past few years are outlined in this review. Methods of preparation, including self-assembly, ionic-gelation, complex coacervation, emulsification, and desolvation method and some others, are summarized. Different applications of PM/NPs in the field of drug-delivery system are highlighted. Besides, another novel application of PM/NPs that are used as emulsifiers to stabilize Pickering emulsion is also introduced. These environmental-friendly particle emulsifiers have received reasonable attention due to their novel applications, especially in food, cosmetics, and pharmaceutics. From literature surveys, we realized that studies on PM/NP systems for different applications have increased rapidly. Hence, the present review is timely.

Alginate nanoparticles as a promising adjuvant and vaccine delivery system

During last decades, diphtheria has remained as a serious disease that still outbreaks and can occur worldwide. Recently, new vaccine delivery systems have been developed by using the biodegradable and biocompatible polymers such as alginate. Alginate nanoparticles as a carrier with adjuvant and prolong release properties that enhance the immunogenicity of vaccines. In this study diphtheria toxoid loaded nanoparticles were prepared by ionic gelation technique and characterized with respect to size, zeta potential, morphology, encapsulation efficiency, release profile, and immunogenicity. Appropriate parameters (calcium chloride and sodium alginate concentration, homogenization rate and homogenization time) redounded to the formation of suitable nanoparticles with a mean diameter of 70±0.5 nm. The loading studies of the nanoparticles resulted in high loading capacities (>90%) and subsequent release studies showed prolong profile. The stability and antigenicity of toxoid were evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and ouchterlony test and proved that the encapsulation process did not affect the antigenic integrity and activity. Guinea pigs immunized with the diphtheria toxoid-loaded alginate nanoparticles showed highest humoral immune response than conventional vaccine. It is concluded that, with regard to the desirable properties of nanoparticles and high immunogenicity, alginate nanoparticles could be considered as a new promising vaccine delivery and adjuvant system.

Novel alginate coated hydrophobically modified chitosan polyelectrolyte complex for the delivery of BSA

Polysaccharides based polyelectrolyte complex nanoparticles (PCNs) intended for use in the delivery of macromolecules were prepared by the self-assembly of deoxycholic acid hydrophobically modified chitosan (CS-DCA) core and then coated with sodium alginate (ALG) shell. The CS-DCA capable of forming nano-sized self-aggregates in medium was prepared by the grafting of DCA to CS. In order to increase the stability of nanoparticles and prevent burst release of drug in bloodstream, polyanionic ALG was coated on the surface of positively charged CS-DCA nanoparticles to form PCNs. Dynamic light scattering results revealed that the mean diameter of the PCNs was about 330 nm, larger than that of uncoated nanoparticles (~150 nm). The zeta potential was big enough to keep the stability of PCNs (-28 mV); no size change was found even upon 1 month storage. Bovine serum albumin could be easily incorporated into the PCNs with encapsulation efficiency (>44 %) and keep a sustained manner without burst release when exposed to PBS (pH 7.4) at 37 °C. These results suggested that PCNs may be a promising drug carrier for a prolonged and sustained delivery in the bloodstream.

Engineered nonviral nanocarriers for intracellular gene delivery applications

The efficient delivery of nucleic acids into mammalian cells is a central aspect of cell biology and of medical applications, including cancer therapy and tissue engineering. Non-viral chemical methods have been received with great interest for transfecting cells. However, further development of nanocarriers that are biocompatible, efficient and suitable for clinical applications is still required. In this paper, the different material platforms for gene delivery are comparatively addressed, and the mechanisms of interaction with biological systems are discussed carefully.

Robust optimization of alginate-Carbopol 940 bead formulations

Formulation process is a very complex activity which sometimes implicates taking decisions about parameters or variables to obtain the best results in a high variability or uncertainty context. Therefore, robust optimization tools can be very useful for obtaining high quality formulations. This paper proposes the optimization of different responses through the robust Taguchi method. Each response was evaluated like a noise variable, allowing the application of Taguchi techniques to obtain a response under the point of view of the signal to noise ratio. A L₁₈ Taguchi orthogonal array design was employed to investigate the effect of eight independent variables involved in the formulation of alginate-Carbopol beads. Responses evaluated were related to drug release profile from beads (t_50% and AUC), swelling performance, encapsulation efficiency, shape and size parameters. Confirmation tests to verify the prediction model were carried out and the obtained results were very similar to those predicted in every profile. Results reveal that the robust optimization is a very useful approach that allows greater precision and accuracy to the desired value.

Chitosan-based nanoparticles as a hepatitis B antigen delivery system

The design of antigen delivery systems, particularly for mucosal surfaces, has been a focus of interest in recent years. In this chapter, we describe the preparation of chitosan-based particles as promising antigen delivery systems for mucosal surfaces already tested by our group with hepatitis B surface antigen. The final proof of the concept is always carried out with immunization studies performed in an appropriate animal model. However, before these important studies, it is advisable that the delivery system should be submitted to a variety of in vitro tests. Among several tests, the characterization of the particles (size, morphology, and zeta potential), the studies of antigen adsorption onto particles, the evaluation of toxicity of the particles, and the studies of particle uptake into lymphoid organs are the most important and will be described in this chapter.

Novel preparation techniques for alginate-poloxamer microparticles controlling protein release on mucosal surfaces

The objective of this study was to develop novel preparation techniques for protein-loaded, controlled release alginate-poloxamer microparticles with a size range suitable for pulmonary administration. Bovine serum albumin (BSA)-loaded microparticles were prepared by spray-drying aqueous polymer-drug solutions, followed by cross-linking the particles in aqueous or ethanolic CaCl(2) or aqueous ZnSO(4) solutions. The microparticles were characterized with respect to their morphology (optical and scanning electron microscopy), particle size (laser light diffraction), calcium content (atom absorption spectroscopy), alginate content (complexation with 1,9-dimethyl methylene blue) and in vitro drug release (modified Franz diffusion cell). The spray-dried microparticles were spherical in shape with a size range of 4-6μm. Aqueous cross-linking led to a significant size increase (10-15μm), whereas ethanolic cross-linking did not. The substantial drug loss (∼50%) during aqueous CaCl(2) cross-linking could be avoided by using aqueous ZnSO(4) or ethanolic CaCl(2) solutions. Protein release from microparticles cross-linked with ethanolic CaCl(2) solutions was much faster than in the case of aqueous CaCl(2) solutions, probably due to the lower calcium content. The salt concentration and temperature of the cross-linking solutions also affected the composition of and drug release from the microparticles. Cross-linked alginate-poloxamer microparticles can be produced in a size range appropriate for deep lung delivery and with controlled protein release kinetics (time frame: hours to days) with these novel preparation techniques. The systems offer an interesting potential for the controlled mucosal delivery of protein drugs.

Novel antigen delivery technologies: a review

Over the past few years, new insights into immunobiology and delivery systems have allowed the development of better vaccines and for a wider range of diseases. Currently available vaccines represent outstanding success story in modern medicine and have had a dramatic effect on morbidity and mortality worldwide. Conventional vaccines have been based on live attenuated, or killed, viruses or bacteria, or recombinant proteins from these organisms. The design of live attenuated vaccines depended to some extent on serendipity and resulted in low success rates. Both live attenuated and killed vaccines require handling of live pathogens and are associated with safety problems. Despite the success of vaccines, there is a clear need for novel antigen delivery technologies to improve vaccine efficacy and safety. Antigen stability, safety, and immunogenicity are the key hurdles in development of novel antigen delivery technologies. Nowadays, various novel drug delivery systems are becoming one of the fastest growing sectors in the pharmaceutical and biotechnological industries. Delivery of vaccines via oral, intranasal, transcutaneous, and intradermal routes will decrease the risk of needle-borne diseases and may eliminate the need for trained personnel and sterile equipment. Currently, various techniques involving DNA vaccines, adjuvants, nanoparticles, liposome, microneedle, and NanoMAP technology are being developed and evaluated. This review focuses on the current development of some novel vaccine delivery systems and will explore the non-parenteral routes of vaccine administrations.

Methods for the preparation and manufacture of polymeric nanoparticles

This review summarizes the different methods of preparation of polymer nanoparticles including nanospheres and nanocapsules. The first part summarizes the basic principle of each method of nanoparticle preparation. It presents the most recent innovations and progresses obtained over the last decade and which were not included in previous reviews on the subject. Strategies for the obtaining of nanoparticles with controlled in vivo fate are described in the second part of the review. A paragraph summarizing scaling up of nanoparticle production and presenting corresponding pilot set-up is considered in the third part of the review. Treatments of nanoparticles, applied after the synthesis, are described in the next part including purification, sterilization, lyophilization and concentration. Finally, methods to obtain labelled nanoparticles for in vitro and in vivo investigations are described in the last part of this review.

Polymer nanocarriers for the delivery of small fragments of nucleic acids: oligonucleotides and siRNA

The success of the application of new therapeutic methods based on RNA interfering strategies requires the in vivo delivery of active ODN or siRNA down to the intracellular compartment of the target cells. This article aims to review the studies related to the formulation of RNA interfering agents in polymer nanocarriers. It will present the different types of polymer nanocarriers used as well as the biological activity of the resulting ODN and siRNA loaded nanocarriers. As will be explained, the part of the in vitro studies provided useful data about the intracellular delivery of the formulated RNA interfering agents. Investigations performed in vivo have considered animal models of different relevant diseases. Results from these investigations have clearly demonstrated the interest of several polymer nanocarriers tested so far to deliver active RNA interfering effectors in vivo making possible their administration by the intravenous route.

Development and characterization of pectinate micro/nanoparticles for gene delivery

The aim of this study was to investigate the possibility of using pectinate micro/nanoparticles as gene delivery systems. Pectinate micro/nanoparticles were produced by ionotropic gelation. Various factors were studied for their effects on the preparation of pectinate micro/nanoparticles: the pH of the pectin solution, the ratio of pectin to the cation, the concentration of pectin and the cation, and the type of cation (calcium ions, magnesium ions and manganese ions). After the preparation, the size and charge of the pectin micro/nanoparticles and their DNA incorporation efficiency were evaluated. The results showed that the particle sizes decreased with the decreased concentrations of pectin and cation. The type of cations affected the particle size. Sizes of calcium pectinate particles were larger than those of magnesium pectinate and manganese pectinate particles. The DNA loading efficiency showed that Ca-pectinate nanoparticles could entrap DNA up to 0.05 mg when the weight ratio of pectin:CaCl(2):DNA was 0.2:1:0.05. However, Mg-pectinate could entrap only 0.01 mg DNA when the weight ratio of pectin:MgCl(2):DNA was 1:100:0.01 The transfection efficiency of both Ca-pectinate and Mg-pectinate nanoparticles yielded relatively low levels of green fluorescent protein expression and low cytotoxicity in Huh7 cells. Given the negligible cytotoxic effects, these pectinate micro/nanoparticles can be considered as potential candidates for use as safe gene delivery carriers.

Preparation of coated nanoparticles for a new mucosal vaccine delivery system

It has been found that the adsorption of antigens onto chitosan particles is an easy and unique mild loading process suitable to be used with vaccines. In order to increase the stability of this particles and to prevent an immediate desorption in gastrointestinal fluids, a coating process with sodium alginate was developed. One of the challenges of this developing process was to keep the particles in the nanosized range in order to be taken up by M-cells of the Peyer's patches. The observed inversion of the particles' zeta potential values after coating suggested the presence of an alginate coating layer. These results were confirmed by FTIR and DSC techniques. Additionally, in vitro release studies showed that the presence of the alginate layer around the particles was able to prevent a burst release of loaded ovalbumin and to improve the stability of the nanoparticles in simulated intestinal fluid at 37 degrees C. The optimisation of the coating process resulted in 35% (w/w) for the loading capacity of the coated particles. SEM investigations confirmed a suitable size of the coated nanoparticles for the uptake by M-cells.

Nanoparticle-mediated gene delivery: state of the art

With the development of genomic and proteomic technologies, the prospect for gene therapy has progressed rapidly. This has been partly possible due to the emergence of a diverse array of polymeric and non-polymeric nanoparticles that are being investigated for their ability to deliver genes and drugs. In this review, particles have been pragmatically divided as chitosan-related and chitosan-unrelated nanomaterials. The state of the art in terms of the development, characterisation and evaluation of their in vitro and/or in vivo potential is discussed for each of these various particles. Although substantial progress has been made, the potential of these particles in the clinical arena and human responses remain to be evaluated. It is hoped that this review will provide an impetus for further studies of these particles, with the ultimate intent that one or more of these diverse nanoparticle-based non-viral approaches for gene transfer will translate from 'bench to bedside' in the future.

Cellulose acetate butyrate microcapsules containing dextran ion-exchange resins as self-propelled drug release system

Sulfopropylated dextran microspheres (SP-Ms), (Dm = 80 microm) loaded with a water soluble drug (Tetracycline HCl), were included in cellulose acetate butyrate (CAB) microcapsules. Spherical CAB microcapsules were obtained by oil in water (o/w) solvent evaporation method in the presence of an inert solvent as cyclohexane (CyH) or n-hexane (N-Hex), and different excipients (Phospholipon, Tween, Span, Eudragit RS 100). Chloroform was found to be the best solvent for the preparation of the microcapsules. Also, the sphericity as well as the porosity of the microcapsules was controlled by the presence of an inert solvent. The final concentration of the drug in CAB microparticles was up to 25% (w/w). The key factors for the successful preparation were also the viscosity of the polymer, while the wettability of the resulted microcapsules, the temperature of the preparation, and the porosity have modulated the release of the drug. The higher is the amount of encapsulated microspheres the thinner is the CAB wall between the compartments created by their incorporation. When these microspheres come in contact with the release medium, the pressure created by their swelling breaks the polymer film and the drug starts to be released. The more drug is released in phosphate buffer the higher is the swelling degree of the encapsulated ion exchange resins and the force created by their supplementary swelling will break the more resistants walls. In this way a self-propelled drug release is achieved, until almost all drug was eliberated.

Drug delivery of oligonucleotides by peptides

Oligonucleotides are promising tools for in vitro studies where specific downregulation of proteins is required. In addition, antisense oligonucleotides have been studied in vivo and have entered clinical trials as new chemical entities with various therapeutic targets such as antiviral drugs or for tumour treatments. The formulation of these substances were widely studied in the past. With this review we will focus on peptides used as drug delivery vehicles for oligonucleotides. Different strategies are summarised. Cationically charged peptides from different origins were used e.g. as cellular penetration enhancers or nuclear localisation tool. Examples are given for Poly-L-lysine alone or in combination with receptor specific targeting ligands such as asialoglycoprotein, galactose, growth factors or transferrin. Another large group of peptides are those with membrane translocating properties. Fusogenic peptides rich in lysine or arginine are reviewed. They have been used for DNA complexation and condensation to form transport vehicles. Some of them, additionally, have so called nuclear localisation properties. Here, DNA sequences, which facilitate intracellular trafficking of macromolecules to the nucleus were explored. Summarizing the present literature, peptides are interesting pharmaceutical excipients and it seems to be feasible to combine the specific properties of peptides to improve drug delivery devices for oligonucleotides in the future.

Production, properties, and applications of hydrocolloid cellular solids

Many common synthetic and edible materials are, in fact, cellular solids. When classifying the structure of cellular solids, a few variables, such as open vs. closed cells, flexible vs. brittle cell walls, cell-size distribution, cell-wall thickness, cell shape, the uniformity of the structure of the cellular solid and the different scales of length are taken into account. Compressive stress-strain relationships of most cellular solids can be easily identified according to their characteristic sigmoid shape, reflecting three deformation mechanisms: (i) elastic distortion under small strains, (ii) collapse and/or fracture of the cell walls, and (iii) densification. Various techniques are used to produce hydrocolloid (gum) cellular solids. The products of these include (i) sponges, obtained when the drying gel contains the occasionally produced gas bubbles; (ii) sponges produced by the immobilization of microorganisms; (iii) solid foams produced by drying foamed solutions or gels containing oils, and (iv) hydrocolloid sponges produced by enzymatic reactions. The porosity of the manufactured cellular solid is subject to change and depends on its composition and the processing technique. The porosity is controlled by a range of methods and the resulting surface structures can be investigated by microscopy and analyzed using fractal methods. Models used to describe stress-strain behaviors of hydrocolloid cellular solids as well as multilayered products and composites are discussed in detail in this manuscript. Hydrocolloid cellular solids have numerous purposes, simple and complex, ranging from dried texturized fruits to carriers of vitamins and other essential micronutrients. They can also be used to control the acoustic response of specific dry food products, and have a great potential for future use in countless different fields, from novel foods and packaging to medicine and medical care, daily commodities, farming and agriculture, and the environmental, chemical, and even electronic industries.

Phagocytosis-mediated retroviral transduction: co-internalization of deactivated retrovirus and calcium-alginate microspheres by macrophages

BACKGROUND

Efficiency of retrovirus-mediated gene transfer has been hampered by short retroviral half-life due to shedding of retroviral envelope proteins which is of utmost importance to the interaction between retrovirus and cell.

METHODS

Calcium-alginate microspheres with average size of 780 nm were prepared by reverse emulsification and characterized by scanning electron microscopy and microelectrophoresis. To obtain deactivated retroviruses produced from 293 packaging cells, retrovirus-containing media were pre-incubated at 37 degrees C for 6, 12, 18, and 24 h, respectively. Murine J774A.1 macrophages were co-treated with Ca-alginate microspheres and deactivated retroviruses encoding the enhanced green fluorescent protein (eGFP) gene. Through phagocytosis, deactivated retroviruses and Ca-alginate microspheres were co-internalized into macrophages. After retroviral transduction for 24 and 48 h, the percentages of macrophages with eGFP expression were determined by bright-field and fluorescence microscopy.

RESULTS

After 48-h incubation with Ca-alginate microspheres and deactivated retroviruses, phagosomes turned into large vacuoles occupied almost half of the cytoplasmic space. This was probably attributed to the erosion of Ca-alginate microspheres by destructive agents within vacuolar compartments and concomitant osmotic swelling. It was reasoned that deactivated retroviruses escaped such enlarged vesicles easily and underwent reverse transcription in the cytosol. The expression of eGFP in macrophages infected by retroviruses pre-incubated for 24 h in the presence of Ca-alginate microspheres was thereby augmented up to tenfold in comparison with the cells treated with 24-h deactivated retroviruses only.

CONCLUSIONS

Ca-alginate microspheres performed as auxiliary agents for the enhancement of retrovirus-mediated gene transfer efficiency even though retroviruses had been deactivated due to the loss of envelope proteins.