In vitro evaluation of PLA nanoparticles containing a lipophilic drug in water-soluble or insoluble form

PLGA nanoparticles containing Intimin-Flagellin fusion protein for E. coli O157:H7 nano-vaccine

Escherichia coli O157:H7 is a foodborne pathogen that can lead to severe gastrointestinal diseases in humans. Vaccination is a promising strategy for preventing E. coli O157:H7 infections, which offers socio-economic benefits and provides the possibility of stimulating both humoral and cellular immune responses at systemic and mucosal sites. In this study, we developed a needle-free vaccine candidate against E. coli O157:H7 using poly(lactic-co-glycolic acid) (PLGA) nanoparticles entrapping a chimeric Intimin-Flagellin (IF) protein. The IF protein was expressed and verified using SDS-PAGE and western blot analysis, with a yield of 1/7 mg/L and a molecular weight of approximately 70 kDa. The prepared nanoparticles showed uniformly shaped spherical particles in the 200-nm range, as confirmed by SEM and DLS analysis. Three different routes of vaccine administration were used, including intranasal, oral, and subcutaneous, and the groups vaccinated with NPs protein had a higher antibody response compared to those receiving free protein. Subcutaneous administration of IF-NPs resulted in the highest level of IgG antibody titer, while oral administration of IF-NPs produced the highest amount of IgA antibody titer. Finally, all mice in the nanoparticle- intranasal and oral administered groups challenged with 100LD50 survived, while all control mice died before day 5. Based on these findings, we conclude that the PLGA-encapsulated IF protein has the potential to serve as a promising needle-free vaccine candidate against E. coli O157:H7.

Nanocarriers with Multiple Cargo Load-A Comprehensive Preparation Guideline Using Orthogonal Strategies

Multifunctional nanocarriers enhance the treatment efficacy for modern therapeutics and have gained increasing importance in biomedical research. Codelivery of multiple bioactive molecules enables synergistic therapies. Coencapsulation of cargo molecules into one nanocarrier system is challenging due to different physicochemical properties of the cargo molecules. Additionally, coencapsulation of multiple molecules simultaneously shall proceed with high control and efficiency. Orthogonal approaches for the preparation of nanocarriers are essential to encapsulate sensitive bioactive molecules while preserving their bioactivity. Preparation of nanocarriers by physical processes (i.e., self-assembly or coacervation) and chemical reactions (i.e., click reactions, polymerizations, etc.) are considered as orthogonal methods to most cargo molecules. This review shall act as a guideline to allow the reader to select a suitable preparation protocol for a desired nanocarrier system. This article helps to select for combinations of cargo molecules (hydrophilic-hydrophobic, small-macro, organic-inorganic) with nanocarrier material and synthesis protocols. The focus of this article lies on the coencapsulation of multiple cargo molecules into biocompatible and biodegradable nanocarriers prepared by orthogonal strategies. With this toolbox, the selection of a preparation method for a known set of cargo molecules to prepare the desired biodegradable and loaded nanocarrier shall be provided.

Osmotic Pressure as Driving Force for Reducing the Size of Nanoparticles in Emulsions

We describe here a method to decrease particle size of nanoparticles synthesized by miniemulsion polymerization. Small nanoparticles or nanocapsules were obtained by generating an osmotic pressure to induce the diffusion of monomer molecules from the dispersed phase of a miniemulsion before polymerization to an upper oil layer. The size reduction is dependent on the difference in concentration of monomer in the dispersed phase and in the upper oil layer and on the solubility of the monomer in water. By labeling the emulsion droplets with a copolymer of stearyl methacrylate and a polymerizable dye, we demonstrated that the migration of the monomer to the upper hexadecane layer relied on molecular diffusion rather than diffusion of monomer droplets to the oil layer. Moreover, surface tension measurements confirmed that the emulsions were still in the miniemulsion regime and not in the microemulsion regime. The particle size can be tuned by controlling the duration during which the miniemulsion stayed in contact with the hexadecane layer, the interfacial area between the miniemulsion and the hexadecane layer and by the concentration of surfactant. Our method was applied to reduce the size of polystyrene and poly(methyl methacrylate) nanoparticles, nanocapsules of a copolymer of styrene and methyl methacrylic acid, and silica nanocapsules. This work demonstrated that a successful reduction of nanoparticle size in the miniemulsion process can be achieved without using excess amounts of surfactant. The method relies on building osmotic pressure in oil droplets dispersed in water which acts as semipermeable membrane.

Increased Encapsulation Efficiency of Methotrexate in Liposomes for Rheumatoid Arthritis Therapy

Methotrexate (MTX) is a common drug used to treat rheumatoid arthritis. Due to the excessive side effects, encapsulation of MTX in liposomes is considered an effective delivery system, reducing drug toxicity, while maintaining its efficacy. The ethanol injection method is an interesting technique for liposome production, due to its simplicity, fast implementation, and reproducibility. However, this method occasionally requires the extrusion process, to obtain suitable size distribution, and achieve a low level of MTX encapsulation. Here, we develop a novel pre-concentration method, based on the principles of the ethanol injection, using an initial aqueous volume of 20% and 1:1 ratio of organic:aqueous phase (v/v). The liposomes obtained present small values of size and polydispersity index, without the extrusion process, and a higher MTX encapsulation (efficiency higher than 30%), suitable characteristics for in vivo application. The great potential of MTX to interact at the surface of the lipid bilayer was shown by nuclear magnetic resonance (NMR) studies, revealing mutual interactions between the drug and the main phospholipid via hydrogen bonding. In vivo experiments reveal that liposomes encapsulating MTX significantly increase the biological benefit in arthritic mice. This approach shows a significant advance in MTX therapeutic applications.

Probiotics at War Against Viruses: What Is Missing From the Picture?

Our world is now facing a multitude of novel infectious diseases. Bacterial infections are treated with antibiotics, albeit with increasing difficulty as many of the more common causes of infection have now developed broad spectrum antimicrobial resistance. However, there is now an even greater challenge from both old and new viruses capable of causing respiratory, enteric, and urogenital infections. Reports of viruses resistant to frontline therapeutic drugs are steadily increasing and there is an urgent need to develop novel antiviral agents. Although this all makes sense, it seems rather strange that relatively little attention has been given to the antiviral capabilities of probiotics. Over the years, beneficial strains of lactic acid bacteria (LAB) have been successfully used to treat gastrointestinal, oral, and vaginal infections, and some can also effect a reduction in serum cholesterol levels. Some probiotics prevent gastrointestinal dysbiosis and, by doing so, reduce the risk of developing secondary infections. Other probiotics exhibit anti-tumor and immunomodulating properties, and in some studies, antiviral activities have been reported for probiotic bacteria and/or their metabolites. Unfortunately, the mechanistic basis of the observed beneficial effects of probiotics in countering viral infections is sometimes unclear. Interestingly, in COVID-19 patients, a clear decrease has been observed in cell numbers of Lactobacillus and Bifidobacterium spp., both of which are common sources of intestinal probiotics. The present review, specifically motivated by the need to implement effective new counters to SARS-CoV-2, focusses attention on viruses capable of co-infecting humans and other animals and specifically explores the potential of probiotic bacteria and their metabolites to intervene with the process of virus infection. The goal is to help to provide a more informed background for the planning of future probiotic-based antiviral research.

PLAGA-PEG-PLAGA Terpolymer-Based Carriers of Herbicides for Potential Application in Environment-Friendly, Controlled Release Systems of Agrochemicals

The present study aimed to develop and prepare new polymer/herbicide formulations for their potential application in environment-friendly, controlled release systems of agrochemicals. Selected biodegradable polymers, including L-Lactide/Glycolide/PEG/Terpolymer (PLAGA-PEG-PLAGA) as well as oligosaccharide-based polymers and their blend with terpolymer, were used to prepare microspheres loaded with two soil-applied herbicides. The degradation process of the obtained polymeric microspheres was evaluated based on (1) their weight loss and surface erosion and (2) the release rate of loaded metazachlor and pendimethalin. The herbicidal effectiveness of the herbicides released to the soil from microspheres was evaluated using the European Weed Research Council (EWRC) rating scale. Moreover, the ecotoxicological effect of herbicide-loaded microspheres buried in soil on the marine bacterial species A. fischeri was assessed. It was found that the gradual degradation rate of microparticles led to the prolonged release of both herbicides that lasted for a few months, i.e., for the entire crop season, which is crucial in terms of agrochemical and environmental protection. Maltodextrin- and dextrin-based microspheres showed higher susceptibility to degradation than terpolymer-based microspheres. The microencapsulation of herbicides protected them from decomposition and excessive leaching into soil and maintained their activity for a longer period than that for non-immobilized herbicides. The ecotoxicological assessment on A. fischeri demonstrated that the proposed microsphere-encapsulated herbicides were less toxic than non-immobilized herbicides.

Carvacrol encapsulation into nanostructures: Characterization and antimicrobial activity against foodborne pathogens adhered to stainless steel

Carvacrol is a natural antimicrobial capable of inhibiting several microorganisms. The encapsulation of this compound may increase its stability, water solubility and provide controlled release. In this study, carvacrol encapsulated into nanoliposomes (NLC) and polymeric Eudragit® nanocapsules (NCC) was tested against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli and Salmonella spp. adhered to stainless steel. NLC showed an average diameter of 270.8 nm, zeta potential of +8.64 mV, and encapsulation efficiency of 98%. Minimum Bactericidal Concentration (MBC) of NLC was 3.53 mg/mL against Salmonella and 5.30 mg/mL against the other bacteria. NCC presented an average diameter of 159.3 nm, zeta potential of +44.8 mV, and encapsulation efficiency of 97%. MBC of NCC was 4.42 mg/mL against E. coli and 3.31 mg/mL against the other bacteria. After 2 h incubation with NCC at carvacrol concentration equivalent to ½ MBC, viable counts of Salmonella and E. coli were below the detection limit (1.69 CFU/mL). The population of L. monocytogenes and S. aureus was reduced by 2 log CFU/mL in 6 h. Afterwards, pools of each bacterium were separately adhered to stainless steel coupons (initial population 6.5 CFU/cm²). Salmonella and E. coli were inhibited below the detection limit using the NCC at concentration equivalent to MBC, while L. monocytogenes and S. aureus were reduced by 4 log CFU/cm² and 3.5 log CFU/cm², respectively. Although free carvacrol presented better results than encapsulated one in all tests performed, using encapsulated carvacrol could be more interesting for food applications by masking the strong aroma of the compound, in addition to a controlled release of carvacrol. The results suggest that NCC have potential for use in food contact surfaces in order to avoid bacterial adhesion and subsequent biofilm formation.

A Perspective on Polylactic Acid-Based Polymers Use for Nanoparticles Synthesis and Applications

Polylactic acid (PLA)-based polymers are ubiquitous in the biomedical field thanks to their combination of attractive peculiarities: biocompatibility (degradation products do not elicit critical responses and are easily metabolized by the body), hydrolytic degradation in situ, tailorable properties, and well-established processing technologies. This led to the development of several applications, such as bone fixation screws, bioresorbable suture threads, and stent coating, just to name a few. Nanomedicine could not be unconcerned by PLA-based materials as well, where their use for the synthesis of nanocarriers for the targeted delivery of hydrophobic drugs emerged as a new promising application. The purpose of the here presented review is two-fold: on one side, it aims at providing a broad overview of PLA-based materials and their properties, which allow them gaining a leading role in the biomedical field; on the other side, it offers a specific focus on their recent use in nanomedicine, highlighting opportunities and perspectives.

Maturation of dendritic cells in vitro and immunological enhancement of mice in vivo by pachyman- and/or OVA-encapsulated poly(d,l-lactic acid) nanospheres

Background

Poly lactide (PLA) was proved in the last years to be good for use in sustained drug delivery and as carriers for vaccine antigens. In our previous research, pachyman (PHY)-encapsulated PLA (PHYP) nanospheres were synthesized and their function of controlling drug release was demonstrated.

Purpose

In order to modify the fast drug-release rate of PHY when inoculated alone, the maturation of bone marrow dendritic cells (BMDCs) in vitro and their immunological enhancement in vivo were explored using PHYP nanospheres.

Methods

The maturation and antigen uptake of BMDCs were evaluated, both alone and with formulated antigen PHYP nanospheres, ie, ovalbumin (OVA)-loaded PHYP nanospheres, as an antigen delivery system, to investigate antigen-specific humoral and cellular immune responses.

Results

The results indicated that, when stimulated by PHYP, the BMDCs matured as a result of upregulated expression of co-stimulatory molecules; the mechanism was elucidated by tracing fluorescently labeled antigens in confocal laser scanning microscopy images and observing the uptake of nanospheres by transmission electron microscopy. It was further revealed that mice inoculated with OVA-PHYP had augmented antigen-specific IgG antibodies, increased cytokine secretion by splenocytes, increased splenocyte proliferation, and activation of cluster of differentiation (CD)4⁺ and CD8⁺ T cells in vivo. Elevated immune responses were produced by OVA-PHYP, possibly owing to the activation and maturation of dendritic cells (in draining lymph nodes).

Conclusion

It was corroborated that PHY- and/or OVA-encapsulated PLA nanospheres elicited prominent antigen-presenting effects on BMDCs and heightened humoral and cellular immune responses compared with other formulations.

Polymeric nanoparticles: A study on the preparation variables and characterization methods

Since the emergence of Nanotechnology in the past decades, the development and design of nanomaterials has become an important field of research. An emerging component in this field is nanomedicine, wherein nanoscale materials are being developed for use as imaging agents or for drug delivery applications. Much work is currently focused in the preparation of well-defined nanomaterials in terms of size and shape. These factors play a significantly role in the nanomaterial behavior in vivo. In this context, this review focuses on the toolbox of available methods for the preparation of polymeric nanoparticles. We highlight some recent examples from the literature that demonstrate the influence of the preparation method on the physicochemical characteristics of the nanoparticles. Additionally, in the second part, the characterization methods for this type of nanoparticles are discussed.

PLA micro- and nano-particles

Poly(d,l-lactic acid) (PLA) has been widely used for various biomedical applications for its biodegradable, biocompatible, and nontoxic properties. Various methods, such as emulsion, salting out, and precipitation, have been used to make better PLA micro- and nano-particle formulations. They are widely used as controlled drug delivery systems of therapeutic molecules, including proteins, genes, vaccines, and anticancer drugs. Even though PLA-based particles have challenges to overcome, such as low drug loading capacity, low encapsulation efficiency, and terminal sterilization, continuous innovations in particulate formulations will lead to development of clinically useful formulations.

A review of the applications of data mining and machine learning for the prediction of biomedical properties of nanoparticles

This article presents a comprehensive review of applications of data mining and machine learning for the prediction of biomedical properties of nanoparticles of medical interest. The papers reviewed here present the results of research using these techniques to predict the biological fate and properties of a variety of nanoparticles relevant to their biomedical applications. These include the influence of particle physicochemical properties on cellular uptake, cytotoxicity, molecular loading, and molecular release in addition to manufacturing properties like nanoparticle size, and polydispersity. Overall, the results are encouraging and suggest that as more systematic data from nanoparticles becomes available, machine learning and data mining would become a powerful aid in the design of nanoparticles for biomedical applications. There is however the challenge of great heterogeneity in nanoparticles, which will make these discoveries more challenging than for traditional small molecule drug design.

Bioerodable PLGA-Based Microparticles for Producing Sustained-Release Drug Formulations and Strategies for Improving Drug Loading

Poly(lactic-co-glycolic acid) (PLGA) is the most widely used biomaterial for microencapsulation and prolonged delivery of therapeutic drugs, proteins and antigens. PLGA has excellent biodegradability and biocompatibility and is generally recognized as safe by international regulatory agencies including the United States Food and Drug Administration and the European Medicines Agency. The physicochemical properties of PLGA may be varied systematically by changing the ratio of lactic acid to glycolic acid. This in turn alters the release rate of microencapsulated therapeutic molecules from PLGA microparticle formulations. The obstacles hindering more widespread use of PLGA for producing sustained-release formulations for clinical use include low drug loading, particularly of hydrophilic small molecules, high initial burst release and/or poor formulation stability. In this review, we address strategies aimed at overcoming these challenges. These include use of low-temperature double-emulsion methods to increase drug-loading by producing PLGA particles with a small volume for the inner water phase and a suitable pH of the external phase. Newer strategies for producing PLGA particles with high drug loading and the desired sustained-release profiles include fabrication of multi-layered microparticles, nanoparticles-in-microparticles, use of hydrogel templates, as well as coaxial electrospray, microfluidics, and supercritical carbon dioxide methods. Another recent strategy with promise for producing particles with well-controlled and reproducible sustained-release profiles involves complexation of PLGA with additives such as polyethylene glycol, poly(ortho esters), chitosan, alginate, caffeic acid, hyaluronic acid, and silicon dioxide.

Nanoparticles Based on Linear and Star-Shaped Poly(Ethylene Glycol)-Poly(ε-Caprolactone) Copolymers for the Delivery of Antitubulin Drug

PURPOSE

Biodegradable polymeric nanoparticles of different architectures based on polyethylene glycol-co-poly(ε-caprolactone) block copolymers have been loaded with noscapine (NOS) to study their effect on its anticancer activity. It was intended to use solubility of NOS in an acidic environment and ability of the nanoparticles to passively target drugs into cancer tissue to modify the NOS pharmacokinetic properties and reduce the requirement for frequent injections.

METHODS

Linear and star-shaped copolymers were synthetized and used to formulate NOS loaded nanoparticles. Cytotoxicity was performed using a sulforhodamine B method on MCF-7 cells, while biocompatibility was determined on rats followed by hematological and histopathological investigations.

RESULTS

Formulae with the smallest particle sizes and adequate entrapment efficiency revealed that NOS loaded nanoparticles showed higher extent of release at pH 4.5. Colloidal stability suggested that nanoparticles would be stable in blood when injected into the systemic circulation. Loaded nanoparticles had IC50 values lower than free drug. Hematological and histopathological studies showed no difference between treated and control groups. Pharmacokinetic analysis revealed that formulation P1 had a prolonged half-life and better bioavailability compared to drug solution.

CONCLUSIONS

Formulation of NOS into biodegradable polymeric nanoparticles has increased its efficacy and residence on cancer cells while passively avoiding normal body tissues. Graphical Abstract ᅟ.

Nanoformulations of anticancer thiosemicarbazones to reduce methemoglobin formation and improve anticancer activity

Triapine and two derivatives were encapsulated into polymeric nanoparticles as well as liposomes. The most stable formulation showed strongly reduced methemoglobin formation and improved anticancer activity.

Determination of factors controlling the particle size and entrapment efficiency of noscapine in PEG/PLA nanoparticles using artificial neural networks

In this study, di- and triblock copolymers based on polyethylene glycol and polylactide were synthesized by ring-opening polymerization and characterized by proton nuclear magnetic resonance and gel permeation chromatography. Nanoparticles containing noscapine were prepared from these biodegradable and biocompatible copolymers using the nanoprecipitation method. The prepared nanoparticles were characterized for size and drug entrapment efficiency, and their morphology and size were checked by transmission electron microscopy imaging. Artificial neural networks were constructed and tested for their ability to predict particle size and entrapment efficiency of noscapine within the formed nanoparticles using different factors utilized in the preparation step, namely polymer molecular weight, ratio of polymer to drug, and number of blocks that make up the polymer. Using these networks, it was found that the polymer molecular weight has the greatest effect on particle size. On the other hand, polymer to drug ratio was found to be the most influential factor on drug entrapment efficiency. This study demonstrated the ability of artificial neural networks to predict not only the particle size of the formed nanoparticles but also the drug entrapment efficiency. This may have a great impact on the design of polyethylene glycol and polylactide-based copolymers, and can be used to customize the required target formulations.

Engineered nanoparticles for drug delivery in cancer therapy

In medicine, nanotechnology has sparked a rapidly growing interest as it promises to solve a number of issues associated with conventional therapeutic agents, including their poor water solubility (at least, for most anticancer drugs), lack of targeting capability, nonspecific distribution, systemic toxicity, and low therapeutic index. Over the past several decades, remarkable progress has been made in the development and application of engineered nanoparticles to treat cancer more effectively. For example, therapeutic agents have been integrated with nanoparticles engineered with optimal sizes, shapes, and surface properties to increase their solubility, prolong their circulation half-life, improve their biodistribution, and reduce their immunogenicity. Nanoparticles and their payloads have also been favorably delivered into tumors by taking advantage of the pathophysiological conditions, such as the enhanced permeability and retention effect, and the spatial variations in the pH value. Additionally, targeting ligands (e.g., small organic molecules, peptides, antibodies, and nucleic acids) have been added to the surface of nanoparticles to specifically target cancerous cells through selective binding to the receptors overexpressed on their surface. Furthermore, it has been demonstrated that multiple types of therapeutic drugs and/or diagnostic agents (e.g., contrast agents) could be delivered through the same carrier to enable combination therapy with a potential to overcome multidrug resistance, and real-time readout on the treatment efficacy. It is anticipated that precisely engineered nanoparticles will emerge as the next-generation platform for cancer therapy and many other biomedical applications.

Evaluation of PEG and mPEG-co-(PGA-co-PDL) microparticles loaded with sodium diclofenac

The aim of this study was to synthesize and evaluate novel biodegradable polyesters namely; poly(ethylene glycol)-Poly(glycerol adipate-co-ω-pentadecalactone), PEG-PGA-co-PDL-PEG, and poly(ethylene glycol methyl ether)-Poly(glycerol adipate-co-ω-pentadecalactone), PGA-co-PDL-PEGme as an alternative sustained release carrier for lung delivery compared with non-PEG containing polymer PGA-co-PDL. The co-polymers were synthesized through lipase catalysis ring opening polymerization reaction and characterized using GPC, FT-IR, (1)H-NMR and surface contact angle. Furthermore, microparticles containing a model hydrophilic drug, sodium diclofenac, were prepared via spray drying from a modified single emulsion and characterized for their encapsulation efficiency, geometrical particle size, zeta potential, tapped density, primary aerodynamic diameter, amorphous nature, morphology, in vitro release and the aerosolization performance. Microparticles fabricated from mPEG-co-polymer can be targeted to the lung periphery with an optimum in vitro deposition. Furthermore, a significantly higher in vitro release (p > 0.05, ANOVA/Dunnett's) was observed with the PEG and mPEG-co-polymers compared to PGA-co-PDL. In addition, these co-polymers have a good safety profile upon testing on human bronchial epithelial, 16HBE14o- cell lines.

In vitro toxicity of Stearoyl-poly(glycerol adipate) nanoparticles

PURPOSE

Poly(glycerol adipate) (PGA)-based nanoparticles are promising carriers for drug delivery with a wide range of available structures. The biodegradable polymer with pendant free hydroxyl groups can be diversely functionalized. In this study, the toxicity of different Stearoyl-PGA nanoparticles with respect to erythrocytes and HepG2 cells was assessed. These cells are crucial test systems for intravenously injected biomedical particles.

METHODS

For this work, a series of PGA polyesters with 0, 20, 50 and 65 mol% of converted hydroxyl groups was synthesized with stearic acid (PGABB, S20, S50, S65). Nanoparticles were prepared with these polymers by an optimized nanoprecipitation method. Physicochemical characterization was performed by photon correlation spectroscopy and zeta potential measurement. Cell compatibility was studied by a hemolysis assay with separated red blood cells as well as a QBlue viability test and a modified LDH cytotoxicity assay with HepG2 cells.

RESULTS AND CONCLUSIONS

Different self-stabilizing nanoparticles with narrow size distributions in the range of 100-140 nm were prepared. All tested nanoparticle samples were nontoxic for HepG2 cells. In fact, increased metabolic activity and proliferation was observed after 24 h incubation with the Stearoyl-PGA particles. Apart from PGAS20, all samples did not show any hemolytic effect. Hemolysis of PGAS20 particles could be considerably decreased by adding Poloxamer 188 during the preparation process.

Cyclodextrin based nanosponges for pharmaceutical use: a review

Nanosponges are a novel class of hyper-crosslinked polymer based colloidal structures consisting of solid nanoparticles with colloidal sizes and nanosized cavities. These nano-sized colloidal carriers have been recently developed and proposed for drug delivery, since their use can solubilize poorly water-soluble drugs and provide prolonged release as well as improve a drug's bioavailability by modifying the pharmacokinetic parameters of actives. Development of nanosponges as drug delivery systems, with special reference to cyclodextrin based nanosponges, is presented in this article. In the current review, attempts have been made to illustrate the features of cyclodextrin based nanosponges and their applications in pharmaceutical formulations. Special emphasis has been placed on discussing the methods of preparation, characterization techniques and applications of these novel drug delivery carriers for therapeutic purposes. Nanosponges can be referred to as solid porous particles having a capacity to load drugs and other actives into their nanocavity; they can be formulated as oral, parenteral, topical or inhalation dosage forms. Nanosponges offer high drug loading compared to other nanocarriers and are thus suitable for solving issues related to stability, solubility and delayed release of actives. Controlled release of the loaded actives and solubility enhancement of poorly water-soluble drugs are major advantages of nanosponge drug delivery systems.

BSA-PLGA-based core-shell nanoparticles as carrier system for water-soluble drugs

PURPOSE

Preparation, optimization and in vitro evaluation of core-shell nanoparticles comprising of a hydrophilic core of BSA surrounded by a hydrophobic shell of PLGA for loading water-soluble drugs.

METHODS

A double emulsion method was optimized for preparation of BSA-PLGA based core-shell nanoparticles. Proof of concept for core-shell type structure was established by visual techniques like confocal microscopy and TEM. Characterization was done for particle size, encapsulation efficiency, drug loading and in vitro drug release. Cellular uptake was assessed using confocal microscopy, bio-TEM and HPLC assay, and cytotoxic activity was tested by MTT assay in MG-63 osteosarcoma cells.

RESULTS

The optimized core-shell nanoparticles showed a particle size of 243 nm (PDI-0.13) and encapsulation efficiency of 40.5% with a drug loading of 8.5% w/w. In vitro drug release studies showed a sustained release for 12 h. Cellular uptake studies indicated a rapid and efficient uptake within 2 h. TEM studies indicated that the core-shell nanoparticles were localized in cytoplasm region of the cells. Gemcitabine loaded core-shell nanoparticles showed enhanced cytotoxicity against MG-63 cells as compared to marketed formulation of gemcitabine (GEMCITE®).

CONCLUSION

These results indicate that core-shell nanoparticles can be a good carrier system for delivering hydrophilic drugs like gemcitabine successfully to the cells with enhanced efficacy.

Nanosized sustained-release pyridostigmine bromide microcapsules: process optimization and evaluation of characteristics

Background

Pyridostigmine bromide (3-[[(dimethylamino)-carbonyl]oxy]-1-methylpyridinium bromide), a reversible inhibitor of cholinesterase, is given orally in tablet form, and a treatment schedule of multiple daily doses is recommended for adult patients. Nanotechnology was used in this study to develop an alternative sustained-release delivery system for pyridostigmine, a synthetic drug with high solubility and poor oral bioavailability, hence a Class III drug according to the Biopharmaceutics Classification System. Novel nanosized pyridostigmine-poly(lactic acid) microcapsules (PPNMCs) were expected to have a longer duration of action than free pyridostigmine and previously reported sustained-release formulations of pyridostigmine.

Methods

The PPNMCs were prepared using a double emulsion-solvent evaporation method to achieve sustained-release characteristics for pyridostigmine. The preparation process for the PPNMCs was optimized by single-factor experiments. The size distribution, zeta potential, and sustained-release behavior were evaluated in different types of release medium.

Results

The optimal volume ratio of inner phase to external phase, poly(lactic acid) concentration, polyvinyl alcohol concentration, and amount of pyridostigmine were 1:10, 6%, 3% and 40 mg, respectively. The negatively charged PPNMCs had an average particle size of 937.9 nm. Compared with free pyridostigmine, PPNMCs showed an initial burst release and a subsequent very slow release in vitro. The release profiles for the PPNMCs in four different types of dissolution medium were fitted to the Ritger-Peppas and Weibull models. The similarity between pairs of dissolution profiles for the PPNMCs in different types of medium was statistically significant, and the difference between the release curves for PPNMCs and free pyridostigmine was also statistically significant.

Conclusion

PPNMCs prepared by the optimized protocol described here were in the nanometer range and had good uniformity, with significantly slower pyridostigmine release than from free pyridostigmine. This novel sustained-release delivery nanosystem for pyridostigmine might alleviate the need to identify new acetylcholinesterase inhibitors.

Dialysis nanoprecipitation of polystyrene nanoparticles

Using a facile dialysis nanoprecipitation method, nanoparticles of several hundred nanometers have been successfully generated from a "traditional," non-biodegradable polymer, that is, polystyrene. The effect of initial polymer concentration inside the dialysis membrane, as well as the polymer/solvent system and the ionic strength (electrolyte concentration) of the dialysis solution, on nanoparticle size is examined. A nucleation-aggregation mechanism has been provided to explain the observed trends. Furthermore, we determine the zeta potential as a function of ionic strength for the generated nanoparticles and show that anionic charging may be present in the system.

Development of poly(glycerol adipate) nanoparticles loaded with non-steroidal anti-inflammatory drugs

The aim of this study was to assess acylated and non-acylated poly(glycerol adipate) polymers (PGA) as suitable nanoparticulate systems for encapsulation and release of ibuprofen, ibuprofen sodium salt (IBU-Na) and ketoprofen as model drugs. Drug encapsulated nanoparticles were prepared using the interfacial deposition method in the absence of surfactants. Physicochemical characterisation studies of the produced loaded nanoparticles showed that drug-polymer interactions depend on the characteristics of the actual active substance. IBU-Na showed strong interactions with the polymers and it was found to be molecularly dispersed within the polymer matrix while ibuprofen and ketoprofen retained their crystalline state. The drug release profiles showed stepwise patterns which involve an initial burst release effect, diffusion of the drug from the polymer matrix and eventually drug release possibly via a combined mechanism. PGA polymers can be effectively used as drug delivery carriers for various active substances.

Polymer-based oral peptide nanomedicines

Oral peptide delivery has been one of the major challenges of pharmaceutical sciences as it could lead to a great improvement of classical therapies, such as insulin, alongside making an important number of new therapies feasible. Successful oral delivery needs to fulfill two key tasks: to protect the macromolecules from degradation in the GI tract and to shuttle them across the intestinal epithelium in a safe and efficient fashion. Over the last decade, there have been numerous approaches based on the chemical modification of peptides and on the use of permeation enhancers, enzyme inhibitors and drug-delivery systems. Among the approaches developed to overcome these restrictions, the design of nanocarriers seems to be a particularly promising approach. This article is an overview on the state of the art of oral-peptide formulation strategies, with special attention to insulin delivery and the use of polymeric nanocarriers as delivery systems.

Low molecular weight poly(lactic acid) microparticles for controlled release of the herbicide metazachlor: preparation, morphology, and release kinetics

The preemergence chloroacetamide herbicide metazachlor was encapsulated in biodegradable low molecular weight poly(lactic acid) micro- and submicroparticles, and its release to the water environment was investigated. Three series of particles, S, M, and L, varying in their size (from 0.6 to 8 μm) and with various initial amounts of the active agent (5%, 10%, 20%, 30% w/w) were prepared by the oil-in-water solvent evaporation technique with gelatin as biodegradable surfactant. The encapsulation efficiencies reached were about 60% and appeared to be lower for smaller particles. Generally, it was found that the rate of herbicide release decreased with increasing size of particles. After 30 days the portions of the herbicide released for its highest loading (30% w/w) were 92%, 56%, and 34% for about 0.6, 0.8, and 8 μm particles, respectively. The release rates were also lower for lower herbicide loadings. Metazachlor release from larger particles tended to be a diffusion-controlled process, while for smaller particles the kinetics was strongly influenced by an initial burst release.

Biodegradable polymeric nanoparticles based drug delivery systems

Biodegradable nanoparticles have been used frequently as drug delivery vehicles due to its grand bioavailability, better encapsulation, control release and less toxic properties. Various nanoparticulate systems, general synthesis and encapsulation process, control release and improvement of therapeutic value of nanoencapsulated drugs are covered in this review. We have highlighted the impact of nanoencapsulation of various disease related drugs on biodegradable nanoparticles such as PLGA, PLA, chitosan, gelatin, polycaprolactone and poly-alkyl-cyanoacrylates.

Targeted delivery with peptidomimetic conjugated self-assembled nanoparticles

Peptides produce specific nanostructures, making them useful for targeting in biological systems but they have low bioavailability, potential immunogenicity and poor metabolic stability. Peptidomimetic self-assembled NPs can possess biological recognition motifs as well as providing desired engineering properties. Inorganic NPs, coated with self-assembled macromers for stability and anti-fouling, and conjugated with target-specific ligands, are advancing imaging from the anatomy-based level to the molecular level. Ligand conjugated NPs are attractive for cell-selective tumor drug delivery, since this process has high transport capacity as well as ligand dependent cell specificity. Peptidomimetic NPs can provide stronger interaction with surface receptors on tumor cells, resulting in higher uptake and reduced drug resistance. Self-assembled NPs conjugated with peptidomimetic antigens are ideal for sustained presentation of vaccine antigens to dendritic cells and subsequent activation of T cell mediated adaptive immune response. Self-assembled NPs are a viable alternative to encapsulation for sustained delivery of proteins in tissue engineering. Cell penetrating peptides conjugated to NPs are used as intracellular delivery vectors for gene expression and as transfection agents for plasmid delivery. In this work, synthesis, characterization, properties, immunogenicity, and medical applications of peptidomimetic NPs in imaging, tumor delivery, vaccination, tissue engineering, and intracellular delivery are reviewed.

A new double emulsion solvent diffusion technique for encapsulating hydrophilic molecules in PLGA nanoparticles

The commonly utilized techniques for encapsulating hydrophilic molecules in NP suffer from low encapsulation efficiency because of the drug rapid partitioning to the external aqueous phase. We hypothesized that combining the double emulsion system with a partially water-soluble organic solvent, could result in better encapsulation yield of hydrophilic molecules in nano-sized NP, and the utilization of both biocompatible surfactants and solvents. As a model drug we used alendronate, a hydrophilic low MW bisphosphonate. The new NP preparation technique, double emulsion solvent diffusion (DES-D), resulted in improved formulation characteristics including smaller size, lower size distribution, higher encapsulation yield, and more biocompatible ingredients in comparison to classical methods. The utilization of partially water-miscible organic solvent (ethyl acetate) enabled rapid diffusion through the aqueous phase forming smaller NP. In addition, the formulated alendronate NP exhibited profound inhibition of raw 264 macrophages, depletion of rabbit's circulating monocytes, and inhibition of restenosis in the rat model. It is concluded that the new technique is advantageous in terms of smaller size, lower size distribution, higher encapsulation yield, and more biocompatible ingredients, with unaltered bioactivity.