Biodegradable monodispersed nanoparticles prepared by pressure homogenization-emulsification

Evaluation of Biodegradable Microparticles for Mucosal Vaccination Against Diphtheria Toxoid: Nasal Efficacy Studies in Guinea Pigs

Objectives

In this study, poly-(ɛ-caprolactone) (PCL) and poly-(lactic-co-glycolic acid) (PLGA) microparticles encapsulating diphtheria toxoid (DT) were investigated for their potential as a mucosal vaccine delivery system.

Materials and Methods

Antigen-containing microparticles were prepared using the double emulsion (w/o/w) solvent evaporation method.

Results

The average geometric diameter of the particles was found to be between 7 and 24 µm, which is suitable for uptake by the antigen-presenting cells in the nasal mucosa. Although the differences were insignificant, the PLGA polymer-containing formulations exhibited the highest encapsulation efficiency. Microparticle formulations, prepared with both PLGA and PCL polymers, were successfully produced at high production yields. The in vitro release profile was presented as a biexponential process with an initial burst effect due to the release of the protein adsorbed on the microsphere surface, and the subsequent sustained release profile is the result of protein diffusion through the channels or pores formed in the polymer matrix. DT-loaded microparticles, DT solution in phosphate-buffered saline (PBS), and empty microparticles (control) were administered via nasal route and subcutaneously to guinea pigs. The antibody content of each serum sample was determined using an enzyme-linked immunosorbent assay (ELISA).

Conclusion

Absorbance values of the ELISA test showed that PLGA- and PCL-bearing microparticles could stimulate an adequate systemic immune response with intranasal vaccination. In addition, PLGA and PCL microparticles resulted in significantly increased IgG titers with intranasal administration as a booster dose following subcutaneous administration. PCL polymer elicited a high immune response compared with PLGA polymer (p <0.05).

Encapsulation of a highly hydrophilic drug in polymeric particles: A comparative study of batch and microfluidic processes

The objective of this work was to investigate the effect of microfluidics on the quality attributes of metformin hydrochloride-loaded poly lactic-co-glycolic acid polymeric particles (MFH-PLGA PPs) when compared to a traditional double emulsion batch method. The relationship of encapsulation and loading efficiencies, yield %, particle size, surface morphology, and release profile with process and formulation variables were determined using design of experiments (DoE). The effects of the dispersal method of the primary (sonication vs. vortex) or secondary emulsion (microfluidics vs. batch), polyvinyl alcohol concentration (PVA), and drug to polymer ratio were investigated. The PPs' size was impacted by both the PVA concentration and the type of primary and secondary emulsion dispersion methods. Microfluidics significantly increased the PPs' yield %, particle size, encapsulation, and loading efficiencies. The higher loaded microfluidic-based PPs had more burst release, following first-order release kinetics when compared to the lower loaded batch-based particles, which followed the Korsmeyer-Peppas model for release kinetics. Microfluidic-based PPs exhibited a smooth, porous, more uniform, and larger particle size with hollow structure than the batch-based PPs with a matrix-like structure. In conclusion, we have elucidated the effect of microfluidics on the quality attributes of MFH-PLGA PPs and their comparison to the traditional batch technique.

Quality by design prospects of pharmaceuticals application of double emulsion method for PLGA loaded nanoparticles

Abstract

QbD approach empowers the pharma researchers to minimize the number of experimental trials and time. It helps identify the significant, influential factors such as critical material attributes, critical formulation variables, and critical process parameters, which may significantly impact the quality of the products. Poly lactic-co-glycolic acid (PLGA), a biocompatible and biodegradable polymer, has gained an immense potential and wide range of applications as a carrier for manufacturing of polymeric nanoparticle drug delivery systems as per US-FDA and European Medicine Agency for drug delivery. The double emulsion method for preparing PLGA nanoparticles to encapsulate hydrophilic drugs has attracted interest in manufacturing processes. The double emulsion is a two-step process consisting of two different emulsification, making the process more complicated. The stability of nanoparticles obtained by a double emulsion method remains questionable due to the many formulations and process attributes. Currently, PLGA based nanoparticles prepared by a double emulsion technique are an alternative pharmaceutical manufacturing operation for getting the quality product by employing the Quality by Design approach. This present review has discussed the QbD elements to elucidate the effect of material attributes, formulation, and process variables on the critical quality attributes of the drug product, such as particle size distribution, encapsulation efficiency, etc. The components of a double emulsion, characteristics of drugs, polymers, and stabilizers used have been discussed in detail in this review.

Graphic abstract

Scaffold-based osteogenic dual delivery system with melatonin and BMP-2 releasing PLGA microparticles

The growing safety problems about the use of bone morphogenetic protein 2 (BMP-2) is one of the recent issues that was improved by using low doses of BMP-2 with the support of other osteoinductive agents and/or using appropriate carriers. The aim of the present study is to investigate the effect of scaffold-based dual release system including melatonin (MEL) and BMP-2 loaded polylactic-co-glycolic acid (PLGA) microparticles on the osteogenic activity of pre-osteoblastic MC3T3-E1 cells. MEL and BMP-2 loaded microparticles were prepared by double emulsion solvent evaporation method in the average diameters of ~2 µm and ~11 µm, respectively and loaded into chitosan/hydroxyapatite (HAp) scaffolds. In vitro MC3T3-E1 culture studies were carried out comparatively with blank scaffolds, single (BMP-2 or MEL) releasing groups and dual (BMP-2 and MEL) releasing group. Microscopic observations and hematoxylin/eosin staining showed enhanced number of cells and dense ECM in dual release group. The expressions of differentiation markers, Runt-related transcription factor 2 (RUNX2) and alkaline phosphatase (ALP) and also mineralization were higher in dual release group than that of the other groups. Our findings showed that BMP-2 at low doses (~20 ng per scaffold) was sufficient in terms of osteogenic activity with controlled release systems where it was used in combination with MEL (~10 µg per scaffold).

Hierarchically electrospraying a PLGA@chitosan sphere-in-sphere composite microsphere for multi-drug-controlled release

Sequential administration and controlled release of different drugs are of vital importance for regulating cellular behaviors and tissue regeneration, which usually demands appropriate carriers like microspheres (MS) to control drugs releases. Electrospray has been proven an effective technique to prepare MS with uniform particle size and high drug-loading rate. In this study, we applied electrospray to simply and hierarchically fabricate sphere-in-sphere composite microspheres, with smaller poly(lactic-co-glycolic acid) MS (∼8–10 μm in diameter) embedded in a larger chitosan MS (∼250–300 μm in diameter). The scanning electron microscopy images revealed highly uniform MS that can be accurately controlled by adjusting the nozzle diameter or voltage. Two kinds of model drugs, bovine serum albumin and chlorhexidine acetate, were encapsulated in the microspheres. The fluorescence-labeled rhodamine-fluoresceine isothiocyanate (Rho-FITC) and ultraviolet (UV) spectrophotometry results suggested that loaded drugs got excellent distribution in microspheres, as well as sustained, slow release in vitro. In addition, far-UV circular dichroism and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) results indicated original secondary structure and molecular weight of drugs after electrospraying. Generally speaking, our research proposed a modified hierarchically electrospraying technique to prepare sphere-in-sphere composite MS with two different drugs loaded, which could be applied in sequential, multi-modality therapy.

Microfluidization trends in the development of nanodelivery systems and applications in chronic disease treatments

Plant bioactive compounds are known for their extensive health benefits and therefore have been used for generations in traditional and modern medicine to improve the health of humans. Processing and storage instabilities of the plant bioactive compounds, however, limit their bioavailability and bioaccessibility and thus lead researchers in search of novel encapsulation systems with enhanced stability, bioavailability, and bioaccessibility of encapsulated plant bioactive compounds. Recently many varieties of encapsulation methods have been used; among them, microfluidization has emerged as a novel method used for the development of delivery systems including solid lipid nanocarriers, nanoemulsions, liposomes, and so on with enhanced stability and bioavailability of encapsulated plant bioactive compounds. Therefore, the nanodelivery systems developed using microfluidization techniques have received much attention from the medical industry for their ability to facilitate controlled delivery with enhanced health benefits in the treatment of various chronic diseases. Many researchers have focused on plant bioactive compound-based delivery systems using microfluidization to enhance the bioavailability and bioaccessibility of encapsulated bioactive compounds in the treatment of various chronic diseases. This review focuses on various nanodelivery systems developed using microfluidization techniques and applications in various chronic disease treatments.

Different methods to determine the encapsulation efficiency of protein in PLGA nanoparticles

BACKGROUND

Effective encapsulation of drugs into the delivery systems could increase the efficiency of nanoparticles in prevention and treatment of diseases.

OBJECTIVE

The purpose of this study was to compare the different methods for determination of encapsulation efficiency of a model protein in the PLGA nanoparticles.

METHODS

The various direct methods include dichloromethane, acetonitrile, modified acetonitrile and NaOH based extraction and radioactive methods were used to directly calculate the encapsulation efficiency of the loaded protein in the PLGA nanoparticles. Furthermore, indirect methods include BCA, Fluorescent and radioactive methods were compared.

RESULTS

The encapsulation efficiencies determined by indirect methods include dichloromethane, acetonitrile, modified acetonitrile, NaOH based extraction and radioactive methods were 12.62% ± 1.97, 17.43% ± 2.51, 64.69% ± 4.31, 86.36% ± 2.25 and 90.15% ± 1.78, respectively. Moreover, the encapsulation efficiencies determined by indirect methods include BCA, fluorescent and radioactive methods were 81.46% ± 1.92, 88.23% ± 1.15 and 89.6% ± 1.9, respectively.

CONCLUSIONS

Among the results obtained by indirect methods, radioactive and fluorescent methods showed more reliable. Moreover, NaOH and radioactive methods were the most reliable methods among the direct methods.

Recent insights in the use of nanocarriers for the oral delivery of bioactive proteins and peptides

Bioactive proteins and peptides have been used with either prophylactic or therapeutic purposes, presenting inherent advantages as high specificity and biocompatibility. Nanocarriers play an important role in the stabilization of proteins and peptides, offering enhanced buccal permeation and protection while crossing the gastrointestinal tract. Moreover, preparation of nanoparticles as oral delivery systems for proteins/peptides may include tailored formulation along with functionalization aiming bioavailability enhancement of carried proteins or peptides. Oral delivery systems, namely buccal delivery systems, represent an interesting alternative route to parenteric delivery systems to carry proteins and peptides, resulting in higher comfort of administration and, therefore, compliance to treatment. This paper outlines an extensive overview of the existing publications on proteins/peptides oral nanocarriers delivery systems, with special focus on buccal route. Manufacturing aspects of most commonly used nanoparticles for oral delivery (e.g. polymeric nanoparticles using synthetic or natural polymers and lipid nanoparticles) advantages and limitations and potential applications of nanoparticles as proteins/peptides delivery systems will also be thoroughly addressed.

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.

Synthesis of semicrystalline nanocapsular structures obtained by Thermally Induced Phase Separation in nanoconfinement

Phase separation of a polymer solution exhibits a peculiar behavior when induced in a nanoconfinement. The energetic constraints introduce additional interactions between the polymer segments that reduce the number of available configurations. In our work, this effect is exploited in a one-step strategy called nanoconfined-Thermally Induced Phase Separation (nc-TIPS) to promote the crystallization of polymer chains into nanocapsular structures of controlled size and shell thickness. This is accomplished by performing a quench step of a low-concentrated PLLA-dioxane-water solution included in emulsions of mean droplet size <500 nm acting as nanodomains. The control of nanoconfinement conditions enables not only the production of nanocapsules with a minimum mean particle diameter of 70 nm but also the tunability of shell thickness and its crystallinity degree. The specific properties of the developed nanocapsular architectures have important implications on release mechanism and loading capability of hydrophilic and lipophilic payload compounds.

Poly(lactic-co-glycolic) Acid-Chitosan Dual Loaded Nanoparticles for Antiretroviral Nanoformulations

Poly(lactic-co-glycolic acid) (PLGA) chitosan (CS) coated nanoparticles (NPs) were loaded with two antiretrovirals (ARVs) either lamivudine (LMV) which is hydrophilic or nevirapine (NVP) which is hydrophobic or both LMV and NVP. These ARVs are of importance in resource-limited settings, where they are commonly used in human immunodeficiency virus (HIV-1) treatment due to affordability and accessibility. NPs prepared by a water-oil-water emulsion and reduced pressure solvent evaporation technique were determined to have a positive zeta potential, a capsule-like morphology, and an average hydrodynamic diameter of 240 nm. Entrapment of NVP as a single ARV had a notable increase in NP size compared to LMV alone or in combination with LMV. NPs stored at room temperature in distilled water maintained size, polydispersity (PDI), and zeta potential for one year. No changes in size, PDI, and zeta potential were observed for NPs in 10% sucrose in lyophilized or nonlyophilized states stored at 4°C and -20°C, respectively. Freezing NPs in the absence of sucrose increased NP size. Drug loading, encapsulation efficiency, and kinetic release profiles were quantified by high performance liquid chromatography (HPLC). Our novel nanoformulations have the potential to improve patient outcomes and expand drug access in resource-limited countries for the treatment of HIV-1.

Tailoring sub-micron PLGA particle release profiles via centrifugal fractioning

Poly(D,L-lactic-co -glycolic) acid (PLGA)-based sub-micron particles are uniquely posed to overcome limitations of conventional drug delivery systems. However, tailoring cargo/payload release profiles from PLGA micro/nanoparticles typically requires optimization of the multi-parameter formulation, where small changes may cause drastic shifts in the resulting release profiles. In this study, we aimed to establish whether refining the average diameter of sub-micron particle populations after formulation alters protein release profiles. PLGA particles were first produced via double emulsion-solvent evaporation method to encapsulate bovine serum albumin. Particles were then subjected to centrifugal fractioning protocols varying in both spin time and force to determine encapsulation efficiency and release profile of differently sized populations that originated from a single batch. We found the average particle diameter was related to marked alterations in encapsulation efficiencies (range: 36.4-49.4%), burst release (range: 15.8-49.1%), and time for total cargo release (range: 38-78 days). Our data corroborate previous reports relating PLGA particle size with such release characteristics, however, this is the first study, to our knowledge, to directly compare particle population size while holding all formulation parameters constant. In summary, centrifugal fractioning to selectively control the population distribution of sub-micron PLGA particles represents a feasible tool to tailor release characteristics. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A 104A: 688-696, 2016.

Comparison of modified starch and Quillaja saponins in the formation and stabilization of flavor nanoemulsions

Modified starch (MS) and Quillaja saponins (QS) were compared to fabricate and stabilize orange oil nanoemulsions using microfluidization. Ester gum (EG) was incorporated in the oil phase at variable proportions (0-60%) as Ostwald ripening inhibitor and viscosity modifier. Optimal viscosity ratios of dispersed to continuous phase (ηd/ηc) were identified as 0.8-3.1 and 2.1-3.3 with MS and QS as emulsifier, respectively. QS was found superior to MS in fabricating nanoemulsion with smallest MDD of 69 nm and turbidity of 102 NTU at 0.05% of dispersed phase. With EG incorporated in the oil phase, QS stabilized nanoemulsions were stable during 2 weeks of storage at 23 °C; whereas MS stabilized nanoemulsions showed significant increases in MDD and turbidity. Zeta potential measurements showed QS imparted higher droplet charge (>-20 mV) than MS (<-5 mV) at pH 3.6 indicating MS stabilized nanoemulsions were destabilized by coalescence due to insufficient interfacial charge.

Optimization of nanoparticles for cardiovascular tissue engineering

Nano-particulate delivery systems have increasingly been playing important roles in cardiovascular tissue engineering. Properties of nanoparticles (e.g. size, polydispersity, loading capacity, zeta potential, morphology) are essential to system functions. Notably, these characteristics are regulated by fabrication variables, but in a complicated manner. This raises a great need to optimize fabrication process variables to ensure the desired nanoparticle characteristics. This paper presents a comprehensive experimental study on this matter, along with a novel method, the so-called Geno-Neural approach, to analyze, predict and optimize fabrication variables for desired nanoparticle characteristics. Specifically, ovalbumin was used as a protein model of growth factors used in cardiovascular tissue regeneration, and six fabrication variables were examined with regard to their influence on the characteristics of nanoparticles made from high molecular weight poly(lactide-co-glycolide). The six-factor five-level central composite rotatable design was applied to the conduction of experiments, and based on the experimental results, a geno-neural model was developed to determine the optimum fabrication conditions. For desired particle sizes of 150, 200, 250 and 300 nm, respectively, the optimum conditions to achieve the low polydispersity index, higher negative zeta potential and higher loading capacity were identified based on the developed geno-neural model and then evaluated experimentally. The experimental results revealed that the polymer and the external aqueous phase concentrations and their interactions with other fabrication variables were the most significant variables to affect the size, polydispersity index, zeta potential, loading capacity and initial burst release of the nanoparticles, while the electron microscopy images of the nanoparticles showed their spherical geometries with no sign of large pores or cracks on their surfaces. The release study revealed that the onset of the third phase of release can be affected by the polymer concentration. Circular dichroism spectroscopy indicated that ovalbumin structural integrity is preserved during the encapsulation process. Findings from this study would greatly contribute to the design of high molecular weight poly(lactide-co-glycolide) nanoparticles for prolonged release patterns in cardiovascular engineering.

Mycolic acids, a promising mycobacterial ligand for targeting of nanoencapsulated drugs in tuberculosis

The appearance of drug-resistant strains of Mycobacterium tuberculosis (Mtb) poses a great challenge to the development of novel treatment programmes to combat tuberculosis. Since innovative nanotechnologies might alleviate the limitations of current therapies, we have designed a new nanoformulation for use as an anti-TB drug delivery system. It consists of incorporating mycobacterial cell wall mycolic acids (MA) as targeting ligands into a drug-encapsulating Poly dl-lactic-co-glycolic acid polymer (PLGA), via a double emulsion solvent evaporation technique. Bone marrow-derived mouse macrophages, either uninfected or infected with different mycobacterial strains (Mycobacterium avium, Mycobacterium bovis BCG or Mtb), were exposed to encapsulated isoniazid-PLGA nanoparticles (NPs) using MA as a targeting ligand. The fate of the NPs was monitored by electron microscopy. Our study showed that i) the inclusion of MA in the nanoformulations resulted in their expression on the outer surface and a significant increase in phagocytic uptake of the NPs; ii) nanoparticle-containing phagosomes were rapidly processed into phagolysosomes, whether MA had been included or not; and iii) nanoparticle-containing phagolysosomes did not fuse with non-matured mycobacterium-containing phagosomes, but fusion events with mycobacterium-containing phagolysosomes were clearly observed.

Nanomedicine scale-up technologies: feasibilities and challenges

Nanomedicine refers to biomedical and pharmaceutical applications of nanosized cargos of drugs/vaccine/DNA therapeutics including nanoparticles, nanoclusters, and nanospheres. Such particles have unique characteristics related to their size, surface, drug loading, and targeting potential. They are widely used to combat disease by controlled delivery of bioactive(s) or for diagnosis of life-threatening problems in their very early stage. The bioactive agent can be combined with a diagnostic agent in a nanodevice for theragnostic applications. However, the formulation scientist faces numerous challenges related to their development, scale-up feasibilities, regulatory aspects, and commercialization. This article reviews recent progress in the method of development of nanoparticles with a focus on polymeric and lipid nanoparticles, their scale-up techniques, and challenges in their commercialization.

Preparation and characterization of Tamoxifen citrate loaded nanoparticles for breast cancer therapy

Background

Four formulations of Tamoxifen citrate loaded polylactide-co-glycolide (PLGA) based nanoparticles (TNPs) were developed and characterized. Their internalization by Michigan Cancer Foundation-7 (MCF-7) breast cancer cells was also investigated.

Methods

Nanoparticles were prepared by a multiple emulsion solvent evaporation method. Then the following studies were carried out: drug-excipients interaction using Fourier transform infrared spectroscopy (FTIR), surface morphology by field emission scanning electron microscopy (FESEM), zeta potential and size distribution using a Zetasizer Nano ZS90 and particle size analyzer, and in vitro drug release. In vitro cellular uptake of nanoparticles was assessed by confocal microscopy and their cell viability (%) was studied.

Results

No chemical interaction was observed between the drug and the selected excipients. TNPs had a smooth surface, and a nanosize range (250–380 nm) with a negative surface charge. Drug loadings of the prepared particles were 1.5%±0.02% weight/weight (w/w), 2.68%±0.5% w/w, 4.09%±0.2% w/w, 27.16%±2.08% w/w for NP1–NP4, respectively. A sustained drug release pattern from the nanoparticles was observed for the entire period of study, ie, up to 60 days. Further, nanoparticles were internalized well by the MCF-7 breast cancer cells on a concentration dependent manner and were present in the cytoplasm. The nucleus was free from nanoparticle entry. Drug loaded nanoparticles were found to be more cytotoxic than the free drug.

Conclusion

TNPs (NP4) showed the highest drug loading, released the drug in a sustained manner for a prolonged period of time and were taken up well by the MCF-7 breast cancer cell line in vitro. Thus the formulation may be suitable for breast cancer treatment due to the good permeation of the formulation into the breast cancer cells.

Cationic core-shell nanoparticles for intravesical chemotherapy in tumor-induced rat model: safety and efficacy

Mitomycin C (MMC) has shown potent efficacy against a wide spectrum of cancers and is clinical first choice in superficial bladder tumors. However, intravesical chemotherapy with MMC has been ineffective due to periodical discharge of the bladder and instability of this drug in acidic pH, both resulting in high rate of tumor recurrence and insufficiency to prevent progression. Nanocarriers may be a promising alternative for prolonged, effective and safe intravesical drug delivery due to their favorable size, surface properties and optimum interaction with mucosal layer of the bladder wall. Hence, the aim of this study was to evaluate and optimize cationic core-shell nanoparticles formulations (based on chitosan (CS) and poly-ϵ-caprolactone (PCL)) in terms of antitumor efficacy after intravesical administration in bladder tumor induced rat model. Antitumor efficacy was determined through the parameters of survival rate and nanoparticle penetration into the bladder tissue. Safety of the formulations were evaluated by histopathological evaluation of bladder tissue as well as observation of animals treated with MMC bound to nanoparticles. Results indicated that chitosan coated poly-ϵ-caprolactone (CS-PCL) nanoparticles presented the longest survival rate among all treatment groups as evaluated by Kaplan-Meier plotting. Histopathological evaluation revealed that cationic nanoparticles were localized and accumulated in the bladder tissue. As intravesical chemotherapy is a local therapy, no MMC was quantified in blood after intravesical instillation indicating no systemic uptake for the drug which could have subsequently led to side effects. In conclusion, core-shell type cationic nanoparticles may be effective tools for the intravesical chemotherapy of recurrent bladder tumors.

Intracellular activity of tedizolid phosphate and ACH-702 versus Mycobacterium tuberculosis infected macrophages

Background

Due to the emergency of multidrug-resistant strains of Mycobacterium tuberculosis, is necessary the evaluation of new compounds.

Findings

Tedizolid, a novel oxazolidinone, and ACH-702, a new isothiazoloquinolone, were tested against M. tuberculosis infected THP-1 macrophages. These two compounds significantly decreased the number of intracellular mycobacteria at 0.25X, 1X, 4X and 16X the MIC value. The drugs were tested either in nanoparticules or in free solution.

Conclusion

Tedizolid and ACH-702 have a good intracellular killing activity comparable to that of rifampin or moxifloxacin.

Effect of lipid viscosity and high-pressure homogenization on the physical stability of "Vitamin E" enriched emulsion

Recently there has been a growing interest in vitamin E for its potential use in cancer therapy. The objective of this work was therefore to formulate a physically stable parenteral lipid emulsion to deliver higher doses of vitamin E than commonly used in commercial products. Specifically, the objectives were to study the effects of homogenization pressure, number of homogenizing cycles, viscosity of the oil phase, and oil content on the physical stability of emulsions fortified with high doses of vitamin E (up to 20% by weight). This was done by the use of a 27-run, 4-factor, 3-level Box-Behnken statistical design. Viscosity, homogenization pressure, and number of cycles were found to have a significant effect on particle size, which ranged from 213 to 633 nm, and on the percentage of vitamin E remaining emulsified after storage, which ranged from 17 to 100%. Increasing oil content from 10 to 20% had insignificant effect on the responses. Based on the results it was concluded that stable vitamin E rich emulsions could be prepared by repeated homogenization at higher pressures and by lowering the viscosity of the oil phase, which could be adjusted by blending the viscous vitamin E with medium-chain triglycerides (MCT).

The shape of things to come: importance of design in nanotechnology for drug delivery

The design of nanoparticle (NP) size, shape and surface chemistry has a significant impact on their performance. While the influences of the particle size and surface chemistry on drug delivery have been studied extensively, little is known about the effect of particle shapes on nanomedicine. In this perspective article, we discuss recent progress on the design and fabrication of NPs of various shapes and their unique delivery properties. The shapes of these drug carriers play an important role in therapeutic delivery processes, such as particle adhesion, distribution and cell internalization. We envision that stimuli-responsive NPs, which actively change their shapes and other properties, might pave way to the next generation of nanomedicine.

Poly-lactide-co-glycolide nanoparticles containing voriconazole for pulmonary delivery: in vitro and in vivo study

Poly-lactide-co-glycolide nanoparticles (207-605 nm) containing voriconazole (VNPs) were developed using a multiple-emulsification technique and were also made porous during preparation in presence of an effervescent mixture for improved pulmonary delivery. Pulmonary deposition of the particles was studied using a customized inhalation chamber. VNPs had a maximum of 30% (w/w) drug loading and a zeta potential (ZP) value around -20 mV. In the initial 2 hours, 20% of the drug was released from VNPs, followed by sustained release for 15 days. Porous particles had a lower mass median aerodynamic diameter (MMAD) than nonporous particles. Porous particles produced the highest initial drug deposition (~120 μg/g of tissue). The drug was detectable in lungs until 7 days and 5 days after administration, for porous and nonporous particles, respectively. VNPs with improved drug loading were successfully delivered to murine lungs. Porous nanoparticles with lower MMADs showed better pulmonary deposition and sustained presence in lungs.

FROM THE CLINICAL EDITOR

In this paper, voriconazole-containing porous nanoparticles were studied for inhalational delivery to lung infections in a murine model, demonstrating prolonged half-life and improved pulmonary deposition.

Magnetic nanoparticles: preparation, physical properties, and applications in biomedicine

Finally, we have addressed some relevant findings on the importance of having well-defined synthetic strategies developed for the generation of MNPs, with a focus on particle formation mechanism and recent modifications made on the preparation of monodisperse samples of relatively large quantities not only with similar physical features, but also with similar crystallochemical characteristics. Then, different methodologies for the functionalization of the prepared MNPs together with the characterization techniques are explained. Theorical views on the magnetism of nanoparticles are considered.

Preparation and in vitro evaluation of doxorubicin-loaded Fe₃O₄ magnetic nanoparticles modified with biocompatible copolymers

BACKGROUND

Superparamagnetic iron oxide nanoparticles are attractive materials that have been widely used in medicine for drug delivery, diagnostic imaging, and therapeutic applications. In our study, superparamagnetic iron oxide nanoparticles and the anticancer drug, doxorubicin hydrochloride, were encapsulated into poly (D, L-lactic-co-glycolic acid) poly (ethylene glycol) (PLGA-PEG) nanoparticles for local treatment. The magnetic properties conferred by superparamagnetic iron oxide nanoparticles could help to maintain the nanoparticles in the joint with an external magnet.

METHODS

A series of PLGA:PEG triblock copolymers were synthesized by ring-opening polymerization of D, L-lactide and glycolide with different molecular weights of polyethylene glycol (PEG(2000), PEG(3000), and PEG(4000)) as an initiator. The bulk properties of these copolymers were characterized using (1)H nuclear magnetic resonance spectroscopy, gel permeation chromatography, Fourier transform infrared spectroscopy, and differential scanning calorimetry. In addition, the resulting particles were characterized by x-ray powder diffraction, scanning electron microscopy, and vibrating sample magnetometry.

RESULTS

The doxorubicin encapsulation amount was reduced for PLGA:PEG(2000) and PLGA:PEG(3000) triblock copolymers, but increased to a great extent for PLGA:PEG(4000) triblock copolymer. This is due to the increased water uptake capacity of the blended triblock copolymer, which encapsulated more doxorubicin molecules into a swollen copolymer matrix. The drug encapsulation efficiency achieved for Fe(3)O(4) magnetic nanoparticles modified with PLGA:PEG(2000), PLGA:PEG(3000), and PLGA:PEG(4000) copolymers was 69.5%, 73%, and 78%, respectively, and the release kinetics were controlled. The in vitro cytotoxicity test showed that the Fe(3)O(4)-PLGA:PEG(4000) magnetic nanoparticles had no cytotoxicity and were biocompatible.

CONCLUSION

There is potential for use of these nanoparticles for biomedical application. Future work includes in vivo investigation of the targeting capability and effectiveness of these nanoparticles in the treatment of lung cancer.

Polymeric nanoparticles for the selective therapy of inflammatory bowel disease

The two main forms of inflammatory bowel disease (IBD) are Crohn's disease and ulcerative colitis. Both diseases are chronic relapsing inflammations of the gut. The challenge for drug carrier systems that are used for the therapy of IBD is the delivery of the active ingredient to the site of inflammation. A site-directed targeting should lead to higher local drug concentrations, less systemic absorption, and therewith to less adverse effects. Because nanoparticulate drug carrier systems have the ability to accumulate in the inflamed regions, they offer a new targeting approach in IBD. We describe preparation techniques for polymeric nanoparticles and methods to characterize their physicochemical properties, their behavior in cell culture, and the therapeutic efficiency in murine experimental colitis models.

Product and process understanding of a novel pediatric anti-HIV tenofovir niosomes with a high-pressure homogenizer

A variety of factors were systemically evaluated in order to establish the characteristics of the niosomes obtained with a high-pressure homogenizer. The vesicular sizing parameters, electrical properties, drug entrapment data and drug release characteristics were investigated using two groups of factors. The first group presented the physical process variables such as pressure of the homogenizer and the times that the samples were processed (cycles). The second group encompassed the compositional variables such as the drug loading, surfactant chain length, cholesterol level and the level of the charge imparting agent. The obtained data showed that the drug distributed within both the aqueous and lipid phases of the formed niosomes. Saturation-like behaviors for both the effect of homogenization cycles on the produced size and the effect of the pressure on the size homogeneity were recorded. In contrast to the drug entrapment and conductivity of the niosomal suspension, the vesicular size parameters as well as the zeta potential were inversely proportional with the homogenization parameters. Drug release was significantly affected by the compositional factors rather than the physical ones. The current study demonstrated the usefulness of the microfluidization for the production and further scale-up of anti-HIV niosomes with very small mean vesicular sizes.