Cristina Fornaguera

PLGA nanoparticles prepared by nano-emulsion templating using low-energy methods as efficient nanocarriers for drug delivery across the blood-brain barrier.

Neurodegenerative diseases have an increased prevalence and incidence nowadays, mainly due to aging of the population. In addition, current treatments lack efficacy, mostly due to the presence of the blood-brain barrier (BBB) that limits the penetration of the drugs to the central nervous system. Therefore, novel drug delivery systems are required. Polymeric nanoparticles have been reported to be appropriate for this purpose. Specifically, the use of poly-(lactic-co-glycolic acid) (PLGA) seems to be advantageous due to its biocompatibility and biodegradability that ensure safe therapies. In this work, a novel approximation to develop loperamide-loaded nanoparticles is presented: their preparation by nano-emulsion templating using a low-energy method (the phase inversion composition, PIC, method). This nano-emulsification approach is a simple and very versatile technology, which allows a precise size control and it can be performed at mild process conditions. Drug-loaded PLGA nanoparticles were obtained using safe components by solvent evaporation of template nano-emulsions. Characterization of PLGA nanoparticles was performed, together with the study of the BBB crossing. The in vivo results of measuring the analgesic effect using the hot-plate test evidenced that the designed PLGA loperamide-loaded nanoparticles are able to efficiently cross the BBB, with high crossing efficiencies when their surface is functionalized with an active targeting moiety (a monoclonal antibody against the transferrin receptor). These results, together with the nanoparticle characterization performed here are expected to provide sufficient evidences to end up to clinical trials in the near future.

Novel non-viral gene delivery systems composed of carbosilane dendron functionalized nanoparticles prepared from nano-emulsions as non-viral carriers for antisense oligonucleotides.

The development of novel and efficient delivery systems is often the limiting step in fields such as antisense therapies. In this context, poly(d,l-lactide-co-glycolide) acid (PLGA) nanoparticles have been obtained by a versatile and simple technology based on nano-emulsion templating and low-energy emulsification methods, performed in mild conditions, providing good size control. O/W polymeric nano-emulsions were prepared by the phase inversion composition method at 25°C using the aqueous solution/polysorbate80/[4 wt% PLGA in ethyl acetate] system. Nano-emulsions formed at oil-to-surfactant (O/S) ratios between 10/90-90/10 and aqueous contents above 70 wt%. Nano-emulsion with 90 wt% of aqueous solution and O/S ratio of 70/30 was chosen for further studies, since they showed the appropriate characteristics to be used as nanoparticle template: hydrodynamic radii lower than 50 nm and enough kinetic stability. Nanoparticles, prepared from nano-emulsions by solvent evaporation, showed spherical shape, sizes about 40 nm, negative surface charges and high stability. The as-prepared nanoparticles were functionalized with carbosilane cationic dendrons through a carbodiimide-mediated reaction achieving positively charged surfaces. Antisense oligonucleotides were electrostatically attached to nanoparticles surface to perform gene-silencing studies. These complexes were non-haemolytic and non-cytotoxic at the concentrations required. The ability of the complexes to impart cellular uptake was also promising. Therefore, these novel nanoparticulate complexes might be considered as potential non-viral carriers in antisense therapy.

Design and in vitro evaluation of biocompatible dexamethasone-loaded nanoparticle dispersions, obtained from nano-emulsions, for inhalatory therapy.

Polymeric nanoparticle dispersions containing dexamethasone (DXM) have been prepared from O/W nano-emulsions of the water/polysorbate 80/[4 wt% poly(lactide-co-glycolide) acid+0.18 wt% DXM in ethyl acetate] system by a low-energy method at 25°C. Nano-emulsions were formed at O/S ratios between 45/55 and 72/25 and water contents above 70 wt% by the phase inversion composition (PIC) method. The mean hydrodynamic diameter of nano-emulsions with a constant water content of 90 wt% and O/S ratios from 50/50 to 70/30 was below 350 nm as assessed by dynamic light scattering. The nanoparticles obtained from these nano-emulsions (by solvent evaporation) showed mean diameters of around 130 nm, as determined by transmission electron microscopy image analysis. Therapeutic concentrations of DXM were encapsulated in the nano-emulsions prior to nanoparticle preparation. DXM entrapment efficiency of the nanoparticle dispersion (above 74 wt%) decreased at increasing O/S ratios of the precursor nano-emulsion while DXM loading, which was around 10 mg/100 mL, showed the reverse tendency. DXM release from nanoparticle dispersions was about an order of magnitude slower than from an aqueous solution. In vitro studies performed in a lung carcinoma cell line and in vitro haemolysis studies performed in red blood cells revealed a dose-dependent toxicity and haemolytic response, respectively. The as-prepared nanoparticle dispersions were non-toxic up to a concentration of 40 μg/mL and non-haemolytic up to a concentration of 1 mg/mL. After purification, nanoparticle dispersions were non-toxic up to a concentration of 90 μg/mL. These results allow concluding that these polymeric nanoparticle dispersions are good candidates for inhalatory therapy.

Personalized Nanomedicine: A Revolution at the Nanoscale

Nanomedicine is an interdisciplinary research field that results from the application of nanotechnology to medicine and has the potential to significantly improve some current treatments. Specifically, in the field of personalized medicine, it is expected to have a great impact in the near future due to its multiple advantages, namely its versatility to adapt a drug to a cohort of patients. In the present review, the properties and requirements of pharmaceutical dosage forms at the nanoscale, so-called nanomedicines, are been highlighted. An overview of the main current nanomedicines in pre-clinical and clinical development is presented, detailing the challenges to the personalization of these therapies. Next, the process of development of novel nanomedicines is described, from their design in research labs to their arrival on the market, including considerations for the design of nanomedicines adapted to the requirements of the market to achieve safe, effective, and quality products. Finally, attention is given to the point of view of the pharmaceutical industry, including regulation issues applied to the specific case of personalized medicine. The authors expect this review to be a useful overview of the current state of the art of nanomedicine research and industrial production, and the future opportunities of personalized medicine in the upcoming years. The authors encourage the development and marketing of novel personalized nanomedicines.

Methods for the In Vitro Characterization of Nanomedicines—Biological Component Interaction

The design of colloidal nanosystems intended for biomedical applications, specifically in the field of personalized medicine, has increased notably in the last years. Consequently, a variety of characterization techniques devoted to studying nanomedicine interactions with proteins and cells have been developed, since a deep characterization of nanosystems is required before starting preclinical and clinical studies. In this context, this review aims to summarize the main techniques used to assess the interaction of nanomedicines with biological systems, highlighting their advantages and disadvantages. Testing designed nanomaterials with these techniques is required in order to have more information about their behavior on a physiological environment. Moreover, techniques used to study the interaction of nanomedicines with proteins, such as albumin and fibrinogen, are summarized. These interactions are not desired, since they usually are the first signal to the body for the activation of the immune system, which leads to the clearance of the exogenous components. On the other hand, techniques for studying the cell toxicity of nanosystems are also summarized, since this information is required before starting preclinical steps. The translation of knowledge from novel designed nanosystems at a research laboratory scale to real human therapies is usually a limiting or even a final point due to the lack of systematic studies regarding these two aspects: nanoparticle interaction with biological components and nanoparticle cytotoxicity. In conclusion, this review will be a useful support for those scientists aiming to develop nanosystems for nanomedicine purposes.

Protein-nanoparticle interactions evaluation by immunomethods: Surfactants can disturb quantitative determinations.

The adsorption of proteins on nanoparticle surface is one of the first events that occur when nanoparticles enter in the blood stream, which influences nanoparticles lifetime and further biodistribution. Albumin, which is the most abundant protein in serum and which has been deeply characterized, is an interesting model protein to investigate nanoparticle-protein interactions. Therefore, the interaction of nanoparticles with serum albumin has been widely studied. Immunomethods were suggested for the investigation of adsorption isotherms because of their ease to quantify the non-adsorbed bovine serum albumin without the need of applying separation methods that could modify the balance between the adsorbed and non-adsorbed proteins. The present work revealed that this method should be applied with caution. Artifacts in the determination of free protein can be generated by the presence of surfactants such as polysorbate 80, widely used in the pharmaceutical and biomedical field, that are needed to preserve the stability of nanoparticle dispersions. It was shown that the presence of traces of polysorbate 80 in the dispersion leads to an overestimation of the amount of bovine serum albumin remaining free in the dispersion medium when determined by both radial immunodiffusion and rocket immunoelectrophoresis. However, traces of poloxamer 188 did not result in clear perturbed migrations. These methods are not appropriate to perform adsorption isotherms of proteins on nanoparticle dispersions containing traces of remaining free surfactant. They should only be applied on dispersions that are free of surfactant that is not associated with nanoparticles.

Electrolytes as a tuning parameter to control nano-emulsion and nanoparticle size

Currently, polymeric nanoparticles are widely used in a wide variety of biomedical applications, which requires different nanoparticle sizes. Their preparation by solvent evaporation from polymeric nano-emulsions has been described as an appropriate methodology. Nano-emulsions can be prepared by the phase inversion composition method, a low-energy emulsification method, apt for biomedical applications since it can be performed at low conditions. Using this methodology, nano-emulsions droplets and resulting nanoparticle properties depend on the selected components. Many studies have been performed varying some of them. In this work, a specific study has been performed for the first time to find out the effect that the presence of electrolytes in the aqueous phase of the template nano-emulsion has on nano-emulsion and nanoparticle physicochemical properties. PLGA nano-emulsions were prepared using the system: aqueous solution (W)/polysorbate 80 (S)/[4 wt% PLGA in ethyl acetate] (O). The addition of increasing concentrations of electrolytes (PBS) in the aqueous phase produced a decrease on droplet hydrodynamic radii from around 200 nm to around 35 nm. Nanoparticle sizes were determined by the droplet sizes of their template nano-emulsions. Nanoparticles dialysis to an electrolyte solution of 0.16 M, required for many biomedical applications to accomplish the physiological pH and osmolality, did not produce changes in nanoparticle sizes. Therefore, it has been demonstrated for the first time that nano-emulsion and nanoparticle size can be tuned by only varying the electrolyte concentration of the template nano-emulsions. Nano-emulsion templating is a versatile technology that enables the obtaining of tunable nanoparticle sizes; appropriate for a wide range of biomedical applications.

Polymeric Nanoparticles for Drug Delivery in Neurological Diseases

Purpose of ReviewThis review aims at describing the state of the art concerning the design of polymeric nanoparticles for the treatment of neurological diseases. The most important methods of polymeric nanoparticle preparation as well as the required properties for neurological diseases have been summarized.Recent FindingsMany studies report the design of polymeric nanoparticles to treat diseases such as brain tumors, neurodegenerative and neuroinflammatory diseases. However, none of the engineered nanoparticles have reached clinical trials. The reasons of the lack of translation of laboratory results have been analyzed. Many limiting steps can be attributed to the lack of reproducible studies, some controversial results or the absence of current regulations concerning systems at the nanoscale. However, recent studies indicate that these drawbacks can be overcome.SummaryIt is expected that in the near future, some of the engineered nanoparticles that are under development will become novel drug delivery systems to cross the BBB, giving an efficient treatment to currently untreatable and devastating neurological diseases such as glioblastoma and Alzehimer’s disease.

PLGA nanoparticles from nano-emulsion templating as imaging agents: Versatile technology to obtain nanoparticles loaded with fluorescent dyes

The interest in polymeric nanoparticles as imaging systems for biomedical applications has increased notably in the last decades. In this work, PLGA nanoparticles, prepared from nano-emulsion templating, have been used to prepare novel fluorescent imaging agents. Two model fluorescent dyes were chosen and dissolved in the oil phase of the nano-emulsions together with PLGA. Nano-emulsions were prepared by the phase inversion composition (PIC) low-energy method. Fluorescent dye-loaded nanoparticles were obtained by solvent evaporation of nano-emulsion templates. PLGA nanoparticles loaded with the fluorescent dyes showed hydrodynamic radii lower than 40nm; markedly lower than those reported in previous studies. The small nanoparticle size was attributed to the nano-emulsification strategy used. PLGA nanoparticles showed negative surface charge and enough stability to be used for biomedical imaging purposes. Encapsulation efficiencies were higher than 99%, which was also attributed to the nano-emulsification approach as well as to the low solubility of the dyes in the aqueous component. Release kinetics of both fluorescent dyes from the nanoparticle dispersions was pH-independent and sustained. These results indicate that the dyes could remain encapsulated enough time to reach any organ and that the decrease of the pH produced during cell internalization by the endocytic route would not affect their release. Therefore, it can be assumed that these nanoparticles are appropriate as systemic imaging agents. In addition, in vitro toxicity tests showed that nanoparticles are non-cytotoxic. Consequently, it can be concluded that the preparation of PLGA nanoparticles from nano-emulsion templating represents a very versatile technology that enables obtaining biocompatible, biodegradable and safe imaging agents suitable for biomedical purposes.

Application of an assay Cascade methodology for a deep preclinical characterization of polymeric nanoparticles as a treatment for gliomas

Abstract Glioblastoma multiforme (GBM) is the most devastating primary brain tumor due to its infiltrating and diffuse growth characteristics, a situation compounded by the lack of effective treatments. Currently, many efforts are being devoted to find novel formulations to treat this disease, specifically in the nanomedicine field. However, due to the lack of comprehensive characterization that leads to insufficient data on reproducibility, only a reduced number of nanomedicines have reached clinical phases. In this context, the aim of the present study was to use a cascade of assays that evaluate from physical-chemical and structural properties to biological characteristics, both in vitro and in vivo, and also to check the performance of nanoparticles for glioma therapy. An amphiphilic block copolymer, composed of polyester and poly(ethylene glycol; PEG) blocks, has been synthesized. Using a mixture of this copolymer and a polymer containing an active targeting moiety to the Blood Brain Barrier (BBB; Seq12 peptide), biocompatible and biodegradable polymeric nanoparticles have been prepared and extensively characterized. In vitro studies demonstrated that nanoparticles are safe for normal cells but cytotoxic for cancer cells. In vivo studies in mice demonstrated the ability of the Seq12 peptide to cross the BBB. Finally, in vivo efficacy studies using a human tumor model in SCID mice resulted in a significant 50% life-span increase, as compared with non-treated animals. Altogether, this assay cascade provided extensive pre-clinical characterization of our polymeric nanoparticles, now ready for clinical evaluation.