Lucía Martín-Banderas

Building functional materials for health care and pharmacy from microfluidic principles and Flow Focusing

In this review, we aim at establishing a relationship between the fundamentals of the microfluidics technologies used in the Pharmacy field, and the achievements accomplished by those technologies. We describe the main methods for manufacturing micrometer drops, bubbles, and capsules, as well as the corresponding underlying physical mechanisms. In this regard, the review is intended to show non-specialist readers the dynamical processes which determine the success of microfluidics techniques. Flow focusing (FF) is a droplet-based method widely used to produce different types of fluid entities on a continuous basis by applying an extensional co-flow. We take this technique as an example to illustrate how microfluidics technologies for drug delivery are progressing from a deep understanding of the physics of fluids involved. Specifically, we describe the limitations of FF, and review novel methods which enhance its stability and robustness. In the last part of this paper, we review some of the accomplishments of microfluidics when it comes to drug manufacturing and delivery. Special attention is paid to the production of the microencapsulated form because this fluidic structure gathers the main functionalities sought for in Pharmacy. We also show how FF has been adapted to satisfy an ample variety of pharmaceutical requirements to date.

Cannabinoid derivate-loaded PLGA nanocarriers for oral administration: formulation, characterization, and cytotoxicity studies

CB13 (1-Naphthalenyl[4-(pentyloxy)-1-naphthalenyl]methanone)-loaded poly(lactic-co-glycolic acid) nanoparticles (NPs) were produced by nanoprecipitation and tested for their in vitro release behavior and in vitro cytotoxicity assays. The effects of several formulation parameters such as polymer type, surfactant concentration, and initial drug amount were studied. NPs had a particle size 90–300 nm in diameter. Results obtained show that the main influence on particle size was the type of polymer employed during the particle production: the greater the hydrophobicity, the smaller the particle size. In terms of encapsulation efficiency (%), high values were achieved (∼68%–90%) for all formulations prepared due to the poor solubility of CB13 in the external aqueous phase. Moreover, an inverse relationship between release rate and NP size was found. On the other hand, low molecular weight and low lactide content resulted in a less hydrophobic polymer with increased rates of water absorption, hydrolysis, and erosion. NPs showed no cytotoxicity and may be considered to be appropriate for drug-delivery purposes.

Drug targeting to cancer by nanoparticles surface functionalized with special biomolecules.

Nanoparticulate-based drug carriers have been developed to overcome the problems of conventional anticancer pharmacotherapy, i.e., the little specificity and low accumulation of the drug into the tumor interstitium, and the extensive biodistribution leading to severe toxicity. Unfortunately, conventional nanoparticles have been demonstrated to merely accumulate the loaded drug into organs associated to the reticuloendothelial system, e.g., the liver. Recently, drug delivery strategies involving the use of nanoplatforms surface decorated with unique biomolecules have demonstrated their potential in concentrating the chemotherapy agent specifically into the malignant cells. This review will be focused on the analysis of the current state of the art and future perspectives of such passive and active targeting strategies based on the enhanced permeability and retention effect and on a ligand-mediated transport, respectively. Special attention will be given to the use of these surface functionalized nanocarriers to overcome multi-drug resistances in cancer cells.

Biocompatible gemcitabine-based nanomedicine engineered by Flow Focusing for efficient antitumor activity.

We investigated the incorporation of gemcitabine into a colloidal carrier based on the biodegradable and biocompatible poly(d,l-lactide-co-glycolide) (PLGA) to optimize its anticancer activity. Two synthesis techniques (double emulsion/solvent evaporation, and Flow Focusing) were compared in terms of particle geometry, electrophoretic properties (surface charge), gemcitabine vehiculization capabilities (drug loading and release), blood compatibility, and in vitro antitumor activity. To the best of our knowledge, the second formulation methodology (Flow Focusing) has never been applied to the synthesis of gemcitabine-loaded PLGA particles. With the aim of achieving the finest (nano)formulation, experimental parameters associated to these preparation procedures were analyzed. The electrokinetics of the particles suggested that the chemotherapy agent was incorporated into the polymeric matrix. Blood compatibility was demonstrated in vitro. Flow Focusing led to a more appropriate geometry, higher gemcitabine loading and a sustained release profile. In addition, the cytotoxicity of gemcitabine-loaded particles prepared by Flow Focusing was tested in MCF-7 human breast adenocarcinoma cells, showing significantly greater antitumor activity compared to the free drug and to the gemcitabine-loaded particles synthesized by double emulsion/solvent evaporation. Thus, it has been identified the more adequate formulation conditions in the engineering of gemcitabine-loaded PLGA nanoparticles for the effective treatment of tumours.

Functional PLGA NPs for oral drug delivery: recent strategies and developments.

This article presents the potential of PLGA nanoparticles for the oral administration of drugs. Different strategies are used to improve oral absorption of these nanoparticles. These strategies are based on modification of nanoparticle surface properties. They can be achieved either by coating the nanoparticle surface with stabilizing hydrophilic bioadhesive polymers or surfactants, or by incorporating biodegradable copolymers containing a hydrophilic moiety. Some substances such as chitosan, vitamin E, methacrylates, lectins, lecithins, bile salts and RGD molecules are employed for this purpose. Of especial interest are nanoparticles production methods and, in order to improve oral bioavailability, the mechanism of each additive.

Insulin-loaded PLGA microparticles: flow focusing versus double emulsion/solvent evaporation

Context: Oral administration of insulin is severely limited by very low bioavailability. Biocompatible polymeric nanocarriers have been investigated to overcome this problem. Flow focusing (FF) has revolutionized current engineering of poly(D,L-lactide-co-glycolide) (PLGA) based micromedicines. This technique has never been used to formulate insulin-loaded PLGA microparticles. Objective: Investigation of the benefits rising from the synthesis of insulin-loaded PLGA microplatforms by FF, compared to double emulsion/solvent evaporation method. Materials and methods: Both synthesis methodologies were compared in terms of geometry, surface physicochemical properties and insulin vehiculization capabilities. The stability of the peptide during the formulation procedure was further analysed. Results: FF permitted the preparation of insulin-loaded microcarriers with better geometry and physicochemical properties for the oral route, along with greater insulin loading capabilities and sustained insulin release kinetics. Discussion and conclusion: Results have lead to the identification of the best formulation conditions for the engineering of insulin-loaded PLGA microparticles against diabetes.

Nanostructures for Drug Delivery to the Brain

This review aims to summarize present approaches employed in delivering drugs to the central nervous system. Changes in blood-brain barrier (BBB) function have been reported in several neurological disorders. A brief description of the blood brain barrier and the main pathologies related to this barrier disfunction are described. Treatments for these disorders are based on several available strategies for delivering drugs into the brain, through circumvention of the BBB, as disruption of the BBB, prodrugs, molecular Trojan horses, among others. Particular attention will be placed on nanocarriers and more specifically on polymeric nanoparticles, which are presented as the most promising strategy for CNS delivery, helping drugs to be targeted more efficiently to the brain. This also allows attacking previously untreatable disorders such as brain tumors and other neurodegenerative diseases. New strategies and technologies commercialized by different pharmaceutical companies are also included.

In vitro and in vivo evaluation of Δ9-tetrahidrocannabinol/PLGA nanoparticles for cancer chemotherapy

Nanoplatforms can optimize the efficacy and safety of chemotherapy, and thus cancer therapy. However, new approaches are encouraged in developing new nanomedicines against malignant cells. In this work, a reproducible methodology is described to prepare Δ(9)-tetrahidrocannabinol (Δ(9)-THC)-loaded poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles against lung cancer. The nanoformulation is further improved by surface functionalization with the biodegradable polymers chitosan and poly(ethylene glycol) (PEG) in order to optimize the biological fate and antitumor effect. Mean nanoparticle size (≈ 290 nm) increased upon coating with PEG, CS, and PEG-CS up to ≈ 590 nm, ≈ 745 nm, and ≈ 790 nm, respectively. Surface electrical charge was controlled by the type of polymeric coating onto the PLGA particles. Drug entrapment efficiencies (≈ 95%) were not affected by any of the polymeric coatings. On the opposite, the characteristic sustained (biphasic) Δ(9)-THC release from the particles can be accelerated or slowed down when using PEG or chitosan, respectively. Blood compatibility studies demonstrated the adequate in vivo safety margin of all of the PLGA-based nanoformulations, while protein adsorption investigations postulated the protective role of PEGylation against opsonization and plasma clearance. Cell viability studies comparing the activity of the nanoformulations against human A-549 and murine LL2 lung adenocarcinoma cells, and human embryo lung fibroblastic MRC-5 cells revealed a statistically significant selective cytotoxic effect toward the lung cancer cell lines. In addition, cytotoxicity assays in A-549 cells demonstrated the more intense anticancer activity of Δ(9)-THC-loaded PEGylated PLGA nanoparticles. These promising results were confirmed by in vivo studies in LL2 lung tumor-bearing immunocompetent C57BL/6 mice.

Comparative study of chitosan- and PEG-coated lipid and PLGA nanoparticles as oral delivery systems for cannabinoids

The cannabinoid derivative 1-naphthalenyl[4-(pentyloxy)-1-naphthalenyl]methanone (CB13) has an important therapeutic potential as analgesic in chronic pain states that respond poorly to conventional drugs. However, the incidence of its mild-to-moderate and dose-dependent adverse effects, as well as its pharmacokinetic profile, actually holds back its use in humans. Thus, the use of a suitable carrier system for oral delivery of CB13 becomes an attractive strategy to develop a valuable therapy. Polymeric poly(lactic-co-glycolic) acid (PLGA) and lipid nanoparticles (LNPs) are widely studied delivery vehicles that improve the bioavailability of lipophilic compounds and present special interest in oral delivery. Their surface can be modified to improve the adhesion of particles to the oral mucosa and increase their circulation time in blood with additives such as chitosan (CS) and polyethylene glycol (PEG), which can be feasibly incorporated onto these particles in a post-production step. In this work, CS- and PEG-modified polymeric PLGA and LNPs were successfully obtained and comparatively evaluated under the same experimental conditions as oral carriers for CB13. All the formulations presented adequate blood compatibility and absence of cytotoxicity in Caco-2 cells. Coating with CS led to a higher interaction with Caco-2 cells and a limited uptake in THP1 cells, while coating with PEG led to a limited uptake in Caco-2 cells and strongly prevented THP1 cells uptake. The performance of each formulation is discussed as a comparison of the potential of these carriers as oral delivery systems of CB13.

Lipid nanoparticles as an emerging platform for cannabinoid delivery: physicochemical optimization and biocompatibility.

Abstract This work aims at developing and optimizing a valuable oral delivery carrier for the cannabinoid derivative CB13, which presents a high therapeutic potential in chronic pain states that respond poorly to conventional analgesics, but also shows highly unfavorable physicochemical properties. CB13-loaded lipid nanoparticles (LNP) formulations were developed through solvent-emulsion evaporation and optimized in terms of physicochemical properties, long-term stability, integrity under gastric simulated conditions and in vitro interaction with NIH 3T3, HEK 293T and Caco-2 cells. An optimized formulation of LNP containing CB13 was obtained from a wide range of conditions assayed and analyzed. The selection of the lipid core, production conditions and the inclusion of lecithin proved to be key factors for the final properties of encapsulation, integrity and performance of the carriers. The LNP formulation proposed proved to be a promising carrier for the oral delivery of CB13, a cannabinoid with high therapeutic potential in chronic pain states that currently lack a valid oral treatment.