Microfluidic preparation of polymer nanospheres

Czaplewska J, Hoeppener S, Werz O, S. Schubert U. Optimized Encapsulation of the FLAP/PGES-1 Inhibitor BRP-187 in PVA-Stabilized PLGA Nanoparticles Using Microfluidics

The dual inhibitor of the 5-lipoxygenase-activating protein (FLAP) and the microsomal prostaglandin E2 synthase-1 (mPGES-1), named BRP-187, represents a promising drug candidate due to its improved anti-inflammatory efficacy along with potentially reduced side effects in comparison to non-steroidal anti-inflammatory drugs (NSAIDs). However, BRP-187 is an acidic lipophilic drug and reveals only poor water solubility along with a strong tendency for plasma protein binding. Therefore, encapsulation in polymeric nanoparticles is a promising approach to enable its therapeutic use. With the aim to optimize the encapsulation of BRP-187 into poly(lactic-co-glycolic acid) (PLGA) nanoparticles, a single-phase herringbone microfluidic mixer was used for the particle preparation. Various formulation parameters, such as total flow rates, flow rate ratio, the concentration of the poly(vinyl alcohol) (PVA) as a surfactant, initial polymer concentration, as well as presence of a co-solvent on the final particle size distribution and drug loading, were screened for best particle characteristics and highest drug loading capacities. While the size of the particles remained in the targeted region between 121 and 259 nm with low polydispersities (0.05 to 0.2), large differences were found in the BRP-187 loading capacities (LC = 0.5 to 7.29%) and drug crystal formation during the various formulations.

Design, Fundamental Principles of Fabrication and Applications of Microreactors

This study highlights the development of small-scale reactors, in the form of microstructures with microchannel networking. Microreactors have achieved an impressive reputation, regarding chemical synthesis ability and their applications in the engineering, pharmaceutical, and biological fields. This review elaborates on the fabrication, construction, and schematic fundamentals in the design of the microreactors and microchannels. The materials used in the fabrication or construction of the microreactors include silicon, polymer, and glass. A general review of the application of microreactors in medical, biological, and engineering fields is carried out and significant improvements in these areas are reported. Finally, we highlight the flow patterns, mixing, and scaling-up of multiphase microreactor developments, with emphasis on the more significant industrial applications.

Fabrication and application of complex microcapsules: a review

The development of new functional materials requires cutting-edge technologies for incorporating different functional materials without reducing their functionality. Microencapsulation is a method to encapsulate different functional materials at nano- and micro-scales, which can provide the necessary protection for the encapsulated materials. In this review, microencapsulation is categorized into chemical, physical, physico-chemical and microfluidic methods. The focus of this review is to describe these four categories in detail by elaborating their various microencapsulation methods and mechanisms. This review further discusses the key features and potential applications of each method. Through this review, the readers could be aware of many aspects of this field from the fabrication processes, to the main properties, and to the applications of microcapsules.

Optimizing biodegradable nanoparticle size for tissue-specific delivery

Nanoparticles (NPs) are promising vehicles for drug delivery because of their potential to target specific tissues [1]. Although it is known that NP size plays a critical role in determining their biological activity, there are few quantitative studies of the role of NP size in determining biodistribution after systemic administration. Here, we engineered fluorescent, biodegradable poly(lactic-co-glycolic acid) (PLGA) NPs in a range of sizes (120-440nm) utilizing a microfluidic platform and used these NPs to determine the effect of diameter on bulk tissue and cellular distribution after systemic administration. We demonstrate that small NPs (∼120nm) exhibit enhanced uptake in bulk lung and bone marrow, while larger NPs are sequestered in the liver and spleen. We also show that small NPs (∼120nm) access specific alveolar cell populations and hematopoietic stem and progenitor cells more readily than larger NPs. Our results suggest that size of PLGA NPs can be used to tune delivery to certain tissues and cell populations in vivo.

Protein Polymer-Based Nanoparticles: Fabrication and Medical Applications

Nanoparticles are particles that range in size from about 1⁻1000 nanometers in diameter, about one thousand times smaller than the average cell in a human body. Their small size, flexible fabrication, and high surface-area-to-volume ratio make them ideal systems for drug delivery. Nanoparticles can be made from a variety of materials including metals, polysaccharides, and proteins. Biological protein-based nanoparticles such as silk, keratin, collagen, elastin, corn zein, and soy protein-based nanoparticles are advantageous in having biodegradability, bioavailability, and relatively low cost. Many protein nanoparticles are easy to process and can be modified to achieve desired specifications such as size, morphology, and weight. Protein nanoparticles are used in a variety of settings and are replacing many materials that are not biocompatible and have a negative impact on the environment. Here we attempt to review the literature pertaining to protein-based nanoparticles with a focus on their application in drug delivery and biomedical fields. Additional detail on governing nanoparticle parameters, specific protein nanoparticle applications, and fabrication methods are also provided.

The importance of microfluidics for the preparation of nanoparticles as advanced drug delivery systems

INTRODUCTION

Nanoparticles are anticipated to overcome persistent challenges in efficient drug delivery, but the limitations associated with conventional methods of preparation are resulting in slow translation from research to clinical applications. Due to their enormous potential, microfluidic technologies have emerged as an advanced approach for the development of drug delivery systems with well-defined physicochemical characteristics and in a reproducible manner.

AREAS COVERED

This review provides an overview of microfluidic devices and materials used for their manufacturing, together with the flow patterns and regimes commonly used for nanoparticle preparation. Additionally, the different geometries used in droplet microfluidics are reviewed, with particular attention to the co-flow geometry used for the production of nanoparticles. Finally, this review summarizes the main and most recent nanoparticulate systems prepared using microfluidics, including drug nanosuspensions, polymeric, lipid, structured, and theranostic nanoparticles.

EXPERT OPINION

The production of nanoparticles at industrial scale is still a challenge, but the microfluidic technologies bring exciting opportunities to develop drug delivery systems that can be engineered in an easy, cost-effective and reproducible manner. As a highly interdisciplinary research field, more efforts and general acceptance are needed to allow for the translation of nanoparticulate drug delivery systems from academic research to the clinical practice.

Tuning the Size of Poly(lactic-co-glycolic Acid) (PLGA) Nanoparticles Fabricated by Nanoprecipitation

Polymeric nanoparticles (PNPs) are promising drug carriers in cancer treatment. Size of the particles has a significant impact on drug loading, in vivo distribution, extravasation, intratumor diffusion and cell uptake, and thus is critical for the successful development of a drug delivery regime. However, methods for manufacturing PNPs of defined size are yet to be established. The goal of this study is to establish a method that can be used to fabricate PNPs with controlled size. The factors that could impact the size of PNPs fabricated by nano-precipitation are systematically investigated. The factors studied include polymer concentration, organic solvent, temperature, aqueous phase ionic strength, organic phase injection rate, aqueous phase agitation rate, gauge of the needles, and final polymer concentration. Polymer concentration, the choice of organic solvent, temperature, and the ionic strength of the aqueous phase are shown to have a significant impact on the size of PNPs, and the effect of these factors can be attributed to a single parameter, the diffusion coefficient of the solvent in water, D_pw . It is possible that by tightly control these four parameters, nanoparticles with highly predictable and desirable size with narrow size distribution can be fabricated.

Application of Nanoparticles as a Drug Delivery System

Small colloidal particles having their diameter in the range of 50 to 500nm are defined as Nanoparticles. These are usually prepared either by using biodegradable or non-biodegradable polymers and are usually classified in two broad categories: (1) Nanocapsules: a type of reservoir system in which an oil or aqueous core is surrounded by a polymeric membrane. (2) Nanospheres: a type of matrix system. Preparation of nanoparticle as a drug delivery system is one of the most widely accepted approach since the prepration of nanoparticle were easy and convenient to scale up. Their high stability and conveniently easy to freeze-dried their preparations provide some additional advantages to choose Nanoparticles as a good drug delivery system. Inspite of them Nanoparticles were were able to achieve with success tissue targeting of many drugs (antibiotics, cytostatics, peptides and proteins, nucleic acids, etc.).

Integrated microfluidic system with simultaneous emulsion generation and concentration

Because the size, size distribution, and concentration of emulsions play an important role in most of the applications, controlled emulsion generation and effective concentration are of great interest in fundamental and applied studies. While microfluidics has been demonstrated to be able to produce emulsion drops with controlled size, size distribution, and hierarchical structures, progress of controlled generation of concentrated emulsions is limited. Here, we present an effective microfluidic emulsion generation system integrated with an orifice structure to separate aqueous droplets from the continuous oil phase, resulting in concentrated emulsion drops in situ. Both experimental and simulation results show that the efficiency of separation is determined by a balance between pressure drop and droplet accumulation near the orifice. By manipulating this balance via changing flow rates and microfluidic geometry, we can achieve monodisperse droplets on chip that have a concentration as high as 80,000 drops per microliter (volume fraction of 66%). The present approach thus provides insights to the design of microfluidic device that can be used to concentrate emulsions (drops and bubbles), colloidal particles (drug delivery polymer particles), and biological particles (cells and bacteria) when volume fractions as high as 66% are necessary.