Abstract

In this Application note we describe the fabrication process of highly monodisperse poly(-lactic-co-glycolic acid) (PLGA) spherical microparticles of 80 µm using Secoya’s RayDrop™ microfluidic device. The complete formation procedure will be described herein, including:

• Droplet formation of PLGA dissolved in solvent;
• Solvent extraction in a collection bath to precipitate PLGA;
• Washing and drying of the particles.

The scaling-up of the production and the options available to access other size ranges are finally discussed.

It is worth noting that the method and conclusions developed in this Application Note can be extended to other polymers that precipitates upon solvent extraction.

Abstract

In this Application Note, poly(ethylene glycol) diacrylate (PEGDA) is used to produce capsules. PEGDA is part of the photo-crosslinkable hydrogel matrices well-known for their biomedical applications, as well as tissue engineering and regenerative medicine, drug delivery, cancer therapies and biosensing . A study of photoinitiators , chemicals added to the PEGDA that initiate the cross-linking reaction (here under the effect of a UV irradiation), is made to understand their influences on the solidification of the PEGDA. Moreover, it is shown that the use of PEGDA with a molecular weight of 250 Da (PEGDA-250) allows to encapsulate either water or oil thanks to the solubility properties of this hydrogel.

Abstract

 

Over the past few decades, core-shell microcapsules have been extensively used for the delivery and release of materials in the pharmaceutical, cosmetic, and food industries. The encapsulation of Active Pharmaceutical Compounds in core-shell microcapsule is of great interest for several purposes: taste and odor masking, controlled release of drugs... In pharmaceutics the possibility to encapsulate drugs, nutrients, and living cells that can be protected by a solid biocompatible shell in order to target a specific site is an intense field of research.

However, classical methods of microencapsulation, like coacervation, spray drying, solvent evaporation, etc, require complex process and equipment and make difficult to control the size and load of the microcapsules.

In contrast, microfluidics allows to produce monodisperse double emulsions which lead to monodispersed microcapsules with a high control over both the size and the structure. Microfluidics tools are also used in order to create capsules of varying compositions. With this technology, it is possible to encapsulate aqueous or oily phases. The encapsulation of aqueous phases allows the capsule to contain proteins or active pharmaceutical ingredients (APIs). On the other hand, oily phases containing lipophilic or poorly water-soluble drugs can also be encapsulated. Moreover, capsules can be used for drug delivery or acid-triggered gastric delivery depending on the composition of the shell.

In this Application Note, PLGA shell/aqueous core microcapsules are obtained using the Raydrop^® Double emulsion device, a capillary based microfluidic device equipped with a 3D printed injection nozzle making the generation of double emulsion easy, in combination with pressure-based flow controllers. The influence of the fluidic parameters on the microcapsule size and the release from the oil across the shell are explored in this application note.

Abstract

 

Over the past few decades, core-shell microcapsules have been extensively used for the delivery and release of materials in the pharmaceutical, cosmetic, and food industries. The encapsulation of Active Pharmaceutical Compounds in core-shell microcapsules is of great interest for several purposes: taste and odor masking, controlled release of drugs... In pharmaceutics the possibility to encapsulate drugs, nutrients, and living cells that can be protected by a solid biocompatible shell in order to target a specific site is an intense field of research.

However, classical methods of microencapsulation like coacervation, spray drying, solvent evaporation, etc, require complex process and equipment and make difficult to control the size and load of the microcapsules.

In contrast, microfluidics allows to produce monodisperse double emulsions which lead to monodispersed microcapsules with a high control over both size and structure. Microfluidic tools are also used in order to create capsules of varying compositions. With this technology, it is possible to encapsulate aqueous or oily phases. The encapsulation of aqueous phases allows the capsule to contain proteins or active pharmaceutical ingredients (APIs). On the other hand, oily phases containing lipophilic or poorly water-soluble drugs can also be encapsulated. Moreover, capsules can be used for drug delivery or acid-triggered gastric delivery depending on the composition of the shell.

In this Application Note, chitosan-shell/oily-core microcapsules are obtained using the Raydrop® double emulsion generator, a capillary based microfluidic device. Indeed, microcapsules consisting of a chitosan shell and an oily core have been extensively studied as chitosan - a cationic polysaccharide - exhibits numerous benefits: excellent biological activity, good biocompatibility and biodegradability and pH sensitivity for acid-triggered gastric delivery. The method of production as well as the influence of the fluidic parameters on the size and the release from the oil across the shell are studied and presented.

Abstract

In this Application Note, we extended the scope of microfluidic-based crystallization methods by introducing solid microcapsules. Hundreds of perfectly similar microcapsules were generated per second, allowing a fast screening of crystallization conditions.

Abstract

The precise manipulation, quick cultivation, and delicate detection of yeast and bacteria are crucial in microbiology and biomedicine for behavior monitoring, identification of phenotypes, physiological assessment, and molecular analysis.

Microfluidic droplets have proven to be an effective method for encapsulating yeast and bacteria in highly monodisperse droplets for high-throughput screening and analysis of their phenotypes, subcellular structures, genes, and metabolites.This application note details the encapsulation of the yeast strain S. cerevisiae CEN.PK 113-7D and the bacterial strain L. cremorsi MG1363_GFP in double emulsions of 42 µm size using the Cell Encapsulation Platform, resulting in Microencapsulation of Bacteria and Yeast.

Abstract

The last decade has seen an exponential increase in new methods for encapsulating and analysing single cells, revealing fundamental insights into cell diversity, tissue organisation, and organismal development. This has increased the need for cell encapsulation and sorting devices that are safer, more efficient and easier to use than current technologies. In particular, droplet microfluidics has become a powerful class of cell encapsulation techniques due to its unprecedented performance and efficiency.
Encapsulation that isolates components from the environment is widely used in the pharmaceutical, food, and cosmetic fields to protect actives, mask the flavor, deliver and release drugs in a controlled manner. Precise control of the encapsulation characteristics of each component is critical to achieving optimal therapeutic efficacy in pharmaceutical applications.

Abstract

Analyzing cellular behavior at a single-cell level is critical to better understand the heterogeneity of cellular responses such as protein secretion or enzymatic activity. Flow cytometry sorting based on FACS (Fluorescence-Activated Cell Sorting) is a convenient tool for selecting among a complex population of cells, those which display a specific fluorescence signal, indicating the production of a molecule of interest, or the expression of a specific phenotype. However, the FACS method alone has two major limitations: secreted molecules are dissolved in the media and are not detected on the cell’s surface unless a binding protocol is performed, and the secretion of the cells influence each other. The analysis then becomes single-cell on a bulk assay of interacting cells. The encapsulation of single cells efficiently overcomes these issues, ensuring the full single-cell feature of the assay as well as confining the secreted molecules in a small volume, making them detectable.

Droplet-based microfluidics emerged in the 2000’s as a powerful tool to generate very monodisperse emulsions. The principle is to flow two immiscible phases in microchannels and have them meet at a T-junction or flow-focusing so that the continuous phase squeezes the dispersed phase into droplets. As a result, the generated simple emulsion droplets are monodispersed to a low size (pL to μL droplets), and the encapsulation rate can be controlled. Conventional emulsions made using microfluidic devices are water-in-oil (W/O) droplets or single emulsions. If such droplets are commonly used to perform single-cell encapsulations, they are not suited to flow cytometry droplet sorting. Indeed, flow cytometry droplet sorting requires the particles to be suspended in an aqueous phase to efficiently sort the particles of interest by applying an electric field. To avoid these limitations, the W/O droplet can be encapsulated in a 2nd aqueous layer to form a water-in-oil-in-water (W/O/W) droplet, also named double emulsion, which is compatible with flow cytometry droplet sorting.

 

Abstract

However, classical methods of microencapsulation, like coacervation, spray drying, solvent evaporation, etc, require complex process and equipment and make difficult to control the size and load of the microcapsules. In contrast, microfluidics allows to produce monodisperse double emulsions which lead to monodispersed microcapsules with a high control over both the size and the structure. Microfluidics tools are also used to create capsules of varying compositions. With this technology, it is possible to encapsulate aqueous or oily solutions. The encapsulation of aqueous solutions allows the capsule to contain proteins or active pharmaceutical ingredients (APIs). On the other hand, oily solutions containing lipophilic or poorly water-soluble drugs can also be encapsulated. Moreover, capsules can be used for drug delivery thanks to programmable active release mechanism.

This Application Note is complementary to the application note entitled Polymethacrylate resin microcapsules synthesis, available on the website of Secoya Technologies . The main difference is the composition of the core phase. In this document, the capsules contain an oily core, which is essential to encapsulate oily-soluble molecules. The capsule formation is, here again, made by the cross-linking of the polymeric shell of the double emulsion.

This reaction consolidates the shell phase and makes it solid. Thus, the oil is encapsulated in polymeric microcapsules (PMCs) with tunable sizes.

 

Abstract

In this Application Note, capsules are formed by consolidating shell phase of the resulting double emulsions by UV-crosslinking of polymers [ ] and photoinitiator used as shell phase. Core and continuous phases are aqueous phases non-miscible with the shell. Fine control of the fluid flows leads to defined capsule and shell dimensions. In-situ polymerization is achieved, meaning that the droplets are exposed to UV-light while still being moving forward in the output tubing connected to the Raydrop®. Hard shell microcapsules are thus directly collected in the collection vial. The in-situ process allows to avoid coalescence and deformation of the droplets that can arise in an ex-situ process where the droplets are polymerized after collection.

Abstract

Traditionally, batch methods are used to produce emulsions in industry. The use of bulk mixing allows to produce huge quantities of emulsions but to the detriment of quality. Indeed, the shear distribution in a bulk mixer is various, leading to numerous particles sizes and a low encapsulation rate in the case of API encapsulation or double emulsion production (core-shell particles). A fortiori, batch method makes the control of multiple emulsions more complex, i.e. the encapsulation of a precise number of droplets of liquid A in a droplet of liquid B.

In general, the use of microfluidics helps to reach low size dispersity and so monodispersed emulsions with a high control over both the size and structure can be obtained. [II] Microfluidic tools are also used to create emulsions of varying compositions. With this technology, it is possible to produce water–in-oil–in-water (W/O/W) emulsions or oil–in-water–in-oil (O/W/O) emulsions. A microfluidic device developed by Secoya Technologies - called the RayDrop® - allows to easily produce such highly controlled emulsions. Examples of applications in double emulsion can be found in the white paper entitled Generation of microcapsules, available on our website.

Inspired by the publication of LI, Er Qiang and al. [III], we wanted to demonstrate the possibility to produce multiple emulsions using the RayDrop®. For instance, these multiple emulsions are precursors in the creation of solid microcapsules used for triggered release. Furthermore, these multicompartmental microspheres are interesting to co-encapsulate incompatible solutions (which would react if they were in contact).

In this Application Note, aqueous droplets (called “core”) in an oily droplet (called “shell”) are obtained using the combination of two RayDrop® devices placed in series. The influence of the fluidic parameters on the number of cores contained in the oily shell is underlined in this application note.

Abstract

This document is intended for trained people who want to produce microcapsules. The goal of this document is to guide you step by step from the filling of the droplet generator to the generation of microcapsules by using the Raydrop Platform. You will use the Raydrop to produce capsules of Poly(D,L-lactide-co-glycolide) (PLGA) with an aqueous core. To follow the instructions of this guide, you will need 4 hours. However, I you just want to produce capsules and you don’t need to encapsulate an API, it is possible to skip steps 5.7 and 5.8 and the whole process will take less time.

Abstract

Emulsions are usually manufactured in batch processes on a large scale. These produced emulsions require large amounts of energy and have wide size distributions with low reproducibility. Moreover, when it comes to encapsulating active pharmaceutical ingredients (APIs) in these drops, the process is complex, and losses are high. Indeed, the APIs must be encapsulated in a material that can then deliver APIs in a delayed and controlled manner. In high value-added areas such as the pharmaceutical industry, the use of microfluidic emulsion systems allows for users to obtain monodisperse emulsions and to improve the quality of the product, with notably reduced API losses due to higher encapsulation efficiency than batch processes.

In this context, Secoya has developed a device named Raydrop®, which is a microfluidic droplet generator that facilitates the production of emulsions. Raydrop® technology aims for a more robust production with less wear than most current microfluidic emulsification devices. Depending on the configuration of the Raydrop®, it is possible to create either simple or double emulsions.

In this white paper, we discuss the Raydrop® and it’s invovlement in the production of double emulsions. Furthermore, the Raydrop® is now a part of a user-friendly microfluidic platform that contains all elements needed to produce a reproducible and high-quality emulsion, such as fluidic elements, mechanic compounds, and optical materials.

Abstract

Emulsions are usually manufactured in batch processes on a large scale. These produced emulsions require large amounts of energy and have wide size distributions with low reproducibility. Moreover, when it comes to encapsulating active pharmaceutical ingredients (APIs) in these drops, the process is complex, and losses are high. Indeed, the APIs must be encapsulated in a material that can then deliver APIs in a delayed and controlled manner. In high value-added areas such as the pharmaceutical industry, the use of microfluidic emulsion systems allows for users to obtain monodisperse emulsions and to improve the quality of the product, with notably reduced API losses due to higher encapsulation efficiency than batch processes.   In this context, Secoya has developed a device named Raydrop®, which is a microfluidic droplet generator that facilitates the production of emulsions. Raydrop® technology aims for a more robust production with less wear than most current microfluidic emulsification devices. Depending on the configuration of the Raydrop®, it is possible to create either simple or double emulsions. In this white paper, we discuss the Raydrop® and it’s invovlement in the production of double emulsions.   Furthermore, the Raydrop® is now a part of a user-friendly microfluidic platform that contains all elements needed to produce a reproducible and high-quality emulsion, such as fluidic elements, mechanic compounds, and optical materials.