Coaxial Electrospinning & Electrospraying Technology
“Doxa® Coaxial Electrospinning & Electrospraying Tech. is the best choice to deal with spherical or fibered micro-nanoparticles (simple/hollow/core-shell) having high loading efficiency whose shows a range of release triggers and is compatible with a wide range of active ingredients”.
This novel one-step method for microencapsulation by which core-shell nanoparticles and nanofibers are obtained (based in simple electrospraying & electrospinning techniques) is highly competitive with other existing strategies of microencapsulation based on either templates and molecular self-assembly. In fact, chemical or physical adherence onto the surface of the template depends on case-specific interactions i.e., a particular approach may not even be adaptable to the synthesis of a chemically similar material.
TWO LIQUIDS
This technique enables the formation of a steady coaxial jet of two immiscible liquids by the action of the Electro-Hydrodynamic (EHD) forces.
TAYLOR CONE
Under the action of the electric field, the compound meniscus adopts a conical shape (Compound Taylor cone). An electrified coaxial jet is issued from the apex cone (diameter independent from those of the needles).The jet diameter can be tailored into the micro or nanometric size range by suitably tuning of the flow rates and liquids properties.
DROPLETS FORMATION
Varicose instabilities generate jet break-up producing micro-droplets. If jet solidification occurs, electrical repulsion draws the jet generating fibered core-shell capsules. Allows generating core-shell capsules from liquid solutions and dispersions.
TWO COAXIAL NEEDLES
The liquids are injected through two coaxial needles connected to a HV power supply.
PROCESS STABILITY
Can be upscaled to get to massive production. Scaling Laws of this process allows predicting the diameter and the electric current transported by the ECJ from the liquid flow rates and physical properties, which allows a good control of the process
Scope
Doxa offers its customers access to this technology for basic or applied research, but also to integrate it in their own labs. To achieve this we employ the latest equipment that allow the fabrication of microfluidics devices.
Features
FULL CONTROL ON PROCESS
The Generation and fine control of the compound jets of immiscible fluids flowing coaxially enables a full control of diameter size varying flow rate and conductivity of outer liquid. Typical diameter sizes range from 50 nanometers to 50 microns.The control of the geometry and the flow rate per each channel for the fluids flowing coaxially enables a full control of the process. Typical diameter sizes range from dozens of microns to 500 microns.
ONE STEP METHOD
This technique enables the microencapsulation in one just one step. There is no need for a freezing chamber (Spray Chilling) or drying (Spray Drying) or a chemical reactor to solidify the microcapsules. Final product is collected in the collector. This technique allows processing bioactive substances which can ́t survive at extreme conditions, e.g. heat or freezing required with other encapsulation techniques.
FULL CONTROL OF FINAL PRODUCT PROPERTIES
Coaxial electrospray enables the production of high monodisperse droplets, the existence of satellite droplets is drastically reduced. It is ensured a low dispersion of the size of nanoparticles. As particles are electrically charged, there is a null coalescence risk. The control on the flow rate in each nozzle allows the microencapsulation of liquids with good control on the characteristics of the structure of the capsule (shell´s thickness and morphology).
FLEXILITY
This technique shows flexibility in the production of different morphologies: Can generate fibers/particles simple, coaxial and/or hollow. The use of DOXA Multi-Injection and Continuous Collection Devices ensure the Scale-Up processes for high throughput production.