Solution «Prilling by Vibration Dry» (100 – 1000 μm)

Formation of beads and capsules with further drying process

You wish to encapsulate various materials into a dry polymeric or wax matrix. We offer the ideal solution with the combination of the Encapsulator B-390 or Encapsulator B-395 Pro and the Rotavapor® system R-215.

Tabs

Overview

Benefits

Efficient

Formation of size controlled beads and capsules
Drying particles straight after the formation process
Short cleaning and setup times due to ergonomic design
Possibility of easy scale-up to pilot or industrial scale multi-nozzle system

Flexible

Many applications in controlled delivery and release
For a wide range of polymer and wax shell materials thanks to temperature control
Production of microbeads and core-shell microcapsules in a single step process

User friendly

Fast and intuitive manipulation of the different process parameters
Real-time visualization of the bead / capsule production process with built-in stroboscopic lamp
Minimal downtime and maintenance thanks to robustness and durability

Voice of the customer

“Thanks to the introduction of the new BUCHI Encapsulator, various micro-beads can be produced quickly, and the production of beads under sterile conditions is easy.“

Dr. Eunhye Lee

Utah-Inha DDS & Advanced Therapeutics Research, Korea

Scope

Applied products

Encapsulator B-390

Encapsulator B-395 Pro

Service & Support

Customized application support
Tools for particle formation
Application database
Workshops training
Minimize downtimes thanks to our service hotline
Preventive maintenance IQ/OQ

Accessories

Options

Concentric nozzle set

Set of 7 external nozzles with high precision opening of 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 and 0.9 mm made of stainless steel incl. 1000 mL pressure bottle

Set of 8 single nozzles

Set of 8 single nozzles with high precision opening of 0.08, 0.12, 0.15, 0.20, 0.30, 0.45, 0.75 and 1.00 mm, made of stainless steel including nozzle rack.

Reaction vessel for sterile apllications

Completely autoclavable reaction vessel made of glass and stainless steel for the sterile production and collection of microcapsules, 2 litre working volume; incl. bead producing unit and set of 8 single nozzles.

Expert Advice

What influences the final bead size?

Bead size is influenced by following parameters:

Nozzle size - major influence
Liquid flow rate - moderate influence
Vibration frequency - moderate influence
Physico-chemical properties of the encapsulation mixture - minor influence.

The most important parameter for bead production is the nozzle size. In general final bead diameter is about twice the size of the nozzle aperture.

What influences final capsule size?

Capsule size is influenced by the following parameters:

Shell (external) nozzle size - major influence
Core (internal) nozzle size – moderate influence
Liquid flow rate for shell - moderate influence
Liquid flow rate for core material – minor influence
Vibration frequency - moderate influence
Physico-chemical properties of the encapsulation mixture - minor influence.

The most important parameter for capsule production is the size of the shell nozzle. In general final capsule diameter is about twice the size of the shell nozzle aperture. What influences the core size within core-shell capsules.

How is the core size influnced?

Shell (external) nozzle size - minor influence
Core (internal) nozzle size – major influence
Liquid flow rate for shell - minor influence
Liquid flow rate for core material – major influence
Vibration frequency - moderate influence
Physico-chemical properties of the encapsulation mixture - minor influence.

The most important parameter for core size within capsules is the size of the core nozzle and the flow rate of the core material. In general final core diameter within capsules is about 1-2.5 times the size of the core nozzle aperture with increasing with increasing flow rates resulting in larger diameters.

Is scale up of the process possible and how can it be achieved?

Scale up is simply done by multiplying the number of nozzles on the machine, and is referred to as the multi-nozzle system. The parameters used for the one nozzle system should also apply to the multi-nozzle system. Therefore a special scale-up development is not required. However the process must work and be stable when using the one nozzle system before switching to a multi-nozzle system: Buchi offers such a multi-nozzle system which enables between 1 and 6 nozzles to be operated simultaneously by the operator.

What is the optimal frequency and amplitude range to work within for different nozzle size?

The optimal frequency and amplitude ranges for different nozzle sizes are given in the following table.

Nozzle Diameter : 1.0 mm Frequency Range: 40 to 200 Hz Amplitude Range: 6 to 9
Nozzle Diameter : 750 microns Frequency Range: 40 to 300 Hz Amplitude Range: 5 to 9
Nozzle Diameter : 500 microns Frequency Range: 100 to 400 Hz Amplitude Range: 2 to 5
Nozzle Diameter : 400 microns Frequency Range: 200 to 500 Hz Amplitude Range: 1 to 4
Nozzle Diameter : 300 microns Frequency Range: 400 to 800 Hz Amplitude Range: 1 to 3
Nozzle Diameter : 200 microns Frequency Range: 600 to 1200 Hz Amplitude Range: 1 to 3
Nozzle Diameter : 150 microns Frequency Range: 800 to 1800 Hz Amplitude Range: 1 to 4
Nozzle Diameter : 80 microns Frequency Range: 1300 to 3000 Hz Amplitude Range: 4 to 4

What effect(s) does the viscosity of the encapsulation mixture have on the process parameters?

The viscosity of the encapsulation mixture has the following effects:

The higher the viscosity the higher the minimal jet velocity
The higher the viscosity the higher the working flow rate
The higher the viscosity the lower the optimal frequency
The higher the viscosity the larger the beads/capsules

What types of polymers can be used to produce the bead structure and how is a polymer selected?

A range of natural and synthetic polymers are commercial available either from Buchi or chemical suppliers. Some of the common materials are follows:

Natural polymers: Na-Alginate, Gelatin, lamda-Carragennan, Agar, Agrose, Chitosan, Cellulose, Whey protein, Collagen, Pectin
Synethtic polymers: Polyacrylamide, Polyvinyl Alcohol (PVA), poly(lactic-co-glycolic acid) (PLGA), Cellulose sulphate, polyDADMAC, poly-l-lysine, Polyethylene Glycol (PEG)
In additional range of waxes can also be used to produce the capsules

What type of alginate should be used?

Alginate is a natural polymer deviated from the cell wall of various different seaweed plants. On account of its natural origin the type of alginate supplied by different suppliers can vary extensively and this variable composition can have a negative effect on the quality of the alginate. This can result in the production of low quality particles or in some cases beads/capsules cannot be produced, while it also affects reproducibility of experiments. Buchi now supplies high quality alginate with a consistent composition. Each batch of alginate is pre-tested by scientists at Buchi to ensure customers can consistently produce high quality beads/capsules in a reproducible manner.

Polymer solution cannot be pumped through the nozzle and bead producing unit. What can I do?

In this case either the nozzle or the bead producing unit is blocked with dried polymer. Cleaning nozzle: See nozzle cleaning section

Cleaning bead production unit: If alginate is being used, soak the unit in 0.1 M NaOH for 1 hour and then pump the NaOH through the unit using a syringe pump or place the unit within a sonication bath for 1 – 5 minutes to loosen the alginate. For gelatin either soak in hot water (> 60 °C) and flush or sonication as above.
For most materials, sonication will help to unblock it and the unit should be flushed with a liquid with can dissolve the entrapped material i.e. for PGLA this can be dichloromethane.
Blocking of the pre-filter in the producing unit can also prevent the pumping of the polymer material through the bead producing unit and should be changed. See YouTube videos for more details.

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