Electrospraying, also called electrohyrodynamic or EHD atomization (EHDA), is a sister technology to electrospinning and is a very promising technique for the preparation of micro- and nanoparticles suitable for the production of drug-delivery molecules.
Standard techniques for the production of drug particles include spray drying, coarcevation, emulsion techniques, and solvent evaporation, among others. However, these methods face numerous challenges including low drug-loading efficiency, particle-size poly-dispersity, low ability to fabricate small particles (below 100 nm), and difficulties for incorporation of hydrophilic drugs. Electrospraying is becoming an attractive method for particle generation as it overcomes many challenges confronting these techniques.
Electrospraying is a method of producing micro- and nano-sized particles by using a high voltage electric field to break up a solution. The particle size is controlled by varying the solution properties such as concentration and conductivity, as well as processing parameters such as flow rate and applied voltage. The solution (drug, polymer) flows through an emitter, a high voltage is applied at the emitter tip and an electrical field is formed with the grounded collector. When the energy of the electric field overcomes the surface tension of the solution, the solution breaks into small charged particles.
There are numerous advantages of electrospraying for particle generation:
1. High drug loading efficiency
· Previous studies electrospraying polymers with an active pharmaceutical ingredients (API) have demonstrated an encapsulation efficiency of up to 100 %.1
2. Narrow particle-size distribution
· The electric field causes the particles to break up with great uniformity.2
3. Micro-sized particles and Nano-sized particles
· By changing the solution and process parameters particles can be formed in both the Nano- or micro size range.3
4. Dry particle formation
· The atomisation causes evaporation of volatile solvents resulting in the deposition of dry particles without the generation of heat that could damage the API or polymer.
5. Ease of particle synthesis due to single-step processing
· The electrospray process lends itself well to efficient high through put particle formation as it is an easy and continuous process.
The future looks bright for the electrospraying world and over the coming weeks and months we will be blogging about other potential areas in industry that electrospraying can easily facilitate.
1. Ramakrishna et al. International Journal of Nanomedicine 2013:8 2997–3017
2. Sridhar R, Ramakrishna S. Electrosprayed nanoparticles for drug delivery and pharmaceutical applications. Biomatter 2013
3. Almeria et al. Journal of Colloid and Interface Science 417 (2014) 121–130