Modified vibrating-mesh nozzles for advanced spray-drying applications

• Nozzle elements of the B-90 spray-dryer were coated by uniform polymer films.
• Adjustment of orifice dimensions resulted in a more efficient formulation atomization (finer droplets).
• Modified nozzle elements generated smaller particles with modified release properties.
• Adequate polymer deposits would allow for powder fabrication matching the needs of the individual application.
• Polymer coated nozzles reveal significant potential for a number of other applications in chemistry and medicine.

This work describes uniform polymer coatings allowing for an adjustment of the orifice dimension of vibrating-mesh nozzles and therefore, size of emerging formulation droplets and dried particles, which is of general interest for diverse spray-drying applications.Chemical vapor deposition of poly(p-xylylene) (PPXN) on aperture templates of the B-90 spray-dryer (orifice diameters: ∼4.0 μm) caused a reduction of the opening cross-sections of ∼50%. Thus, a more efficient formulation atomization was observed (finer droplets). Likewise, application of PPXN-coated, rather than plain nozzles, resulted in significantly smaller (particle diameter: 1.3 vs. 3.6 μm) and narrower distributed (span: ∼1.4 vs. ∼1.8) sildenafil-loaded poly(lactide-co-glycolide) microparticles. Prediction of the size of spray-dried microparticles using the size results of atomized droplets (“residual core method”) was shown to be in agreement with the observed values. Formulations prepared with plain and PPXN-coated nozzles exhibited a sustained sildenafil release profile with mean dissolution times of ∼1.5 and ∼4.0 h, respectively.Regardless of the starting aperture template, any desired orifice dimension and therefore, dried particle size could be achieved by generating adequate polymer deposits.

Figure optionsDownload high-quality image (85 K)Download as PowerPoint slide