Labplant spray dryer

For the spray drying procedure previously described, methods were used with slight modifications (29 (link), 35 (link)). Initially, excipients and phages at titers of 5 × 10¹⁰ PFU/mL (1% phage added to final volume) were dissolved in ultrapure water to make up a 200 mL volume solution. The excipients tested were trehalose (Glentham Life Sciences Ltd, UK), leucine (Glentham Life Sciences Ltd, UK), mannitol (Fisher Scientific, UK) and Eudragit S100 (Evonik, Germany). Eudragit S100 was dissolved in ultrapurified water (5% wt/vol) by the addition of 4 M NaOH (Fisher Scientific, UK) drop by drop, until the solution turned clear, which indicated polymer dissolution (26 (link)).
The excipient-phage solution was spray dried using a laboratory scale LabPlant Spray Dryer (UK) with a two-fluid nozzle for atomization, and the nozzle had a diameter of 0.5 mm (Fig. 1a). Air speed of 4.3 ms⁻¹ and liquid flow rate of 280 mlh⁻¹ were used. The drying temperature was controlled by changing the inlet temperature from 80°C to 100°C, and the corresponding outlet temperatures varied from 40°C to 60°C. Dried powder phages were passed through the cyclone, collected in 100 mL glass bottles, and stored at 4°C until use. To determine phage titer, 0.10 g of dried powder phage was suspended in 900 μL phage suspension buffer, diluted 10-fold, and titered by plaque assays (Kropinski et al., 2009).

For the spray drying procedure previously described, methods were used with slight modifications (29 (link), 35 (link)). Initially, excipients and phages at titers of 5 × 10¹⁰ PFU/mL (1% phage added to final volume) were dissolved in ultrapure water to make up a 200 mL volume solution. The excipients tested were trehalose (Glentham Life Sciences Ltd, UK), leucine (Glentham Life Sciences Ltd, UK), mannitol (Fisher Scientific, UK) and Eudragit S100 (Evonik, Germany). Eudragit S100 was dissolved in ultrapurified water (5% wt/vol) by the addition of 4 M NaOH (Fisher Scientific, UK) drop by drop, until the solution turned clear, which indicated polymer dissolution (26 (link)).
The excipient-phage solution was spray dried using a laboratory scale LabPlant Spray Dryer (UK) with a two-fluid nozzle for atomization, and the nozzle had a diameter of 0.5 mm (Fig. 1a). Air speed of 4.3 ms⁻¹ and liquid flow rate of 280 mlh⁻¹ were used. The drying temperature was controlled by changing the inlet temperature from 80°C to 100°C, and the corresponding outlet temperatures varied from 40°C to 60°C. Dried powder phages were passed through the cyclone, collected in 100 mL glass bottles, and stored at 4°C until use. To determine phage titer, 0.10 g of dried powder phage was suspended in 900 μL phage suspension buffer, diluted 10-fold, and titered by plaque assays (Kropinski et al., 2009).