## 4 Innovation in Surface Disinfection Method
### Antimicrobial Spray Nanocating  
#### 4.1.1 Principle  
Antimicrobial spray nanocoating was recently developed to control surface reactivity and properties. Dray nanospray is one of the most innovative technologies and has many advantages in terms of its ability to produce nanoparticles with much smaller droplets and a narrow area distribution [36]. Nanospray drying offers high stability to control particle size and morphology by optimizing the process parameters and nanoparticle characteristics. Spray drying is able to produce different forms of particle shapes [37]. Nanospray drying allows volume reduction, defined particle size, changing chemical, and physical properties with chemical and biological stability and high specific surface. Additionally, nanospray drying offers easy dosage administering and handling. It was initially utilized in the pharmaceutical field. Table 2 shows examples of FDA-approved medicine using nanospray drying technology as a preparation method. The nanospray drying process consists of six fundamental steps [45; 46; 47; 48]. The first stage is heating the inlet air to the desired temperature not to exceed 220 \({}^{\circ}\)C. The second stage is droplet formation using a two-fluid nozzle or ultrasonic spray head. Before the collection of the particle using cyclone technology or electrostatic particle collector, the drying step between drying gas and sample droplets is important. Then, the finest particles were collected to protect the user and environment using an outlet filter. Finally, was drying gas delivered by aspirator or with compressed air. A piezoelectric actuator vibrates a small replaceable spray cap, containing nanometric holes, to generate droplets. The latter leads to rapid vertical movement of the spray mesh, ejecting many droplets in size accurately through the holes in the drying chamber. The size of the droplets depends on the size of the holes and the physicochemical characteristic of the disinfectant. The flow of concurrent drying gas directs the \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Production Company** & **Product** & **Disease** & **Materials** & **Company** & **FDA Approval** \\ \hline Prograf & Tacrolimus & Immunosuppressant & HPMC & Astellas & 1994 \\  & & (prevents orga rejection) & & Pharma & 1994 \\ \hline Exhubera & Insulin & Diabetes & Manitol, glycine, sodium citrate & Pfizer/ Nektar & 2006 \\ \hline Intelence & Etravirine & HIV medicine & HPMC & Janssen & 2008 \\ \hline Zortress & Everolimus & Immunosuppressant & (prevents orga rejection) & HPMC & Novartis & 2010 \\ \hline Ardid/Osmohale, Bronchiol & - & Asthma/Cystic fibrosis & Manitol & Pharmacis & 2010 \\ \hline TOBI Podnaler & Tobramycin & Inhalation therapy & & DSPC, calcium chloride, sulfuric acid & Novartis & 2013 \\ \hline Rapliva & - & Bleeding control during & Fibrinogen/ Thrombin & Nova Laboratories & 2016 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Examples of FDA-approved medicine using nanospray drying technology as a preparation method [38; 39; 40; 41; 42; 43; 44; 45]. particles to the electrostatic particle collector. The electrostatic particle collector can capture nanometric particles (\(<\)1 \(\upmu\)m) with separation efficiency. The particles are gently removed from the inner surface of the collecting electrode cylinder using the particle scraper [49; 50; 51]. Figure 1 shows a schematic representation of the nanospray dryer principle. The sizes of the particles formed through encapsulation are nano (\(<\)1 \(\upmu\)m) [52; 53; 54; 55] and known as nanocapsules [56]. The smaller the particles, the better the solubility of the encapsulated liquids. The droplets obtained at the nanoscale lead to an increase in the volume distribution in the surface, which generally occurs by reducing the size of the drops, thereby increasing the particles' efficiency [57]. The cost reduces by using nanodrop sterilization instead of other sprayers [58].