AIP Conference Proceedings 1933, 040020 (2018); https://doi.org/10.1063/1.5023990 1933, 040020
© 2018 Author(s).
Simulation model of converging-diverging (CD) nozzle to improve particle delivery system of deoxyribonucleic acid (DNA)
Cite as: AIP Conference Proceedings 1933, 040020 (2018); https://doi.org/10.1063/1.5023990 Published Online: 13 February 2018
Danardono A. Sumarsono, Fera Ibrahim, Satria P. Santoso, et al.
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Simulation Model of Converging-Diverging (CD) Nozzle to Improve Particle Delivery System of Deoxyribonucleic
Acid (DNA)
Danardono A. Sumarsono
1, a), Fera Ibrahim
2, Satria P. Santoso
1,Gema P. Sari
21Department of Mechanical Engineering, Faculty of Engineering, Universitas Indonesia, Indonesia
2Virology and Cancer Pathobiology Research Center (VCPRC) FKUI-RSCM, Department of Microbiology, Faculty of Medicine, Universitas Indonesia, Indonesia
a)Corresponding author: danardon@eng.ui.ac.id
Abstract. Gene gun is a mechanical device which has been used to deliver DNA vaccine into the cells and tissues by increasing the uptake of DNA plasmid so it can generate a high immune response with less amount of DNA. Nozzle is an important part of the gene gun which used to accelerate DNA in particle form with a gas flow to reach adequate momentum to enter the epidermis of human skin and elicit immune response. We developed new designs of nozzle for gene gun to make DNA uptake more efficient in vaccination. We used Computational Fluid Dynamics (CFD) by Autodesk® Simulation 2015 to simulate static fluid pressure and velocity contour of supersonic wave and parametric distance to predict the accuracy of the new nozzle. The result showed that the nozzle could create a shockwave at the distance parametric to the object from 4 to 5 cm using fluid pressure varied between 0.8–1.2 MPa. This is indication a possibility that the DNA particle could penetrate under the mammalian skin. For the future research step, this new nozzle model could be considered for development the main component of the DNA delivery system in vaccination in vivo
INTRODUCTION
DNA (deoxyribonucleic acid) vaccination is an innovation in medical technology which utilizes genetically engineered DNA encoded by antigen(s) to generate an immunologic response on animals. This antigen encoding DNA plasmid will stimulate humoral and cellular immune response against pathogens including disease- producing viruses [1].
Gene gun provides simple yet operative means of DNA vaccine delivery on organisms. Tang (1992) showed that specific antibodies against hGH can be produced with deliver the gene encoding hGH (human growth hormone) using gene gun [2]. Fynan (1993) reported small amount of gene encoding influenza antigens, delivered using gene gun, was proficient to generate antibodies against influenza [3]. Lodmell (1997) showed that plasmid DNA delivered by gene gun Accell™ was able to induce protective antibodies produced against the rabies virus [4]. Loehr (2000) reported that cattle which vaccinated by the DNA vaccine mediated by gene gun as its delivery system managed to be free from bovine herpesvirus 1 (BHV-1) infection [5]. In 2016, Leitner succeed to improve protective immunity-dependent T cells against tumor in mice C57BL / 6 by delivery of DNA vaccines using gene gun [6].
Nozzle is a crucial part on gene gun which will determine the efficiency of DNA vaccine delivery. Nozzle works to modify airflow at gene gun, to regulate the rate of flow, speed, direction, mass, shape, or pressure which is exerted. We used CFD by Autodesk® Simulation CFD 2015 to simulate pressure contour, static pressure, and parametric distance for the new nozzle designs with low helium pressure (145-217 psi). We set the dimension of
this present study was to design the gene gun nozzle and find effective pressure to improve DNA particle velocity for applications in DNA vaccine.
THE OBJECT OF THE STUDY
The high speed conductivity in the form of supersonic wave is needed to penetrate DNA particles to the surface of the cell. The supersonic wave can be obtained by optimizing the entrance and exit flow passages. Moreover, velocity and pressure difference must be considered to get the ideal supersonic wave. To determine the appropriate nozzle design which is effective to deliver DNA vaccine, we used several formulas which were Mach Number Equation, Dynamic Pressure Equation, and De Laval Nozzle Equation [7].
STATE OF THE ART
Subsonic Equation(𝐴 𝐴∗)
2
= 1
𝑀2[ 2
𝛾 + 1(1 + (𝛾 − 1 2 𝑀2)]
(𝛾+1) (𝛾−1)
(1)
Subsonic wave will exist if the mach number increased and A/𝐴∗ decreased.
De Laval Nozzle Formulation
Sonic flow occurs by varying area
𝑑𝑣
𝑣 = 1
1 − 𝑀2 𝑑𝐴
𝐴 →𝑑𝐴
𝐴 = (𝑀2− 1)𝑑𝑣
𝑣 (2)
de Laval Nozzle produces at Mach number M = 1 where dA = 0
Consider steady flow through nozzle with sonic throat;
𝑚̇ = 𝜌𝑣𝐴 = 𝜌∗𝑣∗𝐴∗→ 𝐴
𝐴∗=𝜌∗𝑣∗
𝜌𝑣 (3) 𝜌∗
𝜌 =𝜌∗ 𝜌𝑜
𝜌𝑜
𝜌 = ( 2
𝛾 + 1)
1
𝛾−1(1 +𝛾 − 1 2 𝑀2)
1
𝛾−1 (4)
𝑣∗
𝑣 =√𝛾𝑅𝑇∗
𝑣 =√𝛾𝑅𝑇√𝑇𝑇∗
𝑣 = 1
𝑀√𝑇 𝑇0√𝑇𝑜
𝑇 = 1
𝑀( 2
𝛾 + 1)
1
2(1 +𝛾 − 1 2 𝑀2)
1
2 (5)
Substituting (4) and (5) into (3);
𝐴 𝐴∗= 1
𝑀( 2
𝛾 + 1)
1 2(𝛾+1𝛾−1)
(1 +𝛾 − 1 2 𝑀2)
1 2(𝛾+1𝛾−1)
(6)
The equation (6) is the combination from formulas which are continuity (3), energy (4), and momentum. (5)
Dynamic Pressure Equation
𝑃𝑑𝑦𝑛𝑎𝑚𝑖𝑐 =𝜌𝑓𝑙𝑢𝑖𝑑
2 𝑣2 (7) Equation to found the velocity from the pressure at inlet and outlet.
Mach Number Equation
𝑀 = 𝑣𝑓𝑙𝑢𝑖𝑑
𝑣𝑠𝑜𝑢𝑛𝑑 (8)
After the velocity is obtained, it should be easy to obtain the Mach Number.
RESEARCH METHODS
Nozzle designed based on calculation from subsonic equation, De Laval nozzle formulation, dynamic pressure equation, and Mach number equation, however there was no further study about the existing numerical methods to describe the nozzle. CFD by Autodesk® Simulation 2015 software used to prove the existence of shockwave in the nozzle.
The inlet pressure was varied between 0.8 – 1.2 MPa and the initial condition that entered is between 94.6 – 115.92 m/s. On selecting mesh, we chose refining mesh to be convergent result. Fluid flowed on steady state and it run for 300 iterations. The result on this simulation compared to the analytical calculation based on the theory.
RESULTS AND DISCUSSION
Nozzle is a crucial part of gene gun because it will determine the efficiency of DNA vaccine delivery. Nozzle function are to modify airflow at gene gun and to regulate the rate of flow, speed, direction, mass, shape, or pressure whichis exerted. The presence of shock waves provide vibration canal wall which cause the channel walls wheezes. Schrader valve also will replace the compressor, so that the gene gun can be used in remote areas that do not have a compressor. Quick Exhaust Valve (QEV) acts as regulator valve air release before being discharged into the nozzle and silencer functions as supporting components in the gene gun system, serves to muffle the sound when air is released.
(a) (b)
FIGURE 1. Schematic drawing of converging-diverging nozzle (a) and pneumatic diagram of Gene gun prototype for DNA vaccine delivery (b).
The nozzle models are consisting two parts, the converging nozzle as the first part (Part A) and the diverging nozzle as the second part (Part B) as shown in Figure 1 (a). The converging part contain inlet nozzle where the particle will enter the nozzle through the throat. Part A connected to the Quick Exhaust Valve (QEV) and the
The presence of shock waves provide vibration canal wall which cause the channel walls wheezes. Schrader valve also will replace the compressor, so that the gene gun can be used in remote areas that do not have a compressor.
QEV acts as regulator valve air release before being discharged into the nozzle and silencer functions as supporting components in the gene gun system, serves to muffle the sound when air is released.
Simulation offered the potential to improve the product by predicting its behavior digitally so that it is the best step before production step. CFD is a software which specialized in simulation that analyzes fluid flow, this software will analyze the interaction of liquids and gases with the surfaces defined by boundary condition [7,8].
Five variations of pressure, which were from 0.8 to 1.2 Mpa, were simulated to find the nozzle with the biggest momentum. In vaccination using DNA plasmids, microparticlse must be accelerated by a high speed flow that is began by a traveling shock wave, so that they can achieve a sufficient momentum to infiltrate into the cells of interest [9,10]. In DNA vaccination, powdered vaccines are directly delivered into the antigen presenting cells (APCs) within the epidermis/dermis [9].
Figure 2 represents shockwaves formed by the nozzle on different pressure on the inlet. Blue contour shows the lowest and red contours shows the highest number. On Figure 2. (1a-5a), also shown the red contour which indicates gas compression where gas piled up in one position and ready to blow which produce shockwave.
A normal shockwave formed because it was perpendicular to the velocity vector (Figure 2. (1b-5b).
Shockwave occurred when there was a difference at area at inlet and outlet of the nozzle in some distance. This shockwave produced the supersonic velocity after through the shockwave. Shockwave will increase the velocity drastically and would make DNA particles able to penetrate the mammalian skin.
Figure 3 represents static pressure and velocity profile graphs for each pressure inlet given to the nozzle. On Figure 3 (1c – 5c) graphs, as the pressure increased, the negative pressure will become higher too with range 0.03- 0.045, therefore the shockwave occured. On Figure 3. (4c and 5c) shows the highest pressure when the inlet pressure 1.1 MPa and 1.2 Mpa and the outlet of the nozzle on 0.06 m.On Figure 3 (1d - 5d) the highest velocity was reached in 0.8 MPa and 0.9 MPa where they almost reached 1300 m/s. This reaction happened because the negative pressure on the middle of the nozzle were smaller than the 1.0 MPa above. We can see from Figure 3, graph 1d and 2d were the best output velocity which was affected momentum.
Nitrogen gas used for the medium of DNA vaccine and was enable to damp the thermal shock during normal shockwave occur. Nitrogen gas has an inert property (difficult to burn), so it safe from large friction on the wall.
In Figure 3, shockwave occurred in between 0.04 – 0.05 m in parametric distance.
The flow in the throat was sonic which means the Mach number was equal to one in the throat. Downstream of the throat, the geometry diverges and the flow was isentropically expanded to a supersonic Mach number that depended on the area ratio of the exit to the throat. The expansion of a supersonic flow caused the static pressure and temperature to decrease from the throat to the exit, so the extent of the expansion also determined the exit pressure and temperature. The exit temperature defined the exit speed of sound, which then would determine the exit velocity.
De Laval Nozzle worked based on isentropic flow (adiabatic phase) in which total enthalpy and total pressure were constant, moreover the total temperature was also constant for a perfect gas. As a typical problem, the inlet thermodynamic state (pressure and temperature) was known as well as the inlet velocity (Mach number).
Compressible fluid flowed suddenly from high pressure shall produce a shock wave phenomenon because of compressibility effected of the fluid itself.
In vaccination using DNA plasmids, microparticlse must be accelerated by a high speed flow began by a traveling shock wave, so that they can achieve a sufficient momentum to infiltrate in to the cells of interest [9, 10]. In DNA vaccination, powdered vaccines are directly delivered into the Antigen Presenting Cells (APCs) within the epidermis/dermis [9].
P = 0.8 MPa
P = 0.9 MPa
P = 1.0 MPa
P = 1.1 MPa
P = 1.1 MPa
FIGURE 2. The CFD simulation shows the pressure contour (a) and the velocity contour (b) at different initial pressure P.
(a) Pressure Contour (b) Velocity Contour
FIGURE 3. The CFD simulation shows the graphic of the static pressure (c) and the velocity profile (d) as a function of parametric distance at the different initial pressure P.
P = 0.8 MPa
P = 1.0 MPa
(c) Static Pressure (d) Velocity profile
P = 0.9 MPa
P = 1.1 MPa
P = 1.2 MPa
CONCLUSION
The transient gas inside the prototype of converging-diverging nozzle had been characterized by this simulation. Pressure contour was used to indicate the increase of Mach number on throat and shockwave on diverging section. Velocity contour was used to indicate that the velocity increased on the output, which was much higher than the input. Computational Fluid Dynamics (CFD) by Autodesk® Simulation 2015 can be a powerful and useful tool to develop nozzle for gene gun.
ACKNOWLEDGMENTS
The authors would like to thank to Universitas Indonesia, the Ministry of Health, and the Ministry of Research and Technology the Republic of Indonesia for funding the development of DNA vaccines delivery system research.
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