Production of Encapsulated Micro/Nanoparticles Using Electrohydrodynamic Atomization Technique

Summary

In this study, sodium alginate micro/nanoparticle production containing our patented X-700 adhesive was conducted using electrohydrodynamic atomization technique (EHDA). The particles obtained in this manner would increase the bonding potential of industrial adhesives. Morphological and mechanical properties of the EHDA encapsulated products obtained were determined by performing field emission gun scanning electron microscopy (FEGSEM) and tensile test procedures. These particles with large surface area would expand the surface area to be bonded and offer a more effective coating opportunity.

1. Introduction

The concept of adhesive comprises any material or substance that holds or attracts various materials together to form a mechanical, chemical, and adhesive whole through adhesion or cohesion force. Many products of chemical and plant-based nature are currently being used as adhesives. In its basic sense, it is the bonding of two objects from their front surfaces to each other. The continuity of this bonding over a long period is essential. Some adhesives, when applied from front surfaces, can separate from their interfaces within a certain time. For this reason, adhesives are a serious issue of great industrial importance. In recent years, new types of polymeric experiments in industrial adhesives have attracted attention. Polymeric-based adhesives can demonstrate good strength, water resistance, and sometimes flexibility or rigidity. Micro/nanoparticle production for industrial adhesives using the EHDA system has been provided within the scope of our work. The EHDA system basically consists of a syringe pump, magnetic stirrer, and high-voltage power supply [1-8]. With this system, micro/nanoparticle production of patented X-700 adhesive and SA encapsulated was achieved to improve the adhesion and bonding capacity of industrial adhesives.

2. Material and Method

2.1. Material

In this study, our patented X-700 industrial adhesive was used. Sodium alginate (SA) (Sigma-Aldrich, Germany) and distilled water were preferred. Curcumin active substance was obtained ready as isolated from turmeric. Calcium chloride (CaCl2) (Sigma-Aldrich, Germany) was used as an SA cross-linker. Span 20, Tween 20, and Tween 80 (Sigma-Aldrich, Germany) were used as surfactants in nanoparticle production at regular and equal ratios.

2.2. Method

*Preparation of feeding solutions prior to electrospraying Prior to micro/nanoparticle production in our study, solutions were prepared according to the values given in Table 2.1. The prepared solutions were filtered through Whatman paper to remove undissolved large particles from the solution and prepared for micro/nanoparticle production [9-15]. The surfactant ratios to be added to the solutions to be prepared before electrospraying are shown in Table 2.1. Table 2.1. Surfactant ratios to be added to solutions prior to electrospraying *Micro/nanoparticle production encapsulated by electrohydrodynamic atomization technique The solutions prepared according to the values in Table 2.1 were sequentially placed in beakers and used in the electrospraying process. The polymer solutions to be used in the electrospraying process were drawn into a 10 ml syringe and placed in the syringe pump. The cross-linkers in Table 2.2 were dissolved in distilled water and placed in a beaker. Particle production was achieved by applying the values in Table 1.2. A steel needle tip of 20 gauge was preferred for the anode part of the high-voltage power supply. The cathode part was attached to a stainless steel ring providing conductivity. A working distance of 12 cm was maintained between the syringe needle and stainless steel ring, and micro/nanoparticle production was obtained by implementing the working parameters in Table 2.2. The working parameters in Table 2.2 were applied and the electrospraying process was carried out within a system with a heated magnetic stirrer. Stirring time of 60-65 minutes, speed of 600 rpm, and temperature of 45-50°C were applied to all samples [5-19]. The electrospraying process working parameters are shown in Table 2.2. Table 2.2. Electrospraying process working parameters As a result of the electrospraying process, the produced products were placed in centrifuge tubes and centrifuged at 5,000 rpm for 30 minutes. As a result of the process, half of one container's centrifuge tube was emptied, distilled water was added, and centrifugation was performed at 5,000 rpm for 30 minutes. This procedure was applied three times. After the final process, emptying was applied equal to half of the tubes' capacity, the lids of the centrifuge tubes were removed and sealed with parafilm, and small holes were opened on the parafilm. After the process, the samples were placed in a -80°C refrigerator and left for two days. After the holding period, drying was performed using a lyophilizer device. As a result of the lyophilizer process, micro/nano particles were obtained. The polymer/cross-linker ratio was set at 6/1. In this way, monodisperse particles of equal size were desired to be produced. Micro/nanoparticles were stored at -18°C until use [13-19]. Figure 2.1 shows the micro/nanoparticle production stages of our SA-X-700 patented product. Figure 2.1. Micro/nanoparticle production stages of our SA-X-700 patented product

*Characterization studies

Prior to morphological FEGSEM analysis, samples were coated with gold-palladium. In this way, FEGSEM images were taken. Thirty-eight selected particles' arithmetic means were taken to determine the particle range. Mechanical properties were determined by applying tensile testing according to ASTM standards on wood dumbbell samples using a tensile testing device. Samples were repeated three times and mechanical properties were determined using arithmetic mean.

3. Results and Discussion

Morphological (FEGSEM) analysis results

SA micro/nanoparticle FEGSEM image is shown in Figure 3.1. This is the morphological FEGSEM image of micro/nanoparticles produced by the EHDA system cross-linked with 1% CaCl2 from the solution obtained from a mixture of 2% Sodium Alginate (SA)-100% distilled water. SA particles were produced with the EHDA system and production was achieved through two different parameter optimizations. Improvements in nanoparticle sizes and morphologies were provided by considering surfactant and electrical field strength values. While there was a particle range of 900-1800 micrometers, as a result of parameter optimization, a nanoparticle diameter distribution of 400-780 nm was obtained [4-12]. [caption id="attachment_130479" align="aligncenter"] Figure 3.1. SA micro/nanoparticle FEGSEM image[/caption] [caption id="attachment_130480" align="aligncenter"] Figure 3.2. SA-X700 Patented adhesive micro/nanoparticle FEGSEM image[/caption] Figure 3.2 shows the morphological FEGSEM image of micro/nanoparticles produced by the EHDA system cross-linked with 1% CaCl2 from the solution obtained from a mixture of 2% Sodium Alginate (SA)-1% X700 Patented adhesive-100 distilled water-1% Tween 80-0.5% Tween 20-0.5% Span 60. FEGSEM analysis determined that particles in the range of 300-500 nm were present [7-14].

Mechanical (Tensile) Analysis Results

Prior to the tensile test procedure, adhesive without micro/nanoparticles was applied to a wood surface, and our patented X-700 adhesive containing micro/nanoparticles was applied to another wood surface and left to dry. The wood dumbbell samples prepared in this manner were pulled three times according to ASTM standards to determine mechanical properties. While the wood sample without encapsulated patented X-700 adhesive showed 65 MPa mechanical properties, the sample containing encapsulated patented X-700 adhesive showed 125 MPa mechanical properties. The reason for this is that with the increase in surface area, it exhibits homogeneous distribution and dispersion.

4. Conclusions

Based on the study results, micro/nanoparticle production was successfully achieved using the EHDA technique. Compared to SA particles, SA particles containing patented X-700 adhesive have smaller particle size. Furthermore, since surface area increased, performance effect also increased. Our tensile test results supported this condition. The tensile test procedure was performed in accordance with ASTM standards, and significant differences were revealed in the mechanical properties of EHDA non-encapsulated and non-encapsulated adhesives. The primary reason for this is that EHDA encapsulated particles provide increased surface area and create a synergistic effect resulting from material internal interactions. With the new-generation adhesives containing the obtained particles, the adhesion performance of industrial adhesives will be improved. Erdi Buluş Senior Materials Engineer / Senior Materials Technologies Specialist Istanbul Arel University ArelPOTKAM (Polymer Technologies and Composite Application and Research Center) Gülseren Sakarya Buluş Specialist Nurse Silivri District Health Directorate / Bahçeşehir University Graduate Education Institute / Engineering Management Thesis Master's Program

References / References [1] de Pinho Neves, A. L., Milioli, C. C., Müller, L., Riella, H. G., Kuhnen, N. C., & Stulzer, H. K. (2014). Factorial design as tool in chitosan nanoparticles development by ionic gelation technique. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 445, 34-39. [2] Atun, S., Dewi, Y., & Aznam, N. (2020). Characterization Of Nanocurcuminoid From Ethanol Extract Of Curcuma Xanthorrhiza Rhizome Loaded By Chitosan And Alginic And Its Antioxidant Activity Test. Reproduction Humaine Et Hormones, 2(2), 13-20. [3] Qi L, Xu Z, Jiang X, Hu C, Zou X (2004) Preparation and Antibacterial Activity of Chitosan Nanoparticles. Carbohydrate Research 339:2693-2700 [4] Sarkar SD, Farrugia BL, Dargavill TR, Dhara S (2013) Physico- Chemical/Biological Properties of Tripolyphosphate Cross- Linked Chitosan Based Nanofibers. Materials Science and Engineering C 33 1446-1454 [5] Bhumkar DR, Pokharkar VB (2006) Studies on Effect of pH on Cross-linking of Chitosan With Sodium Tripolyphosphate: A Technical Note. AAPS PharmSciTech 7 (2) Article 50 [6] Braccini I, Pérez S 2001. Molecular basis of Ca2+-induced gelation in alginates and pectins: the egg-box model revisited. Biomacromolecules 2(4):1089-1096. 14. [7] Goh CH, Heng PWS, Chan LW 2012. Alginates as a useful natural polymer for microencapsulation and therapeutic applications. Carbohydrate Polymers 88(1):1-12. [8] Honary, S., Maleki, M., & Karami, M. (2009). The effect of chitosan molecular weight on the properties of alginate/chitosan microparticles containing prednisolone. Tropical Journal of Pharmaceutical Research, 8(1), 53-61. [9] Vimala, K., Yallapu, M. M., Varaprasad, K., Reddy, N. N., Ravindra, S., Naidu, N. S., & Raju, K. M. (2011). Fabrication of curcumin encapsulated chitosan-PVA silver nanocomposite films for improved an [10] Niranjan, R., Kaushik, M., Prakash, J., Venkataprasanna, K. S., Arpana, C., Balashanmugam, P., & Venkatasubbu, G. D. (2019). Enhanced wound healing by PVA/Chitosan/Curcumin patches: In vitro and in vivo study. Colloids and Surfaces B: Biointerfaces, 182, 110339.