Silica nanorattle with enhanced protein loading: A potential vaccine adjuvant

doi:10.1016/j.jcis.2013.03.005

Journal of Colloid and Interface Science

Volume 400, 15 June 2013, Pages 168-174

https://doi.org/10.1016/j.jcis.2013.03.005 Get rights and content

Highlights

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SNs are efficient in protein loading and releasing than MCM-41 and solid silica nanoparticles.
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Controlled releasing of OVA loaded on SNs when incubated in the 5% glucose medium.
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SNs are biocompatible both in vitro and in vivo.
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SNs enhance the humoral immunity reaction when mice vaccinated by SNs–OVA.

Abstract

Nanoparticles are excellent carriers for drug and protein, and have the potential to be used in vaccine delivery system. Here, we prepared different structures silica nanoparticles such as silica nanorattles (SNs), mesoporous silica nanoparticles (MSNs) and solid silica nanoparticles (SSNs), and chosen ovalbumin (OVA) as model protein to study the potential application of silica nanoparticles in protein vaccine delivery system. The results showed that silica nanoparticles were efficient in protein loading and dependent on structure, size and incubation medium. According to the three structure particles, SNs were favorable to be used as protein carriers. Furthermore, we proved low cytotoxicity of silica nanorattle on RAW 264.7 cell line and biocompatibility in vivo. In addition, SNs was capable to up-regulate the humoral immunity reaction when mice were vaccinated with SNs–OVA formulation. Taken together, SNs was excellent carriers for protein vaccine and has the potential to be used as adjuvant.

Graphical abstract

Introduction

Vaccines, known as an effective weapon for human disease prevention, are playing an increasingly important role in the fight against infectious disease. According to the division of preparation, vaccines can be divided into classic vaccine and modern vaccine [1], [2]. The former include inactivated, attenuated and subunit vaccine which be made from some ingredients of natural organism. Modern vaccine refer to those vaccine apply modern biological technology, such as subunit vaccines, gene delete vaccines, recombinant and synthetic peptide vaccine. Classic vaccines have some ingredients like inactivated or low activity microorganism will induce adverse effects [3], [4]. Although modern vaccine showing more safety than classic types, such like recombinant and synthetic peptide vaccine, the less efficient immunity protect effect limits their broader applications [5], [6]. Furthermore, recombinant and synthetic peptide vaccine face many challenges because of their bad stability, short half-life and vulnerability to interference by endogenous substances [7], [8]. It is necessary to provide suitable carrier for prevention and modify of antigen protein in modern vaccine formulation.

Adjuvant has advantages in enhancing vaccine immunity protect effect. Since 1925, first discovered of some other substances (metal salt, lecithin and saponin) can improve the antigen specific immune response by Ramon, all sorts of different material were used as adjuvant [9], [10], [11]. However, there were little numbers of clinical cases. With the booming of nanotechnology, the application of nanomaterials as adjuvant has aroused more concern [12], [13], [14], [15], [16]. Local inflammation and systemic immune response caused by nanoparticles as foreign matter actually can be considered as an immunopotentiation effect. Therefore, it is important to investigate the loading of proteins in nanomaterials and their bio-effect in vivo [17].

Mesoporous materials are of great interest to nanoscience and nanotechnology due to their unique porous structures as well as their tailorable adsorption, catalytic, conductive, and magnetic properties [18], [19]. Among the ordered mesoporous materials, mesoporous silica nanoparticles (MSNs) have become a type of very popular materials with potential applications ranging from adsorption and catalysis to nanotechnology and biotechnology [20], [21]. However, the storage capacity for the conventional mesoporous materials is relatively low, and also the irregular bulk morphology is not perfect for delivery [22]. To overcome these problems, one strategy is to synthesize mesoporous hollow silica nanoparticles with penetrating pore channels from outside to the inner hollow capacity. Recently, we reported a flexible, scalable and robust method to prepare rattle-type mesoporous silica hollow spheres named as silica nanorattles (SNs). SNs are emerging as new and promising class of nanoparticles that developed for drug delivery system due to their special structure and functions [23], [24], [25]. In previous study, we found that low lethal toxicity of SNs when intravenous injection at single dose. We also found that kupffer cells (KCs) are the major target cells when SNs entered the blood stream [26]. These previous research provide advantages of SNs for potential application in adjuvant. However, loading and releasing efficiency of SNs on antigen and potential adverse effect of SNs on immune system or immune response should be determined before the kind of application.

Here, we examined the loading and releasing of silica nanorattle with 110 nm on ovalbumin (OVA). Influencing factors on protein loading and releasing such as nanoparticles structure, size, temperature, medium and time were studied. In addition, we also evaluated the effect of SNs on immune cells and immune organs in vivo and in vitro. Finally, the effect of SNs on OVA antibody levels after vaccination by SNs–OVA formulation were investigated in this study.

Section snippets

Materials

Tetraethylorthosilane (TEOS), N-[3-(trimethoxysilyl)propyl]ethylenediamine (TSD), 3-aminopropyltrimethoxysilane (APTMS), 3-Aminopropyltriethoxysilane (APS), hydrofluoric acid (HF), NaOH, CuSO₄⋅5H2O) and KNaC₄H₄O₆⋅4H₂O were obtained from Beijing Chemical Reagents Company (China). Potassium EDTA, BSA, OVA (grade V), complete freund adjuvant (CFA), hematoxylin and eosin were purchased from Sigma. RAW264.7 cell line was gained from American Type Culture Collection (ATCC). ELISA kit of OVA antibody

Preparation and characterization of silica nanoparticles

SNs, MSNs and SSNs had well monodispersion in 5% glucose solution (Fig.1A, C and D). Fig. 1B shows transmission electron microscopy images of the nanoparticles in glucose, and proteins (black arrow) can be seen bound to the surface of the particles. The average size of SNs and SNs–OVA were 166 ± 7.5 and 188.9 ± 12.5 nm by Zetasizer 3000HSA (Malvern) at 25 °C, respectively. The surface charges of tested silica nanoparticles were listed in Supporting information Table S1. The surface charges of SNs and

Conclusion

In conclusion, we investigated the possibility of SNs in protein vaccine adjuvant applications. SNs had high protein loading efficiency, stability and releasing performance. The toxicity results of SNs in vivo and in vitro also indicate that SNs was a kind of biomaterials with benign biocompatibility. We also proved that SN enhanced antibody level of OVA after single dose vaccination. Further studies for SNs clinical application are in progress to determine whether the novel nanotechnology can

Acknowledgments

The authors acknowledge financial support from the National Natural Science Foundation of China (NSFC) (Nos. 81201814, 81171454, 81000667, 30900349) and Beijing Nova Program (Z111103054511113).

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Silica nanorattle with enhanced protein loading: A potential vaccine adjuvant

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Materials

Preparation and characterization of silica nanoparticles

Conclusion

Acknowledgments

Vaccine

Vaccine

Vaccine

Vaccine

Eur. J. Cancer

Vaccine

Eur. J. Pharm. Sci.

Vaccine

Bioresour. Technol.

Angew. Chem. Int. Ed. Engl.

Biomaterials

Vaccine

J. Control Rel.

Expert Rev. Vaccines

Med. Res. Rev.

Nat. Immunol.

Hum. Vaccin

Immunology