A state-of-the-art review on solid lipid nanoparticles as a nanovaccines delivery system

In the design of vaccine generation, significant attempts have been made to produce novel vaccines and, as well, to increase the effectiveness of available vaccines versus particular diseases. Over the past few years, with nanovaccines, considerable attention has been paid to increasing vaccine effectiveness, immunization approaches, and targeted transfer to attain desirable immune reactions. Solid lipid nanoparticles (SLNs) are on the front line of the quickly advancing nanotechnology field with various powerful uses in the delivery of pharmaceutical, cosmetic active, and vaccine components, from small molecules to proteins and genes with different routes of administration. SLNs have become effective delivery techniques in vaccine generation. SLNs-based vaccines can increase site-specific transfer, antigen presentation, and triggering of innate immune reaction, strong T cell reaction, and harmlessness against infectious diseases, cancers, autoimmune diseases, and neurodegeneration. The present review will briefly explain the characteristics of SLNs and explore the other preparation methods and routes of administration, focusing on SLNs as a delivery system of the different vaccines.

Introduction

Vaccines produce immune reactions versus several pathogens and have also been used to fight tumors in cancer immunotherapy. Usually, they induce lasting cellular and humoral immune responses and elicit a reproduction of memory cells against subsequent infections or reinfection. Conventional entire pathogen vaccines may cause significant inflammation, allergies, and autoimmune reactions. These disadvantages of conventional vaccines have restricted their usage [1]. With the advance of nanotechnology, investigators are paying more attention to the development of nanoparticles (NPs) as hopeful vaccination techniques, not just because NPs have controlled attributes, including dimensions, zeta-potential, surface covering, and antigens encapsulation efficiency, but; as well because of several NPs activated immune reactions via site-specific transfer in target cells [[2], [3], [4]]. This basic information is beneficial in producing nanovaccines by utilizing various injection methods [5]. Nanovaccines contain NPs conjugated or encapsulated with ingredients that require an immune reaction. Nanovaccines have demonstrated the ability to control the immune responses to destroy infectious agents and prevent infections and diseases from progressing. Nanovaccines can have a significant action to play in reducing several diseases. Nanovaccines suggest various potential benefits, such as the targeted transfer of antigens, increased bioavailability of antigens, and a decreased adverse events profile [6,7]. They also increase their consistency in vitro and in vivo, and various mechanisms have been utilized to encapsulate antigens [8]. Lipid-based NPs, polymeric-based NPs, and inorganic NPs, including metal NPs and silica NPs, are used as delivery systems in nanovaccines [1,9]. In addition, this type of vaccine has several benefits over conventional without nano-delivery system (non-encapsulated peptide, DNA, and mRNA) and bioplatforms (DCs, viral, or bacterial vectors), including enhanced constancy, enhanced immunogenic peptides loading, targeted delivery, and improved patient compliance [10]. One of the critical problems in nanovaccine formulation has been the drawback in combining excessively plentiful adjuvants (including liposomes or poly (lactic-co-glycolic acid) (PLGA)), an infringement of the ‘minimalist’ basis. In addition, some nano-delivery systems produce unanticipated immune reactions, which significantly endanger remedial results [[11], [12], [13], [14]].

Over the years, lipids have been used as excipients in numerous pharmaceutical formulations, such as suppositories, ointments, and emulsions, and more recently, as raw materials for nanosized drug carriers. The emulsions are versatile systems that can deliver oil-soluble agents over various routes. They consist of dispersions of a liquid lipid material into an aqueous phase in the case of oil-in-water (O/W) emulsions. Still, drawbacks of these systems include rapid drug release, instability processes, and oxidation [15]. The term solid lipid nanoparticle (SLN) was proposed in the 1990s to harness the features of NPs and biodegradable lipid carriers [16]. SLNs, a substituted delivery method to liposomes and polymeric NPs, have engrossed enhancing consideration because of their biocompatibility, biodegradability, constancy, inexpensiveness, and easiness of wide-ranging production [17]. The capability of SLN to be generated on an industrial measure by high-pressure homogenization and spray drying methods, which have been utilized in a pharmaceutical company, is a vital benefit [18,19]. In addition, other essential features of SLNs are including high affinity at the intracellular membrane surface and in the intracellular space, allowing them to permeate the cells successfully [20]. SLNs for the delivery of proteins, nucleic acid (RNA/DNA), antigens, adjuvants, and hydrophilic and hydrophobic drugs have attracted attention [[21], [22], [23], [24]]. Researchers used SLNs to develop vaccines to prevent and treat infectious, oncological, autoimmune, and neurodegeneration diseases [25].

In the present paper, we investigated SLNs utilized for vaccine transfer and explained the development of SLNs nanovaccines in different diseases, containing the overcoming of physiological obstacles, several routes of injection, and preparation methods.

Excipients mentioned in the study besides other: Compritol 888 ATO, Imwitor 600

Marjan Assefi, Mehrnaz Ataeinaeini, Ahmad Nazari, Arsalan Gholipour, Jacinto Joaquin Vertiz-Osores, Kriss Melody Calla-Vásquez, Bashar Zuhair Talib Al-Naqeeb, Kadhim Hussein Jassim, Hesam Ghafouri Kalajahi, Saman Yasamineh, Mehdi Dadashpour, A state-of-the-art review on solid lipid nanoparticles as a nanovaccines delivery system, Journal of Drug Delivery Science and Technology, 2023, 104623, ISSN 1773-2247,
https://doi.org/10.1016/j.jddst.2023.104623.

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