Subunit vaccination benefits from improved safety over attenuated or inactivated vaccines, but their limited capability to elicit long-lasting, concerted cellular and humoral immune responses is a major challenge. Recent studies have demonstrated that antigen delivery via nanoparticle formulations significantly improve immunogenicity of vaccines due to either intrinsic immunostimulatory properties of the materials or by co-entrapment of molecular adjuvants such as Toll-like receptor agonists. These studies have collectively shown that nanoparticles designed to mimic biophysical and biochemical cues of pathogens offer new exciting opportunities to enhance activation of innate immunity and elicit potent cellular and humoral immunity with minimal cytotoxicity. In this review, we present key research advances that were made within the last 5 years in the field of nanoparticle vaccine delivery systems. In particular, we focus on the impact of biomaterials composition, size, and surface charge of nanoparticles on modulation of particle biodistribution, delivery of antigens and immunostimulatory molecules, trafficking and targeting of antigen presenting cells, and overall immune responses in systemic and mucosal tissues. This review describes recent progresses in the design of nanoparticle vaccine delivery carriers, including liposomes, lipid-based particles, micelles and nanostructures composed of natural or synthetic polymers, and lipid-polymer hybrid nanoparticles.

Here we report the development of a new cationic liposome-hyaluronic acid (HA) hybrid nanoparticle (NP) system and present our characterization of these NPs as an intranasal vaccine platform using a model antigen and F1-V, a candidate recombinant antigen for Yersinia pestis, the causative agent of plague. Incubation of cationic liposomes composed of DOTAP and DOPE with anionic HA biopolymer led to efficient ionic complexation and formation of homogenous liposome-polymer hybrid NPs, as evidenced by fluorescence resonance energy transfer, dynamic light scattering, and nanoparticle tracking analyses. Incorporation of cationic liposomes with thiolated HA allowed for facile surface decoration of NPs with thiol-PEG, resulting in the formation of DOTAP/HA core-PEG shell nanostructures. These NPs, termed DOTAP-HA NPs, exhibited improved colloidal stability and prolonged antigen release. In addition, cytotoxicity associated with DOTAP liposomes (LC50 ~0.2 mg/ml) was significantly reduced by at least 20-fold with DOTAP-HA NPs (LC50 > 4 mg/ml), as measured with bone marrow dendritic cells (BMDCs). Furthermore, NPs co-loaded with ovalbumin (OVA) and a molecular adjuvant, monophosphoryl lipid A (MPLA) promoted BMDC maturation and upregulation of co-stimulatory markers, including CD40, CD86, and MHC-II, and C57BL/6 mice vaccinated with NPs via intranasal route generated robust OVA-specific CD8+ T cell and antibody responses. Importantly, intranasal vaccination with NPs co-loaded with F1-V and MPLA induced potent humoral immune responses with 11-, 23-, and 15-fold increases in F1-V-specific total IgG, IgG1, and IgG2c titers in immune sera by day 77, respectively, and induced balanced Th1/Th2 humoral immune responses, compared with the lack of sero-conversion in mice immunized with the equivalent doses of soluble F1-V vaccine. Overall, these results suggest that liposome-polymer hybrid NPs may serve as a promising vaccine delivery platform for intranasal vaccination against Y. pestis and other infectious pathogens.

The study demonstrates that the physicochemical properties of dendrimers influence their skin transport. Findings can be used to design dendrimer-based nanocarriers for drug delivery to skin.

The study was aimed at investigating localized topical drug delivery to the breast via mammary papilla (nipple). 5-fluorouracil (5-FU) and estradiol (EST) were used as model hydrophilic and hydrophobic compounds respectively. Porcine and human nipple were used for in-vitro penetration studies. The removal of keratin plug enhanced the drug transport through the nipple. The drug penetration was significantly higher through the nipple compared to breast skin. The drug’s lipophilicity had a significant influence on drug penetration through nipple. The ducts in the nipple served as a major transport pathway to the underlying breast tissue. Results showed that porcine nipple could be a potential model for human nipple. The topical application of 5-FU on the rat nipple resulted in high drug concentration in the breast and minimal drug levels in plasma and other organs. Overall, the findings from this study demonstrate the feasibility of localized drug delivery to the breast through nipple.