In situ bio-mineralized Mn nanoadjuvant enhances anti-influenza immunity of recombinant virus-like particle vaccines.

Virus like particles (VLPs) have been well recognized as one of the most important vaccine platforms due to their structural similarity to natural viruses to induce effective humoral and cellular immune responses. Nevertheless, lack of viral nucleic acids in VLPs usually leads the vaccine candidates less efficient in provoking innate immune against viral infection. Here, we constructed a biomimetic dual antigen hybrid influenza nanovaccines THM-HA@Mn with robust immunogenicity via in situ synthesizing a stimulator of interferon genes (STING) agonist Mn3O4 inside the cavity of a recombinant Hepatitis B core antigen VLP (HBc VLP) having fused SpyTag and influenza M2e antigen peptides (Tag-HBc-M2e, THM for short), followed by conjugating a recombinant hemagglutinin (rHA) antigen on the surface of the nanoparticles through SpyTag/SpyCatcher ligating. Such inside Mn3O4 immunostimulator-outside rHA antigen design, together with the chimeric M2e antigen on the HBc skeleton, enabled the synthesized hybrid nanovaccines THM-HA@Mn to well imitate the spatial distribution of M2e/HA antigens and immunostimulant in natural influenza virus. In vitro cellular experiments indicated that compared with the THM-HA antigen without Mn3O4 and a mixture vaccine consisting of THM-HA + MnOx, the THM-HA@Mn hybrid nanovaccines showed the highest efficacies in dendritic cells uptake and in promoting BMDC maturation, as well as inducing expression of TNF-α and type I interferon IFN-ß. The THM-HA@Mn also displayed the most sustained antigen release at the injection site, the highest efficacies in promoting the DC maturation in lymph nodes and germinal center B cells activation in the spleen of the immunized mice. The co-delivery of immunostimulant and antigens enabled the THM-HA@Mn nanovaccines to induce the highest systemic antigen-specific antibody responses and cellular immunogenicity in mice. Together with the excellent colloid dispersion stability, low cytotoxicity, as well as good biosafety, the synthetic hybrid nanovaccines presented in this study offers a promising strategy to design VLP-based vaccine with robust natural and adaptive immunogenicity against emerging viral pathogens.

Oil-in-ionic liquid nanoemulsion-based adjuvant simultaneously enhances the stability and immune responses of inactivated foot-and-mouth disease virus.

Maintaining structural integrity and enhancing stability of inactivated foot-and-mouth disease virus (iFMDV) antigen in adjuvants is crucial to ensure the vaccine potency. Unfortunately, formulation with most reported adjuvants leads to the accelerated dissociation of iFMDV into inactive pentamers. Here, an ionic liquid, i.e., choline and niacin ([Cho][Nic]), which was found to stabilize iFMDV against the acid- and thermo- induced dissociation in buffer solution, was applied to construct a novel oil-in-ionic liquid (o/IL) nanoemulsion adjuvant composed of [Cho][Nic], squalene, and Tween 80. The o/IL nanoemulsion formulated with iFMDV has a monodisperse diameter of 135.8 ± 40.4 nm. The thermostability and long-term stability of iFMDV were remarkably enhanced in o/IL nanoemulsion compared with that in the o/w emulsion without [Cho][Nic] and in the commercial Montanide ISA 206 adjuvant. The o/IL nanoemulsion exerted its adjuvant effects by improving the humoral immune responses. Immunization of o/IL nanoemulsion adjuvanted iFMDV induced specific IgG titers similar to that adjuvanted by Montanide ISA 206 and about 4-fold higher than the un-adjuvanted iFMDV, also promoted the activation of B lymphocytes and the secretion of interleukin-4 in the mice model. This [Cho][Nic]-based o/IL nanoemulsion can serve as a promising adjuvant platform for the foot-and-mouth disease vaccine.

Oil-in-ionic liquid nanoemulsion-based intranasal delivery system for influenza split-virus vaccine.

Effective antigen delivery and immune stimulation in nasal mucosa determine the success of mucosal immunity. Here, an oil-in-ionic liquid (o/IL) nanoemulsion formulated with choline and niacin IL ([Cho][Nic]), squalene, and Tween 80 surfactant is explored as a vaccine delivery system for intranasal mucosal immunization. Compared to the o/w emulsion counterpart without the ILs, the o/IL manoemulsion showed a reduced and more uniform size of approximately 168 nm and significantly improved stability. Studies in mice model showed that when was used as an intranasal vaccine delivery system for influenza split-virus antigens, the antigens in the o/IL nanoemulsion induced strong mucosal immune responses with secretory IgA titers 25- and 5.8-fold higher than those of naked and commercial MF59-adjuvanted antigens, respectively. The o/IL nanoemulsion system also induced stronger systemic humoral responses. The excellent mucosal adjuvant effects of the o/IL nanoemulsion mainly benefited from the prolonged retention of antigens in the nasal cavity, enhanced antigen permeation into the submucosa, and the consequently promoted proliferation of CD11b cells and CD4+ T cells in nasal mucosa-associated lymphoid tissue. Moreover, when used as an injection adjuvant, the o/IL nanoemulsion also induced stronger humoral immune responses than MF59. Thus, the [Cho][Nic]-based o/IL nanoemulsion vaccine delivery system can serve as a promising adjuvant platform.

Synthesis of red/black phosphorus-based composite nanosheets with a Z-scheme heterostructure for high-performance cancer phototherapy.

Two dimensional black phosphorus nanosheets (BP NSs) have attracted plenty of attention in the research field of cancer photonic therapy. However, the poor stability and relatively low efficiency of reactive oxygen species (ROS) generation of BP NSs limit their practical application. To address these drawbacks, herein we report a red/black phosphorus (RP/BP) composite nanosheet, M-RP/BP@ZnFe2O4, which was synthesized by (1) partially converting red phosphorus (RP) to black phosphorus (BP) followed by liquid-phase ultrasonic exfoliation to form RP/BP NSs, (2) in situ synthesis of ZnFe2O4 nanoparticles on the surface of RP/BP NSs, (3) and wrapping with the MCF-7 cell membrane. Due to the presence of RP, BP, ZnFe2O4 and the cell membrane, the M-RP/BP@ZnFe2O4 NSs exhibited high performance in cancer phototherapy with the following features: (i) a Z-scheme heterojunction structure was formed between RP/BP NSs thus enabling high separation efficiency of the photogenerated electrons and holes; (ii) the photoexcitation holes in the valence band of RP can break the tumor microenvironment by oxidizing glutathione; (iii) the NSs could decompose water to produce H2O2 and O2, which can be further converted to toxic ˙OH through the ZnFe2O4 catalyzed Fenton reaction and 1O2 through energy transfer, respectively; and (iv) the cell membrane wrapping improved the targeting of the composite NSs at the tumor site and photonic therapy can be finally triggered by a 660 nm laser to convert O2 to ˙O2- and 1O2. The in vitro cytotoxicity experiments showed that more than 90% cells were killed after photodynamic therapy (PDT) at 0.3 mg mL-1 M-RP/BP@ZnFe2O4 NSs, and the animal experiments with xenograft tumor model mice indicated that tumor growth was completely inhibited and the highest survival rate of 83.3% at 60 days post PDT was obtained.

Thermal-triggered packing of lipophilic NIR dye IR780 in hepatitis B core at critical ionic strength and cargo-host ratio for improved stability and enhanced cancer phototherapy.

Virus-like particles (VLPs) holding internal cavity with diameter from tens up to one hundred nanometers are attractive platform for drug delivery. Nevertheless, the packing of drugs in the nanocage mainly relies on complicated disassembly-reassembly process. In this study, hepatitis B core protein (HBc) VLPs which can withstand temperature up to 90 °C was employed as carrier to load a lipophilic near infrared dye IR780. It was found that an attaching-dis-atching-diffusing process was involved for the entering of IR780 in the cavity of HBc. The first two steps were associated with the electrostatic interactions between oppositely charged HBc and IR780, which was critically manipulated by ionic strength and HBc/IR780 mass ratio at which they were mixed; while the diffusion of IR780 across the shell of HBc showed a temperature-dependent manner that can be triggered by thermal induced pore-opening of the HBc capsid. At optimized condition, about 1055 IR780 molecules were encapsulated in each HBc by simply mixing them for 10 min at 60 °C. Compared with free IR780, the HBc-IR780 particles showed significantly improved aqueous and photostability, as well as enhanced photothermal and photodynamic performance for cancer therapy. This study provides a novel drug loading strategy and nanomemedicine for cancer phototherapies.

Black phosphorus quantum dots encapsulated in anionic waterborne polyurethane nanoparticles for enhancing stability and reactive oxygen species generation for cancer PDT/PTT therapy.

Black phosphorus quantum dots (BPQDs) with excellent biocompatibility, outstanding photothermal and photodynamic efficacies have attracted significant attention in cancer therapy. However, the low environmental stability and poor dispersity of BPQDs limit their practical applications. In the present work, biocompatible anionic waterborne polyurethane (WPU) nanoparticles were synthesized from castor oil to encapsulate the BPQDs. The WPU-BPQDs with a BPQDs loading capacity of about 13.8% (w/w) exhibited significantly improved dispersion and environmental stability without affecting the photothermal efficiency of BPQDs. Intriguingly, it was found that WPU encapsulation led to significant enhancement in the reactive oxygen species (ROS) generation of BPQDs, which indicated the enhanced photodynamic efficacy of the encapsulated BPQDs as compared to the bare BPQDs. The effect of solution pH on the ROS generation efficiency of BPQDs and the pH variation caused by BPQDs degradation was then investigated to explore the possible mechanism. In acidic solution, ROS generation was suppressed, while BPQDs degradation led to the acidification of the solution. Fortunately, after being encapsulated inside the WPU nanoparticles, the degradation rate of BPQDs became slower, while the acidic environment around BPQDs was favorably regulated by WPU nanoparticles having a special electrochemical double layer consisting of interior COO- and exterior NH(Et3)+, thus endowing the WPU-BPQDs-boosted production of ROS as compared to the bare BPQDs. Considering the undesired acidic tumor environment, this unique pH regulation effect of WPU-BPQDs would be beneficial for in vivo photodynamic efficacy. Both in vitro and in vivo experiments showed that WPU-BPQDs could effectively improve photodynamic therapy (PDT) and maintain outstanding photothermal therapy (PTT) effects. Together with the excellent dispersity, biocompatibility, and easy biodegradability, WPU-BPQDs can be a promising agent for PDT/PTT cancer treatments.

A Novel Particulate Delivery System Based on Antigen-Zn2+ Coordination Interactions Enhances Stability and Cellular Immune Response of Inactivated Foot and Mouth Disease Virus.

The interactions between antigen and adjuvant were among the most significant factors influencing the immunogenicity of vaccines, especially for unstable antigens like inactivated foot and mouth disease virus (iFMDV). Here we propose a novel antigen delivery pattern based on the coordination interaction between transition metal ions Zn2+ chelated to chitosan nanoparticles and iFMDV, which is known to be rich in histidine. The zinc chelated chitosan particles (CP-PEI-Zn) were prepared by cross-linking chitosan particles (CP) with sodium tripolyphosphate (TPP), modifying with metal chelator polyethylenimine (PEI), and subsequent chelating of Zn2+. The coordination interaction was confirmed by analyzing the adsorption and desorption behavior of iFMDV on CP-PEI-Zn by high-performance size exclusion chromatography (HPSEC), while the CP-PEI without chelating Zn2+ loads iFMDV mainly through electrostatic interactions. The iFMDV loaded on CP-PEI-Zn showed better thermal stability than that on CP-PEI, as revealed by a slightly higher transition temperature (Tm) related to iFMDV dissociation. After subcutaneous immunization in female Balb/C mice, antigens loaded on CP-PEI and CP-PEI-Zn all induced higher specific antibody titers, better activation of B lymphocytes, and more effector-memory T cells proliferation than the free antigen and iFMDV adjuvanted with ISA 206 emulsion did. Moreover, CP-PEI-Zn showed superior efficacy to CP-PEI in promoting the proliferation of effector-memory T cells and secretion of cytokines, indicating a more potent cellular immune response. In summary, the CP-PEI-Zn stabilized the iFMDV after loading and promoted both humoral and cellular immune responses, thus reflecting its potential to be a promising adjuvant for the iFMDV vaccine and other unstable viral antigens.

Boron-based nanosheets for combined cancer photothermal and photodynamic therapy.

Tumor phototherapy is of great significance for the expansion and advancement of cancer treatment methods. Herein, two-dimensional boron nanosheets (B NSs) with a thickness of 2.4 nm exhibiting an excellent photothermal conversion performance were developed via a simple liquid phase ultrasonic stripping method. Following the loading of the photosensitizer agent chlorin e6 (Ce6) and subsequent modification with poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA), a B@Ce6-PAH-PAA NS nanomedicine exhibiting dual modal imaging-guided cancer photothermal therapy (PTT) and photodynamic therapy (PDT) properties, as well as outstanding stability was developed. The suitable nano-size (120 nm) of B@Ce6-PAH-PAA NSs can allow drugs to target tumor tissue with an enhanced permeability and retention effect (EPR). The cytotoxicity experiments demonstrated that B@Ce6-PAH-PAA NSs exhibited good biocompatibility even at high concentrations. Furthermore, the in vitro and in vivo experiments showed the excellent synergistic therapeutic effect of this nanomedicine for PTT and PDT.

Vegetable-oil-based polymers as future polymeric biomaterials.

Vegetable oils are one of the most important classes of bio-resources for producing polymeric materials. The main components of vegetable oils are triglycerides - esters of glycerol with three fatty acids. Several highly reactive sites including double bonds, allylic positions and the ester groups are present in triglycerides from which a great variety of polymers with different structures and functionalities can be prepared. Vegetable-oil-based polyurethane, polyester, polyether and polyolefin are the four most important classes of polymers, many of which have excellent biocompatibilities and unique properties including shape memory. In view of these characteristics, vegetable-oil-based polymers play an important role in biomaterials and have attracted increasing attention from the polymer community. Here we comprehensively review recent developments in the preparation of vegetable-oil-based polyurethane, polyester, polyether and polyolefin, all of which have potential applications as biomaterials.