A novel method has been developed to prepare amphiphilic core-shell polymer nanospheres via graft copolymerizations of methyl methacrylate (MMA) from water-soluble polymer chains containing amino groups. Thus, amine-substituted biopolymers and synthetic polymers are treated with a small amount of tert-butyl hydroperoxide (TBHP, 0.08 mM) in water at 80 °C to generate free radicals on the amine nitrogens, which subsequently initiate the graft copolymerization of MMA. tert-Butoxy radicals are also generated that either initiate the homopolymerization of MMA or abstract hydrogen from the polymer backbones. The amphiphilic macroradicals generated in situ self-assemble to form polymeric micelle-like microdomains, which promote the emulsion polymerization of the monomer. Thus, well-defined, amphiphilic core-shell nanospheres, which range from 60 to 160 nm in diameter, are produced in the absence of surfactant. The conversion and grafting efficiency of the monomer strongly depend on the TBHP concentration and the structure of the amino-containing water-soluble polymer. Polymers containing primary amine groups are considerably more effective than those containing secondary or tertiary groups, while ammonium cations do not induce the polymerization. The particle size and stability strongly depend on the structure and molecular weight of the hydrophilic polymer, as well as the pH of the mixture. Transmission electron microscopic (TEM) images of the particles clearly show well-defined core-shell morphologies where PMMA cores are coated with hydrophilic polymer shells. The amphiphilic core-shell nanospheres can be produced in high concentrations (up to 22% solids content). This new method is scientifically and technologically significant because it provides a commercially viable route to a wide variety of novel amphiphilic coreshell nanospheres.

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Mucosal immunity plays a significant role in host defense against viruses in the respiratory tract. Because the upper respiratory airway is a primary site of SARS-CoV-2 entry, immunization at the mucosa via the intranasal route could potentially lead to induction of local sterilizing immunity that protects against SARS-CoV-2 infection. In this study, we evaluated the immunogenicity of a receptor-binding domain (RBD) of SARS-CoV-2 spike glycoprotein loaded into N,N,N-trimethyl chitosan nanoparticles (RBD-TMC NPs). We showed that intranasal delivery of RBD-TMC NPs into mice induced robust local mucosal immunity, as evidenced by the presence of IgG and IgA responses in BALs and the lungs of immunized mice. Furthermore, mice intranasally administered with this platform of immunogens developed robust systemic antibody responses including serum IgG, IgG1, IgG2a, IgA and neutralizing antibodies. In addition, these immunized mice had significantly higher levels of activated splenic CD4+ and CD8+ cells compared with those that were administered with soluble RBD immunogen. Collectively, these findings shed light on an alternative route of vaccination that mimics the natural route of SARS-CoV-2 infection. This route of administration stimulated not only local mucosal responses but also the systemic compartment of the immune system.

H-acceptor sites, which are able to form intra-molecular reversible hydrogen bonds (globule conformation below UCST) and inter-molecular bonds with water (coil conformation above UCST). [11][12][13][14][15][16][17][18][19][20][21] The non-ionic polymers have attracted a great deal of attention due to their insensitivity to salts, which make them more attractive for applications in physiological environment. [22][23][24] During the last decade, efforts have been focused toward developing novel water-soluble copolymers exhibiting UCST behavior by copolymerizing H-donor monomers (N-acryloyl glycinamide [11][12][13][14][15][16] or acrylamide [15,[17][18][19][20][21]25] ) and H-acceptor monomers (acrylonitrile, [11,15,18,19,21,25,26] styrene, [15,17] and butyl acrylate [15] ). Such (co)polymers have been mainly prepared using free radical polymerization [11,[14][15][16][17]26] and by thermally initiated controlled radical polymerization such as atom transfer radical polymerization [13] and reversible addition fragmentation chain transfer (RAFT) [11,12,[16][17][18][19]25] The impacts of various parameters on the UCST phase transition, including salts, pH, molecular weight, molecular weight distribution, and chemical composition, have been well evaluated. [7][8][9]25,27] However, such studies were carried out at low polymer concentrations (below 5 wt%). This could induce, an unintentional confusion between the UCST and the apparent cloud point temperature (T CP ), which refers to the temperature at which the phase transition occurs depending on the investigated concentration level. The UCST of a given polymer in solution is obtained from an isobaric phase diagram where T CP are plotted versus the polymer concentrations. [7][8][9] T CP should increase with the polymer concentrations up to a maximum temperature, called UCST, before going down again.In this context, we envisioned to use aqueous photo-mediated RAFT (photo-RAFT) polymerization that would be able to prepare well-controlled UCST-type copolymers directly in water at very high concentration. Although photo-RAFT [28][29][30][31][32][33] has grasped great interests due to its versatility, rapidity, and ability to produce well-controlled polymers, it has never been employed for the synthesis of UCST-type polymers. This study provides new insight into UCST-type copolymers and aims to develop facile approach to investigate such kind of thermoresponsive behavior, less described in the literature currently.

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In this study, we developed and investigated nanoparticles of biologically-derived, biodegradable polyhydroxyalkanoates (PHAs) as carriers of a hydrophobic photosensitizer, 5,10,15,20-Tetrakis(4-hydroxy-phenyl)-21H, 23H-porphine (pTHPP) for photodynamic therapy (PDT). Three PHA variants; polyhydroxybutyrate, poly(hydroxybutyrate-co-hydroxyvalerate) or P(HB-HV) with 12 and 50% HV were used to formulate pTHPP-loaded PHA nanoparticles by an emulsification-diffusion method, where we compared two different poly(vinyl alcohol) (PVA) stabilizers. The nanoparticles exhibited nano-scale spherical morphology under TEM and hydrodynamic diameters ranging from 169.0 to 211.2 nm with narrow size distribution. The amount of drug loaded and the drug entrapment efficiency were also investigated. The in vitro photocytotoxicity was evaluated using human colon adenocarcinoma cell line HT-29 and revealed time and concentration dependent cell death, consistent with a gradual release pattern of pTHPP over 24 h. This study is the first demonstration using bacterially derived P(HB-HV) copolymers for nanoparticle delivery of a hydrophobic photosensitizer drug and their potential application in PDT.

Dengue viruses (DENVs) are among the most rapidly and efficiently spreading arboviruses. WHO recently estimated that about half of the world’s population is now at risk for DENV infection. There is no specific treatment or vaccine available to treat or prevent DENV infections. Here, we report the development of a novel dengue nanovaccine (DNV) composed of UV-inactivated DENV-2 (UVI-DENV) and Mycobacterium bovis Bacillus Calmette-Guerin cell wall components (BCG-CWCs) loaded into chitosan nanoparticles (CS-NPs). CS-NPs were prepared by an emulsion polymerization method prior to loading of the BCG-CWCs and UVI-DENV components. Using a scanning electron microscope and a zetasizer, DNV was determined to be of spherical shape with a diameter of 372.0 ± 11.2 nm in average and cationic surface properties. The loading efficacies of BCG-CWCs and UVI-DENV into the CS-NPs and BCG-CS-NPs were up to 97.2 and 98.4%, respectively. THP-1 cellular uptake of UVI-DENV present in the DNV was higher than soluble UVI-DENV alone. DNV stimulation of immature dendritic cells (iDCs) resulted in a significantly higher expression of DCs maturation markers (CD80, CD86 and HLA-DR) and induction of various cytokine and chemokine productions than in UVI-DENV-treated iDCs, suggesting a potential use of BCG- CS-NPs as adjuvant and delivery system for dengue vaccines.

This study aimed to examine the shear bond strength between cobalt chromium alloy and autopolymerizing acrylic resin using experimental primers containing 5, 10, and 15 wt% of 4-methacryloxyethyl trimellitic anhydride or 1, 2, and 3 wt% of 3-methacryloxypropyl-trimethoxysilane comparison to 5 commercial primers (ML primers, Alloy primer, Metal/Zirconia primer, Monobond S, and Monobond plus). Sixty alloy specimens were sandblasted and treated with each primer before bonded with an acrylic resin. The control group was not primed. The shear bond strengths were tested and statistically compared. Specimens treated with commercial primers significantly increased the shear bond strength of acrylic resin to cobalt chromium alloy (p<0.05). The highest shear bond strength was found in the Alloy primer group. Among experimental group, using 10 wt% of 4-methacryloxyethyl trimellitic anhydride -or 2 wt% of 3-methacryloxypropyltrimethoxysilane enhanced highest shear bond strength. The experimental and commercial primers in this study all improved bonding of acrylic resin to cobalt chromium alloy.