BackgroundWith the increase in production and use of engineered nanoparticles (NP; ≤ 100 nm), safety concerns have risen about the potential health effects of occupational or environmental NP exposure. Results of animal toxicology studies suggest that inhalation of NP may cause pulmonary injury with subsequent acute or chronic inflammation. People with chronic respiratory diseases like asthma or allergic rhinitis may be even more susceptible to toxic effects of inhaled NP. Few studies, however, have investigated adverse effects of inhaled NP that may enhance the development of allergic airway disease.MethodsWe investigated the potential of polyethylene glycol coated amorphous silica NP (SNP; 90 nm diameter) to promote allergic airway disease when co-exposed during sensitization with an allergen. BALB/c mice were sensitized by intranasal instillation with 0.02% ovalbumin (OVA; allergen) or saline (control), and co-exposed to 0, 10, 100, or 400 μg of SNP. OVA-sensitized mice were then challenged intranasally with 0.5% OVA 14 and 15 days after sensitization, and all animals were sacrificed a day after the last OVA challenge. Blood and bronchoalveolar lavage fluid (BALF) were collected, and pulmonary tissue was processed for histopathology and biochemical and molecular analyses.ResultsCo-exposure to SNP during OVA sensitization caused a dose-dependent enhancement of allergic airway disease upon challenge with OVA alone. This adjuvant-like effect was manifested by significantly greater OVA-specific serum IgE, airway eosinophil infiltration, mucous cell metaplasia, and Th2 and Th17 cytokine gene and protein expression, as compared to mice that were sensitized to OVA without SNP. In saline controls, SNP exposure did cause a moderate increase in airway neutrophils at the highest doses.ConclusionsThese results suggest that airway exposure to engineered SNP could enhance allergen sensitization and foster greater manifestation of allergic airway disease upon secondary allergen exposures. Whereas SNP caused innate immune responses at high doses in non-allergic mice, the adjuvant effects of SNP were found at lower doses in allergic mice and were Th2/Th17 related. In conclusion, these findings in mice suggest that individuals exposed to SNP might be more prone to manifest allergic airway disease, due to adjuvant-like properties of SNP.

Epoxy resins are ubiquitous in high-performance composite applications because of their excellent mechanical strength, thermal and chemical resistance, strong adhesion, and low shrinkage after curing. Bio-based epoxy resins derived from natural products such as carbohydrates offer tremendous potential for creating new polymeric materials. Sugars and their derivatives often offer great biodegradability and functionality such as the presence of multiple hydroxyl groups that impart highly cross-linked polymer networks. Moreover, their ring structures can afford polymers with high glass transition temperatures. To develop epoxy resins containing sustainably sourced feedstocks, we designed and synthesized trehalose-and β-cyclodextrin-based carboxylic acid hardeners for epoxy resins and examined the thermal, mechanical, and adhesive properties of the resulting materials. Trehalose and β-cyclodextrin were succinylated with excess succinic anhydride, and the resulting carboxylic acid hardeners formed homogeneous mixtures with trimethylolpropane triglycidyl ether (TTE) in different carboxyl−epoxide ratios. The cured resins were found to be thermally stable (T d5 > 300 °C) and display high Young's moduli of up to 1.4 and 1.8 GPa with mechanical strengths of 47 and 64 MPa for the trehalose-and β-cyclodextrin-based epoxy resins, respectively. Preliminary adhesion tests showed that the cured resins exhibit excellent lap-shear strengths of 3600 and 2100 psi, respectively. The resins were also degradable into water-soluble components in both aqueous acidic and basic solutions but were relatively stable from hydrolysis in neutral aqueous conditions. These results imply that this novel class of hardeners are promising feedstocks for renewable high performance epoxy resins.

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A new class of clickable and biodegradable polylactide was designed and prepared via bulk polymerization of 3,6-dipropargyloxymethyl-1,4-dioxane-2,5-dione (1) which was synthesized from easily accessible propargyloxylactic acid (5). A homopolymer of 1 and random copolymer of 1 with l-lactide were obtained as amorphous materials and exhibit low Tg of 8.5 and 34 °C, respectively, indicating their promising potentials for biomedical applications. The statistical nature of random copolymers was investigated by DSC analysis and 13C NMR spectroscopy, which implies the random distribution of terminal alkyne groups along the back bone of copolymers. The efficient click post-modification of this new class of polylactide with alkyl and mPEG azides affords novel hydrophilic biomaterials, which exhibit reversible thermo-responsive properties as evidenced by their tunable LCST ranging from 22 to 69 °C depending on the balance of the incorporated hydrophilic/hydrophobic side chains. These results indicate the generality of this new class of clickable polylactide in preparing novel smart biomaterials in a simple and efficient manner via click chemistry.