Freestanding substrates with high refractive index modulation, good oxygen resistance, and low volume shrinkage are critical in photolithography for the purpose of high density data storage, image ...patterning and anticounterfeiting. Herein, we demonstrate a novel paradigm of direct holographic image patterning via the radical-mediated thiol–yne click reaction subsequent to the base-catalyzed thiol-Michael addition reaction. With the benefit of a newly synthesized alkyne monomer, 9-(2-((2-(prop-2-yn-1-yloxy)ethyl)thio)ethyl)-9H-carbazole (POETEC), holograms with as high as 96% diffraction efficiency, refractive index modulation of 0.0036, dynamic range of 5.6 per 200 μm and volume shrinkage of 1.1%, are successfully patterned in an aerobic environment. Uniquely and distinctly, an inhibitor is unnecessary to prevent the initiation of the sequential reaction in this framework.
A new group of nitrogen-centered nucleophilic catalysts for the thiol-Michael addition “click” reactions is examined. These nucleophiles showed efficient catalytic activities as compared with ...traditional base catalysts, such as triethylamine, and are demonstrated to be a viable strategy for cross-linking polymerization reactions. Additionally, an experimental and computational mechanistic study was performed, suggesting a pathway for the nitrogen-centered catalyst to undergo the nucleophilic addition mechanism.
BACKGROUND:Despite recent advances, infection remains the most common etiology of arthroplasty failure. Recent work suggests that 25-hydroxyvitamin D (25D) deficiency correlates with the frequency of ...periprosthetic joint infection (PJI). We endeavored to examine whether 25D3 deficiency leads to increased bacterial burden in vivo in an established mouse model of PJI and, if so, whether this effect can be reversed by preoperative 25D3 supplementation.
METHODS:Mice (lys-EGFP) possessing fluorescent neutrophils were fed a vitamin D3-sufficient (n = 20) or deficient (n = 40) diet for 6 weeks. A group of 25D3-deficient mice (n = 20) were “rescued” with 1 intraperitoneal dose of 25D3 at 3 days before surgery. A stainless steel implant was inserted into the knee joint and the joint space was inoculated with bioluminescent Staphylococcus aureus (1 × 10 colony forming units CFUs). In vivo imaging was used to monitor bacterial burden and neutrophil infiltration. Blood was drawn to confirm 25D3 levels 3 days before surgery and on postoperative days (PODs) 0 and 14. Mice were killed at POD 21, and CFUs were quantified after culture. Myeloperoxidase (MPO) and β-N-acetylglucosaminidase (NAG) were assayed to look at neutrophil infiltration and activated tissue macrophage recruitment, respectively.
RESULTS:Serum values confirmed 25D3 deficiency and repletion of the 25D3-rescued group. Bacterial bioluminescence and neutrophil fluorescence were significantly greater (p < 0.05) in the 25D3-deficient group. CFU counts from the joint tissue and implant were also significantly greater in this group (p < 0.05). Rescue treatment significantly decreased bacterial burden and neutrophil infiltration (p < 0.05). Compared with the 25D3-sufficient and 25D3-rescued groups, MPO activity was higher (p < 0.02) and NAG activity was lower (p < 0.03) in the 25D3-deficient group.
CONCLUSIONS:This study demonstrated in vivo in a mouse model of PJI that (1) 25D3 deficiency results in increased bacterial burden and neutrophil infiltration, and (2) this effect can be reversed with preoperative repletion of 25D3.
CLINICAL RELEVANCE:Considering that >65% of patients undergoing arthroplasty have insufficient or low levels of total 25D and that 25D levels can be replenished with ease using a U.S. Food and Drug Administration (FDA)-approved, oral 25D3 product, 25D deficiency may be an important modifiable risk factor in humans undergoing joint replacement.
STUDY DESIGN.A controlled, interventional animal study.
OBJECTIVE.Spinal implant infection (SII) is a devastating complication. The objective of this study was to evaluate the efficacy of a novel ...implant coating that has both a passive antibiotic elution and an active-release mechanism triggered in the presence of bacteria, using an in vivo mouse model of SII.
SUMMARY OF BACKGROUND DATA.Current methods to minimize the frequency of SII include local antibiotic therapy (vancomycin powder), betadine irrigation, silver nanoparticles, and passive release from antibiotic-loaded poly(methyl methacrylate) cement beads, all of which have notable weaknesses. A novel implant coating has been developed to address some of these limitations but has not been tested in the environment of a SII.
METHODS.A biodegradable coating using branched poly(ethylene glycol)-poly(propylene sulfide) (PEG-PPS) polymer was designed to deliver antibiotics. The in vivo performance of this coating was tested in the delivery of either vancomycin or tigecycline in a previously established mouse model of SII. Noninvasive bioluminescence imaging was used to quantify the bacterial burden, and implant sonication was used to determine bacterial colony-forming units (CFUs) from the implant and surrounding bone and soft tissue.
RESULTS.The PEG-PPS-vancomycin coating significantly lowered the infection burden from postoperative day 3 onwards (P < 0.05), whereas PEG-PPS-tigecycline only decreased the infection on postoperative day 5 to 10 (P < 0.05). CFUs were lower on PEG-PPS-vancomycin pins than PEG-PPS-tigecycline and PEG-PPS pins alone on both the implants (2.4 × 10, 8.5 × 10, and 1.0 × 10 CFUs, respectively) and surrounding bone and soft tissue (1.3 × 10, 4.8 × 10, and 5.4 × 10 CFUs, respectively) (P < 0.05).
CONCLUSION.The biodegradable PEG-PPS coating demonstrates promise in decreasing bacterial burden and preventing SII. The vancomycin coating outperformed the tigecycline coating in this model compared to prior work in arthroplasty models, highlighting the uniqueness of the paraspinal infection microenvironment.Level of EvidenceN/A
Combinations of rare earth doped upconverting nanoparticles (UCNPs) and gold nanostructures are sought as nanoscale theranostics due to their ability to convert near infrared (NIR) photons into ...visible light and heat, respectively. However, because the large NIR absorption cross-section of the gold coupled with their thermo-optical properties can significantly hamper the photoluminescence of UCNPs, methods to optimize the ratio of gold nanostructures to UCNPs must be developed and studied. We demonstrate here nucleic acid assembly methods to conjugate spherical gold nanoparticles (AuNPs) and gold nanostars (AuNSs) to silica-coated UCNPs and probe the effect on photoluminescence. These studies showed that while UCNP fluorescence enhancement was observed from the AuNPs conjugated UCNPs, AuNSs tended to quench fluorescence. However, conjugating lower ratios of AuNSs to UCNPs led to reduced quenching. Simulation studies both confirmed the experimental results and demonstrated that the orientation and distance of the UCNP with respect to the core and arms of the gold nanostructures played a significant role in PL. In addition, the AuNS-UCNP assemblies were able to cause rapid gains in temperature of the surrounding medium enabling their potential use as a photoimaging-photodynamic-photothermal agent.
The correlation between P-glycoprotein (Pgp) overexpression and multidrug resistance (MDR) in cancer is well-established. Recently, we identified (2-(4-methoxyphenyl)-4-quinolinyl) ...(2-piperidinyl)methanol (5) (NSC23925) as the most selective and potent MDR inhibitor. NSC23925 binds to Pgp, thus inhibiting its transporter function and reversing MDR in cancer cells. In order to further characterize the chemical properties and Pgp binding mode of the NSC23925 compound, we grew four NSC23925 crystal isomers (NSC23925a, NSC23925b, NSC23925c, and NSC23925d). These crystal isomers were first generated using a vapor diffusion growth technique before their precise structures were analyzed using X-ray crystallography. Functionally, the NSC23925a and NSC23925b isomers share a similar stabilization interaction of Cl− mediated hydrogen bonding. In contrast, in isomer NSC23925c, two Cl− are involved in the stabilization of adjacent molecules. In summary, these solved crystal structures may reveal the different activities of the four NSC23925 stereoisomers.
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•Four NSC23925 crystal isomers were first generated using a vapor diffusion growth technique.•The crystal structures of NSC23925 isomers were analyzed.•The solved NSC23925 crystal structures reveal potential Pgp binding sites.
The utilization of 2-(2-nitrophenyl)propyloxycarbonyl (NPPOC) as a photolabile primary amine cage enables the thiol-Michael 'click' reaction to be photo-triggered. The photolabile amine exhibits ...efficient catalytic activity upon UV irradiation and is shown to initiate the photopolymerization of tetrathiol and diacrylate comonomers
via
Michael addition.
Photo-triggered thiol-Michael addition reaction using NPPOC-hexylamine as a catalyst.
Click chemistry has been employed as one of the most powerful paradigms in materials science. On page 2572, C. N. Bowman and co‐workers deliver the highlights of the click reactions and their ...applications in materials science. This cover image illustrates how click reactions in the flask carry a flow of applications in materials science, such as polymers modification, bioconjugation, block copolymers, responsive materials, surfaces functionalization.
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