Functional nanoparticles are highly interesting imaging agents for positron emission tomography (PET) due to the possibility of multiple incorporation of positron emitting radionuclides thus increasing the signal strength. Furthermore, long-term nanoparticle biodistribution tests with increased signal-to-noise ratio can be achieved with nanoparticles carrying long-lived isotopes. Mesoporous silica nanoparticles, MSNs, have recently attracted a lot of interest as both imaging agents and carriers for drugs in vitro and in vivo. Here we present results related to the synthesis of PET imageable MSNs carrying the long-lived (89)Zr isotope (half-life of 78.4 hours). Here, (89)Zr(4+) was immobilized through covalent attachment of the complexing agent p-isothiocyanatobenzyldesferrioxamine (DFO-NCS) to large-pore MSNs. Due to the presence of the high DFO content on the MSNs, quantitative (89)Zr(4+) labeling was achieved within just a few minutes, and no subsequent purification step was needed in order to remove non-complexed (89)Zr(4+). The stability of the (89)Zr-labeled MSNs against leaching of (89)Zr(4+) was verified for 24 hours. The high signal strength of the (89)Zr-DFO-MSNs was evidenced by successful PET imaging using a mouse model at particle loadings one order of magnitude lower than those previously applied in PET-MSN studies. The biodistribution followed the same trends as previously observed for MSNs of different sizes and surface functionalities. Taken together, our results suggest that (89)Zr-DFO-MSNs are promising PET imaging agents for long-term in vivo imaging.
ObjectivesThe goal of this research was to evaluate how material curl, package structure and handling of pouches containing medical devices affect rates of contact between non-sterile surfaces and sterile devices during aseptic transfer.MethodsOne hundred and thirty-six individuals with practical experience in aseptic technique were recruited. Participants were asked to present the contents of four different pouch designs (a standard, one designed to curl in, another to curl out and one that incorporated a tab) using two transfer techniques. During the first block of trials “standard technique” was used; participants presented using their typical methods to the sterile field. Trials in the second block employed “modified technique”; participants were instructed to grab the package at the top center and present package contents using a single, fluid motion. The outside of the pouch and the backs of the participants’ hands were coated using a simulated contaminant before each trial. The simulant was undetectable in the visible spectrum, but fluoresced under a black light. The dependent variable was recorded in a binary fashion and analyzed using a generalized linear mixed model.ResultsParticipants were between 20–57 and the averaged year 5.1 years of experience in aseptic technique. The data analysis was based on generalized linear mixed effects (GLMM) model, which accommodates the repeated measurements within the same participant. The effect of the pouch design was significant (P‹0.001), but the effect of aseptic technique did not suggest significance (P = 0.088). Specifically, pouches designed with the material curled outward resulted in significantly fewer contacts with non-sterile surfaces than the other styles, including the inward, tab, and standard styles; this was true regardless of the used aseptic technique, standard (P = 0.0171, P = 0.0466, P = 0.0061, respectively) or modified (P‹0.0001 for all comparisons)).ConclusionResults presented here contribute to a growing body of knowledge that investigates packaging as a potential route of contamination for sterile devices during aseptic presentation. Specifically, we provide insights regarding how both package design and opening technique can be informed in ways that build safety into the healthcare system.
The completed first phase of the analyses of a series of physical vapor transport experiments conducted both in low earth orbit on the Space Shuttle Orbiter and in the laboratory is presented. The experiments are the first to use physical vapor transport as a process to grow oriented organic thin films on epitaxially active substrates sealed within demountable ampoules. It was found that the films grown in the microgravity environment were smoother, optically more homogeneous and denser than their unit gravity grown counterparts, and contained predominantly a new polymorph of copper phthalocyanine (CuPc). In this report the gas-phase evolution within the ampoules and resulting convective effects on the substrate temperature have been characterized for four microgravity processed cells and over twenty ground control experiments. The nitrogen-equivalent total pressures and partial pressures of nine common gases are measured within the processed ampoules and the relationships determined empirically among the gas pressures, compositions, and the orientation of the ampoule relative to the earth’s gravitational field. Significant gas evolution amounting to several times the original backfilled buffer gas is found in all the ampoules, and attributed to hydrogen evolution from stainless-steel components and the thermal decomposition of as little as 0.06% of the starting source material. The amounts and compositions are found to be very consistent among the different experiments, leading to the conclusion that this is not a significant variable in the comparisons of microstructure differences observed between the microgravity grown and laboratory grown films. It is observed that the substrate temperature is sensitive not only to the ampoule gas pressure and composition, but also to the ampoule orientation and its external gas environment during the thermal processing. It is concluded that enhanced convective heat transfer to the substrate occurs not only with the hotter end of the ampoule below the cooler end but also when the hotter end is above the cooler end under unit gravity conditions. Finally, estimates of the thermophysical parameters are calculated for a representative ampoule gas composition, including the mixture kinetic viscosity, thermal conductivity, heat capacity, binary diffusivity of the CuPc, and the effective vapor pressure of the CuPc above the substrate.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.