The development of methods to produce nanoparticles with unique properties via the aerosol route is progressing rapidly. Typical characterization techniques extract particles from the synthesis process for subsequent ...The development of methods to produce nanoparticles with unique properties via the aerosol route is progressing rapidly. Typical characterization techniques extract particles from the synthesis process for subsequent offiine analysis, which may alter the particle characteristics. In this work, we use laser-vaporization aerosol mass spectrometry （LV-AMS） with 70-eV electron ionization for real-time, in-situ nanoparticle characterization. The particle characteristics are examined for various aerosol synthesis methods, degrees of sintering, and for controlled condensation of organic material to simulate surface coating/functionalization. The LV-AMS is used to characterize several types of metal nanoparticles （Ag, Au, Pd, PdAg, Fe, Ni, and Cu）. The degree of oxidation of the Fe and Ni nanoparticles is found to increase with increased sintering temperature, while the surface organic-impurity content of the metal particles decreases with increased sintering temperature. For aggregate metal particles, the organic-impurity content is found to be similar to that of a monolayer. By comparing different equivalent-diameter measurements, we demonstrate that the LV-AMS can be used in tandem with a differential mobility analyzer to determine the compactness of synthesized metal particles, both during sintering and during material addition for surface functionalization. Further, materials supplied to the particle production line downstream of the particle generators are found to reach the generators as contaminants. The capacity for such in-situ observations is important, as it facilitates rapid response to undesired behavior within the particle production process. This study demonstrates the utility of real-time, in-situ aerosol mass spectrometric measurements to characterize metal nanoparticles obtained directly from the synthesis process line, including their chemical composition, shape, and contamination, providing the potential for effective optimization of process operating parameters.展开更多
Photoluminescent silicon nanoparticles 1-2 nm in size were synthesized by a wet chemical procedure and derivatized with propylamine （NH2SiNP）. Surface NH2 groups were used as linkers for additional poly（ethylene gl...Photoluminescent silicon nanoparticles 1-2 nm in size were synthesized by a wet chemical procedure and derivatized with propylamine （NH2SiNP）. Surface NH2 groups were used as linkers for additional poly（ethylene glycol） （PEG） and folic acid （Fo） attachment （PEG-NHSiNP and Fo-NHSiNP, respectively） to enable efficient targeting of the particles to tumors and inflammatory sites. The particles were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ζ potential, dynamic light scattering, and time-resolved anisotropy. The photophysical properties and photosensitizing capacity of the particles and their interaction with proteins was dependent on the nature of the attached molecules. While PEG attachment did not alter the photophysical behavior of NH2SiNP, the attachment of Fo diminished particle photoluminescence. Particles retained the capacity for 1O2 generation; however, efficient 1O2 quenching by the attached surface groups may be a drawback when using these particles as 1O2photosensitizers. In addition, Fo attachment provided particles with the capacity to generate the superoxide anion radical （O2-）. The particles were able to bind tryptophan residues of bovine serum albumin （BSA） within quenching distances. NH2SiNP and PEG-NHSLNP ground state complexes with BSA showed binding constants of （3.1 ± 0.3） × 10^4 and （1.3 ±0.4） × 10^3 M-1, respectively. The lower value observed for PEG-NHSiNP complexes indicates that surface PEGylation leads to a reduction in protein adsorption, which is required to prevent opsonization. An increase in particle luminescence upon BSA binding was attributed to the hydrophobic environment generated by the protein. NH2SiNP-BSA complexes were also capable of resonance energy transfer.展开更多
文摘The development of methods to produce nanoparticles with unique properties via the aerosol route is progressing rapidly. Typical characterization techniques extract particles from the synthesis process for subsequent offiine analysis, which may alter the particle characteristics. In this work, we use laser-vaporization aerosol mass spectrometry （LV-AMS） with 70-eV electron ionization for real-time, in-situ nanoparticle characterization. The particle characteristics are examined for various aerosol synthesis methods, degrees of sintering, and for controlled condensation of organic material to simulate surface coating/functionalization. The LV-AMS is used to characterize several types of metal nanoparticles （Ag, Au, Pd, PdAg, Fe, Ni, and Cu）. The degree of oxidation of the Fe and Ni nanoparticles is found to increase with increased sintering temperature, while the surface organic-impurity content of the metal particles decreases with increased sintering temperature. For aggregate metal particles, the organic-impurity content is found to be similar to that of a monolayer. By comparing different equivalent-diameter measurements, we demonstrate that the LV-AMS can be used in tandem with a differential mobility analyzer to determine the compactness of synthesized metal particles, both during sintering and during material addition for surface functionalization. Further, materials supplied to the particle production line downstream of the particle generators are found to reach the generators as contaminants. The capacity for such in-situ observations is important, as it facilitates rapid response to undesired behavior within the particle production process. This study demonstrates the utility of real-time, in-situ aerosol mass spectrometric measurements to characterize metal nanoparticles obtained directly from the synthesis process line, including their chemical composition, shape, and contamination, providing the potential for effective optimization of process operating parameters.
文摘Photoluminescent silicon nanoparticles 1-2 nm in size were synthesized by a wet chemical procedure and derivatized with propylamine （NH2SiNP）. Surface NH2 groups were used as linkers for additional poly（ethylene glycol） （PEG） and folic acid （Fo） attachment （PEG-NHSiNP and Fo-NHSiNP, respectively） to enable efficient targeting of the particles to tumors and inflammatory sites. The particles were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, ζ potential, dynamic light scattering, and time-resolved anisotropy. The photophysical properties and photosensitizing capacity of the particles and their interaction with proteins was dependent on the nature of the attached molecules. While PEG attachment did not alter the photophysical behavior of NH2SiNP, the attachment of Fo diminished particle photoluminescence. Particles retained the capacity for 1O2 generation; however, efficient 1O2 quenching by the attached surface groups may be a drawback when using these particles as 1O2photosensitizers. In addition, Fo attachment provided particles with the capacity to generate the superoxide anion radical （O2-）. The particles were able to bind tryptophan residues of bovine serum albumin （BSA） within quenching distances. NH2SiNP and PEG-NHSLNP ground state complexes with BSA showed binding constants of （3.1 ± 0.3） × 10^4 and （1.3 ±0.4） × 10^3 M-1, respectively. The lower value observed for PEG-NHSiNP complexes indicates that surface PEGylation leads to a reduction in protein adsorption, which is required to prevent opsonization. An increase in particle luminescence upon BSA binding was attributed to the hydrophobic environment generated by the protein. NH2SiNP-BSA complexes were also capable of resonance energy transfer.
