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Nanoscale ; 11(40): 18582-18594, 2019 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-31528944


Although iron is one of Earth's most abundant elements, its availability to plants remains an agricultural challenge, particularly in high pH environments. At high pH, iron forms insoluble ferric oxide-hydroxides that makes it inaccessible to plants. It is estimated that 30% of the world's cropland is too alkaline for optimal plant growth. Staple crops, like rice, are particularly susceptible to iron deficiency, thereby, necessitating the need for continued research in developing iron-based fertilizers. Recent studies have demonstrated the potential of using iron oxide nanoparticles (IONPs) as fertilizers to address iron deficiency in plants, but some studies have generated conflicting results. One of the major challenges associated in investigating IONP plant uptake and translocation is the inability to distinguish between intact IONPs versus leached iron ions. In this study, we utilized a new approach based on magnetic particle spectrometry (MPS) to monitor the uptake and distribution of different sized (10 and 20 nm) chelated IONPs in plants. We exposed garden cress (Lepidium sativum) plants to EDTA-capped IONPs and observed an 8-fold enhancement in total biomass and 1.4 times increase in chlorophyll production compared to plants treated with a commercial chelated iron fertilizer (Fe-EDTA). Moreover, we demonstrated that the uptake and tissue distribution of IONPs can be quantitatively monitored using MPS, and the results of the analysis were validated by atomic absorption spectroscopy, which is the conventional method used to study IONP plant uptake. Our study demonstrates that MPS is a reliable, sensitive, and effective analytical tool for the development of IONP-based fertilizers.

Quelantes , Fertilizantes , Lepidium sativum/metabolismo , Nanopartículas de Magnetita/química , Quelantes/química , Quelantes/farmacologia , Análise Espectral
Birth Defects Res ; 110(13): 1065-1081, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29851302


Pediatric implants are a special subclass of a vast number of clinically used medical implants, uniquely designed to address the needs of young patients who are at the onset of their developmental growth stage. Given the vulnerability of the implant receiver, it is crucial that the implants manufactured for small children with birth-associated defects be given careful considerations and great attention to design detail to avoid postoperative complications. In this review, we focus on the most common types of medical implants manufactured for the treatment of birth defects originating from both genetic and environmental causes. Particular emphasis is devoted toward identifying the implant material of choice and manufacturing approaches for the fabrication of pediatric prostheses. Along this line, the emerging role of 3D printing to enable customized implants for infants with congenital disorders is presented, as well as the possible complications associated with prosthetic-related infections that is prevalent in using artificial implants for the treatment of birth malformations.

Anormalidades Congênitas/terapia , Impressão Tridimensional , Próteses e Implantes , Materiais Biocompatíveis/farmacologia , Criança , Humanos , Infecções Relacionadas à Prótese/terapia
ACS Infect Dis ; 4(8): 1246-1256, 2018 08 10.
Artigo em Inglês | MEDLINE | ID: mdl-29775283


Bacterial biofilms are highly antibiotic resistant microbial cell associations that lead to chronic infections. Unlike free-floating planktonic bacterial cells, the biofilms are encapsulated in a hardly penetrable extracellular polymeric matrix and, thus, demand innovative approaches for treatment. Recent advancements on the development of gel-nanocomposite systems with tailored therapeutic properties provide promising routes to develop novel antimicrobial agents that can be designed to disrupt and completely eradicate preformed biofilms. In our study, we developed a unique thermoresponsive magnetic glycol chitin-based nanocomposite containing d-amino acids and iron oxide nanoparticles, which can be delivered and undergoes transformation from a solution to a gel state at physiological temperature for sustained release of d-amino acids and magnetic field actuated thermal treatment of targeted infection sites. The d-amino acids in the hydrogel nanocomposite have been previously reported to inhibit biofilm formation and also disrupt existing biofilms. In addition, loading the hydrogel nanocomposite with magnetic nanoparticles allows for combination thermal treatment following magnetic field (magnetic hyperthermia) stimulation. Using this novel two-step approach to utilize an externally actuated gel-nanocomposite system for thermal treatment, following initial disruption with d-amino acids, we were able to demonstrate in vitro the total eradication of Staphylococcus aureus biofilms, which were resistant to conventional antibiotics and were not completely eradicated by separate d-amino acid or magnetic hyperthermia treatments.

Aminoácidos/farmacologia , Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Biofilmes/efeitos da radiação , Quitina/análogos & derivados , Compostos Férricos/farmacologia , Hidrogel de Polietilenoglicol-Dimetacrilato , Biofilmes/crescimento & desenvolvimento , Quitina/farmacologia , Temperatura Alta , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Campos Magnéticos , Magnetismo , Nanocompostos/química , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/efeitos da radiação
J Mater Sci Mater Med ; 29(5): 58, 2018 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-29730814


Iron oxide nanoparticles (IONPs) with high-index facets have shown great potential as high performance T2 contrast agents for MRI. Previous synthetic approaches focused mainly on ion-directed or oxidative etching methods. Herein, we report a new synthetic route for preparing high-index faceted iron oxide concave nanocubes using a bulky coordinating solvent. Through the systematic replacement of a non-coordinating solvent, 1-octadecene, with trioctylamine, the solvent interaction with the nanoparticle surface is modified, thereby, promoting the growth evolution of the IONPs from spherical to concave cubic morphology. The presence of the bulky trioctylamine solvent results in particle size increase and the formation of nanoparticles with enhanced shape anisotropy. A well-defined concave nanocube structure was evident from the early stages of particle growth, further confirming the important role of bulky coordinating solvents in nanoparticle structural development. The unique concave nanocube morphology has a direct influence on the magnetic properties of the IONPs, ultimately leading to an ultra-high T2 relaxivity (862.2 mM-1 s-1), and a 2-fold enhancement in T2*-weighted in vivo MRI contrast compared to spherical IONP analogs.

Técnicas de Química Sintética/métodos , Meios de Contraste/síntese química , Compostos Férricos/química , Imagem por Ressonância Magnética , Nanopartículas de Magnetita/química , Nanoestruturas/química , Animais , Meios de Contraste/química , Cristalização , Imagem por Ressonância Magnética/instrumentação , Imagem por Ressonância Magnética/métodos , Magnetismo , Masculino , Camundongos Endogâmicos ICR , Solventes/química , Solventes/farmacologia
J Am Chem Soc ; 137(36): 11550-3, 2015 09 16.
Artigo em Inglês | MEDLINE | ID: mdl-26301320


Although silver nanoparticles are of great fundamental and practical interest, only one structure has been determined thus far: M4Ag44(SPh)30, where M is a monocation, and SPh is an aromatic thiolate ligand. This is in part due to the fact that no other molecular silver nanoparticles have been synthesized with aromatic thiolate ligands. Here we report the synthesis of M3Ag17(4-tert-butylbenzene-thiol)12, which has good stability and an unusual optical spectrum. We also present a rational strategy for predicting the structure of this molecule. First-principles calculations support the structural model, predict a HOMO-LUMO energy gap of 1.77 eV, and predict a new "monomer mount" capping motif, Ag(SR)3, for Ag nanoparticles. The calculated optical absorption spectrum is in good correspondence with the measured spectrum. Heteroatom substitution was also used as a structural probe. First-principles calculations based on the structural model predicted a strong preference for a single Au atom substitution in agreement with experiment.

Nanopartículas Metálicas , Prata/química , Cristalografia por Raios X , Modelos Moleculares , Estrutura Molecular , Espectrometria de Massas por Ionização por Electrospray