Araújo, Joao Medeiros de

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Araújo, Joao Medeiros de
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Araújo, Joao Medeiros de

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  • Publication
    Using single nanoparticle tracking obtained by nanophotonic force microscopy to simultaneously characterize nanoparticle size distribution and nanoparticle-surface interactions
    (Royal Society of Chemistry, 2017-03-13)
    Hristov, Delyan R. 
    ;
    Ye, Dong 
    ;
    Araújo, Joao Medeiros de 
    ;
    Lopez, Hender 
    ;
    Dawson, Kenneth A. 
    ;
    et al. 
    Comprehensive characterization of nanomaterials for medical applications is a challenging and complex task due to the multitude of parameters which need to be taken into consideration in a broad range of conditions. Routine methods such as dynamic light scattering or nanoparticle tracking analysis provide some insight into the physicochemical properties of particle dispersions. For nanomedicine applications the information they supply can be of limited use. For this reason, there is a need for new methodologies and instruments that can provide additional data on nanoparticle properties such as their interactions with surfaces. Nanophotonic force microscopy has been shown as a viable method for measuring the force between surfaces and individual particles in the nano-size range. Here we outline a further application of this technique to measure the size of single particles and based on these measurement build the distribution of a sample. We demonstrate its efficacy by comparing the size distribution obtained with nanophotonic force microscopy to established instruments, such as dynamic light scattering and differential centrifugal sedimentation. Our results were in good agreement to those observed with all other instruments. Furthermore, we demonstrate that the methodology developed in this work can be used to study complex particle mixtures and the surface alteration of materials. For all cases studied, we were able to obtain both the size and the interaction potential of the particles with a surface in a single measurement.
      346Scopus© Citations 8
  • Publication
    Classification and biological identity of complex nano shapes
    (Springer, 2020-06-12)
    Boselli, Luca 
    ;
    Lopez, Hender 
    ;
    Zhang, Wei 
    ;
    Cai, Q. 
    ;
    Giannone, Valeria A. 
    ;
    Li, Jingji 
    ;
    Moura, Alirio 
    ;
    Araújo, Joao Medeiros de 
    ;
    Cookman, Jennifer 
    ;
    Castagnola, Valentina 
    ;
    Yan, Yan 
    ;
    Dawson, Kenneth A. 
    Everywhere in our surroundings we increasingly come in contact with nanostructures that have distinctive complex shape features on a scale comparable to the particle itself. Such shape ensembles can be made by modern nano-synthetic methods and many industrial processes. With the ever growing universe of nanoscale shapes, names such as “nanoflowers” and “nanostars” no longer precisely describe or characterise the distinct nature of the particles. Here we capture and digitise particle shape information on the relevant size scale and create a condensed representation in which the essential shape features can be captured, recognized and correlated. We find the natural emergence of intrinsic shape groups as well-defined ensemble distributions and show how these may be analyzed and interpreted to reveal novel aspects of our nanoscale shape environment. We show how these ideas may be applied to the interaction between the nanoscale-shape and the living universe and provide a conceptual framework for the study of nanoscale shape biological recognition and identity.
      281Scopus© Citations 34