Platinum nanoparticles in nanobiomedicine Pedone, Deborah; Moglianetti, Mauro; De Luca, Elisa ...
Chemical Society reviews,
08/2017, Volume:
46, Issue:
16
Journal Article
Peer reviewed
Open access
Oxidative stress-dependent inflammatory diseases represent a major concern for the population's health worldwide. Biocompatible nanomaterials with enzymatic properties could play a crucial role in ...the treatment of such pathologies. In this respect, platinum nanoparticles (PtNPs) are promising candidates, showing remarkable catalytic activity, able to reduce the intracellular reactive oxygen species (ROS) levels and impair the downstream pathways leading to inflammation. This review reports a critical overview of the growing evidence revealing the anti-inflammatory ability of PtNPs and their potential applications in nanomedicine. It provides a detailed description of the wide variety of synthetic methods recently developed, with particular attention to the aspects influencing biocompatibility. Special attention has been paid to the studies describing the toxicological profile of PtNPs with an attempt to draw critical conclusions. The emerging picture suggests that the material
per se
is not causing cytotoxicity, while other physicochemical features related to the synthesis and surface functionalization may play a crucial role in determining the observed impairment of cellular functions. The enzymatic activity of PtNPs is also summarized, analyzing their action against ROS produced by pathological conditions within the cells. In particular, we extensively discuss the potential of these properties in nanomedicine to down-regulate inflammatory pathways or to be employed as diagnostic tools with colorimetric readout. A brief overview of other biomedical applications of nanoplatinum is also presented.
This review reports a critical overview of the potential applications of platinum nanoparticles in nanomedicine with special focus on their nanozyme properties.
Abstract
The fundamental interactions underlying citrate-mediated chemical stability of metal nanoparticles, and their surface characteristics dictating particle dispersion/aggregation in aqueous ...solutions, are largely unclear. Here, we developed a theoretical model to estimate the stoichiometry of small, charged ligands (like citrate) chemisorbed onto spherical metallic nanoparticles and coupled it with atomistic molecular dynamics simulations to define the uncovered solvent-accessible surface area of the nanoparticle. Then, we integrated coarse-grained molecular dynamics simulations and two-body free energy calculations to define dispersion state phase diagrams for charged metal nanoparticles in a range of medium’s ionic strength, a known trigger for aggregation. Ultraviolet-visible spectroscopy experiments of citrate-capped nanocolloids validated our predictions and extended our results to nanoparticles up to 35 nm. Altogether, our results disclose a complex interplay between the particle size, its surface charge density, and the ionic strength of the medium, which ultimately clarifies how these variables impact colloidal stability.
Understanding how nanomaterials interact with interfaces is essential to control their self-assembly as well as their optical, electronic, and catalytic properties. We present here an experimental ...approach based on neutron reflectivity (NR) that allows the in situ measurement of the contact angles of nanoparticles adsorbed at fluid interfaces. Because our method provides a route to quantify the adsorption and interfacial energies of the nanoparticles in situ, it circumvents problems associated with existing indirect methods, which rely on the transport of the monolayers to substrates for further analysis. We illustrate the method by measuring the contact angle of hydrophilic and hydrophobic gold nanoparticles, coated with perdeuterated octanethiol (d-OT) and with a mixture of d-OT and mercaptohexanol (MHol), respectively. The contact angles were also calculated via atomistic molecular dynamics (MD) computations, showing excellent agreement with the experimental data. Our method opens the route to quantify the adsorption of complex nanoparticle structures adsorbed at fluid interfaces featuring different chemical compositions.
The ability of shape-controlled octahedral Pt nanoparticles to act as nanozyme mimicking glucose oxidase enzyme is reported. Extended {111} particle surface facets coupled with a size comparable to ...natural enzymes and easy-to-remove citrate coating give high affinity for glucose, comparable to the enzyme as proven by the steady-state kinetics of glucose electrooxidation. The easy and thorough removal of the citrate coating, demonstrated by X-ray photoelectron spectroscopy analysis, allows a highly stable deposition of the nanozymes on the electrode. The glucose electrochemical detection (at −0.2 V vs SCE) shows a linear response between 0.36 and 17 mM with a limit of detection of 110 μM. A good reproducibility has been achieved, with an average relative standard deviation (RSD) value of 9.1% (
n
= 3). Similarly, a low intra-sensor variability has been observed, with a RSD of 6.6% (
n
= 3). Moreover, the sensor shows a long-term stability with reproducible performances for at least 2 months (RSD: 7.8%). Tests in saliva samples show the applicability of Pt nanozymes to commercial systems for non-invasive monitoring of hyperglycemia in saliva, with recoveries ranging from 92 to 98%.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Gold nanoparticles protected by a binary mixture of thiolate molecules have a ligand shell that can spontaneously separate into nanoscale domains. Complex morphologies arise in such ligand shells, ...including striped, patchy, and Janus domains. Characterization of these morphologies remains a challenge. Scanning tunneling microscopy (STM) imaging has been one of the key approaches to determine these structures, yet the imaging of nanoparticles’ surfaces faces difficulty stemming from steep surface curvature, complex molecular structures, and the possibility of imaging artifacts in the same size range. Images obtained to date have lacked molecular resolution, and only domains have been resolved. There is a clear need for images that resolve the molecular arrangement that leads to domain formation on the ligand shell of these particles. Herein we report an advance in the STM imaging of gold nanoparticles, revealing some of the molecules that constitute the domains in striped and Janus gold nanoparticles. We analyze the images to determine molecular arrangements on parts of the particles, highlight molecular “defects” present in the ligand shell, show persistence of the features across subsequent images, and observe the transition from quasi-molecular to domain resolution. The ability to resolve single molecules in the ligand shell of nanoparticles could lead to a more comprehensive understanding of the role of the ligand structure in determining the properties of mixed-monolayer-protected gold nanoparticles.
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A rapid point-of-care method for the colorimetric detection of cisplatin was developed, exploiting the efficient conversion of the chemotherapeutic drug into a high-performance nanocatalyst with ...peroxidase enzyme mimics. This assay provides high specificity and ppb-detection sensitivity with the naked eye or a smartphone-based readout, outperforming many standard laboratory-based techniques. The nanocatalyst-enabled colorimetric assay can be integrated with machine-learning methods, providing accurate quantitative measurements. Such a combined approach opens interesting perspectives for the on-site monitoring of both chemotherapeutic patients to achieve optimal treatments and healthcare workers to prevent their unsafe exposure.
Platinum nanoparticles (PtNPs) attract great attention due to their efficient catalysis and good degree of cytocompatibility, but information about their effects on the human immune system is still ...missing. Monocytes are key cells of the innate immune system and the understanding of their reactions to PtNPs is crucial in view of any feasible application to human pathologies. Here, we evaluate the internalization of citrate-coated PtNPs into THP-1 monocytes and its consequences on immune cell responses. We found that the presence of intracellular PtNPs efficiently reduce reactive oxygen species (ROS) without affecting cell viability. The physiological expression of the immune receptors Cluster of Differentiation 14 (CD14), CD11b, CC-Chemokine Receptor 2 (CCR2) and CCR5 and the expression of cytokines and chemokines are not compromised by the presence of PtNPs within THP-1 cells. On the other hand, the treatment with PtNPs modulates the transcription of sixty genes, some of them involved in lipopolysaccharide (LPS) signaling in different cells. However, the treatment with PtNPs of monocytes does not compromise the LPS-induce increase of cytokines in THP-1 monocytes in vitro. Our results demonstrate that citrate-coated PtNPs are non-toxic, perform efficient intracellular reactive oxygen species (ROS) scavenging activity and possess good immune-compatibility, suggesting them as feasible synthetic enzymes for applications in nanomedicine.
Colloid stability is of high importance in a multitude of fields ranging from food science to biotechnology. There is strong interest in studying the stability of small particles (of a size of a few ...nanometres) with complex surface structures, that make them resemble the complexity of proteins and other natural biomolecules, in the presence of oppositely charged nanoparticles. While for nanoparticles with homogeneously charged surfaces an abrupt precipitation has been observed at the neutrality of charges, data are missing about the stability of nanoparticles when they have more complex surface structures, like the presence of hydrophobic patches. To study the role of these hydrophobic patches in the stability of nanoparticles a series of negatively charged nanoparticles has been synthesized with different ratios of hydrophobic content and with control on the structural distribution of the hydrophobic moiety, and then titrated with positively charged nanoparticles. For nanoparticles with patchy nanodomains, the influence of hydrophobic content was observed together with the influence of the size of the nanoparticles. By contrast, for nanoparticles with a uniform distribution of hydrophobic ligands, size changes and hydrophobic content did not play any role in co-precipitation behaviour. A comparison of these two sets of nanoparticles suggests that nanodomains present at the surfaces of nanoparticles are playing an important role in stability against co-precipitation.
Shape-selective, sub-10 nm-sized metal nanoparticles are of high fundamental and practical interest in catalysis and electrocatalysis, where the surface structure dictates the kinetic properties of ...the nanomaterials. Unlike their bimetallic analogues, the synthesis of size-controlled, pure Pt octahedral nanocatalysts has remained a formidable chemical challenge. In bimetallic shaped systems, however, the benefit of shape is often convoluted with surface composition in complex ways. In the present work, a seed-templated approach is presented for the preparation of ultrasmall octahedral platinum nanoparticles (Pt NPs), harnessing the effect of monocrystalline anisotropic seeds and strict control of the reduction rate and other physicochemical parameters while avoiding polymers, surfactants, and organic solvents. The procedure yields previously elusive 6.7 nm, strictly single-crystal, Pt NPs with partially truncated octahedral shape and prevalent extended {111} surface facets. Electrochemical measurements using rotating disk electrodes in an acid electrolyte revealed a much higher electrochemical active surface area (ECSA) over the state-of-the-art octahedral Pt NPs, which is ascribed to small-sized, poison-free, and preferentially {111} orientated facets. The dramatic kinetic benefit for the oxygen reduction reaction (ORR) of the octahedral shape over spherical particle shapes of same size is convincingly demonstrated. More important for practical applications is the fact that the intrinsic specific ORR activity is about 2.4-fold higher than commercial optimized spherical Pt NPs deployed in fuel cell cathodes at comparable ORR stability. In doing this analysis, we validate the voltammetric correspondence between Pt single crystals and Pt nanoparticulate materials and highlight the kinetic benefits of limiting the proportion of {100} facets. Prolonged suppression of {100} facet growth in octahedral Pt catalysts is the reason for the unusually high specific activity and fair stability and calls for their integration and testing as cathode catalysts in fuel cell membrane electrode assemblies.
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Platinum nanoparticles (PtNPs) are antioxidant enzyme-mimetic nanomaterials with significant potential for the treatment of complex diseases related to oxidative stress. Among such diseases, Cerebral ...Cavernous Malformation (CCM) is a major cerebrovascular disorder of genetic origin, which affects at least 0.5% of the general population. Accumulated evidence indicates that loss-of-function mutations of the three known CCM genes predispose endothelial cells to oxidative stress-mediated dysfunctions by affecting distinct redox-sensitive signaling pathways and mechanisms, including pro-oxidant and antioxidant pathways and autophagy. A multitargeted combinatorial therapy might thereby represent a promising strategy for the effective treatment of this disease. Herein, we developed a multifunctional nanocarrier by combining the radical scavenging activity of PtNPs with the autophagy-stimulating activity of rapamycin (Rapa). Our results show that the combinatorial targeting of redox signaling and autophagy dysfunctions is effective in rescuing major molecular and cellular hallmarks of CCM disease, suggesting its potential for the treatment of this and other oxidative stress-related diseases.
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