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  • Open access
  • 114 Reads
Synthesis and Characterization of graphene-oxide reinforced copper matrix composite

In this study, eletrolitical copper powder (Cu) was initially mixed with the aqueous solution of graphene oxide (GO) and later the mixture underwent mechanical stirring for 1 hour, vacuum filtration and drying for 42 hours. The final concentration of GO in the composite was 0.3%wt. Through scanning electron microscopy (SEM) it was possible to observe the homogeneous dispersion of graphene sheets between copper particles, without the presence of agglomerates. In addition, the X-ray diffraction (XRD) of the pure samples and after mixing, revealed that there was no oxidation of the copper and absence of peaks related to other elements, confirming the high purity of the copper used. Still by XRD it was possible to analyze that the graphene oxide used was formed by stacking layers of graphene due to the appearance of a diffraction peak referring to the plane (002), which was confirmed by Raman Spectroscopy performed in GO from the appearance of the 2D bands. Fourier transform infrared spectroscopy (FTIR) allowed the identification of the vibrational spectra referring to the hydroxyl, carbonyl and epoxy functional groups in GO, confirming that the oxidation process was effective in inserting functional groups in the basal graphical plane. Through the GO thermogravimetric analysis (TGA) it was possible to identify a significant loss of mass of approximately 30% at temperatures below 100 ºC, referring to the elimination of water molecules, the most stable functional groups were eliminated at temperatures between 600 ºC and 800 ºC.

  • Open access
  • 71 Reads
Physical investigation of spin-coated MoS2 films

Amongst emerging Transition Metal Dichalcogenides (TMDCs), molybdenum disulfide (MoS2) has attracted a remarkable interest thanks to many possible applications. In particular, MoS2 has potentialities not yet fully realized in solution-based applications. The morphological and the structural properties of MoS2 films deposited by spin-coating onto Si/SiO2 substrates were investigated by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Micro-Raman Spectroscopy. High resolution AFM imaging highlights the presence of a layered structure. The thickness of each layer is estimated to be around 13 nm. Micro-Raman measurements reveal that there is the coexistence of both 2H-MoS2 and 1T-MoS2 phases, which could be useful for electrical applications. Moreover, the band at 290 cm-1 is assigned to the amorphous phase of MoS2. The detectability of the mode E1g in back scattering geometry is ascribed to the disorder of the amorphous phase.

  • Open access
  • 72 Reads
Waveguides in nanoporous glass for optofluidic purposes
Published: 16 November 2020 by MDPI in 2nd International Online-Conference on Nanomaterials session Poster

Bulk waveguides (BWGs) in nanoporous materials are promising to be applied in photonics and sensors industries. Such light guiding components interrogate the internal conditions of nanoporous material and are able to detect chemical or physical reactions occurred inside nanopores especially with small molecules, which represent a separate class for sensing technologies.

Recent years have demonstrated remarkable progress in the design and fabrication of optical porous glass (PG) sensors applied for monitoring and controlling different media and object parameters. Basically, such sensors consist of three main parts: a light source, receiver, and primary transducer. The primary transducer is a PG plate, which stores indicator; it is ready to absorb the target molecules. When the PG sensor is placed in an environment with target molecules, the primary transducer converts the chemical reaction occurring in nanopores into a measurable optical signal, for example, the absorption of radiation from the light source at a certain spectral range.

In this work, we suggest a novel concept of the primary transducer. It is the BWG inside a PG plate fabricated by the laser direct writing technique using a femtosecond laser (220 fs, 1035 nm, 1 MHz). After the writing step, PG plates are impregnated with the indicator - rhodamine 6G, which penetrates through the nanoporous framework of glass to the BWG cladding. The radiation transmitted through BWG interacts with the indicator generating a fluorescence signal at the output. The fluorescence spectrum is sensitive to chemical reactions occurred in the nanoporous framework in the cladding. The sensitivity of the peak shift in the fluorescence spectrum to the refractive index of the solution is quantified as 6250 ± 150 nm/RIU.

The results obtained open an opportunity to build a novel sensing photonics platform for detecting small doses of nanoscale objects captured by porous glass.

  • Open access
  • 110 Reads
Systematic Literature Reviews as a tool to develop Adverse Outcome Pathway landscapes in Nanotoxicology: case study of ingested Titanium dioxide nanomaterials
Published: 23 November 2020 by MDPI in 2nd International Online-Conference on Nanomaterials session Poster

Worldwide, Titanium dioxide nanomaterials are one of the most frequently applied nanomaterial as food additive, pharmaceuticals and toothpastes. Many studies addressed their potential adverse effects considering the nanomaterials primary physicochemical characteristics. However, surrounding matrix can affect their properties and consequently the secondary features may be more relevant for determining the toxicological outcome. In this regard, further research is needed. In fact, the potential of Ingested TiO2 nanomaterials (Ing-TiO2) to cause undesirable effects on human life is still unknown. Of major concern is their potential to lead to genotoxicity that may contribute to cancer. A valuable tool in predictive nanotoxicology is the establishment of Adverse Outcome Pathways (AOPs) landscapes. However, there is a lack of systematic approaches to assess this issue. A systematic literature review (SLR), that integrates information produced on this topic and provides data for a standardized assessment of the evidence, is necessary.

The goal of this study was to conduct a SLR evaluating the genotoxicity of Ing-TiO2, for identifying key cellular and molecular events leading to adverse health outcomes in order to guide future research needs on the assessment of potential AOPs.

It is expected that a framework of AOPs for Ing-TiO2, that describes a sequence of causally linked events at different levels of biological organization leading to adverse health effects, may contribute to support risk assessment based on mechanistic reasoning. Strengths and limitations of this strategy are discussed in view of their usefulness as a tool for risk assessment.

Funded by FCT/MCTES through national funds (PIDDAC), PTDC/SAU-PUB/29481/2017 and co-funded by ToxOmics (UIDB/00009/2020) and CESAM (UIDP/50017/2020+UIDB/50017/2020).

  • Open access
  • 139 Reads
Engineered NanoMedicine Targets Intractable Cancers

In recent decades, unprecedented progress has been made in the field of Oncology. Yet, cancer continues to affect millions of people globally despite major breakthroughs. Again, the advances in cancer therapy for all types of cancers have not been uniform, and certain types of cancer remain intractable. No doubt that there is a need for innovative and multidimensional efforts to solve this persistent problem. In our laboratory, we use polymeric micelle based nanomedicines that offer a unique ability for realizing coordinated functionality, such as active targeting and spatiotemporally controlled drug action, which can efficiently transport and selectively activate the drug in the tumor microenvironment (TME). With useful biocompatible and biodegradable features, block copolymer micelles are offering significant clinical translation potential. As a step forward, we have developed next-generation nanomedicines that can better synchronize with intrinsic TME features, such as dysregulated pH or metabolic alteration. Furthermore, the use of a clinically relevant nanomedicine, incorporating an ICD-inducing drug, has been expanded by reversing cold GBM into hot tumors to synergize the efficacy of anti-PD1 therapy.