| 1. |
- Zaman, Quaid, et al.
(author)
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Water Diffusion Effectsat Gold-Graphene Interfaces Supporting Surface Plasmon Polaritons
- 2022
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In: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455. ; 126:32, s. 13905-13919
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Journal article (peer-reviewed)abstract
- We present a detailed investigation on the effects of water diffusion at the different interfaces of gold-graphene plasmonic sensors on the propagation of the supported surface plasmon polaritons (SPPs). The substrate/metal interfacial chemical reactions are investigated by monitoring the full width at half-maximum of the SPR reflectivity curve. Although protection by single-layer graphene (SLG) grown by chemical vapor deposition inhibits the chemical reactions happening at the metal-dielectric interfaces, SPR experimental results confirm that water diffusion paths through the borders of graphene domains are still present into the plasmonic sensors. Density functional theory calculations show that the doping level of SLG after the transfer on gold as well as interfacial charge transfer can be tuned in the presence of water molecules. On these bases, we propose a simplified effective medium approach for heterogeneous metal-carbon interfaces, where the interaction between the surface atomic layers of the gold thin film, water molecules, and the SLG induces the creation of an extended charge density difference region crossing the Au/H2O/SLG/H2O heterointerface. The latter is modeled as an ultrathin effective medium with a thickness and extraordinary optical susceptivity and conductivity that are different from those of the free-standing graphene. In this context, the extraordinary refractive index and thickness of the graphene-gold effective medium are measured in the near-infrared on the low-damping SPR platforms by applying the two-medium SPR method. The results are coherent with graphene n-doping in water environment, showing that the optically excited electrons along the extraordinary axis have a substantial bonding character and that the enhancement of the sensitivity of the gold-graphene plasmonic sensors is not related to a shift in the plasma frequency of the metal layer but to the changes in the extraordinary polarizability of graphene. The research highlights the importance of the SLG-substrate and SLG-environment interactions in graphene-protected plasmonics and optoelectronics.
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| 2. |
- Barbosa, Pedro, et al.
(author)
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Bariatric Surgery Induces Alterations in the Immune Profile of Peripheral Blood T Cells
- 2024
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In: Biomolecules. - : MDPI. - 2218-273X. ; 14:2
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Journal article (peer-reviewed)abstract
- Low-grade inflammation is closely linked to obesity and obesity-related comorbidities; therefore, immune cells have become an important topic in obesity research. Here, we performed a deep phenotypic characterization of circulating T cells in people with obesity, using flow cytometry. Forty-one individuals with obesity (OB) and clinical criteria for bariatric surgery were enrolled in this study. We identified and quantified 44 different circulating T cell subsets and assessed their activation status and the expression of immune-checkpoint molecules, immediately before (T1) and 7-18 months after (T2) the bariatric surgery. Twelve age- and sex-matched healthy individuals (nOB) were also recruited. The OB participants showed higher leukocyte counts and a higher percentage of neutrophils. The percentage of circulating Th1 cells were negatively correlated to HbA1c and insulin levels. OB Th1 cells displayed a higher activation status and lower PD-1 expression. The percentage of Th17 and Th1/17 cells were increased in OB, whereas the CD4+ Tregs' percentage was decreased. Interestingly, a higher proportion of OB CD4+ Tregs were polarized toward Th1- and Th1/17-like cells and expressed higher levels of CCR5. Bariatric surgery induced the recovery of CD4+ Treg cell levels and the expansion and activation of Tfh and B cells. Our results show alterations in the distribution and phenotype of circulating T cells from OB people, including activation markers and immune-checkpoint proteins, demonstrating that different metabolic profiles are associated to distinct immune profiles, and both are modulated by bariatric surgery.
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| 3. |
- Barbosa, Pedro, et al.
(author)
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CD8+Treg cells play a role in the obesity-associated insulin resistance
- 2024
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In: Life Sciences. - : Elsevier. - 0024-3205 .- 1879-0631. ; 336
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Journal article (peer-reviewed)abstract
- Obesity-related chronic low-grade inflammation may trigger insulin resistance and type 2 diabetes (T2D) development. Cells with regulatory phenotype have been shown to be reduced during obesity, especially CD4+ Treg cells. However, little is known about the CD8+ Treg cells. Therefore, we aim to characterize the CD8+ Treg cells in human peripheral blood and adipose tissue, specifically, to address the effect of obesity and insulin resistance in this regulatory immune cell population. A group of 42 participants with obesity (OB group) were recruited. Fourteen of them were evaluated pre-and post-bariatric surgery. A group of age-and sex-matched healthy volunteers (n = 12) was also recruited (nOB group). CD8+ Treg cell quantification and phenotype were evaluated by flow cytometry, in peripheral blood (PB), subcutaneous (SAT), and visceral adipose tissues (VAT). The OB group displayed a higher percentage of CD8+ Treg cells in PB, compared to the nOB. In addition, they were preferentially polarized into Tc1-and Tc1/17-like CD8+ Treg cells, compared to nOB. Moreover, SAT displayed the highest content of CD8+ Tregs infiltrated, compared to PB or VAT, while CD8+ Tregs infiltrating VAT displayed a higher percentage of cells with Tc1-like phenotype. Participants with pre-diabetes displayed a reduced percentage of TIM-3+CD8+ Tregs in circulation, and PD-1+CD8+ Tregs infiltrated in the VAT. An in-crease in the percentage of circulating Tc1-like CD8+ Treg cells expressing PD-1 was observed post-surgery. In conclusion, obesity induces significant alterations in CD8+ Treg cells, affecting their percentage and phenotype, as well as the expression of important immune regulatory molecules.
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| 4. |
- Santangelo, James S., et al.
(author)
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Global urban environmental change drives adaptation in white clover
- 2022
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 375
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Journal article (peer-reviewed)abstract
- Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural dines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale.
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