Giorgia Figari’s research while affiliated with Instituto Superior Técnico and other places

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Publications (1)

Transmission electron microscope image illustrating the regular shape and size of the mesoporous silica nanoparticles. Inset: probability distribution of nanoparticles’ radius obtained from a sample of 30 nanoparticles; the red line corresponds to the Gaussian fitting function of μ = 49 and σ² = 32.6, corresponding to a particle radius R = 49 ± 6 nm.
Solution ¹H-NMR (silica structure destroyed at pH = 13) of functionalized MSN with (a) APTES and (b) TMPS groups. Peaks are identified with the corresponding functional groups in accordance with chemical structures in the insets. Residual ethanol protons are denoted by (*).
FTIR spectra of FNB@MSNs (blue), FNB@MSNs_APTES (green) and FNB@MSNs_TMPS (pink) in (a) 4000–2600 cm⁻¹ hydroxyl and aliphatic CH regions and (b) 1800–1550 cm⁻¹ carboxylic region. See Figure S2 as well, in which the resulting spectra after subtracting the weighted spectrum of the corresponding unloaded MSNs are represented. Spectrum of bulk FNB (black) is displayed on right axis.
Heating thermograms of FNB@MSNs obtained at 10 °C min⁻¹ with the following: (a) Two successive cycles with final temperature of 100 °C (water content ~4.9%); inset shows a scale up of the glass transition region for bulk amorphous FNB (black) and hydrated FNB@MSN (light blue). (b) Evolution of the glass transition step by varying the final temperature from Tend-1 = 50 °C to Tend-2 = 70 °C, Tend-3 = 100 °C and Tend-4 = 100 °C; the arrows indicate the onset of each step associated to the bimodal glass transition. The inset shows the schematic temperature vs. time procedure applied.
(a) Permittivity spectra (ε″) collected at −90 °C for hydrated unloaded MSNs, and (b) relaxation map of all of the processes detected in hydrated unloaded matrices (fitting in M″(f)). Straight lines represent the fitting with an Arrhenius function for processes I, I* and II, respectively, in light gray, dark gray and white shadowed regions. An Arrhenius function for process II was only fitted for the low-temperature branch.

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Understanding Fenofibrate Release from Bare and Modified Mesoporous Silica Nanoparticles
  • Article
  • Full-text available

May 2023

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81 Reads

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6 Citations

Giorgia Figari

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José L. M. Gonçalves

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To investigate the impact of the surface functionalization of mesoporous silica nanoparticle (MSN) carriers in the physical state, molecular mobility and the release of Fenofibrate (FNB) MSNs with ordered cylindrical pores were prepared. The surface of the MSNs was modified with either (3-aminopropyl) triethoxysilane (APTES) or trimethoxy(phenyl)silane (TMPS), and the density of the grafted functional groups was quantified via ¹H-NMR. The incorporation in the ~3 nm pores of the MSNs promoted FNB amorphization, as evidenced via FTIR, DSC and dielectric analysis, showing no tendency to undergo recrystallization in opposition to the neat drug. Moreover, the onset of the glass transition was slightly shifted to lower temperatures when the drug was loaded in unmodified MSNs, and MSNs modified with APTES composite, while it increased in the case of TMPS-modified MSNs. Dielectric studies have confirmed these changes and allowed researchers to disclose the broad glass transition in multiple relaxations associated with different FNB populations. Moreover, DRS showed relaxation processes in dehydrated composites associated with surface-anchored FNB molecules whose mobility showed a correlation with the observed drug release profiles.

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Citations (1)

... Besides, biofilm microenvironments prevent antimicrobial diffusion through the deeper layers of the matrix, which reduces the activity of potent agents [24]. nMS have been applied as the carrier to deliver drugs into microorganisms and improve antimicrobial performance, which encapsulate agents and target specific tissue to keep a sustained drug concentration in lesion [25][26][27][28][29]. ...

Reference:

Silica nanoparticles containing nano-silver and chlorhexidine to suppress Porphyromonas gingivalis biofilm and modulate multispecies biofilms toward healthy tendency
Understanding Fenofibrate Release from Bare and Modified Mesoporous Silica Nanoparticles
Giorgia Figari

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José L. M. Gonçalves

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