Nadia Valletti

Mrs. Nadia Valletti

Università di Siena
orcid

Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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12 December 2022 in Pharmaceutics
Verified
Journal Article
Open access
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PApaola albanese
paola albanese
SCSimone Cataldini
Simone Cataldini
CRChloe Z.-J. Ren
Chloe Z.-J. Ren
NVNadia Valletti
Nadia Valletti
JBJlenia Brunetti
Jlenia Brunetti
Federico RossiFederico Rossi
Federico Rossi
In this work, giant unilamellar vesicles (GUVs) were synthesized by blending the natural phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) with a photoswitchable amphiphile (1) that undergoes photoisomerization upon irradiation with UV-A (E to Z) and blue (Z to E) light. The mixed vesicles showed marked changes in behavior in response to UV light, including changes in morphology and the opening of pores. The fine control of membrane permeability with consequent cargo release could be attained by modulating either the UV irradiation intensity or the membrane composition. As a proof of concept, the photocontrolled release of sucrose from mixed GUVs is demonstrated using microscopy (phase contrast) and confocal studies. The permeability of the GUVs to sucrose could be increased to ~4 × 10–2 μm/s when the system was illuminated by UV light. With respect to previously reported systems (entirely composed of synthetic amphiphiles), our findings demonstrate the potential of photosensitive GUVs that are mainly composed of natural lipids to be used in medical and biomedical applications, such as targeted drug delivery and localized topical treatments.

14 January 2023 in Water Research
Verified
Journal Article
Open access
NVNadia Valletti
Nadia Valletti
MBMarcello A. Budroni
Marcello A. Budroni
PAPaola Albanese
Paola Albanese
NMNadia Marchettini
Nadia Marchettini
Margarita Sanchez-DominguezMargarita Sanchez-Dominguez
Margarita Sanchez-Dominguez
Federico RossiFederico Rossi
Federico Rossi
The use of surfactants represents a viable strategy to boost the removal yield of Dense Non-Aqueous Phase Liquids (DNAPLs) from groundwater and to shorten the operational timing of the remediation process. Surfactants, in general, help in reducing the interfacial tension at the DNAPL/water interface and enhance the solubility of the pollutant in the water phase through the formation of dispersed systems, such as micelles and emulsions. In this paper, we show that a suitable choice of a surfactant, in this case belonging to the bio-degradable class of ethoxylated alcohols, allows for the formation of hydrodynamic interfacial instabilities that further enhances the dissolution rate of the organic pollutant into the water phase. In a stratified configuration (denser organic phase at the bottom and lighter water phase on top), the instabilities appear as upward-pointing fingers that originate from the inversion of the local density at the interface. This inversion stems from the synergetic coupling of two effects promoted by the ethoxylated surfactant: i) the enhanced co-solubility of the DNAPL into the water (and viceversa), and (ii) the differential diffusion of the DNAPL and the surfactant in the aqueous phase. By dissolving into the DNAPL, the surfactant also reduces locally the surface tension at the liquid-liquid interface, thereby inducing transversal Marangoni flows. In our work, we carefully evaluated the effects of the concentration of different surfactants (two different ethoxylated alcohols, sodium dodecylsulphate, cetyltrimethyl ammonium bromide, N-tetradecyl-N, N-dimethylamine oxide and bis(2-ethylhexyl) sulfosuccinate sodium salt) on the onset of the instabilities in 3 different DNAPLs/water stratifications, namely chloroform, trichloroethylene and tetrachloroethylene, with a special emphasis on the trichloroethylene/water system. By means of a theoretical model and nonlinear simulations, supported by surface tension, density and diffusivity measurements, we could provide a solid explanation to the observed phenomena and we found that the type of the dispersed system, the solubility of the DNAPL into the water phase, the solubility of the surfactant in the organic phase, as well as the relative diffusion and density of the surfactant and the DNAPL in the aqueous phase, are all key parameters for the onset of the instabilities. These results can be exploited in the most common remediation techniques.

3 September 2021 in Reactions
Verified
Journal Article
Open access
PDF file
NVNadia Valletti
Nadia Valletti
MBMarcello A. Budroni
Marcello A. Budroni
ILIstván Lagzi
István Lagzi
NMNadia Marchettini
Nadia Marchettini
Margarita Sanchez-DominguezMargarita Sanchez-Dominguez
Margarita Sanchez-Dominguez
Federico RossiFederico Rossi
Federico Rossi
The fate of dense non-aqueous phase liquids (DNAPLs) in the environment and the consequential remediation problems have been intensively studied over the last 50 years. However, a scarce literature is present about the mass transfer at the DNAPL/water interface. In this paper, we present a fast method for the evaluation of the mass transfer performance of a surfactant that can easily be employed to support an effective choice for the so-called enhanced remediation strategies. We developed a lab-scale experimental system modelled by means of simple ordinary differential equations to calculate the mass transfer coefficient (K) of trichloroethylene, chosen as representative DNAPL, in the presence and in the absence of two ethoxylated alcohols belonging to the general class of Synperonic surfactants. Our findings revealed that it exists an optimal surfactant concentration range, where K increases up to 40% with respect to pure water.

1 January 2024
Verified
Conference Paper
Closed access
MIMasaki Itatani
Masaki Itatani
GHGábor Holló
Gábor Holló
PAPaola Albanese
Paola Albanese
NVNadia Valletti
Nadia Valletti
SKSándor Kurunczi
Sándor Kurunczi
ILIstván Lagzi
István Lagzi
We present the synthesis and multifaceted applications of Giant Unilamellar Vesicles (GUVs) in cellular modeling and the development of advanced materials. GUVs, known for their capacity to mimic cell membranes, are synthesized through a phase transfer method using self-assembling amphiphilic molecules that form bilayers, creating isolated environments ideal for both biological and material science experiments. In the realm of cellular modeling, GUVs are utilized to replicate complex cellular behaviors, such as enzymatic reaction networks, signal transduction, and self-division, offering a simplified yet dynamic model to explore fundamental biological processes and the mechanisms underlying cellular communication.

1 January 2024
Verified
Conference Paper
Closed access
Norbert NémetNorbert Német
Norbert Német
GHGábor Holló
Gábor Holló
SFS. Farkas
S. Farkas
GSGabor Schuszter
Gabor Schuszter
NVNadia Valletti
Nadia Valletti
ILIstván Lagzi
István Lagzi
One of the most widely used techniques for generating crystalline materials is wet synthesis. In this procedure, the reagents are mixed, and crystals form due to the nucleation and growth processes. In crystal growth and engineering, the most crucial is the temporal control of the processes over time to obtain samples with a desired average size and dispersity. Here, we review recent alternative methods for the synthesis of the zeolitic imidazolate framework-8 (ZIF-8). We present the chemically coded time-programmed method driven by a clock reaction. Additionally, we highlight the advantage of the application of a gel reactor utilizing diffusion and ionic migration driven by a direct electric field.