Influence of a Solid Surface on PNIPAM Microgel Films.

Stimuli-responsive microgels have attracted great interest in recent years as building blocks for fabricating smart surfaces with many technological applications. In particular, PNIPAM microgels are promising candidates for creating thermo-responsive scaffolds to control cell growth and detachment via temperature stimuli. In this framework, understanding the influence of the solid substrate is critical for tailoring microgel coatings to specific applications.

Applying Gel-Supported Liquid Extraction to Tutankhamun's Textiles for the Identification of Ancient Colorants: A Case Study.

The identification of the dyes present on a linen fragment from the tomb of Pharaoh Tutankhamun is the objective of the present study. Fiber optic reflectance spectroscopy (FORS) was applied to the archaeological sample for preliminary identification of the dyes and to better choose the extraction methodology for different areas of the sample. The innovative gel-supported micro-extraction with agar gel and the Nanorestore Gel High Water Retention (HWR) gel were applied to the archaeological sample after testing of the best concentration for the extraction of the agar gels substrates, performed on laboratory mock-ups by means of UV-Vis transmittance spectroscopy.

Bragg Curve Detection of Low-Energy Protons by Radiophotoluminescence Imaging in Lithium Fluoride Thin Films.

Lithium fluoride (LiF) crystals and thin films are utilized as radiation detectors for energy diagnostics of proton beams. This is achieved by analyzing the Bragg curves in LiF obtained by imaging the radiophotoluminescence of color centers created by protons. In LiF crystals, the Bragg peak depth increases superlinearly with the particle energy.

Evaluating the Conservation State of Naturally Aged Paper with Raman and Luminescence Spectral Mapping: Toward a Non-Destructive Diagnostic Protocol.

Micro-Raman and luminescence spectroscopy were combined with morphological analysis to study the conservation state of differently degraded paper samples, dated from 1873 to 2021. The aim of the work reported in this paper was to obtain ageing markers based on variations of Raman and fluorescence spectral features. Raman and luminescence spectra were acquired by scanning non-printed areas of books, and Raman and fluorescence maps were built by contrasting spectral parameters point by point, obtaining a micron-scale space resolved imaging of the degradation pattern.

Thermal Behaviour of Microgels Composed of Interpenetrating Polymer Networks of Poly(-isopropylacrylamide) and Poly(acrylic acid): A Calorimetric Study.

Stimuli-responsive microgels have recently attracted great attention in fundamental research as their soft particles can be deformed and compressed at high packing fractions resulting in singular phase behaviours. Moreover, they are also well suited for a wide variety of applications such as drug delivery, tissue engineering, organ-on-chip devices, microlenses fabrication and cultural heritage. Here, thermoresponsive and pH-sensitive cross-linked microgels, composed of interpenetrating polymer networks of poly(-isopropylacrylamide) (PNIPAM) and poly(acrylic acid) (PAAc), are synthesized by a precipitation polymerization method in water and investigated through differential scanning calorimetry in a temperature range across the volume phase transition temperature of PNIPAM microgels.

Glass and Jamming Rheology in Soft Particles Made of PNIPAM and Polyacrylic Acid.

The phase behaviour of soft colloids has attracted great attention due to the large variety of new phenomenologies emerging from their ability to pack at very high volume fractions. Here we report rheological measurements on interpenetrated polymer network microgels composed of poly(-isopropylacrylamide) (PNIPAM) and polyacrylic acid () at fixed content as a function of weight concentration. We found three different rheological regimes characteristic of three different states: a Newtonian shear-thinning fluid, an attractive glass characterized by a yield stress, and a jamming state.

Chemical-Physical Behaviour of Microgels Made of Interpenetrating Polymer Networks of PNIPAM and Poly(acrylic Acid).

Microgels composed of stimuli responsive polymers have attracted worthwhile interest as model colloids for theorethical and experimental studies and for nanotechnological applications. A deep knowledge of their behaviour is fundamental for the design of new materials. Here we report the current understanding of a dual responsive microgel composed of poly(N-isopropylacrylamide) (PNIPAM), a temperature sensitive polymer, and poly(acrylic acid) (PAAc), a pH sensitive polymer, at different temperatures, PAAc contents, concentrations, solvents and pH.

Gellan Gum Microgels as Effective Agents for a Rapid Cleaning of Paper.

Microgel particles have emerged in the past few years as a favorite model system for fundamental science and for innovative applications ranging from the industrial to biomedical fields. Despite their potentialities, no works so far have focused on the application of microgels for cultural heritage preservation. Here we show their first use for this purpose, focusing on wet paper cleaning.

Study of network composition in interpenetrating polymer networks of poly(N isopropylacrylamide) microgels: The role of poly(acrylic acid).

Hypothesis: The peculiar swelling behaviour of poly(N-isopropylacrylamide) (PNIPAM)-based responsive microgels provides the possibility to tune both softness and volume fraction with temperature, making these systems of great interest for technological applications and theoretical implications. Their intriguing phase diagram can be even more complex if poly(acrylic acid) (PAAc) is interpenetrated within PNIPAM network to form Interpenetrating Polymer Network (IPN) microgels that exhibit an additional pH-sensitivity. The effect of the PAAc/PNIPAM polymeric ratio on both swelling capability and dynamics is still matter of investigation.

Microglia-Derived Microvesicles Affect Microglia Phenotype in Glioma.

Extracellular-released vesicles (EVs), such as microvesicles (MV) and exosomes (Exo) provide a new type of inter-cellular communication, directly transferring a ready to use box of information, consisting of proteins, lipids and nucleic acids. In the nervous system, EVs participate to neuron-glial cross-talk, a bidirectional communication important to preserve brain homeostasis and, when dysfunctional, involved in several CNS diseases. We investigated whether microglia-derived EVs could be used to transfer a protective phenotype to dysfunctional microglia in the context of a brain tumor.

Interpenetrating Polymer Network Microgels in Water: Effect of Composition on the Structural Properties and Electrosteric Interactions.

Microgels of cross-linked interpenetrating polymer networks (IPNs) are very versatile systems combining the properties of colloids and polymers. Herein we study IPN microgels composed of poly(N-isopropylacrylamide) and poly(acrylic acid) to understand how weight composition and reactant concentrations affect their structural, conformational and electrosteric properties in water. The results show that it is possible to drive the formation of microgels with the desired properties by adjusting IPN composition and preparation method during the synthesis.

Dynamical behavior of microgels of interpenetrated polymer networks.

Microgel suspensions of an interpenetrated Polymer Network (IPN) of PNIPAM and PAAc in DO have been investigated through dynamic light scattering as a function of temperature, pH and concentration across the Volume Phase Transition (VPT). The dynamics of the system is slowed down under H/D isotopic substitution due to different balance states between polymer/polymer and polymer/solvent interactions suggesting the crucial role played by H-bonding. The swelling behavior, reduced with respect to PNIPAM and water, has been described by the Flory-Rehner theory, tested for PNIPAM microgel and successfully expanded to higher order for IPN microgels.

Local structure of temperature and pH-sensitive colloidal microgels.

The temperature dependence of the local intra-particle structure of colloidal microgel particles, composed of interpenetrated polymer networks, has been investigated by small-angle neutron scattering at different pH and concentrations, in the range (299÷315) K, where a volume phase transition from a swollen to a shrunken state takes place. Data are well described by a theoretical model that takes into account the presence of both interpenetrated polymer networks and cross-linkers. Two different behaviors are found across the volume phase transition.

Effect of organic enrichment and thermal regime on denitrification and dissimilatory nitrate reduction to ammonium (DNRA) in hypolimnetic sediments of two lowland lakes.

We analyzed benthic fluxes of inorganic nitrogen, denitrification and dissimilatory nitrate reduction to ammonium (DNRA) rates in hypolimnetic sediments of lowland lakes. Two neighbouring mesotrophic (Ca' Stanga; CS) and hypertrophic (Lago Verde; LV) lakes, which originated from sand and gravel mining, were considered. Lakes are affected by high nitrate loads (0.