Valerio Causin

Forensic differentiation of paper by X-ray diffraction and infrared spectroscopy

The possibility to discriminate between sheets of paper can be of considerable importance in questioned document examinations. 19 similar types of office paper were characterized by infrared spectroscopy and X-ray diffraction to individuate the most discriminating features that could be measured by these techniques. The discriminating value associated to them was also assessed. By using a sequence of these two techniques, all the samples could be differentiated.

Water-soluble peptide-coated nanoparticles: control of the helix structure and enhanced differential binding to immune cells.

The stabilizing action of C(α)-tetrasubstituted α-amino acids inserted into a sequence of short peptides allowed for the first time the preparation of water-soluble nanoparticles of different materials coated with a helix-structured undecapeptide. This peptide coating strongly favors nanoparticle uptake by human immune system cells.

The Discrimination Potential of Ultraviolet‐Visible Spectrophotometry, Thin Layer Chromatography, and Fourier Transform Infrared Spectroscopy for the Forensic Analysis of Black and Blue Ballpoint Inks

Abstract:  The knowledge of the discriminating power of analytical techniques used for the differentiation of writing inks can be useful when interpreting results. Ultraviolet‐visible (UV‐VIS) spectrophotometry, thin layer chromatography (TLC), and diffuse reflectance Fourier transform infrared spectroscopy (FT‐IR) were used to examine a population of 21 black and 12 blue ballpoint writing inks. Based on corroborative results of these methods, the discrimination power for UV‐VIS, TLC, and FT‐IR was determined to be 100% and 98% for the black and blue inks, respectively. Generally, TLC and UV‐VIS can be used to differentiate the colorant components (i.e., dyes and some pigments) found in inks. As FT‐IR can be utilized to identify some of the noncolorant components, it was determined to be an excellent complementary technique that can be implemented into an analytical scheme for ink analysis.

Highly PEGylated silica nanoparticles: “ready to use” stealth functional nanocarriers

The peculiar properties of silica nanoparticles make them well suited to the development of smart nanomaterials for medicine. Here we report a new procedure to prepare doped and PEGylated silica-based nanoparticles. Thus, a complex multifunctional system is obtained simply by a one-pot reaction followed by a straightforward purification procedure. Control of the nanoparticles final size is obtained by carefully choosing reactants and conditions. Moreover, reactive functional groups necessary to allow subsequent bioconjugation are easily introduced in the PEG coating by the same procedure. Unprecedented high-density surface coating is obtained and this successfully stabilizes the nanoparticles against aggregation both in saline solution and in the presence of serum proteins. The absence of cytotoxicity and “stealth” behaviour toward phagocytic capture by human macrophages has been demonstrated and this enables such nanosystems as candidates for the development of drug delivery agents.

Effect of asymmetric substitution on the mesomorphic behaviour of low-melting viologen salts of bis(trifluoromethanesulfonyl)amide

We report on the synthesis and characterisation of novel ionic liquid crystals and ionic liquids based on asymmetric viologen salts of bis(trifluoromethanesulfonyl)amide (Tf2N−). The thermotropic behaviour of the salts has been thoroughly characterized by DSC, X-ray diffraction and polarized light optical microscopy. The occurrence of smectic mesophases and the temperature range over which they are stable has been discussed as a result of the asymmetry of the viologen dications. Strongly asymmetric systems, not showing mesomorphism, have a rather low melting point (just beyond 40 °C) while slightly asymmetric samples exhibit a smectic phase with a wide range of stability, from about 0 °C up to above 140 °C, thus increasing the range of stability of the mesophase observed for the symmetric compounds. Finally, we report on the lyotropic behaviour in non-polar solvents, such as benzene, where liquid clathrates have been found.

Ionic liquid crystals based on viologen dimers: tuning the mesomorphism by varying the conformational freedom of the ionic layer

ABSTRACT We investigated the liquid crystal behaviour of newly synthesised bistriflimide salts of symmetric viologen dimers. A smectic A phase was observed for intermediate spacer lengths and for relatively long lateral alkyl chains. The systems were characterised by thermal analysis, polarised optical microscopy, X-ray scattering and solid-state NMR. An intermediate ordered smectic phase was also exhibited by the compounds (except for systems with very short lateral chains) consisting of molten layers of alkyl chains and partially ordered ionic layers. These results, relating to the mesomorphic behaviour of viologen salts, are qualitatively compared to those of the more common imidazolium salts, highlighting the importance of the conformational degrees of freedom of the anions and of the cationic core. It appears that fine tuning of the conformational degrees of freedom of the ionic layer is an important component of mesophase stabilisation. Graphical Abstract

Next-Generation Polymer Shells for Inorganic Nanoparticles are Highly Compact, Ultra-Dense, and Long-Lasting Cyclic Brushes

Cyclic poly-2-ethyl-2-oxazoline (PEOXA) ligands for superparamagnetic Fe3 O4 nanoparticles (NPs) generate ultra-dense and highly compact shells, providing enhanced colloidal stability and bio-inertness in physiological media. When linear brush shells fail in providing colloidal stabilization to NPs, the cyclic ones assure long lasting dispersions. While the thermally induced dehydration of linear PEOXA shells cause irreversible aggregation of the NPs, the collapse and subsequent rehydration of similarly grafted cyclic brushes allow the full recovery of individually dispersed NPs. Although linear ligands are densely grafted onto Fe3 O4 cores, a small plasma protein such as bovine serum albumin (BSA) still physisorbs within their shells. In contrast, the impenetrable entropic shield provided by cyclic brushes efficiently prevents nonspecific interaction with proteins.

Characteristics of TEMPO-oxidized cellulose fibril-based hydrogels induced by cationic ions and their properties

Cellulose microfibrils (CMFs) and cellulose nanofibrils (CNFs) were isolated from hardwood pulp by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation, which produced negatively-charged carboxylate groups on their surface. First, these CMFs and CNFs were used to prepare microgels and nanogels, respectively, at different concentrations of cellulose and trivalent Al3+ cation by inducing ionic interactions between the negatively charged carboxylates and the metal cation. Then, two other cations (i.e., divalent Ca2+ and monovalent H+ were employed to understand the structure–property relationship these hydrogels. We characterized their morphology, chemical groups, mechanical properties, surface area, and pore size, and evaluated their drug-release behaviors using theophylline. Compared to the hydrogels prepared from divalent or monovalent cations, both microgel and nanogel prepared from trivalent Al3+ showed the highest stiffness and compressive strength, which indicated that they possessed the strongest ionic cross-linking via intra- and inter-fibrillar interactions. With a decrease in the valency of the cation used, the surface area of both hydrogels decreased, while their pore radius and calculated fibril diameter increased, indicating that a higher valency cation produced a hydrogel with higher porosity and a tighter network structure. The nanogel prepared from Al3+ also showed the highest swelling ratio and the lowest release of theophylline, while that of microgel was, in contrast, consistent. The low total drug-release behavior in nanogels was attributed to their compact and highly porous structure. The Higuchi model was the best-fit model of drug release kinetics. These results indicate that the characteristics and internal structure of hydrogel has a great impact on its properties and drug-release profile, and that it may be possible to finely tune hydrogel properties and drug release profile by altering the internal structure of hydrogels during its preparation.

Polymers on the crime scene: How can analytical chemistry help to exploit the information from these mute witnesses?

Polymers are ubiquitous in everyday life, so it is very likely that they may be encountered on a crime scene as well. In order to exploit to the fullest extent the amount of information that these items contain, it is necessary to properly characterise them. The state of the art and the most recent advances in the forensic characterisation of polymeric items are presented. The qualitative and quantitative determination of the formulation is discussed, along with more innovative approaches, that focus on the features directly related to the macromolecular nature of such traces (molecular weight, degree of crystallinity, presence of comonomers, etc.).

Innovative biofilm inhibition and anti-microbial behavior of molybdenum sulfide nanostructures generated by microwave-assisted solvothermal route

The incessant use of antibiotics against infectious diseases has translated into a vicious circle of developing new antibiotic drug and its resistant strains in short period of time due to inherent nature of micro-organisms to alter their genes. Many researchers have been trying to formulate inorganic nanoparticles-based antiseptics that may be linked to broad-spectrum activity and far lower propensity to induce microbial resistance than antibiotics. The way-out approaches in this direction are nanomaterials based (1) bactericidal and (2) bacteriostatic activities. We, herein, present hitherto unreported observations on microbial abatement using non-cytotoxic molybdenum disulfide nanostructures (MSNs) which are synthesized using microwave assisted solvothermal route. Inhibition of biofilm formation using MSNs is a unique feature of our study. Furthermore, this study evinces antimicrobial mechanism of MSNs by reactive oxygen species (ROS) dependent generation of superoxide anion radical via disruption of cellular functions.