Passive biomonitoring of airborne microplastics using lichens: A comparison between urban, natural and protected environments.

Currently, natural and urban ecosystems are affected by different types of atmospheric deposition, which can compromise the balance of the environment. Plastic pollution represents one of the major threats for biota, including lichens. Epiphytic lichens have value as bioindicators of environmental pollution, climate change, and anthropic impacts. In this study, we aim to investigate the lichen bioaccumulation of airborne microplastics along an anthropogenic pollution gradient. We sampled lichens from the Genera Cladonia and Xanthoria to highlight the effectiveness of lichens as tools for passive biomonitoring of microplastics. We chose three sites, a "natural site" in Altipiani di Arcinazzo, a "protected site" in Castelporziano Presidential estate and an "urban site" in the centre of Rome. Overall, we sampled 90 lichens, observed for external plastic entrapment, melt in oxygen peroxide and analysed for plastic entrapment. To validate the method, we calculated recovery rates of microplastics in lichen. Particularly, 253 MPs particles were detected across the 90 lichen samples: 97 % were fibers, and 3 % were fragments. A gradient in the number of microplastic fibers across the sites emerged, with increasing accumulation of microplastics from the natural site (n = 58) to the urban site (n = 116), with a direct relationship between the length and abundance of airborne microplastic fibers. Moreover, we detected the first evidences of airborne mesoplastics entrapped by lichens. On average, the natural site experienced the shortest fibre length and the centre of Rome the longest. No differences in microplastics accumulation emerged from the two genera. Our results indicated that lichens can effectively be used for passive biomonitoring of microplastic deposition. In this scenario, the role of lichens in entrapping microplastics and protecting pristine areas must be investigated. Furthermore, considering the impact that airborne microplastics can have on human health and the effectiveness of lichens as airborne microplastic bioindicators, their use is encouraged.

Copper-Decorated Titanium Electrodes: Impact of Surface Modifications of Substrate on the Morphology and Electrochemical Performance.

This study investigates the effect of surface modifications of the titanium substrate on the growth of electrochemically deposited copper. These materials are intended to serve as cathodes in the electroreduction of nitrates in aqueous solutions. Surface modifications included the use of hydrogen fluoride for titanium etching and anodization to promote the growth of a structured titania nanotube array. The effect of an intermediate calcination step for the nanotubes before deposition was assessed along with a comparison to an untreated substrate electrode. The materials were comprehensively characterized by SEM, XRD, contact angle, potentiodynamic tests, EIS, and cyclic voltammetry. Their electrocatalytic ability was tested in the reduction of aqueous solutions containing nitrates. The results reveal that surface finishing impacted the shape and size of the Cu microparticles, as well as the nucleation mechanism enabling a crystal-facet-controllable synthesis. All the materials exhibited microsized copper particles with a spherical shape with some clusters. On the etched titanium surface, a high number of heterogeneous submicroscopic particles were also present. The thermally treated anodized substrate promoted the development of a combination of sparse microparticles corresponding to defect sites in amorphous titanium and the presence of a diffuse coating of octahedral nanosized particles whose growth was promoted by the tetragonal structure of anatase crystals. Electrochemical tests display reduced charge transfer resistance upon copper deposition on the modified substrates, which is indicative of the enhanced conductivity of the coated materials. Additionally, cyclic voltammetry and electrolysis experiments reveal the electrodes' potential for nitrate reduction, showing a better response for the etched titanium substrate (30% nitrate removal, after 2 h at 25 mA cm-2).

Multifunctional Platform for Covalent Titanium Coatings: Micro-FTIR, XPS, and NEXAFS Characterizations.

This work aims at preparing and characterizing a versatile multifunctional platform enabling the immobilization of macromolecules on a titanium surface by robust covalent grafting. Functionalized titanium is widely used in the biomedical field to improve its properties. Despite its high biocompatibility and osteointegrability, titanium implants are not very stable in the long term due to the onset of inflammation and bacterial infections. The proposed method allows the superficial insertion of three different organic linkers to be used as anchors for the attachment of biopolymers or bioactive molecules. This strategy used green solvents and is a good alternative to the proposed classic methods that employ organic solvents. The uniformly modified surfaces were characterized by micro-Fourier transform infrared spectroscopy (micro-FTIR), X-ray Photoelectron spectroscopy (XPS) and Near-Edge X-ray Absorption Fine Structure (NEXAFS). The latter made it possible to assess the orientation of the linker molecules with respect to the titanium surface. To test the efficiency of the linkers, two polymers (alginate and 2-(dimethylamino)-ethyl methacrylate (PDMAEMA)), with the potential ability to increase biocompatibility, were covalently attached to the titanium surfaces. The obtained results are a good starting point for the realization of stable polymeric coatings permanently bonded to the surface that could be used to extend the life of biomedical implants.

Cerium Coatings on Pristine and Nanostructured Ti and Ti6Al4V Surfaces: Bioactivity, Resistance in Simulated Inflammatory Conditions, and Antibacterial Performance.

Despite the significant contribution of titanium and its alloys for hard tissue regenerative medicine, some major issues remain to be solved. Implants' long-term stability is threatened by poor osseointegration. Moreover, bacterial adhesion and excessive inflammatory response are also to be considered in the design of a device intended to be integrated into the human body. Here, a cerium mixed oxide (CeOx) coating was realized on pristine and nanotubular-structured Ti and Ti6Al4V surfaces using a simple layer-by-layer drop-casting technique. Bioactivity, resistance in simulated inflammatory conditions, and bactericidal capacity were evaluated as a function of morphological surface characteristics combined with the cerium quantity deposited. The results obtained suggest that the presence of CeOx on the surfaces with nanotubes enhanced osseointegration, while on the non-nanostructured surfaces, this coating improved resistance under oxidative stress and provided excellent antibacterial properties.

Considerations on chemical composition of psammoma bodies: Automated detection strategy by infrared microspectroscopy in ovarian and thyroid cancer tissues.

Ectopic calcifications are observed in many soft tissues and are associated with several diseases, including cancer. The mechanism of their formation and the correlation with disease progression are often unclear. Detailed knowledge of the chemical composition of these inorganic formations can be very helpful in better understanding their relationship with unhealthy tissue. In addition, information on microcalcifications can be very useful for early diagnosis and provide insight into prognosis. In this work the chemical composition of psammoma bodies (PBs) found in tissues of human ovarian serous tumors was examined. The analysis using Micro Fourier Transform Infrared Spectroscopy (micro-FTIR) revealed that these microcalcifications contain amorphous calcium carbonate phosphate. Moreover, some PB grains showed the presence of phospholipids. This interesting result corroborates the proposed formation mechanism reported in many studies according to which ovarian cancer cells switch to a calcifying phenotype by inducing the deposition of calcifications. In addition, other techniques as X-ray Fluorescence Spectroscopy (XRF), Inductively Coupled Plasma Optical Emission Spectroscopy(ICP-OES) and Scanning electron microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDX) were performed on the PBs from ovary tissues to determine the elements present. The PBs found in ovarian serous cancer showed a composition comparable to PBs isolated from papillary thyroid. Based on the chemical similarity of IR spectra, using micro-FTIR spectroscopy combined with multivariate analysis, an automatic recognition method was constructed. With this prediction model it was possible to identify PBs microcalcifications in tissues of both ovarian cancers, regardless of tumor grade, and thyroid cancer with high sensitivity. Such approach could become a valuable tool for routine macrocalcification detection because it eliminates sample staining, and the subjectivity of conventional histopathological analysis.

Effect of Precursors on the Electrochemical Properties of Mixed RuOx/MnOx Electrodes Prepared by Thermal Decomposition.

Growing thin layers of mixed-metal oxides on titanium supports allows for the preparation of versatile electrodes that can be used in many applications. In this work, electrodes coated with thin films of ruthenium (RuOx) and manganese oxide (MnOx) were fabricated via thermal decomposition of a precursor solution deposited on a titanium substrate by spin coating. In particular, we combined different Ru and Mn precursors, either organic or inorganic, and investigated their influence on the morphology and electrochemical properties of the materials. The tested salts were: Ruthenium(III) acetylacetonate (Ru(acac)3), Ruthenium(III) chloride (RuCl3·xH2O), Manganese(II) nitrate (Mn(NO3)2·4H2O), and Manganese(III) acetylacetonate (Mn(acac)3). After fabrication, the films were subjected to different characterization techniques, including scanning electron microscopy (SEM), polarization analysis, open-circuit potential (OCP) measurements, electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) experiments. The results indicate that compared to the others, the combination of RuCl3 and Mn(acac) produces fewer compact films, which are more susceptible to corrosion, but have outstanding capacitive properties. In particular, this sample exhibits a capacitance of 8.3 mF cm-2 and a coulombic efficiency of higher than 90% in the entire range of investigated current densities.

Optical gas sensor based on the combination of a QD photoluminescent probe and a QD photodetector.

We report on a sensor architecture for detection of hazardous gases. The proposed device is based on the integration of a solid-state quantum dot (QD) photoluminescent probe with a QD photodetector on the same substrate. The effectiveness of the approach is demonstrated by developing a compact optical sensor for trace detection of explosives in air. The proposed architecture is very simple and consists of a silicon substrate with both surfaces coated with QD films. The upper layer acts as photoluminescent probe, pumped by a blue LED. The change of photoluminescence intensity associated to the interaction between the QDs and the target analyte is measured by the QD photodetector fabricated on the opposite side of the substrate. The sensor is mounted into a small chamber provided with the LED and the front-end electronics. The device is characterized by using nitrobenzene as representative nitroaromatic compound. Extremely low concentrations (down to 0.1 ppm) can be detected by the proposed device, with a theoretical detection limit estimated to be as low as 2 ppb. Results are repeatable and no ageing effect is observed over a 70 d period. The proposed architecture may provide a promising solution for explosive detection in air as well as other sensing applications, thanks to its sensitivity, simple fabrication process, practical usability and cost effectiveness.

A primer to traction force microscopy.

Traction force microscopy (TFM) has emerged as a versatile technique for the measurement of single-cell-generated forces. TFM has gained wide use among mechanobiology laboratories, and several variants of the original methodology have been proposed. However, issues related to the experimental setup and, most importantly, data analysis of cell traction datasets may restrain the adoption of TFM by a wider community. In this review, we summarize the state of the art in TFM-related research, with a focus on the analytical methods underlying data analysis. We aim to provide the reader with a friendly compendium underlying the potential of TFM and emphasizing the methodological framework required for a thorough understanding of experimental data. We also compile a list of data analytics tools freely available to the scientific community for the furtherance of knowledge on this powerful technique.

Identification of remodeled collagen fibers in tumor stroma by FTIR Micro-spectroscopy: A new approach to recognize the colon carcinoma.

The tumor stroma plays a pivotal role in colon cancer genesis and progression. It was observed that collagen fibers in the extracellular matrix (ECM) of cancer stroma, undergo a strong remodeling. These fibrous proteins result more aligned and compact than in physiological conditions, creating a microenvironment that favors cancer development. In this work, micro-FTIR spectroscopy was applied to investigate the chemical modifications in the tumor stroma. Using Fuzzy C-means clustering, mean spectra from diseased and normal stroma were compared and collagen was found to be responsible for the main differences between them. Specifically, the modified absorptions at 1203, 1238, 1284 cm-1 and 1338 cm-1 wavenumbers, were related to the amide III band and CH2 bending of side chains. These signals are sensitive to the interactions between the α-chains in the triple helices of collagen structure. This provided robust chemical evidence that in cancer ECM, collagen fibers are more parallelized, stiff and ordered than in normal tissue. Principal Component Analysis (PCA) applied to the spectra from malignant and normal stroma confirmed these findings. Using LDA (Linear Discriminant Analysis) classification, the absorptions 1203, 1238, 1284 and 1338 cm-1 were examined as spectral biomarkers, obtaining quite promising results. The use of a PCA-LDA prediction model on samples with moderate tumor degree further showed that the stroma chemical modifications are more indicative of malignancy compared to the epithelium. These preliminary findings have shown that micro-FTIR spectroscopy, focused on collagen signals, could become a promising tool for colon cancer diagnosis.

A Simple Cerium Coating Strategy for Titanium Oxide Nano-tubes' Bioactivity Enhancement.

Despite the well-known favorable chemical and mechanical properties of titanium-based materials for orthopedic and dental applications, poor osseointegration of the implants, bacteria adhesion, and excessive inflammatory response from the host remain major problems to be solved. Here, the antioxidant and anti-inflammatory enzyme-like abilities of ceria (CeOx) were coupled to the advantageous features of titanium nanotubes (TiNTs). Cost-effective and fast methods, such as electrochemical anodization and drop casting, were used to build active surfaces with enhanced bioactivity. Surface composition, electrochemical response, and in vitro ability to induce hydroxyapatite (HA) precipitation were evaluated. The amount of cerium in the coating did not significantly affect wettability, yet a growing ability to induce early HA precipitation from simulated body fluid (SBF) was observed as the oxide content at the surface increased. The presence of 4%wt CeOx was also able to stimulate rapid HA maturation in a (poorly) crystalline form, indicating an interesting potential to induce rapid in vivo osseointegration process.

A Nanoindentation Approach for Time-Dependent Evaluation of Surface Free Energy in Micro- and Nano-Structured Titanium.

Surface free energy (SFE) of titanium surfaces plays a significant role in tissue engineering, as it affects the effectiveness and long-term stability of both active coatings and functionalization and the establishment of strong bonds to the newly growing bone. A new contact-mechanics methodology based on high-resolution non-destructive elastic contacting nanoindentation is applied here to study SFE of micro- and nano-structured titanium surfaces, right after their preparation and as a function of exposure to air. The effectiveness of different surface treatments in enhancing SFE is assessed. A time-dependent decay of SFE within a few hours is observed, with kinetics related to the sample preparation. The fast, non-destructive method adopted allowed for SFE measurements in very hydrophilic conditions, establishing a reliable comparison between surfaces with different properties.

On the chemical composition of psammoma bodies microcalcifications in thyroid cancer tissues.

Recently the knowledge of chemical composition of pathological mineralizations is an important topic extensively studied because it could give more in-depth information to understand pathologies themselves and to improve prevention methods. In this work, psammoma bodies (PBs) microcalcifications in thyroid cancer tissue are investigated by different and complementary analytical methods as: micro-Fourier transformed spectroscopy, X-ray fluorescence spectroscopy, Inductively Coupled plasma Optical Emission Spectroscopy (ICP-OES) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy imaging (EDX). For the first time the micro-FTIR analysis of the only inorganic phase isolated from PBs was reported. Signals of the recorded spectrum showed that the main component of the calcifications is the amorphous carbonated calcium phosphate, and the IR spectrum of thyroid PBs is strongly consistent with that of PBs in human ovarian tumors. The XRF and the ICP analysis detected also the presence of iron ad zinc in thyroid PBs. These results are validated by scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy imaging (EDX) carried out on tissue samples of the papillary thyroid carcinoma. By these analytical methods magnesium and sodium were detected within PBs while the presence of iron was confirmed by the Perls test. Summarizing the results of applied analytical methods, the main detected elements within the thyroid psammoma bodies are Ca, P, Mg, Na, Fe and Zn. Magnesium and sodium are found in malignant breast cancer microcalcifications, thus they seem correlated to neoplastic transformation. The Fe and Zn elements could give information about the origin of these pathological microcalcifications.

Micro-FTIR spectroscopy as robust tool for psammoma bodies detection in papillary thyroid carcinoma.

The presence of psammoma bodies (PBs), concentric lamellated calcified structures, in thyroid tissues is considered a reliable diagnostic marker for Papillary thyroid carcinoma (PTC) and has been correlated to aggressive tumour behaviours such as multifocality and lymph node metastasis. Fourier transform infrared (FTIR) microspectroscopy already proved to be a powerful tool for biological tissues study thanks to its ability to spatially resolve information on the chemical composition of the analysed samples. FTIR maps were collected from thyroid tumour resections and analysed by multivariate unsupervised Principal Component Analysis (PCA) and Clustering (K-means and fuzzy c-means clustering) techniques. The resulting spectral images were compared to the corresponding hematoxylin-eosin stained tissue section which provided histopathological validation. The 850-1100 cm-1 spectral range was the most reliable for detection of PBs and the characteristic bands of carboapatite, present in this region, were correctly identified by the multivariate techniques. These findings disclose the possibility to use a combination of FTIR microspectroscopy and multivariate spectral processing as objective and robust tools for automated PBs recognition and consequently for PTC early diagnosis.

Chitosan functionalization of titanium and Ti6Al4V alloy with chloroacetic acid as linker agent.

In this work, a new covalent grafting of chitosan on titanium and Ti6Al4V alloy surfaces is reported using chloroacetic acid as linker agent. Good results were obtained both on titanium and on Ti6Al4V alloy. The effect of the surface acid pretreatments on the subsequent functionalization with chitosan is evaluated. The morphological aspect of acid etched metal surfaces before chitosan grafting has been characterized by scanning electron microscopy (SEM). The presence of carboxylic groups on metal surfaces and then the efficiency of chitosan covalent immobilization were detected by Fourier transformed infrared-Attenuated Total Reflectance (FTIR-ATR) and X-Ray photoelectron spectroscopy (XPS). Cyclic voltammetry tests, using the functionalized titanium and Ti6Al4V samples as electrodes, were conducted in different aqueous solutions, to detect the presence of the homogeneous overlayer of chitosan on the surface, and to evaluate the importance of the carboxyl groups as linker agent.

Functionalization of poly(ε-caprolactone) surface with lactose-modified chitosan via alkaline hydrolysis: ToF-SIMS characterization.

Functionalization of poly(ε-caprolactone) (PCL) was performed via hydrolysis and subsequent grafting of lactose-modified chitosan (chitlac) at two different degrees of derivatization (9% and 64%). Time of flight secondary ion mass spectrometry (ToF-SIMS) and multivariate analysis (principal component analysis) were successfully applied to the characterization of PCL surface chemistry, evidencing changes in the biopolymer surface following base-catalyzed hydrolysis treatment. ToF-SIMS analysis also confirmed positive EDC/NHS-catalyzed (EDC: N-ethyl-N'-(3-(dimethylamino)propyl)carbodiimide; NHS: N-hydroxysuccinimide) immobilization of chitlac onto activated PCL surface, with formation of amide bonds between PCL surface carboxyl groups and amine residues of chitlac. Yield of grafting reaction was also shown to be dependent upon the lactosilation degree of chitlac.

Umpolung reactions in an ionic liquid catalyzed by electrogenerated N-heterocyclic carbenes. Synthesis of saturated esters from activated α,ß-unsaturated aldehydes.

The umpolung reaction of α,ß-unsaturated aldehydes to saturated esters has been carried out in an ionic liquid by organocatalysis of electrogenerated NHC. The roles of solvent, precatalyst and proton donor of the ionic liquid have been verified and good to high yields of esters have been obtained using a "green" and mild methodology.

Electrogenerated NHC as an organocatalyst in the Staudinger reaction.

Electrogenerated N-heterocyclic carbene can behave as an organocatalyst in the Staudinger reaction (from imine and acyl chloride) in a very polar solvent, such as an ionic liquid.

Electrochemically promoted C-N bond formation from acetylenic amines and CO2. Synthesis of 5-methylene-1,3-oxazolidin-2-ones.

[reaction: see text] An efficient electrochemical synthesis of 5-methylene-1,3-oxazolidin-2-ones (2a-h) from acetylenic amines (1a-h) and carbon dioxide has been achieved by direct electrolysis of solution of MeCN and Et4NPF6 containing the amine, with subsequent CO2 bubbling and heating. The yields vary from good to excellent, the conditions are mild, and the use of toxic and harmful chemicals and catalysts is avoided.

Stereoselective electrochemical carboxylation: 2-phenylsuccinates from chiral cinnamic acid derivatives.

Chiral 2-phenyl succinic ester derivatives have been obtained under mild conditions, in short times and with satisfactory yields by electrochemical reduction of chiral cinnamic acid derivatives under a CO2 atmosphere. When 4R-(diphenylmethyl)-oxazolidin-2-one was used as a chiral auxiliary the two diastereoisomers could be easily separated by flash chromatography and the R-isomer was obtained as major product.

An innovative strategy for electrochemically-promoted addition reactions.

A new strategy based on the catalytic release of the supporting electrolyte agent in the electrolysis medium proved to be effective for the direct electroactivation of suitable C-H acid-containing compounds vs. catalytic addition processes, under solvent-free conditions.