Photoluminescence-Based Techniques for the Detection of Micro- and Nanoplastics

The growing numbers related to plastic pollution are impressive, with ca. 70 % of produced plastic (>350 tonnes/year) being indiscriminately wasted in the environment. The most dangerous forms of plastic pollution for biota and human health are micro- and nano-plastics (MNPs), which are ubiquitous and more bioavailable. Their elimination is extremely difficult, but the first challenge is their detection since existing protocols are unsatisfactory for microplastics and mostly absent for nanoplastics. After a discussion of the state of the art for MNPs detection, we specifically revise the techniques based on photoluminescence that represent very promising solutions for this problem. In this context, Nile Red staining is the most used strategy and we show here its pros and limitations, but we also discuss other more recent approaches, such as the use of fluorogenic probes based on perylene-bisimide and on fluorogenic hyaluronan nanogels, with the added values of biocompatibility and water solubility

Towards a More Sustainable Photocatalyzed α-Arylation of Amines: Green Solvents, Catalyst Recycling and Low Loading

A more sustainable and efficient protocol for the photocatalytic α-amino arylation promoted by fac-Ir(ppy)3 was developed. Three noteworthy results were achieved: i) the replacement of toxic medium DMA with the greener solvents NBP and NHP, and the concurrent improvement of the process efficiency by lowering both the amine and the base amount; ii) the development of a recycling protocol for both the sustainable solvent NHP and the commercially available costly photocatalyst fac-Ir(ppy)3, achieving environmental and economic benefits. This approach to the photocatalyst recovery avoids very demanding catalyst structural modifications; iii) the protocol in green solvents proved to be scalable up to 10 mmol of limiting reagent, maintaining excellent performance also lowering the photocatalyst loading down to 0.05 mol%. This is the first example of photocatalytic α-arylation of amines promoted by such a low amount of catalyst. Lastly, the versatility of this approach was demonstrated by extending the use of the green solvent NBP to another photoredox process

Chemodivergent Photocatalytic Synthesis of Dihydrofurans and β,γ-Unsaturated Ketones

A synthetic procedure, catalysed by Ir(ppy)3 under visible-light irradiation, for the chemodivergent synthesis of 2,3-dihydrofurans (3) or β,γ-unsaturated ketones (7) starting from α-halo ketones (1) and alkenes (2) has been developed. The mild reaction conditions and the redox-neutral nature of the process make it particularly sustainable avoiding the use of both sacrificial reactants and stoichiometric strong oxidants. Careful experimental investigations, supported by DFT calculations, allowed to disclose in details a possible mechanistic pathway and to direct the synthesis chemodivergently either toward 3 or 7, depending not only on the nature of the substrates, but also on the choice of the experimental conditions. (Figure presented.)

Allenamides Playing Domino: A Redox-Neutral Photocatalytic Synthesis of Functionalized 2-Aminofurans

A photoredox catalytic synthesis of functionalized 2-aminofurans is proposed starting from α-halo carbonyl substrates and N-allenamides. The protocol proves to be efficient and sustainable thanks to: i) the use of visible light as green energy source, ii) the redox-neutral nature of the transformation, allowing to avoid additives and strong oxidants, iii) the mild reaction conditions and the functional groups tolerance, iv) the low photocatalyst loading and the absence of excess reagents, v) the one-pot formation of three new bonds in a domino sequence. According to our mechanistic hypothesis, the transformation is configured as a double radical-polar crossover reaction, in which the photocatalyst is excited, oxidized and reduced twice for each molecule of 2-aminofuran produced. The novelty of the designed synthetic approach also lies in the use of N-allenamides as substrates, which, after the addition of the first electrophilic radical, preserve a further reactive π-system, making possible the addition of a second α-keto radical and enabling the installation of a keto functionality at a remote position. The good yields, the broad scope, and the possibility to further synthetically elaborate the obtained furans make this protocol particularly promising for the construction of useful products. (Figure presented.)

New lanthanide metalloligands and their use for the assembly of Ln-Ag bimetallic coordination frameworks : stepwise modular synthesis, structural characterization, and optical properties

Stepwise self-assembly processes using new lanthanide metalloligands (Ln-MLs) and silver salts have been successfully applied to isolate 4f-4d heterometallic coordination networks of four different structural types. In particular, the new lanthanide tetrakis-chelate complexes NEt4[Ln(L1)4] [HL1 = 1,3-bis(4\u2032-cyanophenyl)-1,3-propanedione; Ln = Eu (1a), La (1b), Nd (1c), Tb (1d)] and NEt4[Ln(L2)4] (HL2 = 1,3-bis(4\u2032-pyridyl)-1,3-propanedione; Ln = Eu (1e), Nd (1f)] have been synthetized, characterized and reacted with different silver salts. The use of NEt4[Ln(L1)4] allowed then to isolate and characterize i) neutral one-dimensional ladder-like species of formula [Ln(L1)4Ag] [Ln = Eu (2a), La(2b), Nd(2c), Tb(2d)] and ii) their supramolecular isomers [Ln(L1)4Ag] [Ln = Eu (3a), La (3b), Nd (3c), Tb (3d)] showing a very unstable 2D network structure, iii) the cationic 2D species [Ln(L1)4Ag2]X [Ln = Eu, X = PF6\u203e, CF3SO3\u203e, ClO4\u203e (4a\u20134c); Ln = Tb, Nd, La X = PF6\u203e (4d\u20134f)] and, only for lanthanum, iv) a fourth 2D species of formula [La(L1)4(H2O)Ag] (5) and sql topology. Of the eight nitrile groups on the MLs potentially coordinating, only a partial number is used for networking with Ag(I), that is, only two in families 2 and 3, and four in family 4 and in network 5. Finally, the four structural types are rationalized in terms of a new \u201cpincer-like\u201d Secondary Building Unit (SBU) consisting of a silver cation coordinating two central carbon atoms (\uf067 carbon) of two different diketonate ligands on the same ML. Therefore, it is shown that compounds 5, 4 and 2\u20133 contain, respectively, none, one or two of such pincer-like SBUs. The luminescence properties of the Ln-MLs and some of their polymeric species have been also investigated in solution and in the solid state

Biodistribution of Near-Infrared Fluorescent Nanoparticles:an in vivo study

Introduction: Research in new fluorescent nanoparticles is today an important field for preclinical studies in the optical imaging technique area. Great expectation concerns new fluorescent markers engeneered for particular applications (conjugated with antibody or pharmaceutical compounds) or alone to study nano-compound intrinsic behaviour in living organisms. In particular, nanosized fluorescent particles (silica nanopaticles1 and quantum dots2-3) are promising tools for the development of luminescent probes and markers provided by great brightness and high photostability respect to traditional organic fluorophores. Here we present an in vivo study of biodistribution in a small laboratory animal model of silica-core / PEG-shell fluorescent nanoparticles (20-30nm) doped with a CY7 NIR emitting dye ((2-((E)-2-((E)-2-chloro-3-((Z)-2-(3-ethyl-1,1-dimethyl-1H-benzo[e]indol-2(3H)-ylidene) ethylidene)cyclohex-1-enyl)vinyl)-3-ethyl-1,1-dimethyl-1H-benzo[e]indolium iodide). Silica particles, due to the recognized low toxicity of their chemical composition, could be interesting for future clinical applications. Methods: Silica fluorescent nanoparticles biodistribution was studied. We have observed with Optical Imager the biodistribution kinetics and tissue accumulation during three hours immediately after fluorescent tracer administration, in gas anaesthetized mice. Optical images were acquired with IVIS\uae 200 (Xenogen Corporation, Alameda USA). Data were extracted using Living Image 2.6 software. Silica nanoparticles, with an emission peak around 810 nm, were excited with ICG exc. filter (710-760 nm) and the fluorescent emission acquired with ICG ems. filter (810-875 nm). Results: Biodistribution kinetics and accumulation of the silica nanoparticles was studied in all anatomical districts4 for three hours after injection using the fluorescent signal escaping from the animal surface and acquired in the optical images. The fluorescent emission was measured on anatomical Region of Interest (ROIs) traced on the optical images corresponding to the plane projection of the organs. and directly on the surgically extracted organs. Actually we are analysing section from explanted organs with the aim of histologically localizing the exact accumulation sites and to detect the (nanoparticles) fluorescent signal. Conclusions: Fluorescent silica-core / PEG-shell nanoparticles showed a very good fluorescent efficiency comparable with commercial semiconductors nanocrystals (quantum dots, QDs) actually used in preclinical research. They can be successfully used for in vivo applications allowing to follow the biodistribution for hours in a small animal model. The very low intrinsic toxicity of the chemical composition encourages the employ of such fluorescent markers for many in vivo applications in preclinical research and to investigate the possibility to engineering them with biomelcules for targeting bio-analytical applications

Determinants of weight, psychological status, food contemplation and lifestyle changes in patients with obesity during the COVID-19 lockdown: a nationwide survey using multiple correspondence analysis

Introduction The corona virus disease 2019 (COVID-19) pandemic forced most of the Italian population into lockdown from 11 March to 18 May 2020. A nationwide survey of Italian Clinical Nutrition and Dietetic Services (Obesity Centers or OCs) was carried out to assess the impact of lockdown restrictions on the physical and mental wellbeing of patients with obesity (PWO) who had follow-up appointments postponed due to lockdown restrictions and to compare determinants of weight gain before and after the pandemic. Methods We designed a structured 77-item questionnaire covering employment status, diet, physical activity and psychological aspects, that was disseminated through follow-up calls and online between 2 May and 25 June 2020. Data were analyzed by multiple correspondence analysis (MCA) and multiple linear regression. Results A total of 1,232 PWO from 26 OCs completed the questionnaires (72% female, mean age 50.2 +/- 14.2 years; mean BMI 34.7 +/- 7.6 kg/m(2); 41% obesity class II to III). During the lockdown, 48.8% gained, 27.1% lost, while the remainder (24.1%) maintained their weight. The mean weight change was +2.3 +/- 4.8 kg (in weight gainers: +4.0 +/- 2.4 kg; +4.2% +/- 5.4%). Approximately 37% of participants experienced increased emotional difficulties, mostly fear and dissatisfaction. Sixty-one percent reduced their physical activity (PA) and 55% experienced a change in sleep quality/quantity. The lack of online contact (37.5%) with the OC during lockdown strongly correlated with weight gain (p < 0.001). Using MCA, two main clusters were identified: those with unchanged or even improved lifestyles during lockdown (Cluster 1) and those with worse lifestyles during the same time (Cluster 2). The latter includes unemployed people experiencing depression, boredom, dissatisfaction and increased food contemplation and weight gain. Within Cluster 2, homemakers reported gaining weight and experiencing anger due to home confinement. Conclusions Among Italian PWO, work status, emotional dysregulation, and lack of online communication with OCs were determinants of weight gain during the lockdown period