Metal-free phthalimide-labeled peptide nucleic acids for electrochemical biosensing applications

Peer reviewedPublisher PD

Sintesi e applicazioni di agenti trasferitori di catena per la modifica di superfici di vetro e ossido di silicio mediante polimeri ottenuti con processi di polimerizzazione raft

Il processo RAFT (Radical Addiction Fragmentation Transfer polymerization) consente di condurre la sintesi di polimeri ad architettura controllata. Mediante le polimerizzazioni viventi \ue8 possibile generare polimeri a blocchi. Spacer macromolecolari vengono introdotti attraverso la sintesi di un primo segmento direttamente legato alle superfici. Agenti trasferitori di catena presenti nel primo segmento, permettono di riiniziare la polimerizzazione di un secondo segmento, costituito da monomeri reattivi verso biomolecole. I CTAs (Chain Transfer Agents) nel processo RAFT sono anche in grado di controllare la cinetica di polimerizzazione al fine di ottenere polimeri con Peso Molecolare uniforme (Indice di polidispersit\ue0 ~ 1). I polimeri a blocchi cos\uec ottenuti trovano interessanti applicazioni nel campo del Biosensoring e dell\u2019Elettroforesi Capillare, per la modifica di superfici di vetro e di silicio. I numerosi vantaggi dei processi RAFT, quali l\u2019aumento della densit\ue0 superficiale del polimero che consente l\u2019incremento dei gruppi reattivi e il miglioramento dell\u2019accessibilit\ue0 delle biomolecole porterebbero ad un aumento della sensibilit\ue0 di questi sistemi analitici. Sono stati quindi preparati nuovi esteri del ditiobenzoato come agenti trasferitori di catena facenti parte della classe degli amido-based. Le polimerizzazioni, in solvente organico, di monomeri di tipo acrilammidico mediata da questi CTA, hanno permesso la costruzione di building blocks aventi nel segmento pi\uf9 esterno monomeri capaci di immobilizzare biomolecole quali oligonucleotidi e proteine nella tecnologia dei microarrays. Altri CTAs amido-based, sono stati preparati al fine di ottenere polimeri covalentemente legati alle superfici vetrose di capillari per elettroforesi. I rivestimenti polimerici cos\uec ottenuti, grazie all\u2019incremento della densit\ue0 superficiale, saranno utilizzati per migliorare l\u2019efficienza di soppressione del Flusso ElettroendoOsmotico (EOF) e la stabilit\ue0 nel temp

Front Cover: Diversified Syntheses of Tetrathia[7]helicenes by Metal‐Catalyzed Cross‐Coupling Reactions (Eur. J. Org. Chem. 3/2021)

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Rh(I) Coordination Chemistry of Chiral α-Aminophosphine(η 6 -arene)chromium Tricarbonyl Ligands

International audienceThe diastereoselective addition of Ph2PH to the chiral ortho-substituted η6-benzaldimine complexes (η6-o-XC6H4CHNAr)Cr(CO)3 (1, X = MeO, Ar = p-C6H4OMe; 2, X = Cl, Ar = Ph) leads to the formation of the corresponding chiral aminophosphines (α-P,N) Ph2P−CH(Ar1)−NHAr2 (3, Ar1 = o-C6H4(OCH3)[Cr(CO)3], Ar2 = p-C6H4OCH3; 4, Ar1 = o-C6H4Cl[Cr(CO)3], Ar2 = Ph) in equilibrium with the starting materials. The uncomplexed benzaldimine (o-ClC6H4CHNPh), 2‘, analogously produces an equilibrium amount of the corresponding aminophosphine Ph2P−CH(Ar1)−NHAr2 (4‘, Ar1 = o-C6H4Cl, Ar2 = Ph). Depending on the equilibrium constant, the subsequent addition of 1/2 equiv of [RhCl(COD)]2 (COD = 1,5-cyclooctadiene) leads to either Ph2PH oxidative addition in the case of 3 or to the corresponding [RhCl(COD)(α-P,N)] complexes [RhCl(COD)(Ph2P−CH{o-C6H4Cl[Cr(CO)3]}−NHPh)] (5) and [RhCl(COD)(Ph2P−CH(o-C6H4Cl)−NHPh)] (5‘) in the cases of the aminophosphines 4 and 4‘. The addition of the latter ligands, as racemic mixtures, to 1/4 equiv of [Rh(CO)2Cl]2 leads to the [RhCl(CO)(α-P,N)2] complexes [RhCO(Ph2P−CH{o-C6H4Cl[Cr(CO)3]}−NHPh)2Cl] (7) or [RhCO(Ph2P−CH(o-C6H4Cl)−NHPh)2Cl] (7‘) as mixtures of (RC,SC)/(SC,RC) and (RC,RC)/(SC,SC) diastereomers. The rhodium complexes 5 and 7‘ have been fully characterized by IR and 31P NMR spectroscopies and X-ray crystallography. These compounds exhibit intramolecular Rh−Cl···H−N interactions in the solid state and in solution. The stability of the new rhodium complexes has been studied under different CO pressures. Under 1 atm of CO, 5 is converted to an unstable complex [RhCl(CO)2(α-P,N)], 6, which undergoes ligand redistribution leading to 7 plus an unidentified complex. This reaction is inhibited under higher CO or syngas pressure, as confirmed by the observation of the same catalytic activity in hydroformylation when styrene was added to a catalytic mixture that was either freshly prepared or left standing for 20 h under high CO pressure

Pressure mapping with textile sensors for compression therapy monitoring

Compression therapy is the cornerstone of treatment in the case of venous leg ulcers. The therapy outcome is strictly dependent on the pressure distribution produced by bandages along the lower limb length. To date, pressure monitoring has been carried out using sensors that present considerable drawbacks, such as single point instead of distributed sensing, no shape conformability, bulkiness and constraints on patient’s movements. In this work, matrix textile sensing technologies were explored in terms of their ability to measure the sub-bandage pressure with a suitable temporal and spatial resolution. A multilayered textile matrix based on a piezoresistive sensing principle was developed, calibrated and tested with human subjects, with the aim of assessing real-time distributed pressure sensing at the skin/bandage interface. Experimental tests were carried out on three healthy volunteers, using two different bandage types, from among those most commonly used. Such tests allowed the trends of pressure distribution to be evaluated over time, both at rest and during daily life activities. Results revealed that the proposed device enables the dynamic assessment of compression mapping, with a suitable spatial and temporal resolution (20 mm and 10 Hz, respectively). In addition, the sensor is flexible and conformable, thus well accepted by the patient. Overall, this study demonstrates the adequacy of the proposed piezoresistive textile sensor for the real-time monitoring of bandage-based therapeutic treatments

(BO)2 -Doped Tetrathia[7]helicene: A Configurationally Stable Blue Emitter

Helicenes combine two central themes in chemistry: extended pi-conjugation and chirality. Hetero-atom doping preserves both characteristics and allows modulation of the electronic structure of a helicene. Herein, we report the (BO)(2)-doped tetrathia[7]helicene 1, which was prepared from 2-methoxy-3,3 '-bithiophene in four steps. 1 is formally derived by substituting two (Mes)B-O moieties in place of (H)C=C(H) fragments in two benzene rings of the parent tetrathia[7]helicene. X-ray crystallography revealed a dihedral angle of 50.26(9)degrees between the two terminal thiophene rings. The (P)-/(M)-1 enantiomers were separated by chiral HPLC and are configurationally stable at room temperature. The experimentally determined enantiomerization barrier of 27.4 +/- 0.1 kcal mol(-1) is lower than that of tetrathia[7]helicene (39.4 +/- 0.1 kcal mol(-1)). The circular dichroism spectra of (P)- and (M)-1 show a perfect mirror-image relationship. 1 is a blue emitter (lambda(em)=411 nm) with a photoluminescence quantum efficiency of phi(PL)=6 % (cf. tetrathia[7]helicene: lambda(em)approximate to 405 nm, phi(PL)=5 %)