Full-field photonic biosensors based on tunable bio-doped sol-gel glasses

A full-field generic photonic biosensor approach, which relies on a bio-doped polymeric strip waveguide configuration, is described. We show the potential of tailor-made hybrid polymeric materials prepared by sol-gel technology for the fabrication of ultra-compact biosensor devices, where both the transducer and the recognition elements are merged into one single microstructure. Such devices were fabricated by micromolding in capillaries (MIMIC) soft lithographic technique. In contrast to evanescent field sensors, the sensor response does not only rely on the interaction of the evanescent wave with the recognition element, but on the interaction of the whole field, thus enabling a reduction of the sensor dimensions and/or a decrease of its limit of detection (LOD). The potential of this generic approach was demonstrated by developing a biosensor for the detection of H(2)O(2) using horseradish peroxidase (HRP) as the doping agent. Solutions containing 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS) and different concentrations of H(2)O(2) were dispensed over the waveguide and the green-coloured cation radical ABTS*(+) product was mainly obtained inside the photonic structure, resulting in a maximum absorption increase of 2.5 a.u. at a set working wavelength of 670 nm over the H(2)O(2) concentration range studied. The sensor exhibited a sensitivity of (3.1+/-0.2) x 10(3) a.u./mol L(-1) and a limit of detection (LOD) of 4.4 x 10(-5) mol L(-1) H(2)O(2). These results anticipate that full-field waveguide microstructures based on bio-doped sol-gel polymers will enable the fabrication of cost-effective photonic biosensors. Moreover, the ease of fabrication by a soft lithography technique and the use of such polymeric materials are fully compatible with their integration in compact automatic analysis systems.     

Luminescent PtII and PtIV Platinacycles with Anticancer Activity Against Multiplatinum-Resistant Metastatic CRC and CRPC Cell Models

Platinum-based chemotherapy persists to be the only effective therapeutic option against a wide variety of tumours. Nevertheless, the acquisition of platinum resistance is utterly common, ultimately cornering conventional platinum drugs to only palliative in many patients. Thus, encountering alternatives that are both effective and non-cross-resistant is urgent. In this work, we report the synthesis, reduction studies, and luminescent properties of a series of cyclometallated (C,N,N′)Pt^IV compounds derived from amine–imine ligands, and their remarkable efficacy at the high nanomolar range and complete lack of cross-resistance, as an intrinsic property of the platinacycle, against multiplatinum-resistant colorectal cancer (CRC) and castration-resistant prostate cancer (CRPC) metastatic cell lines generated for this work. We have also determined that the compounds are effective and selective for a broader cancer panel, including breast and lung cancer. Additionally, selected compounds have been further evaluated, finding a shift in their antiproliferative mechanism towards more cytotoxic and less cytostatic than cisplatin against cancer cells, being also able to oxidize cysteine residues and inhibit topoisomerase II, thereby holding great promise as future improved alternatives to conventional platinum drugs.     

Tapered copolymers of styrene and 4-vinylbenzocyclobutene via carbanionic polymerization for crosslinkable polymer films

Well-defined polystyrene homopolymers with surface-adhesive triethoxysilyl end group were synthesized via living carbanionic polymerization, epoxide end-functionalization and subsequent hydrosilylation with triethoxysilane. Grafting-to performance of polymers with various molecular weight (M_n = 3000–14,000 g mol⁻¹) to a silicon surface was examined in dependence of reaction time, polymer concentration, solvent and number of alkoxysilyl end groups. Crosslinkable polymers for surface modification were synthesized by statistical carbanionic copolymerization of 4-vinylbenzocyclobutene (4-VBCB) and styrene, followed by epoxide end-functionalization and triethoxysilane modification (M_n = 4000–14,000 g mol⁻¹). The copolymers were characterized by ¹H-NMR, THF-SEC, and matrix-assisted laser desorption and ionization time-of-flight mass spectrometry. In situ ¹H-NMR kinetic studies in cyclohexane-d₁₂ provided information regarding the monomer gradient in the polymer chains, with styrene being the more reactive monomer (r_s = 2.75, r_4-VBCB = 0.23). Thin polymer films on silicon wafers were prepared by grafting-to surface modification under conditions derived for the polystyrene homopolymer. The traceless, thermally induced crosslinking reaction of the benzocyclobutene units was studied by DSC in bulk as well as in 3–6 nm thick polymer films. Crosslinked films were analyzed by atomic force microscopy, ellipsometry, and nanoindentation, showing smooth polymer films with an increased modulus. © 2019 The Authors. Journal of Polymer Science published by Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 181–192     

Study of bulk chain coupling reactions. I. Reaction between bisoxazolones and amine-terminated polyamide 12

2,2′-Bis(4,4-dimethyl-5(4H)-oxazolone) ( B3 ) and 2,2′-(1,2-ethylene)-bis(4,4-dimethyl-5(4H)oxazolone) ( B4 ) have been reacted in the bulk with α, ω-diamino polyamide-12 ( PA12 ) of M?_n = 1000. The reactions have been studied by SEC, and ¹H- and ¹³C-NMR and resulting polymers characterized by DSC and TGA. The chain coupling reaction is fast and gives high molar mass polymers within 10 min at 200°C with B4 while some side reactions occur with B3 leading to polymers of lower molar mass. The crystallinity of resulting polymers is lower than that of starting oligomer. However, the thermal stability is higher. Model reactions using B3 or B4 and hexamethylene diamine or 1-dodecanamine have been carried out and studied. An intramolecular cyclodehydration giving 2-imidazolin-5-ones takes place during the reactions. Higher cyclization extent is found in the presence of amino group excess. 2-Imidazolin-5-one heterocyclic structures are also observed in the chains of the polymers obtained from PA12 and B3 or B4 . © 1993 John Wiley & Sons, Inc.     

A straightforward synthesis and structure of unprecedented iminium salts of dihydropyrido[3,2-e][1,3]thiazines

Unprecedented 2-iminium chloride salts of 5,8-dihydro-2H-pyrido[3,2-e][1,3]thiazines derivatives (8) were easily synthesized in one step from the corresponding o-chloroformyl-1,4-dihydropyridine (2) and thiourea. The structural study has been carried out by X-ray crystallography and theoretical calculations at the B3LYP/6-31G* levels and reveal that the new salts exhibit appropriate structural features to behave as calcium channel modulators.     

Re-examination of 7,7′-dimethyl-7-germanorbornadiene photocleavage in solution and in organic glasses

Dimethylgermylene and its Ge=Ge doubly bonded dimer, tetramethyldigermene, have been characterized directly in solution by 308-nm laser flash photolysis in n-hexane solution, as well as 254-nm photolysis in hydrocarbon glasses at t = 77 K. An absorption band maximum of λ _max ≈ 430 nm and molar absorption coefficient of ε ≈ 2,700 M⁻¹ cm⁻¹ have been shown to be attributable to low-temperature glasses, while the absorption band maximum of λ _max ≈ 480 nm and molar absorption coefficient of ε ≈ 2,400 M⁻¹ cm⁻¹ have been shown to be related to dimethylgermylene in n-hexane solution. The molar absorption coefficient of tetramethyldigermene (λ _max ≈ 380 nm) was determined to be ε ≈ 84,000 M⁻¹ cm⁻¹. The germylene is formed via (formal) cheletropic photocycloreversion of 7,7′-dimethylgerma-1,4,5,6-tetraphenyl-2,3-benzo-norbornadiene. Tetramethyldigermene and 1,2,3,4-tetraphenylnaphthalene in the triplet state were formed, together with dimethylgermylene. We attempted to explain the various contradictory interpretations of experimental data existing in the literature on this reaction.     

Erratum to: Solution behavior of aqueous mixtures of low and high molecular weight hydrophobic amphiphiles

Mixtures of a hydrophobic triblock copolymer (L121, PEO₅PPO₆₈PEO₅) and a hydrophobic anionic surfactant (AOT, Sodium bis(2-ethylhexyl)sulfosuccinate), each alone forming turbid vesicular solutions in water, aggregate to produce a thermodynamically stable, transparent and isotropic solution. Mixed AOT/L121 aggregates could be confirmed by fluorescence, surface tension, differential scanning calorimetry (DSC) and isothermal titration calorimetry (ITC). In an isotropic region, where mixed aggregates are formed, there is a synergistic interaction between monomers of AOT and L121 in the mixture. In addition, Small Angle Neutron Scattering (SANS) experiments provided evidence that mixed aggregates have the shape of either spheres (with a certain polydispersity) or very short ellipsoids (axial ratio below 2), confirming a transition from giant multilamellar vesicles to small aggregates upon mixing the two hydrophobic amphiphiles. Upon dilution, the morphology changes to disk-like. From an examination of the results of all the methods the peculiar behavior of the mixed AOT/L121 system is explained.     

Highly selective and sensitive chromo-fluorogenic detection of the Tetryl explosive using functional silica nanoparticles

Silica nanoparticles containing polyamines and thiol groups have been used as probes for the selective detection of Tetryl.     

Synthetic prodiginine obatoclax (GX15-070) and related analogues: anion binding, transmembrane transport, and cytotoxicity properties

Synthetic prodiginine obatoclax shows promise as a potential anticancer drug. This compound promotes apoptosis of cancer cells, although the mechanism of action is unclear. To date, only the inhibition of BCL-2 proteins has been proposed as a mechanism of action. To gain insight into other possible modes of action, we have studied the anion-binding properties of obatoclax and related analogues in solution, in the solid state, and by means of density functional theory calculations. These compounds are well suited to interact with anions such as chloride and bicarbonate. The anion-transport properties of the compounds synthesized were assayed in model phospholipid liposomes by using a chloride-selective-electrode technique and (13)C NMR spectroscopy. The results demonstrated that these compounds are efficient anion exchangers that promote chloride, bicarbonate, and nitrate transport through lipid bilayers at very low concentrations. In vitro studies on small-cell lung carcinoma cell line GLC4 showed that active ionophores are able to discharge pH gradients in living cells and the cytotoxicity of these compounds correlates well with ionophoric activity.