HEMA-Lysine-Based Cryogels for Highly Selective Heparin Neutralization.

Unfractionated heparin (UFH) and its low-molecular-weight fragments (LMWH) are widely used as anticoagulants for surgical procedures and extracorporeal blood purification therapies such as cardiovascular surgery and dialysis. The anticoagulant effect of heparin is essential for the optimal execution of extracorporeal blood circulation. However, at the end of these procedures, to avoid the risk of bleeding, it is necessary to neutralize it. Currently, the only antidote for heparin neutralization is protamine sulphate, a highly basic protein which constitutes a further source of serious side events and is ineffective in neutralizing LMWH. Furthermore, dialysis patients, due to the routine administration of heparin, often experience serious adverse effects, among which HIT (heparin-induced thrombocytopenia) is one of the most severe. For this reason, the finding of new heparin antagonists or alternative methods for heparin removal from blood is of great interest. Here, we describe the synthesis and characterization of a set of biocompatible macroporous cryogels based on poly(2-hydroxyethyl methacrylate) (pHEMA) and L-lysine with strong filtering capability and remarkable neutralization performance with regard to UFH and LMWH. These properties could enable the design and creation of a filtering device to rapidly reverse heparin, protecting patients from the harmful consequences of the anticoagulant.

Simultaneous monitoring of vocal doses and breathing patterns in professional singers.

BACKGROUND: When learning and improving singing, the quantitative characterization of artists' performances based only on vocal parameters does not provide enough information to identify strategies for improvement. Simultaneous monitoring of sound production and breathing patterns in professional singers can allow the exploration of the mechanisms that promote effective singing modalities through association with respiratory efforts. METHODS: We developed and tested a novel portable device that simultaneously monitors vocal activity and breathing patterns without interfering with natural singing. The device utilizes a combination of a miniature accelerometer to measure vocal doses from skin vibrations on the neck and two respiratory inductive plethysmography (RIP) bands to estimate the breathing pattern by measuring changes in the thoracoabdominal cross-sectional area. RESULTS: The device was tested on 13 professional baroque-style singers and 14 untrained individuals during the execution of singing tasks. It was accurate compared with reference systems (R2 = 0.99 and R2 = 0.91 for the accelerometer and RIP, respectively) and showed differences between the two groups (p ≤ 0.001). CONCLUSIONS: By allowing a quantitative characterization of the effectiveness of singing technique, this novel device can help provide a better understanding of the physiology of singing and may be a tool for support learning and training optimization for professional singers.

ZnO-pHEMA Nanocomposites: An Ecofriendly and Reusable Material for Water Remediation.

The design of new hybrid nanocomposites based on poly(2-hydroxyethylmethacrylate) (pHEMA) graphene oxide (GO) cryosponges, wherein ZnO nanolayers have been deposited to induce photocatalytic properties, is reported here. Atomic layer deposition at low temperature is specifically selected as the deposition technique to stably anchor ZnO molecules to the pendant polymer OH groups. Furthermore, to boost the pHEMA cryogel adsorption capability versus organic dyes, GO is added during the synthetic procedure. The morphology, the crystallinity, and the chemical composition of the samples are deeply investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction analyses, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Swelling properties, mechanical performance, and adsorption kinetics models of the hybrid materials are also evaluated. Finally, the adsorption and photocatalytic performance are tested and compared for all of the samples using methylene blue as a dye. Particularly, the adsorption efficiency of ZnO/pHEMA and ZnO/pHEMA-GO nanocomposites, as well as their in situ regeneration via photocatalysis, renders such devices very appealing for advanced wastewater treatment technology.

Potential Eye Drop Based on a Calix[4]arene Nanoassembly for Curcumin Delivery: Enhanced Drug Solubility, Stability, and Anti-Inflammatory Effect.

Curcumin is an Indian spice with a wide spectrum of biological and pharmacological activities but poor aqueous solubility, rapid degradation, and low bioavailability that affect medical benefits. To overcome these limits in ophthalmic application, curcumin was entrapped in a polycationic calix[4]arene-based nanoaggregate by a simple and reproducible method. The calix[4]arene-curcumin supramolecular assembly (Calix-Cur) appeared as a clear colloidal solution consisting in micellar nanoaggregates with size, polydispersity index, surface potential, and drug loading percentage meeting the requirements for an ocular drug delivery system. The encapsulation in the calix[4]arene nanoassembly markedly enhanced the solubility, reduced the degradation, and improved the anti-inflammatory effects of curcumin compared to free curcumin in both in vitro and in vivo experiments. Calix-Cur did not compromise the viability of J774A.1 macrophages and suppressed pro-inflammatory marker expression in J774A.1 macrophages subjected to LPS-induced oxidative stress. Histological and immunohistochemical analyses showed that Calix-Cur reduced signs of inflammation in a rat model of LPS-induced uveitis when topically administrated in the eyes. Overall, the results supported the calix[4]arene nanoassembly as a promising nanocarrier for delivering curcumin to anterior ocular tissues.

Novel pH responsive calix[8]arene hydrogelators: self-organization processes at a nanometric scale.

Water soluble amphiphilic calix[8]arenes have been found to form pH-responsive and reversible supramolecular hydrogels at sub-millimolar concentration. Depending on their upper rim functionalization, pH variations trigger hydrogelation under basic or acidic conditions. Studies on self-organization processes by atomic force microscopy (AFM) measurements on differently charged surfaces are reported.

Polycationic calix[8]arenes able to recognize and neutralize heparin.

A mutual induced fit mechanism is responsible for the exceptional complexation performances exhibited by calix[8]arene polycations towards heparin. The recognition process was studied in comparison with two other heparin antagonists: protamine and polylysine. The arrangement of multiple functional groups on the flexible macrocyclic scaffold of calix[8]arene, with respect to the conformationally rigid protamine and low ordered polylysine, allowed a mutual adaptability between calixarene polycations and heparin, significantly enhancing the recognition performances. Fluorescence, NMR titration, and activated partial thromboplastin time (aPTT) experiments confirmed that these calixarene derivatives have a very high specificity and affinity towards heparin neutralization as in aqueous solution as in blood. Analogous results were obtained with low molecular weight heparin (LMWH) whose effect protamine is unable to completely reverse.

Vesicle-to-micelle transition in aqueous solutions of amphiphilic calixarene derivatives.

Structure and conformation of spontaneous self-assembled calix[8]arenes derivatives are studied by means of static and dynamic light scattering and electrophoretic mobility. These amphiphilic molecules are in the aggregated form in aqueous solution, in a wide range of pH; they take a vesicle structure in neutral and basic pH environment, but, in relatively strong acidic conditions (below pH=4.5), a transition from vesicle to micelle occurs. The structural change is driven by the surface charge density. At neutral pH calix[8]arenes take a negative surface charge, which prevents coagulation and ensures stability; at acidic pH the surface charge tend to become positive because of the protonation of the hydrophilic head. These pH-responsive aggregates, able to release an encapsulated hydrophilic guest, are promising systems for application as nanocarriers.

Synthesis and lectin binding ability of glycosamino acid-calixarenes exposing GlcNAc clusters.

Novel calix[4 or 8]arene-based glycoconjugates exposing terminal N-acetyl-D-glucosamine clusters have been synthesized using amino acid-calixarenes as building blocks. The obtained glycosamino acid-calixarenes 9b-14b have lectin-binding ability and amplified inhibitory effects on erythrocyte agglutination induced by wheat germ (Triticum vulgaris) agglutinin (WGA). The inhibitory ability is dependent on the presence of the spacer and on the shape and rigidity of the calixarene skeleton.

Designed calix[8]arene-based ligands for selective tryptase surface recognition.

Basic amino acid calix[8]arene receptors for tryptase surface recognition have been synthesized. The tetrameric arrangement and the negative charge distribution close to the active sites of the enzyme, have suggested the design of complementary multifunctional receptors that might bind to the active region of the protein blocking the approach of the substrate. Kinetic inhibition analysis on recombinant lung tryptase have showed a time-dependent competitive inhibition with both initial and steady-state rate constants in the nanomolar range.

Atropisomerism in 1,5-bridged calix[8]arenes.

[structure: see text] The first example of two discrete calix[8]arene conformational isomers, 2 and 2a, has been obtained by exhaustive benzylation of 1,5-tetramethylene-bridged calix[8]arene 1. It is demonstrated, with the aid of X-ray crystallography, that these atropisomers have two 3/4-cone halves oriented syn or anti with respect to the bridge/bridgeheads moiety. VT NMR studies indicate that the tert-butyl-through-the-annulus inversion is inhibited in 1, while groups larger than n-hexyl or benzyl are required for curtailing the O-through-the-annulus route.

Methylation of p-tert-Butylcalix[8]arene. Products Obtained in the Presence of Strong Bases.

Methylation of p-tert-butylcalix[8]arene with MeI in the presence of strong bases (NaH, BaO/Ba(OH)(2), or Cs(2)CO(3)) in THF has been investigated. Composition of the reaction mixtures differs remarkably from those obtained using weak bases and described in a preceding paper. Several previously unreported methylated products [two dimethoxy- (2(1,5) and 2(1,4)), a trimethoxy- (3(1,2,5)), a tetramethoxy- (4(1,2,3,6)), two pentamethoxy- (5(1,2,3) and 5(1,2,4)), and three hexamethoxy- (6(1,2), 6(1,3), and 6(1,4))] have been isolated. In many cases the substitution pattern was assigned unambiguously on the basis of spectroscopic evidence only, while in others chemical correlation with known compounds was required.

Alkylation Products of a Calix[8]arene Trianion. Effect of Charge Redistribution in Intermediates.

The behavior of a well-defined calix[8]arene trianion under alkylation conditions was investigated by reacting the tetraethylammonium salt of p-tert-butylcalix[8]arene trianion with p-methylbenzyl bromide. Chromatography of the reaction mixture afforded the following derivatives in order of decreasing yields: 1,3,5,7-tetrakis-, 1,3-bis-, 1,3,5-tris-, 1,2,4-tris-, and mono(p-methylbenzyl)-p-tert-butylcalix[8]arene, besides trace amounts of 1,4- and 1,5-disubstituted compounds. Comparable results were obtained using p-tert-butylbenzyl bromide. The observed regioselectivity has been explained by assuming that after each alkylation step the left negative charge is redistributed, by exchange equilibria, over the remaining phenolic groups with preferential localization at those positions where contiguous H-bond stabilization is possible and the electrostatic repulsion is minimized. The occurrence of protonation/deprotonation equilibria allows the formation of 1,3,5,7-tetrasubstituted calix[8]arene.