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In this study, we introduce an approach for synthesizing polydopamine (PDA) through the controlled oxidation of dopamine using metallic copper. Traditional methods of PDA synthesis often encounter challenges such as scalability, reproducibility, and control over polymerization. Our approach utilizes the catalytic properties of metallic copper in the presence of dissolved oxygen to generate reactive oxygen species (ROS) without additional chemicals. This process allows for precise control over dopamine oxidation, leading to reliable, materials and cost-effective upscalable PDA production. We investigated the reaction kinetics and the role of copper and ROS in dopamine oxidation, using several different experimental techniques. Our results demonstrate that, even at low pH, the copper-assisted method produces PDA with properties comparable to those synthesized through conventional means. We propose a mechanism for PDA synthesis that is initiated by oxygen adsorption onto copper surface, leading to the generation of various ROS which act as oxidizing agents in PDA synthesis. This method presents an advancement in the scalable and controlled production of PDA, with potential applications in various scientific and industrial fields.

Deep eutectic solvents (DESs) formed by hydrogen bond donors and acceptors are a promising new class of solvents. Both hydrophilic and hydrophobic binary DESs readily absorb water, making them ternary mixtures, and a small water content is always inevitable under ambient conditions. We present a thorough study of a typical hydrophobic DES formed by a 1:2 mole ratio of tetrabutyl ammonium chloride and decanoic acid, focusing on the effects of a low water content caused by absorbed water vapor, using multinuclear NMR techniques, molecular modeling, and several other physicochemical techniques. Already very low water contents cause dynamic nanoscale phase segregation, reduce solvent viscosity and fragility, increase self-diffusion coefficients and conductivity, and enhance local dynamics. Water interferes with the hydrogen-bonding network between the chloride ions and carboxylic acid groups by solvating them, which enhances carboxylic acid self-correlation and ion pair formation between tetrabutyl ammonium and chloride. Simulations show that the component molar ratio can be varied, with an effect on the internal structure. The water-induced changes in the physical properties are beneficial for most prospective applications but water creates an acidic aqueous nanophase with a high halide ion concentration, which may have chemically adverse effects.

The alkaline cleavage of two types of sugar nucleotides has been studied by 1 H and 31 P NMR in order to obtain information on the stability and decomposition pathways in aqueous solutions under alkaline conditions. The reaction of glucose 1-UDP is straightforward, and products are easy to identify. The results obtained with ribose 5-UDP and ribose 5-phosphate reveal, in contrast, a more complex reaction system than expected, and the identification of individual intermediate species was not possible. Even though definite proof for the mechanisms previously proposed could not be obtained, all the spectroscopic evidence is consistent with them. Results also emphasise the significant effect of conditions, pH, ionic strength, and temperature, on the reactivity under chemical conditions.

The spin-spray-assisted layer-by-layer (LbL) assembly technique was used to prepare coordinative oxidative multilayers from Ce(IV), inorganic polyphosphate (PP), and graphene oxide (GO). The films consist of successive tetralayers and have a general structure (PP/Ce/GO/Ce) n . Such oxidative multilayers have been shown to be a general platform for the electrodeless generation of conducting polymer and melanin-type films. Although the incorporation of GO enhances the film growth, the conventional dip LbL method is very time consuming. We show that the spin-spray method reduces the time required to grow thick multilayers by the order of magnitude and the film growth is linear from the beginning, which implies a stratified structure. We have deposited poly(3,4-ethylenedioxothiophene), PEDOT, on the oxidative multilayers and studied these redox-active films as models for melanin-type capacitive layers for supercapacitors to be used in biodegradable electronics, both before and after the electrochemical reduction of GO to rGO. The amount of oxidant and PEDOT scales linearly with the film thickness, and the charge transfer kinetics is not mass transfer-limited, especially after the reduction of GO. The areal capacitance of the films grows linearly with the film thickness, reaching a value of ca . 1.6 mF cm -2 with 20 tetralayers, and the specific volumetric (per film volume) and mass (per mass of PEDOT) capacitances are ca . 130 F cm -3 and 65 F g -1 , respectively. 5,6-Dihydroxyindole can also be polymerized to a redox-active melanin-type film on these oxidative multilayers, with even higher areal capacitance values.

Enthalpies of combustion of 2,2- trans -4,6- ( 1 ) and 4,4,6,6-tetramethyl- ( 2 ) and 2,4,4,6,6- ( 3 ) and 2,2,4,4,6-pentamethyl-1,3-dioxanes ( 4 ) were determined to estimate their enthalpies of formation in the gas phase. By comparing the latter with the corresponding enthalpies estimated based on the various bond-bond interactions allowed to determine the chair-2,5-twist energy difference (Δ H CT = 29.8 kJ mol -1 ) for 1 since C-13 shift correlations indicate that it escapes to the 2,5-twist form where the 2-methyl groups are isoclinal and 4- and 6-methyl groups pseudoequatorial to avoid syn-axial interactions. Compounds 2 and 3 in turn give the values 21.0 and 21.6 kJ mol -1 for the 4,6-diaxial Me,Me-interaction. Finally compound 4 , which retains the chair conformation to avoid pseudoaxial interactions in the twist forms gives the value 19.5 kJ mol -1 for the 2,4-diaxial Me,Me-interaction indicating that its chair form appears to be somewhat deformed.

Autoxidation of dopamine to polydopamine by dissolved oxygen is a slow process that requires highly alkaline conditions. Polydopamine can be formed rapidly also in mildly acidic and neutral solutions by using redox-active transition-metal ions. We present a comparative study of polydopamine nanoparticles formed by autoxidation and aerobic or anaerobic oxidation in the presence of Ce(IV), Fe(III), Cu(II), and Mn(VII). The UV-vis spectra of the purified nanoparticles are similar, and dopaminechrome is an early intermediate species. At low pH, Cu(II) requires the presence of oxygen and chloride ions to produce polydopamine at a reasonable rate. The changes in dispersibility and surface charge take place at around pH 4, which indicates the presence of ionizable groups, especially carboxylic acids, on their surface. X-ray photoelectron spectroscopy shows the presence of three different classes of carbons, and the carbonyl/carboxylate carbons amount to 5-15 atom %. The N 1s spectra show the presence of protonated free amino groups, suggesting that these groups may interact with the π-electrons of the intact aromatic dihydroxyindole moieties, especially in the metal-induced samples. The autoxidized and Mn(VII)-induced samples do not contain metals, but the metal content is 1-2 atom % in samples prepared with Ce(IV) or Cu(II), and ca. 20 atom % in polydopamine prepared in the presence of Fe(III). These differences in the metal content can be explained by the oxidation and complexation properties of the metals using the general model developed. In addition, the nitrogen content is lower in the metal-induced samples. All of the metal oxidants studied can be used to rapidly prepare polydopamine at room temperature, but the possible influence of the metal content and nitrogen loss should be taken into account.

We present a general thermodynamic top-down analysis of the effects of oxidants and pH on dopamine oxidation and cyclization, supplemented with UV-vis and electrochemical studies. The model is applicable to other catecholamines and various experimental conditions. The results show that the decisive physicochemical parameters in autoxidation are the p K values of the semiquinone and the amino group in the oxidized quinone. Addition of Ce(IV) or Fe(III) enhances dopamine oxidation in acidic media in aerobic and anaerobic conditions by the direct oxidation of dopamine and, in the presence of oxygen, also by the autoxidation of the formed semiquinone. At pH 4.5, the enhancement of the one-electron oxidation of dopamine explains the overall reaction enhancement, but at a lower pH, cyclization becomes rate-determining. Oxidation by Cu(II) at reasonable rates requires the presence of oxygen or chloride ions.

The effect of adsorption and confinement on ibuprofen was studied by immersion loading the molecules into porous silicon (PSi) microparticles. The PSi microparticles were modified into thermally oxidized PSi (TOPSi) and thermally hydrocarbonized PSi (THCPSi) to evaluate the effects of the loading solvent and the surface chemistry on the obtainable drug payloads. The payloads, location, and the molecular state of the adsorbed drug were evaluated using thermal analysis. The results showed that after the adsorption of ∼800 mg/cm 3 (w drug /v pores ) of drug into the mesopores, depending on the solvent used in the immersion, the drug began to rapidly recrystallize on the external surface of the particles. Moderate concentrations, however, enabled payloads of 800-850 mg/cm 3 without excessive surface crystallization, and thus, there was no need for rinsing the samples to remove the externally crystallized portion. The results showed that the confined ibuprofen forms nanocrystals inside of the mesopores after approximately 200 mg/cm 3 payloads were obtained, accounting for half of the adsorbed drug amount. The presence of both crystalline and noncrystalline phases was further characterized using variable temperature solid-state nuclear magnetic resonance (NMR) measurements. The interactions between the drug molecules and the pore walls of TOPSi and THCPSi were observed using Fourier transform infrared and 1 H NMR spectroscopies, and the hydrogen bonding between the silanol groups of TOPSi and the adsorbed ibuprofen was confirmed, but having only limited effect on the overall state of the confined drug. In vitro drug permeation studies in Caco-2 and Caco-2/HT29 cocultures showed that the adsorption onto hydrophilic or hydrophobic PSi microparticles had no significant effects on the ibuprofen permeation, whether the drug was partially nanocrystalline or completely in a liquidlike state.

Antifungal lipopeptides produced by an antagonistic bacterium, Paenibacillus ehimensis strain IB-X-b, were purified and analyzed. The acetone extract of the culture supernatant contained an antifungal amphiphilic fraction stainable with ninhydrin on thin layer chromatography. The fraction was further purified with water-methanol extraction followed by a chromatography on a C 18 -support. The analysis with LC-MS showed presence of two main series of homologous compounds, family of depsipeptides containing a hydroxy fatty acid, three 2,4-diaminobutyric acid (Dab) residues, five hydrophobic amino acids and one Ser/Thr residue, and cyclic lipopeptides of bacillomycin L and fengycin/plipastatin/agrastatin families. The prevailing compounds in this group are bacillomycin L-C 15 , fengycin/plipastatin A-C 16 together with their homologues responsible for the majority of fungal growth inhibition by P. ehimensis IB-X-b., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Thermally hydrocarbonized porous silicon (THCPSi) microparticles were loaded with indomethacin (IMC) and griseofulvin (GSV) using three different payloads between 6.2-19.5 and 6.2-11.4 wt %, respectively. The drug loading parameters were selected to avoid crystallization of the drug molecules on the external surface of the particles that would block the pore entrances. The successfulness of the loadings was verified with TG, DSC, and XRPD measurements. The effects of the confinement of IMC and GSV into the small mesopores of THCPSi were analyzed with helium pycnometry, FTIR, and NMR spectroscopy. The results showed the density of the THCPSi loaded drugs to be ca. 10% lower than the bulk crystalline forms, while a melt quenched amorphous drugs showed a density reduction of 3-7.5%. DSC and FTIR results confirmed that the drugs reside in an amorphous form within the THCPSi pores. Similar results were obtained with NMR, which also indicated that IMC may reside as both amorphous clusters and individual molecules within the pores. The (1)H transverse relaxation times (T2) of amorphous and THCPSi loaded drugs showed IMC relaxation times of 0.28 ms for both the cases, whereas for GSV the values were 0.32 and 0.39 ms, respectively, indicating similar limited mobility in both cases. The results indicated that strong drug-carrier interactions were not necessary for stabilizing the amorphous state of the adsorbed drug. Dissolution tests using biorelevant media, fasted state simulated intestinal fluid (FaSSIF) and simulated gastric fluid (SGF), showed that THCPSi-loaded IMC and GSV were rapidly released in FaSSIF with comparable rates to the amorphous forms, whereas in SGF the THCPSi reduced the pH dependency in the dissolution of IMC.

The reaction of WOCl(4) with 2,4-di-tert-butyl-6-((isopropylamino)methyl)phenol followed by the reaction with phenyl isocyanate leads to the formation of imidotungsten(VI) complex [W(NPh)Cl(3)(OC(6)H(3)(CH(2)NH-i-Pr)-2-t-Bu(2)-4,6)] 4 with a chelating aminophenolate ligand. When the same procedure was applied using aminophenols with bulkier substituents in the amino group, the final product was an unexpected Schiff-base complex [W(NPh)Cl(3)(OC(6)H(3)(CH=NPh)-2-t-Bu(2)-4,6)] 5, where the ligand is derived from 2,4-di-tert-butyl-6-((phenylimino)methyl)phenol. Complex 5 is also formed in the thermal degradation of 4. On the whole, 5 appears to be formed by a disproportionation of intermediate compounds, which are analogous to complex 4. The solid-state structures of 4 and 5 have been determined by X-ray crystallography whereas the solution structures were studied by (1)H and (13)C NMR.

The 14 and 70 eV electron ionization mass spectra of five sets (R1 = Me, Et, i-Pr, t-Bu and Ph) of seven 2-aryl-4-R1-substituted (Ar = C6H4X; X = p-NO2, m-Br, p-Cl, H, p-Me, p-OMe and p-NMe2) (1-5) and of seven 2-aryl-5-phenyl-substituted 1,3-oxazolidines (6; for Ar, see above) were recorded to study their ring-chain equilibria in the gas phase. These equilibria were also studied by 1H NMR spectroscopy in CDCl3 for compounds 5 and 6. A few 2,4- and 2,5-dimethyl-2-aryl derivatives (7, 8: Ar = C6H4X; X = m-Br, H and p-OMe) were studied both in CDCl3 and in the gas phase. The main characteristics of the ring-chain equilibria expressed by the variable SigmaRA% of the ring and of the chain form proved to be a strong dependence on the nature of the substituents on C-2 and C-4. The results in the gas phase are compared with those in CDCl3.

The reaction of tetrapyrazine Pt(II) with adenine under basic conditions yielded two products both disubstituted by adenine and bound in all cases to the N-9 nitrogen of adenine. Crystals amenable to X-crystallographic analysis were obtained for one product which was consequently identified as trans-[Pt(II)(N9-adeH)2(pz)2](NO3)(4).H2O. The other product, though, was identified as the cis isomer based on extensive and comparative NMR structural studies whereby the two compounds were examined as both neutral and tetraprotonated species in solution. The major product of the reaction was unexpectedly the cis isomer, thus obtained in contrast to the trans effect, and the reason for this result is speculated on. Computational calculations using DFT at the B3LYP/TZVP-MARI-J level of theory provided the head-to-tail conformer as the overwhelmingly more stable species over the head-to-head conformer for both compounds whilst the trans product was found to be more stable than the cis. Thus the reaction does not follow a thermodynamic course and rather is kinetically controlled in concert with the speculated mode of reaction.

The electron ionization mass spectra of the 1-phenyl-, 1-benzyl- and 6-benzyl-1-phenyl-2,3-dihydroimidazo[1,2-a]pyrimidine-5,7(1H,6H)-dione derivatives were recorded at 70 eV to find out the effects of substituents on their fragmentations. Fragmentation pathways were studied using B/E and B(2)/E scans. Some fragmentations involved the loss of C(3)HO(2) or carbon suboxide. The possibility of keto-enol tautomerism was also studied. For comparison selected compounds were studied using (1)H and (13)C NMR spectroscopy to reveal the presence of possible tautomerism. Some ions including [M-OH](+) and [M-HCO](+) and NMR results indicate that the enol form is predominant both in the gas and in the liquid phase., (Copyright 2007 John Wiley & Sons, Ltd.)

The regioselective syntheses of 3-alkyl(aryl)-2-(anthracen-9'-ylimino)-1,3-thiazolidin-4-ones (2) and 2-alkyl(aryl)imino-3-(anthracen-9'-yl)-1,3-thiazolidin-4-ones (3) from N-(anthracen-9-yl)-N'-alkyl(aryl)thioureas were accomplished effectively using methyl bromoacetate and bromoacetyl bromide, respectively. Detailed structural characteristics were confirmed mainly by NMR techniques. The mass spectrometric behavior of the resulting sets of compounds of known structures was shown to be characteristic for each set. Some interesting fragmentation pathways involving the transfer and rearrangements of various moieties were also revealed, as well as regioisomerization for particular substituent-specific fragmentations., (Copyright 2003 John Wiley & Sons, Ltd.)

A modified in vitro lipid peroxidation inhibition assay was used to guide the fractionation and the isolation of antioxidative principles of Fnnish pine bark extract. This approach yielded 3,4-dihydroxybenzoic acid (protocatechuic acid) and taxifolin-3-O-beta-glucopyranoside as major antioxidative compounds from the plant material. The structural elucidation of these compounds was undertaken with the help of HPLC-DAD and HPLC-ESI-MS analyses. Their IC50 values, in comparison to trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), were: trolox (1.78 +/- 0.56 microM) < protocatechuic acid (5.77 +/- 1.63 microM) < taxifolin-3-O-beta-glucopyranoside (16.30 +/- 1.98 microM). The method for the determination of antioxidant activity proved reproducible and quick for routine analyses with 96 well plates.

Genetic factors may contribute to the development of an aberrant pro-inflammatory immune response during pregnancy, thereby increasing the risk of some pregnancy-related pathologies such as recurrent spontaneous abortion (RSA). Interleukin 1 receptor antagonist is an important anti-inflammatory molecule encoded by the IL1RN gene, in which an intronic polymorphism has been described. Even though the molecular genetic mechanisms are not understood, this non-coding polymorphism, and especially IL1RN*2, has been associated with several chronic inflammatory and autoimmune diseases. IL1RN*2 is also associated with increased activity of IL-1beta, which is an important pro-inflammatory cytokine. We investigated the genetic variants of IL1RN in 37 Finnish women with RSA and 800 randomly selected Finnish blood donors. The women with RSA showed a significantly increased frequency of genotypes bearing the rare allele IL1RN*3 compared to the blood donors (10.8 vs 2.1%, odds ratio 5.6, 95% CI: 1.5-19.0, P=0.006). Our results suggest that IL1RN polymorphisms may predispose to RSA in a small subgroup of patients.

The marine, icosahedral bacteriophage PM2 was isolated in the late 1960s. It was the first phage for which lipids were firmly demonstrated to be part of the virion structure and it has been classified as the type organism of the Corticoviridae family. The host, Pseudoalteromonas espejiana BAL-31, belongs to a common group of marine bacteria. We developed a purification method producing virions with specific infectivity approximately as high as that of the lipid-containing phages PRD1 and &phi;6. The sensitivity of the virus to normally used purification media such as those containing sucrose is demonstrated. We also present an alternative host, a pseudoalteromonad, that allows enhanced purification of the virus under reduced salt conditions. We show, using N-terminal amino acid sequencing and comparison with the genomic sequence, that there are at least eight structural proteins in the infectious virus., (Copyright 1999 Academic Press.)

Bacteriophage PM2 was isolated from the Pacific Ocean off the coast of Chile in the late 1960s. It was a new virus type, later classified as Corticoviridae, and also the first bacterial virus for which it was demonstrated that lipids are part of the virion structure. Here we report the determination and analysis of the 10, 079-bp circular dsDNA genome sequence. Noteworthy discoveries are the replication initiation system, which is related to the rolling circle mechanism described for phages such as &phi;X174 and P2, and a 1.2-kb sequence that is similar to the maintenance region of a plasmid found in a marine Pseudoalteromonas sp. strain A28., (Copyright 1999 Academic Press.)