The BSA-encapsulated gold nanoclusters (AuNC@BSA) have drawn considerable interest and demonstrated applications as biological sensors. In this study, we demonstrated that the red-emitting AuNC@BSA ...prepared using a modified procedure fully retained the binding of standard BSA-ligands (small molecule drugs), significantly improving fluorescence detection in some cases due to the red-emission property. Further, we showed that AuNC@BSA efficiently bind a series of aflatoxin-related mycotoxins as well as the aliphatic mycotoxin FB1, reporting interactions in the nanomolar range by instantaneous emission change at 680 nm. Such red emission detection is advantageous over current detection strategies for the same mycotoxins, based on complex mass spectrometry procedures or, eventually (upon chemical modification of the mycotoxin), by fluorescence detection in the UV range (<400 nm). The later technique yields fluorescence strongly overlapping with the intrinsic absorption and emission of biorelevant mixtures in which mycotoxins appear. Thus, here we present a new approach using the AuNC@BSA red fluorescence reporter for mycotoxins as a fast, cheap, and simple detection technique that offers significant advantages over currently available methods.
The innovative design of a triarylborane (TB)-dye with one NMe2-alkylated (propargylated) group and one NMe2 group yielded a system that is both an NMe2 π-donor and an inductive NMe2-alkyl cationic ...acceptor. Consequently, the new TB-dye was highly sensitive to a “click” reaction with an azide-substituted lysine side chain (yielding TB-lysine), resulting in a bathochromic shift of emission of 100 nm. In addition, fluorene attached to the lysine C-terminus showed FRET with the TB-chromophore, also sensitive to interactions with targets. Both the TB-dye and TB-lysine showed high affinities towards both DNA and proteins, reporting binding by an opposite fluorimetric response for DNA/RNA (quenching) vs. BSA (increase). Thus, the novel TB-dye is an ideal fluorimetric probe for orthogonal incorporation into bio-targets by “click” reactions due to fluorescence reporting of the progress of the “click” reaction and further sensing of the binding site composition. The TB-dye is moderately toxic to human cell lines after 2–3 days of exposure, but efficiently enters cells in 90 min, being non-toxic at short exposure. The most important product of the “click” reaction, TB-lysine, was non-toxic to cells and showed equal distribution between mitochondria and lysosomes. Further studies would focus particularly on the very convenient monitoring of the progress of “click” conjugation of the TB-dye with biorelevant targets inside living cells by confocal microscopy.
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•Azithromycin conjugates macrozones exhibit activity against resistant bacteria.•Atomic details of interactions between macrozones and biological receptors revealed.•Two-site binding ...mechanism responsible for improved activity against resistant strains.•Platform for further efforts directed towards discovery of new anti-infective macrolides.
Macrozones are novel conjugates of azithromycin and thiosemicarbazones, which exhibit very good in vitro antibacterial activities against susceptible and some resistant bacterial strains thus showing a potential for further development. A combination of spectrometric (fluorimetry, STD and WaterLOGSY NMR) and molecular docking studies provided insights into atomic details of interactions between selected macrozones and biological receptors such as E. coli ribosome and bovine serum albumin. Fluorimetric measurements revealed binding constants in the micro-molar range while NMR experiments provided data on binding epitopes. It has been demonstrated that both STD and WaterLOGSY gave comparable and consistent results unveiling atoms in intimate contacts with biological receptors. Docking studies pointed towards main interactions between macrozones and E. coli ribosome which included specific π - π stacking and hydrogen bonding interactions with thiosemicarbazone part extending down the ribosome exit tunnel. The results of the docking experiments were in fine correlation with those obtained by NMR and fluorimetry.
Our investigation pointed towards a two-site binding mechanism of interactions between macrozones and E. coli ribosome which is the most probable reason for their activity against azithromycin-resistant strains. Much better activity of macrozone-nickel coordinated compound against E. coli ribosome compared to other macrozones has been attributed to the higher polarity which enabled better bacterial membrane penetration and binding of the two thiosemicarbazone units thus additionally contributing to the overall binding energy. The knowledge gained in this study should play an important role in anti-infective macrolide design in the future.
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•The kinetic parameters of BSA adsorption on different types of CaPs, TiNMs, and their composites (CaPs/TiNMs) were determined.•The kinetics of BSA adsorption on all studied materials ...was best described by pseudo-second order kinetics.•Adsorption on nanowires, calcium deficient hydroxyapatite and all composites involved intraparticle diffusion.•Stronger binding was observed for the titanium nanomaterials on which adsorption was slower.•Even small differences in materials properties can lead to significant differences in their interaction with BSA.
Among key factors determining the fate of biomaterials in vivo are their interactions with blood serum proteins, which can lead to either successful integration or rejection/encapsulation. Although there are a number of studies investigating the interactions between proteins and bioimplants, comparable data for different types of biomaterials are lacking. To fill this gap, the adsorption kinetics and binding interactions of bovine serum albumin (BSA) with calcium phosphates (CaPs), namely hydroxyapatite (HA) and calcium deficient apatite (CaDHA), different TiO2 nanomaterials (TiNMs) presenting various morphologies such as nanoparticles (TiNPs), nanoplatelets (TiNPls), nanotubes (TiNTs) and nanowires (TiNWs), as well as their composites with CaDHA (CaDHA/TiNMs) were investigated. The kinetics of BSA adsorption on all studied materials was best described by pseudo-second order kinetics. The rate coefficient values obtained for the composites were lower than those for CaDHA and the corresponding TiNMs, while the adsorption density was higher for the composites than for CaDHA, except for the composites with TiNTs. Adsorption on TiNWs, CaDHA and all composites involved intraparticle diffusion, which was the rate-limiting step only for CaDHA/TiNTs. Fluorimetric titration experiments revealed that the number of binding sites was in larger than 1, except for TiNTs and TiNWs, indicating positive binding cooperativity. Interestingly, the values of the binding constants were lower for the TiNMs with a higher adsorption rate coefficient. Overall, BSA adsorption on the studied materials proved to be a complex process, which depended on the different surface properties of the adsorbents. Which property had a dominant role depended on the chemical identity of the adsorbent. The obtained comparable data for different types of materials point to the way of modifying their protein adsorption and binding properties.
A novel tri-pyrene polyamine (TAL3PYR) bearing net five positive charges at biorelevant conditions revealed strong intramolecular interactions in aqueous medium between pyrenes, characterised by ...pronounced excimer fluorescence. A novel compound revealed strong binding to ds-DNA and ds-RNA, along with pronounced thermal stabilisation of DNA/RNA and extensive changes in DNA/RNA structure, as evidenced by circular dichroism. New dye caused pronounced ds-DNA or ds-RNA condensation, which was attributed to a combination of electrostatic interactions between 5+ charge of dye and negatively charged polynucleotide backbone, accompanied by aromatic and hydrophobic interactions of pyrenes within polynucleotide grooves. New dye also showed intriguing antiproliferative activity, strongly enhanced upon photo-induced activation of pyrenes, and is thus a promising lead compound for theranostic applications on ds-RNA or ds-DNA targets, applicable as a new strategy in cancer and gene therapy.
Rad donosi popise isplata vojsci u Hrvatskoj i Slavonskoj krajini u listopadu i studenome 1556. godine, transkript izvora te tablicu koja sistematizira u njima navedene podatke. Popraćen je i kratkom ...uvodnom studijom. U njoj su navedene osnovne informacije o projektu, ishodišnom dokumentu i postojećoj literaturi o temi rane vojnokrajiške povijesti. Studija također donosi kratku analizu struktura vlasti, etničke slike i društvene mobilnosti na Krajini te brojnosti, prostornog razmještaja i opskrbljenosti krajiških utvrda 1556. godine.
At one point in Cosmopolis, DeLillo’s character Benno Levin quotes
Saint Augustine of Hippo: “I have become an enigma to myself” (189). However, the similarities between the two narratives go beyond ...a simple reference. Although centuries apart and operating within different temporal and philosophical frameworks, both are examples of confessional prose, an inherently introspective genre which offers insight into the narrator’s emotional development. The works at hand explore concepts key to the human condition, such as time and temporality, corporeality, and morality. The narrators also seek to define themselves in relation to (or against) a superior, ubiquitous, and almighty Other (Saint Augustine in relation to God, and Benno Levin against Eric Packer, the embodiment of cybercapitalism). Apart from thematic similarities, biographical and structural similarities are also to be observed. Hence, as DeLillo is building on (or rather, subverting) what is considered to be the first piece of confessional prose in the Western tradition, the comparative method can be applied in analysing Cosmopolis. Such an approach makes possible the singling out and defining of peculiarities as depicted in the novel, which allows for an(other) analysis of the American here and now.
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