Amphiphilic Peptide with Dual Functionality Resists Biofouling

Biofouling, the accumulation of organisms on surfaces, can lead to several undesirable phenomena, including hospital-acquired infections, blockage of water purification systems, and food contamination. The solution to the problem should be nontoxic and environmentally friendly, so that it could be applied on different surfaces and could come into contact with food, water, or human tissues. Peptides can provide such a solution, since they are biocompatible and biodegradable materials that can resist biofouling, either by preventing the attachment of organisms to the surface (antifouling) or by killing the bacteria (antimicrobial activity). This paper presents an amphiphilic peptide with antifouling, antimicrobial, and adhesive properties. The peptide adheres to titanium surfaces and inhibits the adhesion of both Gram-negative and Gram-positive bacteria to surfaces. In addition, it reduces the growth of bacteria in solution. This peptide has both antifouling and antimicrobial properties, which could be useful in health care systems, food packaging, and other systems that suffer from biocontamination

A Mechanistic Approach on the Self-Organization of the Two-Component Thermoreversible Hydrogel of Riboflavin and Melamine

The riboflavin (R) and melamine (M) supramolecular complex in the mole ratio of 3:1 (RM31) produces a thermoreversible gel in aqueous medium. The gelation mechanism has been elucidated from morphological investigations using optical, electron, and atomic force microscopy together with time-dependent circular dichroism (CD) and photoluminescence (PL) spectroscopy. Optical microscopy indicates spherulitic morphology at lower gelation temperature (≤25 °C), but at higher temperature fibrillar network morphology develops. Electron and atomic force microscopy indicate the presence of left handed helical structures in the fibrils. Kinetic study of gel formation using circular dichroism (CD) and photoluminescence (PL) spectra indicates that there are three steps:  (1) RM complex formation, (2) conformational ordering, and (3) π−π-stacking of ordered conformers. The first step of RM complex formation is already established from Fourier transform infrared (FTIR) spectroscopy (Manna, S.; Saha, A.; Nandi, A. K. Chem. Commun. 2006, 4285), and the second step is detected from the CD spectra. Here, the ellipticity value of the n−π* transition increases by 600 times during gel formation. The dramatic increase of ellipticity is attributed to conformational ordering of the ribityl chain followed by helical fibril formation. The third step is concluded from fluorescence spectroscopy, which also shows a 30 times increase in intensity. The substantial increase in PL intensity is caused by hydrophobic core formation during π-stacking of the complex. Both the ellipticity and PL intensity show a sigmoidal increase with time, and analysis of data using the Avrami equation shows n values close to 1.5 for the former and close to 2 for the latter. The rate constant values obtained from the intercepts of Avrami plots are different in the two methods. The rate constant data from the CD spectra show a small positive temperature coefficient, but the rate constant values from the PL data show a negative temperature coefficient except the data at 30 and 35 °C. Arrhenius treatment of the rate constant values of the CD data indicates an activation energy of ∼13 kcal/mol, signifying that the conformational transition is the cause of ellipticity increase. The negative temperature coefficient of the rate constant obtained from the fluorescence data has been attributed to the spherulitic crystal formation, and the increase of the rate constant at 30 and 35 °C has been attributed to fibril formation. The fluorescence intensity and peak position change with temperature and with the concentration of the RM complex in the gel. A probable explanation from fibrillar thickness is offered

MORE ON INTERVAL-VALUED INTUITIONISTIC FUZZY SOFT MULTI SETS

In 2013, Mukherje et al. developed the concept of interval-valued intuitionistic fuzzy soft multi set as a mathematical tool for making descriptions of the objective world more realistic, practical and accurate in some cases, making it very promising. In this paper we define some operations in interval-valued intuitionistic fuzzy soft multi set theory and show that the associative, distribution and De Morgan’s type of results hold in interval-valued intuitionistic fuzzy soft multi set theory for the newly defined operations in our way. Also, we define the necessity and possibility operations on interval-valued intuitionistic fuzzy soft multi set theory and study their basic properties and some results

A Simplified Approach for the Aqueous Synthesis of Luminescent CdSe/ZnS Core/Shell Quantum Dots and Their Applications in Ultrasensitive Determination of the Biomarker 3‑Nitro‑l‑tyrosine

In contrast to the hot-injection organometallic routes, synthesizing stable and highly luminescent core/shell nanocrystals with encapsulation of biocompatible groups through an aqueous route is a long-standing challenge. In recent years, relatively high quantum efficiency and unique properties of core/shell nanostructured materials (quantum dots) have contributed toward enhancement in sensing capability. The present work reports a facile aqueous synthesis process of core/shell CdSe/ZnS quantum dots (QDs) with encapsulation of glutathione (GSH). The optimal conditions for the synthesis of the most stable particles were ascertained, and the different experimental analyses suggest that the stable core/shell QDs in question have good crystallinity with a size around 4.7 nm with a shell thickness of 0.7 nm and a photoluminescence quantum yield of about 35%. Further, it is demonstrated that the as-synthesized material has great potential in detecting as low as 0.28 nM 3-nitro-l-tyrosine (3-NT), an important marker for oxidative stress, the level of which in our body signals several chronically diseased conditions. The enthalpy-driven interactions of CdSe/ZnS-GSH QDs with 3-NT were characterized through steady-state and time-resolved luminescence spectroscopy and isothermal microcalorimetry. The devised method of probing 3-NT was further validated with human serum samples. Thus, the proposed strategy may provide a protocol for selective determination of 3-NT under different pathological conditions

Two-Component Thermoreversible Hydrogels of Melamine and Gallic Acid

A new two-component hydrogel of melamine and gallic acid is reported for three different compositions of the components. Optical and scanning electron microscopy indicate the fibrillar network structure of the gel, and the DSC study indicates a reversible first-order phase transition in the system. The storage modulus (G’) versus frequency plot is linear and invariant at 35 and 50 °C but not at 70 °C, where it is in the sol state. The rheological melting point of 58 °C is close to the gel melting point obtained from DSC. The system shows a strong influence of pH on gelation. An FTIR study indicates H-bond formation between the >CO group of gallic acid and the −NH2 group of melamine. 1H NMR spectra indicate the presence of π−π stacking in the gel. The UV−vis peak positions of gallic acid remain unaffected during complexation; however, the normalized absorption intensity is higher in the GM13 sol compared to that of other complexes. The photoluminescence (PL) spectra of the gels are interesting, showing a two-order increase in intensity in the gel state compared to that in the sol state. Three different structures of the complexes are proposed for the three different compositions of the components

Folate-Directed Shape-Transformative Synthesis of Hollow Silver Nanocubes: Plasmon Tunability, Growth Kinetics, and Catalytic Applications

A unique role of folate as a shape- and structure-directing agent has been found in nanosynthesis. Folate-capped Ag2O nanospheres transformed into hollow silver nanocubes (HAgNCs) having spherical void spaces during reduction with hydrazine hydrate (HH). HAgNCs with tunable plasmon peaks (λSPR) at 510, 550, 570, 590, and 630 nm were synthesized (hence named as HAgNC-510, HAgNC-550, HAgNC-570, HAgNC-590, and HAgNC-630, respectively). The corresponding edge-lengths were 33 ± 4, 45 ± 8, 60 ± 8, 70 ± 10 and 100 ± 15 nm as determined by HRTEM and the aspect ratio (edge length/void diameter) remained constant at 2.3. The plasmon peak varied linearly while the molar extinction coefficient scaled exponentially with edge-length. The maximum red-shift was obtained with a molar ratio of 1:0.33:150 for Ag+:folate:HH at 50 °C with a stirring speed of 180 rpm. However, zero rpm synthesis yielded HAgNC-510 having lowest fwhm signifying high monodispersity. Within a short time span of 6–50 s, the particle-evolution was completed. It followed first-order kinetics with a faster reduction occurring at zero rpm. In addition, the HAgNCs were found to be good catalysts in dark as well as in sunlight, for the degradation of a model dye, methyl orange (MO). HAgNC-630 exhibited 3.3 times higher catalytic efficiency in sunlight as compared to solid silver nanospheres (λSPR = 400 nm). Thus, the red-end of the visible solar spectrum displayed greater efficiency with HAgNCs as plasmonic photocatalysts

Ruthenium(II) Polypyridyl-Based Photocages for an Anticancer Phytochemical Diallyl Sulfide: Comparative Dark and Photoreactivity Studies of Caged and Precursor Uncaged Complexes

The spatiotemporal control over the drug’s action offered by ruthenium(II) polypyridyl complexes by the selective activation of the prodrug inside the tumor has beaconed toward much-desired selectivity issues in cancer chemotherapy. The photocaging of anticancer bioactive ligands attached synergistically with cytotoxic Ru(II) polypyridyl cores and selective release thereof in cancer cells are a promising modality for more effective drug action. Diallyl sulfide (DAS) naturally found in garlic has anticancer, antioxidant, and anti-inflammatory activities. Herein, we designed two Ru(II) polypyridyl complexes to cage DAS having a thioether-based donor site. For in-depth photocaging studies, we compared the reactivity of the DAS-caged compounds with the uncaged Ru(II)-complexes with the general formula [Ru(ttp)(NN)(L)]+/2+. Here, in the first series, ttp = p-tolyl terpyridine, NN = phen (1,10-phenanthroline), and L = Cl– (1-Cl) and H2O (1-H2O), while for the second series, NN = dpq (pyrazino[2,3-f][1,10]phenanthroline), and L = Cl– (2-Cl) and H2O (2-H2O). The reaction of DAS with 1-H2O and 2-H2O yielded the caged complexes [Ru(ttp)(NN)(DAS)](PF6)2, i.e., 1-DAS and 2-DAS, respectively. The complexes were structurally characterized by X-ray crystallography, and the solution-state characterization was done by 1H NMR and ESI-MS studies. Photoinduced release of DAS from the Ru(II) core was monitored by 1H NMR and UV–vis spectroscopy. When irradiated with a 470 nm blue LED in DMSO, the photosubstitution quantum yields (Φ) of 0.035 and 0.057 were observed for 1-DAS and 2-DAS, respectively. Intriguing solution-state speciation and kinetic behaviors of the uncaged and caged Ru(II)-complexes emerged from 1H NMR studies in the dark, and they are depicted in this work. The caged 1-DAS and 2-DAS complexes remained mostly structurally intact for a reasonably long period in DMSO. The uncaged 1-Cl and 2-Cl complexes, although did not undergo substitution in only DMSO but in the 10% DMSO/H2O mixture, completely converted to the corresponding DMSO-adduct within 16 h. Toward gaining insights into the reactivity with the biological targets, we observed that 1-Cl upon hydrolysis formed an adduct with 5′-GMP, while a small amount of GSSG-adduct was observed when 1-Cl was reacted with GSH in H2O at 323 K. 1-Cl after hydrolysis reacted with l-methionine, although the rate was slightly slower compared with that with DMSO, suggesting varying reaction kinetics with different sulfur-based linkages. Although 1-H2O reacted with sulfoxide and thioether ligands at room temperature, the rate was much faster at higher temperatures obviously, and thiol-based systems needed higher thermal energy for conjugation. Overall, these studies provide insight for thoughtful design of new generation Ru(II) polypyridyl complexes for caging suitable bioactive organic molecules

α‑Cyclodextrin Interacts Close to Vinblastine Site of Tubulin and Delivers Curcumin Preferentially to the Tubulin Surface of Cancer Cell

Tubulin is the key cytoskeleton component, which plays a crucial role in eukaryotic cell division. Many anticancer drugs have been developed targeting the tubulin surface. Recently, it has been shown that few polyhydroxy carbohydrates perturb tubulin polymerization. Cyclodextrin (CD), a polyhydroxy carbohydrate, has been extensively used as the delivery vehicle for delivery of hydrophobic drugs to the cancer cell. However, interaction of CD with intracellular components has not been addressed before. In this Article, we have shown for the first time that α-CD interacts with tubulin close to the vinblastine site using molecular docking and Förster resonance energy transfer (FRET) experiment. In addition, we have shown that α-CD binds with intracellular tubulin/microtubule. It delivers a high amount of curcumin onto the cancer cell, which causes severe disruption of intracellular microtubules. Finally, we have shown that the inclusion complex of α-CD and curcumin (CCC) preferentially enters into the human lung cancer cell (A549) as compared to the normal lung fibroblast cell (WI38), causes apoptotic death, activates tumor suppressor protein (p53) and cyclin-dependent kinase inhibitor 1 (p21), and inhibits 3D spheroid growth of cancer cell

Vanillin Benzothiazole Derivative Reduces Cellular Reactive Oxygen Species and Detects Amyloid Fibrillar Aggregates in Alzheimer’s Disease Brain

The misfolding of amyloid beta (Aβ) peptides into Aβ fibrillary aggregates is a major hallmark of Alzheimer’s disease (AD), which responsible for the excess production of hydrogen peroxide (H2O2), a prominent reactive oxygen species (ROS) from the molecular oxygen (O2) by the reduction of the Aβ-Cu(I) complex. The excessive production of H2O2 causes oxidative stress and inflammation in the AD brain. Here, we have designed and developed a dual functionalized molecule VBD by using π-conjugation (CC) in the backbone structure. In the presence of H2O2, the VBD can turn into fluorescent probe VBD-1 by cleaving of the selective boronate ester group. The fluorescent probe VBD-1 can undergo intramolecular charge transfer transition (ICT) by a π-conjugative system, and as a result, its emission increases from the yellow (532 nm) to red (590 nm) region. The fluorescence intensity of VBD-1 increases by 3.5-fold upon binding with Aβ fibrillary aggregates with a high affinity (Kd = 143 ± 12 nM). Finally, the VBD reduces the cellular toxic H2O2 as proven by the CCA assay and DCFDA assay and the binding affinity of VBD-1 was confirmed by using in vitro histological staining in 8- and 18-month-old triple transgenic AD (3xTg-AD) mice brain slices

Nucleolin Discriminates Drastically between Long-Loop and Short-Loop Quadruplexes

We investigate herein the interaction between nucleolin (NCL) and a set of G4 sequences derived from the CEB25 human minisatellite that adopt a parallel topology while differing in the length of the central loop (from nine nucleotides to one nucleotide). It is revealed that NCL strongly binds to long-loop (five to nine nucleotides) G4 while interacting weakly with the shorter variants (loop with fewer than three nucleotides). Photo-cross-linking experiments using 5-bromo-2′-deoxyuridine (BrU)-modified sequences further confirmed the loop-length dependency, thereby indicating that the WT-CEB25-L191 (nine-nucleotide loop) is the best G4 substrate. Quantitative proteomic analysis (LC-MS/MS) of the product(s) obtained by photo-cross-linking NCL to this sequence enabled the identification of one contact site corresponding to a 15-amino acid fragment located in helix α2 of RNA binding domain 2 (RBD2), which sheds light on the role of this structural element in G4-loop recognition. Then, the ability of a panel of benchmark G4 ligands to prevent the NCL–G4 interaction was explored. It was found that only the most potent ligand PhenDC3 can inhibit NCL binding, thereby suggesting that the terminal guanine quartet is also a strong determinant of G4 recognition, putatively through interaction with the RGG domain. This study describes the molecular mechanism by which NCL recognizes G4-containing long loops and leads to the proposal of a model implying a concerted action of RBD2 and RGG domains to achieve specific G4 recognition via a dual loop–quartet interaction