Doxorubicin Encapsulation in Carbon Nanotubes Having Haeckelite or Stone–Wales Defects as Drug Carriers: A Molecular Dynamics Approach

Doxorubicin (DOX), a recognized anticancer drug, forms stable associations with carbon nanotubes (CNTs). CNTs when properly functionalized have the ability to anchor directly in cancerous tumors where the release of the drug occurs thanks to the tumor slightly acidic pH. Herein, we study the armchair and zigzag CNTs with Stone–Wales (SW) defects to rank their ability to encapsulate DOX by determining the DOX-CNT binding free energies using the MM/PBSA and MM/GBSA methods implemented in AMBER16. We investigate also the chiral CNTs with haeckelite defects. Each haeckelite defect consists of a pair of square and octagonal rings. The armchair and zigzag CNT with SW defects and chiral nanotubes with haeckelite defects predict DOX-CNT interactions that depend on the length of the nanotube, the number of present defects and nitrogen doping. Chiral nanotubes having two haeckelite defects reveal a clear dependence on the nitrogen content with DOX-CNT interaction forces decreasing in the order 0N > 4N > 8N. These results contribute to a further understanding of drug-nanotube interactions and to the design of new drug delivery systems based on CNTs.     

Anti-Cancer Effects of Carnosine—A Dipeptide Molecule

Background: Carnosine is a dipeptide molecule (β-alanyl-l-histidine) with anti-inflammatory, antioxidant, anti-glycation, and chelating properties. It is used in exercise physiology as a food supplement to increase performance; however, in vitro evidence suggests that carnosine may exhibit anti-cancer properties. Methods: In this study, we investigated the effect of carnosine on breast, ovarian, colon, and leukemic cancer cell proliferation. We further examined U937 promonocytic, human myeloid leukemia cell phenotype, gene expression, and cytokine secretion to determine if these are linked to carnosine’s anti-proliferative properties. Results: Carnosine (1) inhibits breast, ovarian, colon, and leukemic cancer cell proliferation; (2) upregulates expression of pro-inflammatory molecules; (3) modulates cytokine secretion; and (4) alters U937 differentiation and phenotype. Conclusion: These effects may have implications for a role for carnosine in anti-cancer therapy.     

Facile preparation and properties of superhydrophobic nanocellulose membrane

Superhydrophobic nanocellulose membrane was prepared by synergistically modifying biodegradable nanocellulose with low-carbon perfluoroorganosiloxane and ethyl orthosilicate. The effects of four kinds of low-carbon perfluoroorganosiloxanes with different structures and their ratio to ethyl orthosilicate on the hydrophobic properties of nanocellulose membrane were investigated, and then FT-IR, XPS, XRD, SEM, TEM, AFM, TG and contact angle goniometer were used to characterize the structure and hydrophobic properties of nanocellulose membrane before and after modification. It is found that when the molar ratio of 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (PFOTMS) to ethyl orthosilicate (TEOS) is 1, the modified nanocellulose membrane PFOTMS-TEOS-CNF is loaded with silica nanoparticles both inside and on its surface, and a micro-nano hierarchical rough morphology with low surface energy is constructed. At this point, the root-mean-square roughness (Rq) of nanocellulose membrane is 112 nm, and the static contact angle of water droplet is 153.5°, successfully realizing superhydrophobicity. In addition, compared to unmodified nanocellulose membrane, PFOTMS-TEOS-CNF with better thermal stability includes an additional maximum weight loss rate temperature (491.2 °C). The above advantages markedly improve the shortcomings of pristine nanocellulose, such as superhydrophilicity and insufficient thermal stability, and also broadens its high-value application in many fields.     

UPLC-Q/TOF-MS coupled with multivariate analysis for comparative analysis of metabolomic in Dendrobium nobile from different growth altitudes

Dendrobium nobile alkaloids (DNLA) and glycosides are the main active components extracted from Dendrobium nobile Lindl. (D. nobile) used for thousands of years in China. The pharmacological effects of the above chemical components are significantly different. D. nobile is mainly grown at an altitude ranging from 230 to 800 m in Chishui City, Northwest Guizhou Province. However, it is unclear whether the metabolite in D. nobile is influenced by the planting altitude. Hence, to reveal the different metabolite in D. nobile cultivated at the altitude of 336 m, 528 m, and 692 m, ultra-high performance liquid chromatography with Q/TOF-MS couple with multivariate analysis were developed. Using the orthogonal partial least squares-discriminant analysis, 19 different metabolites were discovered and then tentatively assigned their structures as alkaloids and glycosides by comparing mass spectrometry data with in-house database and literature. Moreover, the result of semiquantitative analysis showed the content of dendrobine that was belonged to alkaloids significantly increased at the altitude of 692 m, whereas the content of glycosides demonstrated an accumulation trend at the altitude of 528 m. The results could provide valuable information for the optimal clinical drug therapeutics and provide a reference for quality control.     

Goos-Hänchen and Imbert-Fedorov shifts in tilted Weyl semimetals

We establish the beam models of Goos-Hänchen (GH) and Imbert-Fedorov (IF) effects in tilted Weyl semimetals (WSMs), and systematically study the influences of Weyl cone tilting and chemical potential on the GH and IF shifts at a certain photon energy 1.96 eV. It is found that the GH and IF shifts in tilted type-I and type-Ⅱ WSMs are both almost symmetric about the Weyl cone tilting. Meanwhile, the GH and IF shifts in type-I WSMs almost do not change with the tilt degree of Weyl cones, while those in type-Ⅱ WSMs are extremely dependent on tilt degree. These trends are mainly due to the nearly symmetric distribution of WSMs conductivities, where the conductivities keep stable in type-I WSMs and gradually decrease with tilt degree in type-Ⅱ WSMs. By adjusting the chemical potential, the boundary between type-I and type-Ⅱ WSMs widens, and the dependence of the beam shifts on the tilt degree can be manipulated. Furthermore, by extending the relevant discussions to a wider frequency band, the peak fluctuation of GH shifts and the decrease of IF shifts occur gradually as the frequency increases, and the performance of beam shifts at photon energy 1.96 eV is equally suitable for other photon frequencies. The above findings provide a new reference for revisiting the beam shifts in tilted WSMs and determining the types of WSMs.     

Synthesis of 29H,31H-phthalocyanine and chloro (29H,31H-phthalocyaninato) aluminum derivatives showed anti-cancer and anti-bacterial actions

Continuous administration of most chemotherapeutic drugs can induce different types of side effects. There has been growing interest in exploring an alternative approach to synthesizing compounds that are most effective and have fewer side effects. We synthesized 29H,31H-Phthalocyanine, and Chloro (29H,31H- phthalocyaninato) aluminum at low temperatures using lithium in the present study with diisopropylamide as the nucleophile. The physical characteristics of 29H,31H-Phthalocyanine, and Chloro (29H,31H- phthalocyaninato) aluminum were confirmed by FT-IR method, XRD, SEM, and the impact of these compounds on human colorectal carcinoma (HCT-116) and human cervical cells (HeLa) was examined. Treatment with 29H,31H-Phthalocyanine significantly decreased cancer cell growth and proliferation, as determined by MTT and DAPI staining analysis. In contrast, Chloro (29H,31H- phthalocyaninato) aluminum treatment did not show any inhibitory action on colon or cervical cancer cells. We also calculated the inhibitory concentration (IC50) of 29H,31H-Phthalocyanine, which was 30 µg/ml (HCT-116) and 33 µg/ml (HeLa cells). The antibacterial effectiveness of 29H,31H-Phthalocyanine, and chloro (29H,31H- phthalocyaninato) aluminum was studied using Enterococcus faecalis (E. faecalis). The CFU (colony frequency unit) assay confirmed significant activity against the test bacterium after treatment with 29H,31H-Phthalocyanine. However, no activity was seen upon treatment with chloro (29H,31H- phthalocyaninato) aluminum against E. faecalis.     

19F-detected dual-optimized inverted 1JCC 1,n-ADEQUATE

Modification of the recently reported ¹⁹F-detected 1,1-ADEQUATE experiment that incorporates dual-optimization to selectively invert a wide range of ¹J_CC correlations in a 1,n-ADEQUATE experiment is reported. Parameters for the dual-optimization segment of the pulse sequence were modified to accommodate the increased size of ¹J_CC homonuclear coupling constants of poly- and perfluorinated molecules relative to protonated molecules to allow broadband inversion of the ¹J_CC correlations. The observation and utility of isotope shifts are reported for the first time for 1,1- and 1,n-ADEQUATE correlations.     

Palladium-catalyzed vinylation of cyclohexenes using a directing-group strategy

Palladium-promoted vinylation of cyclohexenes via employment of a directing-group strategy to yield the coupled vinyl cyclohexenes with excellent regio- and stereoselectivity was studied. Typically, reaction of 2-(cyclohex-2-en-1-yl)-N-tosylacetamide ( 1a ) with (Z)-styryl bromides ( 2 ) gave cis-2-[(E)-styryl]cyclopent-3-en-1-yl-N-tosylacetamides in good to excellent yields. It is noticed that (Z)-styryl moiety was inverted into (E)-form in products. Unfortunately, (E)-styryl bromide substrates were not suitable for this reaction under the condition investigated. Further studies on norbornene system, we found that palladium-catalyzed reaction of endo-N-tosylbicyclo[2.2.1]hept-5-ene-2-carboxamide ( 6 ) with styryl bromides gave the Aza-Heck type products.     

Evidence for Multiple Binding Modes in the Initial Contact Between SARS-CoV-2 Spike S1 Protein and Cell Surface Glycans**

Infection of host cells by SARS-CoV-2 begins with recognition by the virus S (spike) protein of cell surface heparan sulfate (HS), tethering the virus to the extracellular matrix environment, and causing the subunit S1-RBD to undergo a conformational change into the ‘open’ conformation. These two events promote the binding of S1-RBD to the angiotensin converting enzyme 2 (ACE2) receptor, a preliminary step toward viral-cell membrane fusion. Combining ligand-based NMR spectroscopy with molecular dynamics, oligosaccharide analogues were used to explore the interactions between S1-RBD of SARS CoV-2 and HS, revealing several low-specificity binding modes and previously unidentified potential sites for the binding of extended HS polysaccharide chains. The evidence for multiple binding modes also suggest that highly specific inhibitors will not be optimal against protein S but, rather, diverse HS-based structures, characterized by high affinity and including multi-valent compounds, may be required.