Natural Enantiomers: Occurrence,Biogenesis and Biological Properties

The knowledge that natural products (NPs) are potent and selective modulators of important biomacromolecules (e.g., DNA and proteins) has inspired some of the world’s most successful pharmaceuticals and agrochemicals. Notwithstanding these successes and despite a growing number of reports on naturally occurring pairs of enantiomers, this area of NP science still remains largely unexplored, consistent with the adage “If you don’t seek, you don’t find”. Statistically, a rapidly growing number of enantiomeric NPs have been reported in the last several years. The current review provides a comprehensive overview of recent records on natural enantiomers, with the aim of advancing awareness and providing a better understanding of the chemical diversity and biogenetic context, as well as the biological properties and therapeutic (drug discovery) potential, of enantiomeric NPs.     

Biological entities as chemical reactors for synthesis of nanomaterials: Progress,challenges and future perspective

Synthesis of nanomaterials is being gained extensive attention in the fields of chemistry, applied physics, catalysis, drug delivery and the most important in diagnosis and therapeutic applications. Recently, many reports have been published on physical and chemical synthesis of magnetic as well as metallic nanoparticles (NPs) with viable surface functionalization, but still there is a dire need of such strategies that can combine synthetic methodology with stable surface modification found in nature. Synthesis of NPs via biological methods is the possible way to solve these barriers. However, systematized summary and outlooks of NPs synthesis via biological entities with various influencing factors e.g. temperature, pH, concentration of reactants and reaction time has rarely been reported. This review will present the distinct advantages of biological synthesis of NPs over physical and chemical methods. It will also highlight the recent progress on synthesis of NPs via various biological systems i.e. plant, fungus, bacteria, and yeast. Furthermore, it will explain various factors that control the size, shape, and morphology of these NPs. Finally, it would present the future perspectives of green chemistry for the development of nano-science and -biotechnology.     

Traditional uses,phytochemistry, pharmacology and other potential applications of Vitellaria paradoxa Gaertn. (Sapotaceae): A review

Vitellaria paradoxa Gaertn. is a multipurpose medicinal plant of the family Sapotaceae, and it has been widely used usually in the clinical traditional medicine as remedy for a wide range of diseases for several decades. In addition, the plant has also found applications in confectionery, cosmetics and soaps, and pharmaceuticals both locally and internationally. V. paradoxa, which has been identified with >150 phytoconstituents, is rich in oleanane-type triterpene acids and glycosides, such as paradoxosides A-E, tieghemelin A, parkiosides A-C, bassic acid, as well as flavonoids such as quercetin and catechin-type compounds. The extracts and the active constituents of V. paradoxa have been investigated for various pharmacological activities, including but not limited to anticancer, melanogenesis-inhibitory, antibacterial, anti-diabetic, antioxidant, anti-inflammatory, anti-diarrhoeal, and antifungal activities. Additionally, V. paradoxa has also been utilized in nanoparticles (NPs) synthesis. These NPs among other things have shown significant antinociceptive and antiedematogenic activities as well as environmental friendly adsorptive properties for the removal of pollutants from pharmaceutical effluents. Overall, this review comprehensively examines the traditional uses, phytochemistry, pharmacology, toxicology, clinical studies, and nanoparticles synthesized from V. paradoxa and their applications.     

Synthesis,Characterization, and Assessment of Anti-Cancer Potential of ZnO Nanoparticles in an In Vitro Model of Breast Cancer

Advanced innovations for combating variants of aggressive breast cancer and overcoming drug resistance are desired. In cancer treatment, ZnO nanoparticles (NPs) have the capacity to specifically and compellingly activate apoptosis of cancer cells. There is also a pressing need to develop innovative anti-cancer therapeutics, and recent research suggests that ZnO nanoparticles hold great potential. Here, the in vitro chemical effectiveness of ZnO NPs has been tested. Zinc oxide (ZnO) nanoparticles were synthesized using Citrullus colocynthis (L.) Schrad by green methods approach. The generated ZnO was observed to have a hexagonal wurtzite crystal arrangement. The generated nanomaterials were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV-visible spectroscopy. The crystallinity of ZnO was reported to be in the range 50–60 nm. The NPs morphology showed a strong absorbance at 374 nm with an estimated gap band of 3.20 eV to 3.32 eV. Microscopy analysis proved the morphology and distribution of the generated nanoparticles to be around 50 nm, with the elemental studies showing the elemental composition of ZnO and further confirming the purity of ZnO NPs. The cytotoxic effect of ZnO NPs was evaluated against wild-type and doxorubicin-resistant MCF-7 and MDA-MB-231 breast cancer cell lines. The results showed the ability of ZnO NPs to inhibit the prefoliation of MCF-7 and MDA-MB-231 prefoliation through the induction of apoptosis without significant differences in both wild-type and resistance to doxorubicin.     

Synthesis, characterization and antibacterial activity against Gram positive and Gram negative bacteria of biomimetically coated silver nanoparticles

In the present work, we describe a simple procedure to produce biomimetically coated silver nanoparticles (Ag NPs), based on the postfunctionalization and purification of colloidal silver stabilized by citrate. Two biological capping agents have been used (cysteine Cys and glutathione GSH). The composition of the capped colloids has been ascertained by different techniques and antibacterial tests on GSH-capped Ag NPs have been conducted under physiological conditions, obtaining values of Minimum Inhibitory Concentration (MIC) of 180 and 15 μg/mL for Staphylococcus aureus and Escherichia coli, respectively. The antibacterial activity of these GSH capped NPs can be ascribed to the direct action of metallic silver NPs, rather than to the bulk release of Ag(+).     

Biological identity of nanomaterials: Opportunities and challenges

The emergence of nanoparticles (NPs) has attracted tremendous interest of the scientific community for decades due to their unique properties and potential applications in diverse areas, including drug delivery and therapy. Many novel NPs have been synthesized and used to reduce drug toxicity, improve bio-availability, prolong circulation time, control drug release, and actively target to desired cells or tissues. However, clinical translation of NPs with the goal of treating particularly challenging diseases, such as cancer, will require a thorough understanding of how the NP properties influence their fate in biological systems, especially in vivo. Many efforts have been paid to studying the interactions and mechanisms of NPs and cells. Unless deliberately designed, the NPs in contact with biological fluids are rapidly covered by a selected group of biomolecules especially proteins to form a corona that interacts with biological systems. In this view, the recent development of NPs in drug delivery and the interactions of NPs with cells and proteins are summarized. By understanding the protein-NP interactions, some guidelines for safety design of NPs, challenges and future perspectives are discussed.     

Impact of Metallic Nanoparticles on In Vitro Culture,Phenolic Profile and Biological Activity of Two Mediterranean Lamiaceae Species: Lavandula viridis L’Hér and Thymus lotocephalus G. López and R. Morales

Nanoparticles (NPs) recently emerged as new chemical elicitors acting as signaling agents affecting several processes in plant metabolism. The aim of this work was to investigate the impact of the addition of copper oxide (CuO), zinc oxide (ZnO) and iron oxide (Fe₃O₄) NPs (<100 nm) at different concentrations (1, 5 and 10 mg/L) to the culture media on several morphological, physiological and -biochemical parameters of in vitro shoot cultures of Lavandula viridis L’Hér and Thymus lotocephalus G. López and R. Morales (Lamiaceae), as well as on phenolic profile and bioactivity (antioxidant and enzyme inhibition capacities). Although some decreases in shoot number and length were observed in response to NPs, biomass production was not affected or was improved in both species. Most NPs treatments decreased total chlorophyll and carotenoid contents and increased malondialdehyde levels, an indicator of lipid peroxidation, in both species. HPLC-HR-MS analysis led to the identification of thirteen and twelve phenolic compounds, respectively, in L. viridis and T. lotocephalus extracts, being rosmarinic acid the major compound found in all the extracts. ZnO and Fe₃O₄ NPs induced an increase in total phenolic and rosmarinic acid contents in T. lotocephalus extracts. Additionally, some NPs treatments also increased antioxidant activity in extracts from this species and the opposite was observed for L. viridis. The capacity of the extracts to inhibit tyrosinase, acetylcholinesterase and butyrylcholinesterase enzymes was not considerably affected. Overall, NPs had a significant impact on different parameters of L. viridis and T. lotocephalus in vitro shoot cultures, although the results varied with the species and NPs type.     

Shape evolution and thermal stability of Ag nanoparticles on spherical SiO2 substrates

In this paper, the shape evolution and thermal stability of Ag nanoparticles (NPs) on spherical SiO₂ substrates were investigated by means of in situ transmission electron microscopy (TEM) imaging and differential scanning calorimetry (DSC). The initial Ag NPs at room temperature were semispherical-like, with an average size of 9 nm in half-height width, well-dispersed on spherical SiO₂ substrates. No obvious shape change was observed when the semispherical NPs of Ag were heated at temperature lower than 550 °C. The shape of the semispherical Ag NPs changed gradually into a spherical one in the temperature range of 550-700 °C, where surface diffusion and surface premelting took place. When the heating temperature was increased up to 750 °C, the spherical Ag NPs were found to desquamate from the substrates due to the decreases of the contact area and the binding force between Ag NPs and SiO₂ substrates. A possible mechanism for the desquamation of Ag NPs from the SiO₂ sphere surface is proposed according to the results of in situ TEM observation and DSC analysis.     

Citrus sinensis leaf aqueous extract green-synthesized silver nanoparticles: Characterization and cytotoxicity,antioxidant, and anti-human lung carcinoma effects

The present work demonstrates the synthesis of Ag nanoparticles (Ag NPs) by using aqueous extract of Citrus sinensis as green reductant and capping agent without any toxic reagent. Physicochemical characteristics of the said nanoparticles were elucidated by field emission scanning electron microscopy (FESEM), fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible spectroscopy (UV-Vids) techniques. The biogenic Ag NPs are uniformly globular. The Ag NPs has been explored biologically in the anticancer and antioxidant assays. In the cellular and molecular part of the recent study, the treated cells with Ag NPs were assessed by MTT assay for 48 h about the cytotoxicity and anti-human lung carcinoma properties on normal (HUVEC) and lung carcinoma cell lines i.e. NCI-H661, HLC-1, NCI-H1563, LC-2/ad, NCI-H1299, and PC-14. The viability of malignant lung cell line reduced dose-dependently in the presence of Ag NPs. The IC50 of Ag NPs were 82, 139, 170, 66, 62, and 50 µg/mL against NCI-H661, HLC-1, NCI-H1563, LC-2/ad, NCI-H1299, and PC-14 cell lines, respectively. In the antioxidant test, the IC50 of Ag NPs and vitamin E against 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals were 21 and 15 µg/mL, respectively. After clinical study, Ag NPs containing Citrus sinensis leaf aqueous extract may be used to formulate a new chemotherapeutic drug or supplement to treat the several types of human lung adenocarcinoma.     

Hybrids of organic molecules and flat, oxide-free silicon: high-density monolayers, electronic properties, and functionalization

Since the first report of Si-C bound organic monolayers on oxide-free Si almost two decades ago, a substantial amount of research has focused on studying the fundamental mechanical and electronic properties of these Si/molecule surfaces and interfaces. This feature article covers three closely related topics, including recent advances in achieving high-density organic monolayers (i.e., atomic coverage >55%) on oxide-free Si(111) substrates, an overview of progress in the fundamental understanding of the energetics and electronic properties of hybrid Si/molecule systems, and a brief summary of recent examples of subsequent functionalization on these high-density monolayers, which can significantly expand the range of applicability. Taken together, these topics provide an overview of the present status of this active area of research.     

Chromium speciation in solid matrices and regulation: a review

In recent years, the extensive use of chromium in industrial processes has led to the promotion of several directives and recommendations by the European Union, that try to limit and regulate the presence of Cr(VI) in the environment and to protect industrial workers using chromium and end-users of manufactured products. As a consequence, new standard methods and analytical procedures have been published at the EU level for Cr(VI) determination in soil, sludge, sediment, and similar waste materials, workplace atmospheres, cement, packaging materials, industrially produced samples, and corrosion-protection layers on some components of vehicles and electrical and electronic equipment. The objective of this article is to summarize the different directives and recommendations and to critically review the currently existing standard methods and the methods published in the literature for chromium speciation in the above mentioned solid matrices, putting the emphasis on the different extraction procedures which have been developed for each matrix. Particular attention has been paid to Cr(III) and Cr(VI) inter-conversions that can occur during extraction and efforts to minimize these unwanted reactions. Although the use of NaOH-Na₂CO₃ solutions with hot plate extraction seems to be the more widespread procedure, species transformation can still occur and several studies suggest that speciated isotope-dilution mass spectrometry (SIDMS) could be a suitable tool for correction of these interconversions. Besides, recent studies have proved the role of Cr(III) in chromium toxicology. As a consequence, the authors suggest an update of standard methods in the near future.     

Antibacterial Mechanisms of Zinc Oxide Nanoparticle against Bacterial Food Pathogens Resistant to Beta-Lactam Antibiotics

The increase in β-lactam-resistant Gram-negative bacteria is a severe recurrent problem in the food industry for both producers and consumers. The development of nanotechnology and nanomaterial applications has transformed many features in food science. The antibacterial activity of zinc oxide nanoparticles (ZnO NPs) and their mechanism of action on β-lactam-resistant Gram-negative food pathogens, such as Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Serratia marcescens, Klebsiella pneumoniae, and Proteus mirabilis, are investigated in the present paper. The study results demonstrate that ZnO NPs possesses broad-spectrum action against these β-lactamase-producing strains. The minimal inhibitory and minimal bactericidal concentrations vary from 0.04 to 0.08 and 0.12 to 0.24 mg/mL, respectively. The ZnO NPs elevate the level of reactive oxygen species (ROS) and malondialdehyde in the bacterial cells as membrane lipid peroxidation. It has been confirmed from the transmission electron microscopy image of the treated bacterial cells that ZnO NPs diminish the permeable membrane, denature the intracellular proteins, cause DNA damage, and cause membrane leakage. Based on these findings, the action of ZnO NPs has been attributed to the fact that broad-spectrum antibacterial action against β-lactam-resistant Gram-negative food pathogens is mediated by Zn²⁺ ion-induced oxidative stress, actions via lipid peroxidation and membrane damage, subsequently resulting in depletion, leading to β-lactamase enzyme inhibition, intracellular protein inactivation, DNA damage, and eventually cell death. Based on the findings of the present study, ZnO NPs can be recommended as potent broad-spectrum antibacterial agents against β-lactam-resistant Gram-negative pathogenic strains.     

Synthesis,Nanoformulations, and In Vitro Anticancer Activity of N-Substituted Side Chain Neocryptolepine Scaffolds

The naturally occurring neocryptolepine (5-Methylindolo [2,3-b]quinoline) and its analogs exhibited prominent anticancer and antimalarial activity. However, the main problem of this class of compounds is their poor aqueous solubility, hampering their bioavailability and preventing their clinical development. To overcome the problem of insolubility and to improve the physicochemical and the pharmacological properties of 5-Methylindolo [2,3-b]quinoline compounds, this work was designed to encapsulate such efficient medical compounds into mesoporous silica oxide nanoemulsion (SiO₂NPs). Thus, in this study, SiO₂NPs was loaded with three different concentrations (0.2 g, 0.3, and 0.6 g) of 7b (denoted as NPA). The findings illustrated that the nanoparticles were formed with a spherical shape and exhibited small size (less than 500 nm) using a high concentration of the synthesized chemical compound (NPA, 0.6 g) and good stabilization against agglomeration (more than −30 mv). In addition, NPA-loaded SiO₂NPs had no phase separation as observed by our naked eyes even after 30 days. The findings also revealed that the fabricated SiO₂NPs could sustain the release of NPA at two different pH levels, 4.5 and 7.4. Additionally, the cell viability of the produced nanoemulsion system loaded with different concentrations of NPA was greater than SiO₂NPs without loading, affirming that NPA had a positive impact on increasing the safety and cell viability of the whole nanoemulsion. Based on these obtained promising data, it can be considered that the prepared NPA-loaded SiO₂NPs seem to have the potential for use as an effective anticancer drug nanosystem.     

European ring exercise on water toxicity using different bioluminescence inhibition tests based on Vibrio fischeri, in support to the implementation of the water framework directive

An inter-laboratory comparison exercise was conducted under the European Union funded project entitled: Screening Methods for Water Data Information in Support of the Implementation of the Water Framework Directive (SWIFT-WFD) and coordinated by the Consejo Superior de Investigaciones Científicas (CSIC), in order to evaluate the reproducibility of different toxicity tests based on the bioluminescence inhibition of Vibrio fischeri, for the rapid water toxicity assessment.For the first time, this type of exercise has been organized in Europe, and using different tests based on the same principle. In this exercise, 10 laboratories from 8 countries (Austria, Cyprus, Germany, Greece, Italy, Portugal, Romania, and Spain) took place, and a total number of 360 samples were distributed.During the exercise, six series of six samples were analyzed along 5 months. Every batch of samples was composed by three real samples and three standard solutions. The real samples were: a raw influent and the effluent of a wastewater treatment plant (WWTP), and a sample from a first settlement of the WWTP spiked with a mixture of toxicant standards.A final number of 330 (91.7%) samples was analyzed, 3300 values in duplicate were collected, and the results for each sample were expressed as the 50% effective concentration (EC₅₀) values calculated through five points of dilution inhibition curves, after 5 and 15 min of incubation times.A statistical study was initiated using 660 results. The mean values, standard deviations (σ), variances (σ²), and upper and lower warning limits (UWL and LWL) were obtained, using the EC₅₀ values calculated with the result from the participating laboratories.The main objectives of this toxicity ring study were to evaluate the repeatability (r) and reproducibility (R) when different laboratories conduct the test, the influence of complex matrix samples, the variability between different tests based on the same principle, and to determine the rate at which participating laboratories successfully completed tests initiated.In this exercise, the 3.93% toxicity values were outliers according with the Z-score values and the Dixon test. The samples with the greater number of outliers were those with the smallest variability coefficient, corresponding to the greater and the smaller toxicity level.No relation was found through the cluster analysis, between the final results and the different commercial devices involved. Testing by multiple commercial devices did not appear to reduce the precision of the results, and the variability coefficient for the exercise was nearby to the average value for past editions carried out at national level, where the different participants used the same commercial device.Stability of samples was also followed during the exercise. While statistical significance differences were not found for the greater part of samples, for the sample from the WWTP influent, a significant decrease of the toxicity value was found along this study. Nevertheless, this was a type of sample with a high toxicity level during all the exercise.On the other hand, in order to obtain the chemical characterization of real samples, those were analyzed by chromatographic techniques, using different sequential solid phase extraction (SSPE) procedures, followed by liquid chromatography coupled with mass spectrometry (LC-MS), and gas chromatography-mass spectrometry (GC-MS). Good agreement was found between the chemical analysis results and the toxicity level of the samples.     

Synthesis,Characterization and Employed Doxycycline Capped Gold Nanoparticles on TRP Channel Expressions in SKBR3 Breast Cancer Cells and Antimicrobial Activity

Doxycycline capped gold nanoparticles (doxy-Au(0) NPs) were prepared in an aqueous medium. Particle size and shape were determined by Transmission electron microscopy which showed the monodispersed morphology. The Fourier transform infrared spectra were represented the interaction of doxycycline with surface of doxy-Au(0) NPs. X-ray powder diffraction study gave crystalline nature of the doxy-Au(0) NPs. These doxy-Au(0) NPs have an impact on the expression levels of TRP channel genes in the breast cancer line (SKBR3) and the breast epithelial cell line (CRL-4010). Additionally, the antimicrobial activities have been evaluated to be used for multiple applications. Our results showed that the expression levels of TRP genes can be changed following the treatment of AuNPs (50 and 100 µg/mL). Furthermore, the antimicrobial activies have achieved some significant results. Finally, it has been concluded that doxy-Au(0) NPs are novel and can be used as alternative nanomedicine and extendable for control of other reducible contaminants as well.

     

Design and fabrication of thermally stable nanoparticles for well-defined nanocomposites

The nanocomposites consisted of polymer and nanoparticles (NPs) have been regarded as one of core materials in the nanotechnology. From the practical viewpoint, the heat treatment is often required in many nanocomposite fabrication processes. However, some NPs such as gold NPs exhibit the low thermal stability due to the dissociation of ligands from the nanoparticle surface at elevated temperature, limiting their use in many applications. Herein, we provide an overview of the recent efforts in strategies for the design and fabrication of inorganic NPs which have enhanced thermal stability. The recent investigation on the phase behavior of thermally stable NPs within the polymer matrices (polymer blends and block copolymer), morphologies of nanocomposites induced by NPs, and examples of their applications are also discussed. These approaches may provide useful strategy to employ the NPs for the fabrication of nanocomposites in diverse applications especially where heat treatment are required. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013     

Application of synergistic β-lactamase inhibitors and antibiotics in the treatment of wounds infected by superbugs

Amoxicillin appears to be clinically drug-resistant due to the presence of β-lactamase in bacteria. Here, we designed and prepared a hollow Prussian Blue (HPB)-based therapeutic nanoplatform that was constructed by encapsulating amoxicillin into polyethyleneimine with β-lactamase inhibitor 4-carboxyphenylboronic acid (4-Cpba) decorated HPB nanoparticles (CPA NPs). The antibacterial effect of the CPA NPs on drug-resistant bacteria was observed by in vitro colony-forming unit, minimum inhibitory concentration, scanning electron microscopy, and fluorescence tests. The results show that amoxicillin effectively inhibited Escherichia coli and Staphylococcus aureus-resistant bacteria in the presence of 4-Cpba. The in vivo experimental results show that the CPA NPs exhibited a synergistic anti-infective effect in vivo, which inhibited the inflammatory response and apoptosis induced by the drug-resistant bacterial infection, and promoted wound healing in mice. The hematoxylin and eosin staining and blood biochemical experiments revealed that the acute toxicity of the material was negligible and it had good biocompatibility. Our results verify our design that CPA NPs can restore the antibacterial activity of amoxicillin.     

Nanomaterials for Biomedical Applications: Production,Characterisations, Recent Trends and Difficulties

Designing of nanomaterials has now become a top-priority research goal with a view to developing specific applications in the biomedical fields. In fact, the recent trends in the literature show that there is a lack of in-depth reviews that specifically highlight the current knowledge based on the design and production of nanomaterials. Considerations of size, shape, surface charge and microstructures are important factors in this regard as they affect the performance of nanoparticles (NPs). These parameters are also found to be dependent on their synthesis methods. The characterisation techniques that have been used for the investigation of these nanomaterials are relatively different in their concepts, sample preparation methods and obtained results. Consequently, this review article aims to carry out an in-depth discussion on the recent trends on nanomaterials for biomedical engineering, with a particular emphasis on the choices of the nanomaterials, preparation methods/instruments and characterisations techniques used for designing of nanomaterials. Key applications of these nanomaterials, such as tissue regeneration, medication delivery and wound healing, are also discussed briefly. Covering this knowledge gap will result in a better understanding of the role of nanomaterial design and subsequent larger-scale applications in terms of both its potential and difficulties.