Wei Zhe Teo

The Cytotoxicity of Layered Black Phosphorus

Black phosphorus (BP), the latest addition to the family of 2D layered materials, has attracted much interest owing to potential optoelectronics, nanoelectronics, and biomedicine applications. Little is known about its toxicity, such as whether it could be as toxic as white phosphorus. In response to the possibility of BP employment into commercial products and biomedical devices, its cytotoxicity to human lung carcinoma epithelial cells (A549) was investigated. Following a 24 h exposure of the cells with different BP concentrations, cell viability assessments were conducted using water-soluble tetrazolium salt (WST-8) and methylthiazolyldiphenyltetrazolium bromide (MTT) assays. The toxicological effects were found to be dose-dependent, with BP reducing cell viabilities to 48% (WST-8) and 34% (MTT) at 50 μg mL(-1) exposure. This toxicity was observed to be generally intermediate between that of graphene oxides and exfoliated transition-metal dichalcogenides (MoS2, WS2, WSe2). The relatively low toxicity paves the way to utilization of black phosphorus.

Fe0 Nanomotors in Ton Quantities (1020 Units) for Environmental Remediation

Despite demonstrating potential for environmental remediation and biomedical applications, the practical environmental applications of autonomous self-propelled micro-/nanorobots have been limited by the inability to fabricate these devices in large (kilograms/tons) quantities. In view of the demand for large-scale environmental remediation by micro-/nanomotors, which are easily synthesized and powered by nontoxic fuel, we have developed bubble-propelled Fe(0) Janus nanomotors by a facile thermally induced solid-state procedure and investigated their potential as decontamination agents of pollutants. These Fe(0) Janus nanomotors, stabilized by an ultrathin iron oxide shell, were fuelled by their decomposition in citric acid, leading to the asymmetric bubble propulsion. The degradation of azo-dyes was dramatically increased in the presence of moving self-propelled Fe(0) nanomotors, which acted as reducing agents. Such enhanced pollutant decomposition triggered by biocompatible Fe(0) (nanoscale zero-valent iron motors), which can be handled in the air and fabricated in ton quantities for low cost, will revolutionize the way that environmental remediation is carried out.

Motion Control of Micro‐/Nanomotors

As we progress towards employing self-propelled micro-/nanomotors in envisioned applications such as cargo delivery, environmental remediation, and therapeutic treatments, precise control of the micro-/nanomotors direction and their speed is essential. In this Review, major emerging approaches utilized for the motion control of micro-/nanomotors have been discussed, together with the lastest publications describing these approaches. Future studies could incorporate investigations on micro-/nanomotors motion control in a real-world environment in which matrix complexity might disrupt successful manipulation of these small-scale devices.

Fluorinated Nanocarbons Cytotoxicity.

As the research in nanotechnology progresses, there will eventually be an influx in the number of commercial products containing different types of nanomaterials. This phenomenon might damage our health and environment if the nanomaterials used are found to be toxic and they are released into the waters when the products degrade. In this study, we investigated the cytotoxicity of fluorinated nanocarbons (CXFs), a group of nanomaterials which can find applications in solid lubricants and lithium primary batteries. Our cell viability findings indicated that the toxicological effects induced by the CXF are dependent on the dose, size, shape, and fluorine content of the CXF. In addition, we verified that CXFs have insignificant interactions with the cell viability assays-methylthiazolyldiphenyl-tetrazolium bromide (MTT) and water-soluble tetrazolium salt (WST-8), thus suggesting that the cytotoxicity data obtained are unlikely to be affected by CXF-induced artifacts and the results will be reliable.

Toxicity of layered semiconductor chalcogenides: beware of interferences

The absence of bandgap in graphene has opened exploration in a new class of 2D nanomaterials: layered semiconductor chalcogenides. Research has found that they have promising properties which are advantageous for applications in a wide range of fields such as solar energy conversion, field effect transistors, optoelectronic devices, energy storage, and is expanding into biomedical applications. However, little is known about their toxicity effects. In view of the possibility of employing these materials into consumer products, we investigated the cytotoxicity of two common layered semiconductor chalcogenides, namely GaSe and GeS, based on cell viability assessments using water-soluble tetrazolium salt (WST-8) and methyl-thiazolyldiphenyl-tetrazolium bromide (MTT) assays after a 24 h exposure to varying concentrations of the nanomaterials on human lung carcinoma epithelial cells (A549). The cytotoxicity results indicated that GaSe is relatively more toxic than another group of 2D layered chalcogenide: transition metal dichalcogenides (MoS2, WS2, WSe2). On the other hand, GeS appeared to be non-toxic, with the concentration of GeS introduced having a positive correlation with the cell viability. Control experiments in cell-free conditions revealed that both GaSe and GeS interfered with the absorbance data gathered in the two assays, but the interference effect induced by GaSe could be minimized by additional washing steps to remove the nanomaterials prior to the cell viability assessments. In the case of GeS, however, the interference effect between GeS and both assay dyes were still significant despite the washing steps adopted, thereby giving rise to the false cytotoxicity results observed for GeS. Therein, we wish to highlight that control experiments should always be carried out to check for any possible interferences between the test specimen and cell viability markers when conducting cell viability assessments for cytotoxicity studies.

Cytotoxicity of fluorographene

Fluorinated graphenes (F-G) are gaining popularity in recent years and should they be introduced commercially in the future, these nanomaterials will inevitably be released into the environment through disposal or wearing of the products. In view of this, we attempted to investigate the cytotoxicity of three F-G nanomaterials in this study, with the use of two well-established cell viability assays, to find out their impact on mammalian cells and how their physiochemical properties might affect the extent of their cytotoxicity. Cell viability measurements on A549 cells following 24 h exposure to the F-G revealed that F-G does impart dose-dependent toxicological effects on the cells, and the level of cytotoxicity induced by the nanomaterials differed vastly. It was suggested that the fluorine content, in particular the types of fluorine-containing groups present in the nanomaterial played significant roles in affecting its cytotoxicity. In addition, control experiments which were conducted for possible nanomaterial-induced artifacts on the cell viability assays showed that absorbance readouts from the cell viability assays are free from interference from the nanomaterials.

Environmental impact and potential health risks of 2D nanomaterials

The prospective intensive utilization of two-dimensional (2D) nanomaterials, such as graphene, transition metal dichalcogenides, and black phosphorus, increased the requirements for thorough comprehension of their potential impact on the environment and health. The unique properties of 2D materials originate from their parent material crystalline structure composed of vertically stacked layers. This enables the reduction of their thickness on the atomic layer scale while simultaneously changing their physicochemical properties. Layered nanomaterials are revealing their promising employment in a wide range of applications, from the fabrication of products for everyday use to water purification and applications in biomedicine. The degradation of such materials, their biocompatibility, and their effect on living organisms have begun to attract increased attention since their auspicious application potential is still increasing. Here, we summarize recent knowledge regarding the environmental and health risks of graphene-based materials, transition metal dichalcogenides, and black phosphorus. We have summarized the current progress and findings concerning their biocompatibility, nanotoxicity, and biodistribution, bringing awareness to the complexity of these phenomena.

Direct voltammetric determination of redox-active iron in carbon nanotubes.

With the advances in nanotechnology over the past decade, consumer products are increasingly being incorporated with carbon nanotubes (CNTs). As the harmful effects of CNTs are suggested to be primarily due to the bioavailable amounts of metallic impurities, it is vital to detect and quantify these species using sensitive and facile methods. Therefore, in this study, we investigated the possibility of quantifying the amount of redox-available iron-containing impurities in CNTs with voltammetric techniques such as cyclic voltammetry. We examined the electrochemistry of Fe3 O4 nanoparticles in phosphate buffer solution and discovered that its electrochemical behavior could be affected by pH of the electrolyte. By utilizing the unique redox reaction between the iron and phosphate species, the redox available iron content in CNTs was determined successfully using voltammetry.

Direct voltammetric determination of redox-active iron in carbon nanotubes

A new reaction-based probe for the fluorescence signaling of Hg2+ ions using dithiane derivative of ESIPT probe has been investigated. Probe showed prominent off-on type fluorescence signaling behaviour towards Hg2+ ions in aqueous DMSO solution. The interfering response of Cu2+ ions was efficiently removed by using a citrate buffer as a masking agent. By using citrate buffer, the selective signaling behaviour is not affected by the presence of other metal ions that are usually present in environmental samples. Hg2+ ions signaling by a large fluorescence enhancement (66-fold) was possible with a detection limit of 1.8 ×10-7 M.As a test of a practical use for the designed probe, we created a test strip that could be used to detect Hg2+ ions in aqueous solution.D lysosomal Zn(II) is an important issue because it acts as downstream marker for the LMP process. Development of fluorescent probe which can detect lysosomal Zn(II) ions is necessary to study the oxidative stress levels in biological systems. Herein, we have developed innovative two-photon probe using naphthalimide dye composed of N,N-di-(2-picolyl) ethylenediamine (DPEN) ligand and a morpholine unit. The probe can detect Zn(II) ions in lysosomes with high sensitivity and selectivity over the most competing Cd(II) ions. The probe can also enabled fluorescence imaging of mouse brain tissues under two-photon excitation at 900 nm. The probe can be an effective tool for studying biological processes related to lysosomal Zn(II) ions by two-photon microscopy.Background: Calcineurin (CN) is a Ca 2+ /calmodulin- dependent phosphatase and has been implicated in both transcription-dependent and transcription-independent apoptosis. Objectives: We aim to interpret the correlation between CN and apoptosis in relation to pathogenesis of breast cancer. Materials and Methods: Both CN level and activity, as well as caspase-3 activity, were evaluated in tissue homogenate of 50 breast cancer patients, 20 patients with fibroadenoma and 15 healthy women. Results: CN activity was significantly decreased in malignant breast tissues compared with fibroadenoma and normal breast tissue (P 0.05). While caspase-3 showed a significant higher activity in a malignant group compared with other groups (P < 0.05). In addition, there was a significant negative correlation between CN activity with grade, stage (P < 0.001) and a significant positive correlation with its level (P = 0.039). Conclusion: CN activity, but not its level might have a role in breast neoplasia; restoration of its normal activity may act as an adjuvant factor to control breast cancer pathogenesis.T smart and simple spectrophotometric methods are developed and validated for simultaneous determination of Itopride hydrochloride (IT) and Rabeprazole sodium (RB) in their binary mixture namely; Constant Center method (CC) and Ratio difference method (RD). The calibration curves are linear over the concentration range of 10-110 μg /μL for Itopride hydrochloride and 4-44 μg /μL for Rabeprazole sodium, with mean recoveries 99.69 ± 0.391, 99.86 ± 0.440 for Itopride hydrochloride using CC and RD; respectively and 100.39 ± 0.537, 100.25 ± 0.458 for Rabeprazole sodium using CC and RD methods; respectively. The proposed methods are applied to pharmaceutical formulation without preliminary separation steps. To assess the speceficity of the methods, analysis of synthetic mixtures containing different ratios of the two studied drugs and their capsules dosage form is done. The statistical comparison shows that there is no significant difference between the results obtained by the proposed methods and the reported HPLC method with regard to both accuracy and precision.The applied methods are validated according to ICH guidelines and can be used for quality control laboratories for the studied mixture. The proposed methods have lower cost and more environmental friendly than the HPLC ones. The methods are also appropriate to be used in laboratories which have deficiency in liquid chromatographic instruments.M frameworks (MOFs) have potential applications in the fields of sorption and separation, catalysis and luminescence. Here, a 3D compound {[Zn2(BPF)(NH2-BDC)2]}n (1) was constructed with 2,7′-bis(4-pyridyl)fluorine (BPF) and 2-aminoterephthalic acid (NH2-BDC ) as bridging ligand. The single crystal X-ray study showed that compound 1 displays pillar-layered structure. The solid-state emission spectra of the compound have been studied at room temperature. Compound 1 shows strong emission at 495 nm, which is stronger than that observed in the free BPF (424 nm). The enhancement of luminescence may be attributed to the chelation of ligand with metal center, which effectively increases the rigidity of the ligand and reduces the loss of energy by radiation decay. The band gap (2.75 eV) was measured by a solid state visible light diffuse reflection measurement method at room temperature. We select methylene blue (MB) as a model of dye contaminant to evaluate the photocatalytic effectiveness. Approximately 50% of MB was degraded in four hours under neon light at 500 W.T determination of minerals and trace elements in foodstuffs is an important part of nutritional and toxicological analyses. Although copper, chromium, iron and zinc play an important role in human metabolism and so, they are essential micronutrients for human health. Their higher intake as well as the prolonged intake of even low concentration (Ni) can cause serious toxic effects. The interest in these elements is increasing together with reports of relationships between trace element status and oxidative diseases. Environmental pollution is the main cause of heavy metal contamination in the food chain. Of all foods, legumes most adequately meet the recommended dietary guidelines for healthful eating because they are high in carbohydrate and dietary fiber, mostly low in fat, supply adequate protein while being a good source of vitamins and minerals. In this study, nickel and chromium concentrations were determined in legumes taken from Turkish markets. Further, sulfur concentrations of the samples were also determined and the relationship between metals and sulfur were examined. The element concentrations were measured by using ICP-MS after digestion by microwave digestion system. It was found that the highest Ni concentration is 2.5 mg/kg for beans. To check the reliability, the SRM was examined for the studied elements.T oral delivery of anticancer drugs represents a significant challenge for global scientist. N-trimethyl chitosan (TMC) is a polymer with the potential to facilitate effective oral drug delivery. Recently, the peptide CSKSSDYQC (CSK) has been conjugated to TMC as a means of active goblet cell targeting for gastrointestinal uptake. The aim of the study is to develop and optimize a TMC-CSK modified nanoparticules for oral delivery of gemcitabine. TMC was synthesised from deacetylated chitosan using a novel two-step synthesis, then conjugated with CSK to actively target goblet cells. Gemcitabine-loaded TMCCSK nanoparticles were prepared via ionic gelation. Characterisation studies including particle size, zeta potential, entrapment efficiency and in vitro drug release were then carried out. Cytotoxicity of drug solution and drug loaded formulation was tested on 4T1 breast cancer cell. Lastly, in-vivo pharmacokinetic and pharmacodynamics studies were conducted. The results showed the optimal delivery system showed particle size of 173.6±7.7 nm and zeta potential of 18.5±0.2 mV. Entrapment efficiency of 66.44±0.02%, and a sustained drug release profile was obtained. LD50 of 0.23 μg/mL was determined in cytotoxicity studies. Gemcitabine loaded TMC-CSK nanoparticles significantly improved the oral bioavailability, raised the plasma half-life, and AUC0-∞ of 4.5 fold higher than for gemcitabine solution in pharmacokinetic studies. Obvious tumour size reduction of 2.6 fold was observed for TMC-CSK nanoparticles compared to drug solution in pharmacodynamics studies. In conclusion, gemcitabine can be delivered using this TMC-CSK modified nanoparticulate delivery systems via oral route to elevate its oral bioavailability and therapeutic anticancer effect.O of the methods of obtaining functionalized heterocycles is the 1,3-dipolar cycloaddition reaction involving nitroalkenes as dipolarophiles containing a trihalogenmethyl group at β-position in their structure. 1,3 dipolar cycloaddition of phenylazide to 1 nitroand 1 bromo 1 nitro 3,3,3 trifluoro(chlorine)propenes was carried out through the intermediate formation of regioisomeric triazolines, which under the reaction conditions underwent intramolecular transformation (denitration, dehydrogenation, dehydrohalogenation) culminating in the formation of the corresponding triazoles with or without nitro-group. The structure of obtained compounds is proved by modern physical-chemical research methods and the formation of these compounds does not contradict with reference data on such adducts obtaining in reaction of 1,3-dipolar cycloaddition with the same structure type nitroalkenes which contain CO2R and P(O)(OR)2 groups instead of the С(Hlg)3 substitute in their structure.T contribution will explore cutting edge molecular (Raman, IR, fluorescence, SNOM, AFM, TERS, femtosecond spectroscopy) mapping and time resolved dynamics of cellular structures of cancers, localization of drugs and nanoparticles in cells and tissues. The multidisciplinary nature of the studies span the a diverse range of biological, chemical, and physical sciences related to cancer biology. This contribution will provide insight regarding the new molecular mapping and their ability to monitor biochemistry of biomolecules in the cells and tissues, distribution of drugs, and nanomaterials as they interact with cells and tissues. The main focus will be on the presentation of integrated picture of cancer by near field microscopy SNOM, AFM and hyperspectral Raman imaging to look inside human breast ducts. We will demonstrate how this approach gives important answer about location and distribution of biochemical components in human cells and tissue during cancer development. The lecture shows new look inside human breast duct using Raman imaging, an emerging technology of molecular imaging, that may bring revolution in understanding of cancer biology. Our contribution is a first report in the literature demonstrating such a detailed analysis of normal and cancerous ducts in human breast tissue. The main advantage of Raman imaging is that it gives spatial information about various chemical constituents in defined cellular organelles in contrast to conventional methods (LC/MS, NMR, HPLC) that rely on bulk or fractionated analyses of extracted components.