Label-free electrochemical aptasensor for the detection of HepG2 hepatocellular carcinoma cells.

Hepatocellular carcinoma (HCC) is the most common liver malignancy and is characterized by increasing incidence and high mortality rates. Current methods for the screening and diagnosis of HCC exhibit inherent limitations, highlighting the ever-growing need for the development of new methods for the early diagnosis of HCC. The aim of this work was to develop a novel electrochemical aptasensor for the detection of HepG2 cells, a type of circulating tumor cells that can be used as biomarkers for the early detection of HCC. A carbon screen-printed electrode was functionalized with a composite suspension containing graphene oxide, chitosan, and polyaniline nanoparticles to increase the electrode surface and provide anchoring sites for the HepG2 cell-specific aptamer. The aptamer was immobilized on the surface of the functionalized electrode using multipulse amperometry, an innovative technique that significantly reduces the time required for aptamer immobilization. The innovative platform was successfully employed for the first time for the amplification-free detection of HepG2 cells in a linear range from 10 to 200,000 cells/mL, with a limit of detection of 10 cells/mL. The platform demonstrated high selectivity and stability and was successfully used for the detection of HepG2 cells in spiked human serum samples with excellent recoveries.

Co3O4/activated carbon nanocomposites as electrocatalysts for the oxygen evolution reaction.

The Oxygen Evolution Reaction (OER) is crucial in various processes such as hydrogen production via water splitting. Several electrocatalysts, including metal oxides, have been evaluated to enhance the reaction efficiency. Zeolitic Imidazolate Framework-67 (ZIF-67) has been employed as a precursor to produce Co3O4, showing high OER activity. Additionally, the formation of composites with carbon-based materials improves the activity of these materials. Thus, this work focuses on synthesizing ZIF-67 and commercial activated carbon (AC) composites, which were used as precursors to obtain Co3O4/C electrocatalysts by calculating ZIF-67/CX (X = 10, 30, and 50, the mass percentage of AC). The obtained materials were thoroughly characterized by employing X-ray powder diffraction (XRD), confirming the cobalt oxide structure with a sphere-like morphology as observed in the TEM images. The presence of oxygen vacancies was confirmed by infrared spectroscopy and EPR measurements. The electrocatalytic performance in the OER was investigated by linear sweep voltammetry (LSV), which revealed an overpotential of 325 mV at 10 mA cm-2 and a Tafel slope value of 65.32 mV dec-1 for Co3O4/C10, superior in activity to several previously reported studies in the literature and electrochemical stability of up to 8 hours. The reduced value of charge transfer resistance, high double-layer capacitance, and the presence of Co3+ ions justify the superior performance of the Co3O4/C10 electrocatalyst.

Insight into synthesis and characterisation of Ga0.9Fe2.1O4 superparamagnetic NPs for biomedical applications.

A Ga3+-substituted spinel magnetite nanoparticles (NPs) with the formula Ga0.9Fe2.1O4 were synthesized using both the one-pot solvothermal decomposition method (TD) and the microwave-assisted heating method (MW). Stable colloidal solutions were obtained by using triethylene glycol, which served as a NPs stabilizer and as a reaction medium in both methods. A narrow size distribution of NPs, below 10 nm, was achieved through selected nucleation and growth. The composition, structure, morphology, and magnetic properties of the NPs were investigated using FTIR spectroscopy, thermal analysis (TA), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and magnetic measurements. NPs with the expected spinel structure were obtained in the case of the TD method, while the MW method produced, additionally, an important amount of gallium suboxide. The NPs, especially those prepared by TD, have superparamagnetic behavior with 2.02 µB/f.u. at 300 K and 3.06 µB/f.u. at 4.2 K. For the MW sample these values are 0.5 µB/f.u. and 0.6 µB/f.u. at 300 K and 4.2 K, respectively. The MW prepared sample contains a secondary phase and very small NPs which affects both the dimensional distribution and the magnetic behavior of NPs. The NPs were tested in vitro on amniotic mesenchymal stem cells. It was shown that the cellular metabolism is active in the presence of Ga0.9Fe2.1O4 NPs and preserves an active biocompatible cytoskeleton.

Characterization and In Vitro Biocompatibility of Two New Bioglasses for Application in Dental Medicine-A Preliminary Study.

Bioactive glasses (BGs), also known as bioglasses, are very attractive and versatile materials that are increasingly being used in dentistry. For this study, two new bioglasses-one with boron (BG1) and another with boron and vanadium (BG2)-were synthesized, characterized, and tested on human dysplastic keratinocytes. The in vitro biological properties were evaluated through pH and zeta potential measurement, weight loss, Ca2+ ions released after immersion in phosphate-buffered saline (PBS), and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) analysis. Furthermore, biocompatibility was evaluated through quantification of lactate dehydrogenase activity, oxidative stress, transcription factors, and DNA lesions. The results indicate that both BGs presented the same behavior in simulated fluids, characterized by high degradation, fast release of calcium and boron in the environment (especially from BG1), and increased pH and zeta potential. Both BGs reacted with the fluid, particularly BG2, with irregular deposits covering the glass surface. In vitro studies demonstrated that normal doses of the BGs were not cytotoxic to DOK, while high doses reduced cell viability. Both BGs induced oxidative stress and cell membrane damage and enhanced NFkB activation, especially BG1. The BGs down-regulated the expression of NFkB and diminished the DNA damage, suggesting the protective effects of the BGs on cell death and efficacy of DNA repair mechanisms.

Design, in vitro bioactivity and in vivo influence on oxidative stress and matrix metalloproteinases of bioglasses in experimental skin wound.

BACKGROUND: The bioactive glasses (BGs) are very attractive materials increasingly used in healing skin lesions due to their antibacterial effect and stimulation of collagen deposition and angiogenesis. In this study, three specimens of bioactive glasses (BG1, BG2 and BG3) have been synthesized and characterized. METHODS: In order to evaluate their in vitro bioactivity, the pH measurements, zeta potential and the concentration of Ca2+ and fluor ions released after immersion in phosphate buffered saline (PBS) followed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, inductively coupled plasma optical emission spectrometry (ICP-OES) and for BG1 and BG3, X-ray powder diffraction analysis, were performed. X-ray photoelectron spectroscopy (XPS) was also used for detection of different ions in the solid bioglasses before immersion in PBS. The impact of BG1 and BG3 on skin healing mechanisms was evaluated by oxidative stress and matrix metalloproteases (MMP)-2 and -9 and by histopathological analysis. RESULTS: The results have shown that all the BGs tested are characterized by a very high degradation rate and a very fast Ca2+, fluor and boron releases and displayed changed surface morphology at SEM, after 7 and 14 days of immersion in PBS. In addition, BG1 and BG3 reduced in vivo the lipid peroxidation, increased the nitric oxide, especially at 14 days and improved superoxide dismutase activity, mainly in BG1 treated animals. In parallel, both BG1 and BG3, diminished MMP-9 at 14 days and increased the proportion of normal collagen in the bed of the wound, particularly BG3. CONCLUSION: These results suggested that due to the antioxidant and anti-inflammatory properties of components released from BGs and regulatory properties on MMPs activities, BGs can exert beneficial effects in wound healing.

Photocatalytic and Electrocatalytic Properties of NGr-ZnO Hybrid Materials.

N-doped graphene-ZnO hybrid materials with different N-doped graphene:ZnO wt% ratios (1:10; 1:20; 1:30) were prepared by a simple and inexpensive sol-gel method. The materials denoted NGr-ZnO-1 (1:10), NGr-ZnO-2 (1:20), and NGr-ZnO-3 (1:30) were investigated with advanced techniques and their morpho-structural, photocatalytic, and electrocatalytic properties were reported. Hence, pure N-doped graphene sample contains flakes with the size ranging from hundreds of nanometers to micrometers. In the case of all NGr-ZnO hybrid materials, the flakes appear heavily decorated with ZnO nanoparticles, having a cauliflower-like morphology. The X-ray powder diffraction (XRD) investigation of N-doped graphene sample revealed that it was formed by a mixture of graphene oxide, few-and multi-layer graphene. After the ZnO nanoparticles were attached to graphene, major diffraction peaks corresponding to crystalline planes of ZnO were seen. The qualitative and quantitative compositions of the samples were further evidenced by X-ray photoelectron spectroscopy (XPS). In addition, UV photoelectron spectroscopy (UPS) spectra allowed the determination of the ionization energy and valence band maxima. The energy band alignment of the hybrid materials was established by combining UV-Vis with UPS results. A high photocatalytic activity of NGr-ZnO samples against rhodamine B solution was observed. The associated reactive oxygen species (ROS) generation was monitored by electron paramagnetic resonance (EPR)-spin trapping technique. In accordance with bands alignment and identification of radical species, the photocatalytic mechanism was elucidated.

Photocatalytic activity of SnO2-TiO2 composite nanoparticles modified with PVP.

Interface modified SnO2-TiO2 composite nanoparticles were produced in two stages: first SnO2 nanoparticles were prepared by chemical precipitation in the presence of polyvinylpyrrolidone (PVP) and thermally treated at 500 °C then TiO2 was deposited on top of modified SnO2 and followed by a final annealing. As a consequence SnO2-TiO2 composite nanoparticles get crystallized while PVP is decomposed into monomer units and other attached smaller molecular fragments. TGA coupled with FT-IR spectroscopy confirmed the presence of monomers and other moieties as a result of PVP thermal fragmentation. The crystalline phases and composition of the two oxides were evidenced by X-ray diffraction, HRTEM and XPS. It was found that specific surface area of the composites increases with the increase in the initial amount of PVP. Also, the oxidation potential of the TiO2 shell, as determined by UV photoelectron spectroscopy (UPS), significantly decreases as the PVP quantity increase and further modifies the band alignment between SnO2 and TiO2 components. Additionally, both XPS and UPS spectra as well as EPR investigations indicate the presence of many localized states inside the band gap of TiO2. With a moderate PVP content the combined effects of band alignment, gap localized states and porosity make possible an increased number of reactive oxygen species (ROS) generation thus increasing photocatalytic activity against RhB dye solution under visible irradiation. The photocatalytic mechanism was elucidated based on the identification of radical species involved and in accordance with energy bands alignment, gap states, and porosity. Besides water purification by photocatalysis, SnO2-TiO2, as ROS generating heterostructures may be used in applications like antibacterial and antitumoral, deodorizing, air purifying, self-cleaning, gas sensing, as well as in hydrogen production.

Nano forsterite biocomposites for medical applications: Mechanical properties and bioactivity.

The aim of the present study was to obtain and to investigate nano forsterite and nano forsterite biocomposites for biomedical application. New self-curing forsterite biocomposites were obtained by mixing nano forsterite powder (5, 15, 30, 50, 70 wt %) with 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)-phenyl]propane (bis-GMA) and triethyleneglycol dimethacrylate (TEGDMA) monomers. The new nano forsterite biocomposites were investigated for mechanical properties: compressive strength (CS) (143-147.12 MPa), compressive modulus (CM) (1.67-2.75 GPa), diametral tensile strength (DTS) (27.33-31.55 MPa), flexural strength (FS) (59.47-83.20 MPa) and flexural modulus (FM) (2.05-8.60 GPa). Increases of CS, DTS, FS with increasing amount of forsterite were observed up to 50 wt %. The highest CM and FM values were registered for 70 wt % and a direct correlation between the forsterite volume fraction (%) was observed. SEM micrographs revealed the morphology of surface of fractured biocomposites after CS test. XPS indicated that these biocomposites promoted the hydroxyapatite formation on their surface immersed in simulated body fluid (SBF). AFM images showed that the growth of the hydroxyapatite layer occurs with a preferred orientation on the surface of forsterite biocomposites after immersion in SBF. Incorporation of nano forsterite in the polymer matrix (bis-GMA/TEGDMA) did show osteoblast adhesion and proliferation was improved on nano forsterite biocomposites. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1290-1301, 2016.

Reversing chemoresistance of malignant glioma stem cells using gold nanoparticles.

The low rate of survival for patients diagnosed with glioblastoma may be attributed to the existence of a subpopulation of cancer stem cells. These stem cells have certain properties that enable them to resist chemotherapeutic agents and ionizing radiation. Herein, we show that temozolomide-loaded gold nanostructures are efficient in reducing chemoresistance and destroy 82.7% of cancer stem cells compared with a 42% destruction rate using temozolomide alone. Measurements of in vitro cytotoxicity and apoptosis indicate that combination with gold facilitated the ability of temozolomide, an alkylating drug, to alter the resistance of these cancer stem cells, suggesting a new chemotherapy strategy for patients diagnosed with inoperable recurrent malignant glioma.