A series of Fe
3-x
Gd
x
O
4
(
x
= 0, 0.1, 0.2) nanoparticles with an average diameter of around 8 nm were prepared by the coprecipitation method and coated by citric acid (CA). The nanoparticles ...show superparamagnetic behavior at room temperature and transition to a blocked state, at a temperature from ~ 89 K to ~ 213 K, depending on Gd concentration. The saturation magnetization of Fe
3-
x
Gd
x
O
4
tended to drop for samples with a higher content of Gd. High colloidal stability is mandatory in medical applications of magnetic nanoparticles, and here we demonstrate a new procedure for its improvement. A colloidal sample of Fe
3
O
4
@CA was mechanically milled, after which dynamic light scattering and zeta potential measurements were used to monitor the hydrodynamic size and colloidal stability of the acquired suspensions. After 90 min of milling, the average hydrodynamic diameter decreased by 40%, and size distribution changed from polymodal to monomodal, while the negative zeta potential increased from − 30.5 mV to − 52.8 mV. Additionally, Fe
2.80
Gd
0.20
O
4
@CA nanoparticles were embedded in human serum albumin to produce magnetic microspheres (MMS), which could be used as a drug delivery platform. FE-SEM images showed that magnetic nanoparticles form clusters within MMS.
•State-of-the-art technology for the improvement of the materials and enzyme immobilization.•Droplet impedimetric detection was proposed.•Promising basis for construction of Point-of-Care devices was ...developed.
Herein, we proposed a novel approach and state-of-the-art technology for the improvement of the materials and enzyme immobilization at the electrode surface and construction of impedimetric glucose biosensor. We silanized titanium dioxide nanoparticles using (3-aminopropyl)triethoxysilane (APTES), for the preparation of cross-linked material nanoparticles, with carboxylic graphene. The silanization of titanium dioxide nanoparticles and an increase in electron shuttle was proven feasible when this composite was able to achieve about 30% higher current than non-silanized material. The proposed approach was used for the modification of the printed three-electrode system and the development of the impedimetric glucose biosensor. The material morphology and electrochemical characteristics were confirmed by spectroscopic and electrochemical methods. The present combination effectively modified the electrode surface and serve as a promising basis for the construction of Point-of-Care devices. Developed biosensor possesses wide operating linear range toward glucose detection from 50 µmol to 1000 µmol, with the limit of detection of 24 µmol. Finally, negligible interference effect and application in the real sample indicate that the proposed mechanism can be successfully applied to the assessment of glucose level in only one drop of real sample.
S‐Adenosyl‐L‐Homocysteine (AdoHcy) is a crucial pathological factor in homocysteine‐associated disorders. We developed an impedimetric approach for single drop S‐Adenosyl‐L‐Homocysteine detection, ...based on S‐Adenosyl‐L‐Homocysteine hydrolase (SAH), produced in the prokaryotic expression system (E. coli) by recombinant DNA technology, immobilized on citrate acid‐coated gallium oxyhydroxide dispersed over single‐walled carbon nanotubes (CA/GaO(OH)@SWCNT). The proposed biosensor offers detection of AdoHcy, with a limit of detection (LOD) of 0.17 μM. with operating linear range from 1 to 44 μM. The remarkable stability of gallium oxyhydroxide crystal was further improved by citric acid coating and its optical, electrical and physical anisotropy was skipped using SWCNTs.
•Novel platform for the detection of histamine based on based on single drop detection.•AuNPs decorated MnO2 microcomposite was synthesized and applid for modification of SPCE.•Excellent limit of ...detection was achieved.•Application in real samples was proposed.
In order to ensure high food quality, one of the prime importance is the detection and quantification of histamine, well known marine food poison. In this work, we constructed novel electrochemical biosensor for the detection of histamine based on gold nanoparticles decorated on manganese dioxide (Au/MnO2) and used for modification of screen-printed carbon electrode (Au/MnO2@SPCE). The constructed sensor was then used for the estimation of histamine content in a single drop. Materials used in this study were synthesized and characterized using HR-TEM, XRPD and electrochemical methods. The amperometric detection method was optimized and, under selected operating parameters (supporting electrolyte pH 6, working potential of 1 V), the proposed sensor possesses linear working range from 0.3 µM to 5.1 µM, with a detection limit of 0.08 µM. The effect of selected interferences was investigated and it was found that the developed approach offers accurate, precise, selective, fast and reproducible quantification of histamine using only one drop of the sample. In the end, this work stands as a proof-of-concept of the modified electrodes and electrochemical detection as a promising and prospective approach for the applications in real-time monitoring of the food quality.
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The mechanisms underlying the cytotoxic action of pure fullerene suspension (nano-C60) and water-soluble polyhydroxylated fullerene C60(OH)n were investigated. Crystal violet assay for cell viability ...demonstrated that nano-C60 was at least three orders of magnitude more toxic than C60(OH)n to mouse L929 fibrosarcoma, rat C6 glioma, and U251 human glioma cell lines. Flow cytometry analysis of cells stained with propidium iodide (PI), PI/annexin V–fluorescein isothiocyanate, or the redox-sensitive dye dihydrorhodamine revealed that nano-C60 caused rapid (observable after few hours), reactive oxygen species (ROS)–associated necrosis characterized by cell membrane damage without DNA fragmentation. In contrast, C60(OH)n caused delayed, ROS-independent cell death with characteristics of apoptosis, including DNA fragmentation and loss of cell membrane asymmetry in the absence of increased permeability. Accordingly, the antioxidant N-acetylcysteine protected the cell lines from nano-C60 toxicity, but not C60(OH)n toxicity, while the pan-caspase inhibitor z-VAD-fmk blocked C60(OH)n-induced apoptosis, but not nano-C60–mediated necrosis. Finally, C60(OH)n antagonized, while nano-C60 synergized with, the cytotoxic action of oxidative stress–inducing agents hydrogen peroxide and peroxynitrite donor 3-morpholinosydnonimine. Therefore, unlike polyhydroxylated C60 that exerts mainly antioxidant/cytoprotective and only mild ROS-independent pro-apoptotic activity, pure crystalline C60 seems to be endowed with strong pro-oxidant capacity responsible for the rapid necrotic cell death.
The aim of this study was to develop a dual-modality PET/MR imaging probe by radiolabeling iron oxide magnetic nanoparticles (IONPs), surface functionalized with water soluble stabilizer ...2,3-dicarboxypropane-1,1-diphosphonic acid (DPD), with the positron emitter Gallium-68. Magnetite nanoparticles (Fe3O4 MNPs) were synthesized via coprecipitation method and were stabilized with DPD. The Fe3O4-DPD MNPs were characterized based on their structure, morphology, size, surface charge, and magnetic properties. In vitro cytotoxicity studies showed reduced toxicity in normal cells, compared to cancer cells. Fe3O4-DPD MNPs were successfully labeled with Gallium-68 at high radiochemical purity (>91%) and their stability in human serum and in PBS was demonstrated, along with their further characterization on size and magnetic properties. The ex vivo biodistribution studies in normal Swiss mice showed high uptake in the liver followed by spleen. The acquired PET images were in accordance with the ex vivo biodistribution results. Our findings indicate that Ga68-Fe3O4-DPD MNPs could serve as an important diagnostic tool for biomedical imaging.
The adsorption properties of two zeolite types, faujasite (NaY, ZnY, CoY) and LTA-4A zeolite (NaA, ZnA, CoA), towards technetium were studied in batch static experiments. The Si/Al ratio, acidity, ...dealumination, chargebalance cations of zeolite, contact time and temperature determined the adsorption efficiency. The maximum removal efficiency of 98.8% and
K
d
value (2.06 × 10
−4
cm
3
g
−1
) was achieved using CoY (zeolite type Y). The kinetics of technetium adsorption followed the pseudo-second order model. The TcO
2
adsorption is mainly due to the hydrogen bonds between protons of the zeolitic structural OH groups (Bronsted acid center) and oxygen from the TcO
2
−
.
Abstract Because of the ability to induce cell death in certain conditions, the fullerenes (C60 ) are potential anticancer and toxic agents. The colloidal suspension of crystalline C60 (nano-C60 , n ...C60 ) is extremely toxic, but the mechanisms of its cytotoxicity are not completely understood. By combining experimental analysis and mathematical modelling, we investigate the requirements for the reactive oxygen species (ROS)-mediated cytotoxicity of different n C60 suspensions, prepared by solvent exchange method in tetrahydrofuran (THF/ n C60 ) and ethanol (EtOH/ n C60 ), or by extended mixing in water (aqu/ n C60 ). With regard to their capacity to generate ROS and cause mitochondrial depolarization followed by necrotic cell death, the n C60 suspensions are ranked in the following order: THF/ n C60 >EtOH/ n C60 >aqu/ n C60 . Mathematical modelling of singlet oxygen (1 O2 ) generation indicates that the1 O2 -quenching power (THF/ n C60 <EtOH/ n C60 <aqu/ n C60 ) of the solvent intercalated in the fullerene crystals determines their ability to produce ROS and cause cell damage. These data could have important implications for toxicology and biomedical application of colloidal fullerenes.
Using the rat glioma cell line C6 and the human glioma cell line U251, we demonstrate the multiple mechanisms underlying the in vitro anticancer effects of the C
60 fullerene water suspension (nano-C
...60 or
nC
60) produced by solvent exchange method. Nano-C
60 in a dose-dependent manner reduced the tumor cell numbers after 24 h of incubation. The observed antiglioma action of
nC
60 at high concentration (1 μg/ml) was due to a reactive oxygen species-mediated necrotic cell damage that was partly dependent on oxidative stress-induced activation of extracellular signal-regulated kinase (ERK). On the other hand, low-dose
nC
60 (0.25 μg/ml) did not induce either necrotic or apoptotic cell death, but caused oxidative stress/ERK-independent cell cycle block in G
2/M phase and subsequent inhibition of tumor cell proliferation. Treatment with either high-dose or low-dose
nC
60 caused the appearance of acidified intracytoplasmic vesicles indicative of autophagy, but only the antiglioma effect of low-dose
nC
60 was significantly attenuated by inhibiting autophagy with bafilomycin A1. Importantly, primary rat astrocytes were less sensitive than their transformed counterparts to a cytostatic action of low-dose
nC
60. These data provide grounds for further development of
nC
60 as an anticancer agent.
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