52 research outputs found
Optical detection of gadolinium(iii) ions quantum dot aggregation
A rapid, sensitive and selective optical readout of the presence of gadolinium(iii) ions would have a wide range of applications for clinical and environmental monitoring. We demonstrate that water-soluble CdTe quantum dots (QDs) are induced to aggregate by Gd3+ ions in aqueous solution. By using a combination of photoluminescence spectroscopy, dynamic light scattering and fluorescence correlation spectroscopy (FCS) to monitor quantum dot aggregation kinetics, we correlate the efficiency of the self-quenching process with the degree of aggregation across a broad range of conditions, including different sizes of QDs. We attribute the aggregation to metal binding to the QD's surface ligands and the quenching to intra-aggregate energy transfer between QDs. When the strategy was applied to additional trivalent ions, the aggregation rate varied according to the particular trivalent metal ion used, suggesting that the selectivity can be enhanced and controlled by appropriate design of the capping ligands and solution conditions
Synthesis of an IRMOF-1@SiO<sub>2</sub> CoreâShell and Amino-Functionalization with APTES for the Adsorption of Urea and Creatinine Using a Fixed-Bed Column Study
Kidney dysfunction is a clinical disease that disables
the kidneys
to remove the waste products and uremic toxins from the circulation
and may lead to fatal kidney failure. Hemodialysis is advantageous
in this circumstance since it prevents the accumulation of waste products
in the body and facilitates the removal of uremic toxins. However,
hemodialysis cannot entirely remove some uremic toxins, such as urea
and creatinine. In this paper, a high-performance fixed-bed column
for urea and creatinine removal was offered. As a result, a MOF layer
was built on SiO2, which was then amino-functionalized
using APTES. Numerous assays were used to characterize the final adsorbent.
The adsorption of urea and creatinine was evaluated in batch and continuous
conditions. Thus, it was demonstrated that the adsorption behavior
of A(0.2)-IRMOF-1@SiO2 followed the Langmuir isotherm,
and it exhibited the maximum adsorption capacity. The batch experiment
determined that urea and creatinine had an adsorption capacity of
1325.73 and 625.00 mg·gâ1, respectively. The
adsorption capacity was increased, which was due to the presence of
amino groups (APTES) on the MOF surface. The continuous operation
was evaluated using the A(0.2)-IRMOF-1@SiO2 fixed-bed column.
Thomas and Nelsonâs models were examined to achieve a better
understanding of the adsorption behaviors. The A(0.2)-IRMOF-1@SiO2 fixed-bed column successfully removed 92.57% of urea and
80.47% of creatinine. The separation factor for urea in comparison
to creatinine was 2.40 in the A(0.2)-IRMOF-1@SiO2 fixed-bed
column
Synthesis of GQD@ZIF-8 nano hybrids and its application as a lead optical sensor
The present study is aimed to investigate ZIF-8 metal organic frameworks, graphene quantum Dots, and their hybrid materials (GQD@ZIF-8) in the terms of sensing heavy metals. Brilliant property of graphene quantum Dots in fluorescence emission with a high intensity and ZIF-8 with high porosity and specific surface area (as adsorbent) were great stimulants to fabricate the aforementioned sensing system. The prepared hybrid material was successfully employed for the measurement of heavy metals such as lead in aqueous samples. The concentration of lead in various samples was measured using GQD@ZIF-8 hybrid materials via the method of single parameter during the time. In order to characterize GQD@ZIF-8 hybrid materials, Scanning Electron Microscopy (SEM), Furrier Transform Infrared spectroscopy (FT-IR), and nitrogen adsorption/ desorption (BET and BJH analysis) were employed in present study. Different parameters such as time, pH, and the concentration of adsorbent were also optimized in present study. The optimized values for concentration of adsorbent, time, and pH were found to be 0.05 mg/ml, 5 min, and 5 respectively. Importantly, limit of detection (LOD) for lead was calculated as 0.86 ppm. Low amount of LOD can be attributed to high fluorescence intensity and great specific surface area of the proposed sensor. The obtained results for LOD were compared with the other existing methods for detection of lead, presented in literature. The obtained results demonstrates that the proposed hybrid material possess high potential for detection and removal of lead from real samples
Quantitative structure activity relationship study of p38α MAP kinase inhibitors
The quantitative structure activity relationship (QSAR) of the novel pyrazole derivatives as inhibitors of p38α mitogen activated protein (MAP) kinase was studied. The suitable set of the molecular descriptors was calculated and the important descriptors using the variable selections of the stepwise (SW) and the genetic algorithm (GA) were selected. The predictive quality of the QSAR models was tested for an external set of nine compounds, randomly chosen out of 44 compounds. A comparison between the attained results indicated the superiority of the genetic algorithm over the stepwise method in the feature selection. The genetic algorithm-multiple linear regression (GA-MLR) model with six selected descriptors was obtained. The accuracy of the proposed model is illustrated using the following evaluation techniques: cross-validation, validation through an external test set, applicability domain, and Y-randomization. The analyses may be used to design more potent pyrazole derivatives and predict their activity prior to synthesis
Prussian Blue Analogues-Derived Molecularly Imprinted Nanozyme Array for Septicemia Detection
Septicemia,
a severe bacterial infection, poses significant risks
to human health. Early detection of septicemia by tracking specific
biomarkers is crucial for a timely intervention. Herein, we developed
a molecularly imprinted (MI) TiO2âFeâCeO2 nanozyme array derived from Ce[Fe(CN)6] Prussian
blue analogues (PBA), specifically targeting valine, leucine, and
isoleucine, as potential indicators of septicemia. The synthesized
nanozyme arrays were thoroughly characterized using various analytical
techniques, including Fourier transform infrared spectroscopy, X-ray
diffraction, field-emission scanning electron microscope, and energy-dispersive
X-ray. The results confirmed their desirable physical and chemical
properties, indicating their suitability for the oxidation of 3,3âČ,5,5âČ-tetramethylbenzidine
serving as a colorimetric probe in the presence of a persulfate oxidizing
agent, further highlighting the potential of these arrays for sensitive
and accurate detection applications. The MITiO2 shell selectively
captures valine, leucine, and isoleucine, partially blocking the cavities
for substrate access and thereby hindering the catalyzed TMB chromogenic
reaction. The nanozyme array demonstrated excellent performance with
linear detection ranges of 5 ÎŒM to 1 mM, 10â450 ÎŒM,
and 10â450 ÎŒM for valine, leucine, and isoleucine, respectively.
Notably, the corresponding limit of detection values were 0.69, 1.46,
and 2.76 ÎŒM, respectively. The colorimetric assay exhibited
outstanding selectivity, reproducibility, and performance in the detection
of analytes in blood samples, including C-reactive protein at a concentration
of 61 mg/L, procalcitonin at 870 ng/dL, and the presence of Pseudomonas aeruginosa bacteria. The utilization
of Ce[Fe(CN)6]-derived MITiO2âFeâCeO2 nanozyme arrays holds considerable potential in the field
of septicemia detection. This approach offers a sensitive and specific
method for early diagnosis and intervention, thereby contributing
to improved patient outcomes
Design and fabrication of a novel optical sensor for determination of trace amounts of lutetium ion
In this study, for the first time we report a highly selective and sensitive lutetium ions chemical optical sensor based on immobilization of a asymmetrically SâN Schiffâs base, namely N-(thien-2-ylmethylene)pyridine-2,6-diamine (TPD) on a triacetylcellulose membrane. This optode exhibits a linear range of 5.0 Ă10-7 â1.0 Ă10-5 M of the Lu(III) ion concentration with a detection limit of 9.3 Ă10-8 M at a wavelength of 336 nm. The influence of responsible factors for improving sensitivity of the sensor was studied and identified. Response time of the newly designed optode was within 20-30 s depending on the Lu(III) ion concentration. Response of the optical sensor is independent of the pH of the solution in the range of 3.0â9.0. It manifests advantages of fast response time, low detection limit and most significantly, very good selectivity with respect to a number of lanthanide ions. The sensor can readily be regenerated with thiourea solutions and its response was reversible and reproducible. This optode was applied to the determination of Lu(III) in aqueous and CRM samples
- âŠ