Stannous Chloride Concentration Research Articles

99mTc-Labeled, Colistin Encapsulated, Theranostic Liposomes for Pseudomonas aeruginosa Infection

Infectious diseases are still the major issue not only due to antibiotic resistance but also causing deaths if not diagnosed at early-stages. Different approaches including nanosized drug delivery systems and theranostics are researched to overcome antibiotic resistance, decrease the side effects of antibiotics, improve the treatment response, and early diagnose. Therefore, in the present study, nanosized, radiolabeled with 99mTc, colistin encapsulated, neutral and cationic liposome formulations were prepared as the theranostic agent for Pseudomonas aeruginosa infections. Liposomes exhibited appropriate physicochemical properties thanks to their nano-particle size (between 173 and 217nm), neutral zeta potential value (about - 6.5 and 2.8mV), as well as encapsulation efficiency of about 75%. All liposome formulations were radiolabeled with over 90% efficiency, and the concentration of stannous chloride was found as 1mg.mL-1 to obtain maximum radiolabeling efficiency. In alamar blue analysis, neutral liposome formulations were found more biocompatible compared with the cationic formulations. Neutral colistin encapsulated liposomes were found to be more effective against P. aeruginosa strain according to their time-dependent antibacterial effect, in addition to their highest bacterial binding capacity. As conclusion, theranostic, nanosized, colistin encapsulated, neutral liposome formulations were found as promising agents for the imaging and treating of P. aeruginosa infections.

Unraveling the diagnostic phase of 99mTc-doped iron oxide nanoprobe in sarcoma bearing mice

Most current single photon emission computed tomography (SPECT) nano-tracers are designed via a chelator-based radiolabeling approach which requires sophisticated optimization and faces limited in-vivo stability. Here, 99mTc can be intrinsically interchelated to the core of iron oxide nanoparticles (IO-NPs) providing a promising alternative radiolabeling approach to develop 99mTc-doped IO nanoplatform for tumor diagnosis without using an organic chelator or temperature dependent procedure. 99mTc-doped IO nanoplatform was prepared via a validated one-step radiochemical doping mechanism during the polyvinyl pyrrolidone capped IO-NPs (IO-PVP-NPs) co-precipitation synthesis where stannous chloride concentration and pH adjustment played a vital role. It was synthesized with high radiolabeling efficiency 96.5 ± 0.79%, convenient hydrodynamic size 12.54 ± 2.54 nm, reasonable biocompatibility profile and appropriate in-vitro stability up to 24 h. The in-vivo evaluation in sarcoma bearing mice revealed reduced RES's organs uptake, lustrous tumor accumulations (26.5 ± 1.17 and 69.32 ± 0.97% ID/g at 60 and 30 min post i.v. and i.t., respectively) and sparkling target/non-targeting ratios at all the experimental time points with magnitude 31.17 and 62.17 at 60 min post i.v. and i.t., respectively. Hence, this IO-NPs based in-situ radiochemical doping mechanism could open a plethora of novel SPECT based nano-tracers for convenient cancer diagnosis.

The Effect of Sn(II) Precursor on Morphology and Surface Area of as Synthesis SnO<sub>2</sub> Nanotube

Tin oxide nanotubes (STs) were synthesized by the hydrothermal process using manganese dioxide nanowires (MWs) as a template and followed by oxalic acid treatment. The effect of the stannous chloride concentration on the structure and crystallite size of the product were investigated. The phase composition was determined by XRD. Morphologies were revealed by FESEM and TEM. Firstly, manganese dioxide nanowires were fabricated from KMnO4. Then, tin oxide nanoparticles were coated on the wall surfaces of MWs templates. The template was then leached out by oxalic acid treatment. Nanotubular structure of the final product was formed by the agglomeration of the tin oxide nanoparticles coating on the template surfaces. On increasing the stannous chloride amount, crystallite size and the electrochemical properties increased, while the specific surface area decreased.

99mTc-doxorubicin-loaded gallic acid-gold nanoparticles (99mTc-DOX-loaded GA-Au NPs) as a multifunctional theranostic agent.

The development of cancer theranostic nanomedicines is recommended to concurrently achieve and evaluate the therapeutic benefit and progress. The current work aims to develop gallic acid-gold nanoparticles (GA-Au NPs) as a theranostic probe for 99mTc-Doxorubicin (99mTc-DOX) based on the spatiotemporal release pattern induced intra-tumoral (IT) delivery. DOX-loaded GA-Au NPs were developed and identified via UV-Vis spectroscopy. The system was characterized for drug loading efficiency%, particle size, zeta potential, topography, in vitro DOX release and anti-proliferative activity against the MCF-7 cell-line. The factors influencing radiolabeling efficiency of DOX with 99mTc (DOX concentration, stannous chloride concentration, reaction time and pH) were optimized. The in vitro stability in mice serum and in vivo distribution studies in mice of 99mTc-DOX-loaded GA-Au NPs were investigated following IV and IT administration. Dox-loaded GA-Au NPs had a loading efficiency of 91%, a small particle size (≈50nm), a promising zeta potential (-20mV) and a sustained drug release profile at pH 5.3. GA-Au NPs exhibited increased anti-proliferative activity, with approximately a four-fold lower IC50 value (0.15μg/ml) than free DOX. The optimized radiolabeling efficiency of 99mTc-DOX was ≈93%. It showed good physiological stability in mice serum for at least 8h. The IT delivery of 99mTc-DOX-loaded GA-Au NPs in tumor-induced mice showed dramatic tumor accumulation. A maximum magnitude of 86.73%ID/g was achieved, at 15min post-injection, with a target/non-target ratio of ≈56. 99mTc-DOX-loaded GA-Au NPs could be used for the selective IT delivery of a chemotherapeutic agent and an imaging agent to a target organ.

Characterization, optimization, and in vitro evaluation of Technetium-99m-labeled niosomes.

Background and purposeNiosomes are nonionic surfactant-based vesicles that exhibit certain unique features which make them favorable nanocarriers for sustained drug delivery in cancer therapy. Biodistribution studies are critical in assessing if a nanocarrier system has preferential accumulation in a tumor by enhanced permeability and retention effect. Radiolabeling of nanocarriers with radioisotopes such as Technetium-99m (99mTc) will allow for the tracking of the nanocarrier noninvasively via nuclear imaging. The purpose of this study was to formulate, characterize, and optimize 99mTc-labeled niosomes.MethodsNiosomes were prepared from a mixture of sorbitan monostearate 60, cholesterol, and synthesized D-α-tocopherol polyethylene glycol 1000 succinate-diethylenetriaminepentaacetic acid (synthesis confirmed by 1H and 13C nuclear magnetic resonance spectroscopy). Niosomes were radiolabeled by surface chelation with reduced 99mTc. Parameters affecting the radiolabeling efficiency such as concentration of stannous chloride (SnCl2·H2O), pH, and incubation time were evaluated. In vitro stability of radiolabeled niosomes was studied in 0.9% saline and human serum at 37°C for up to 8 hours.ResultsNiosomes had an average particle size of 110.2±0.7 nm, polydispersity index of 0.229±0.008, and zeta potential of −64.8±1.2 mV. Experimental data revealed that 30 µg/mL of SnCl2·H2O was the optimal concentration of reducing agent required for the radiolabeling process. The pH and incubation time required to obtain high radiolabeling efficiency was pH 5 and 15 minutes, respectively. 99mTc-labeled niosomes exhibited high radiolabeling efficiency (>90%) and showed good in vitro stability for up to 8 hours.ConclusionTo our knowledge, this is the first study published on the surface chelation of niosomes with 99mTc. The formulated 99mTc-labeled niosomes possessed high radiolabeling efficacy, good stability in vitro, and show good promise for potential use in nuclear imaging in the future.

Factorial and Doehlert designs in the optimization of a separation procedure using polyurethane foam as a solid phase extractant for platinum determination in ferrous matrices using inductively coupled plasma optical emission spectroscopy

A procedure for separation of platinum from ferrous matrices was developed using platinum sorption as chloride complexes on polyurethane foam, with subsequent determination by inductively coupled plasma optical emission spectrometry (ICP OES). The procedure was optimized using a two-level full factorial and Doehlert designs. Four variables (foam mass, shaking time, stannous chloride concentration and hydrochloric acid concentration) were regarded as factors in the extraction optimization. Results of the two-level full factorial design, 24 with 16 runs based on Analysis of Variance (ANOVA) showed that only two factors (foam mass and shaking time) are statistically significant. Doehlert design was applied in order to determine the optimum conditions for platinum separation. The proposed procedure allowed platinum determination with a detection limit of 66 μg L−1 and a precision, calculated as relative standard deviation (RSD), of 1.2% in a set of 10 measurements for a platinum concentration of 10.0 μg L−1. The studied procedure was applied to platinum determination in several ferrous matrices (iron ores, pure iron and catalysts). Spike tests on iron ores and pure iron showed good performance in platinum recovery. The good accuracy of the proposed procedure was confirmed by analysis of an ore platinum standard reference material (SARM-7).

An efficient, reproducible and fast preparation of 188Re-anti-CD20 for the treatment of non-Hodgkin's lymphoma

Therapies using Y-anti-CD20 or I-anti-CD20 have demonstrated their efficacy in patients with B-cell non-Hodgkin's lymphoma. Re is a radionuclide useful for radioimmunotherapy. To develop a procedure for efficient labelling of anti-CD20 with Re from lyophilized formulations to achieve high radiochemical yield, high specific activity and preservation of the molecular recognition after a simple kit reconstitution without further purification. Re-anti-CD20 was prepared by a direct labelling method using sodium tartrate as a weak competing ligand. Different lyophilized formulations were prepared to optimize tartrate and stannous chloride concentration, pH and reaction time. To evaluate the biological recognition a comparative study of the in-vitro binding of Re-anti-CD20, I-anti-CD20 (positive control) and Re-anti-CEA (negative control) to normal B lymphocytes was performed. Biodistribution studies in normal mice were accomplished to assess the in-vivo Re-anti-CD20 complex stability. Re labelled anti-CD20 was obtained with high radiochemical purities (>97%) and high specific activity (0.5-0.7 GBq . mg) 1-1.5 h after addition of sodium perrhenate solution to a kit containing 4.4 muM anti-CD20, 4 mM anhydrous stannous chloride, and 140 mM dihydrate sodium tartrate at pH 4. The binding of Re-anti-CD20 to cells was in the same range as I-anti-CD20 (>80%) and was significantly different to cell binding of Re-anti-CEA (<10%). No evidence of free Re release was found at 2, 4 and 24 h after Re-anti-CD20 administration in mice. Lyophilized kits showed high stability during the storage at 4 degrees C for 6 months. Optimal reaction conditions were defined enabling high radiochemical purities of Re-anti-CD20 to be obtained routinely and therefore potentially useful in the treatment of non-Hodgkin's lymphoma.

Study of perrhenate reduction by capillary electrophoresis

The influence of perrhenate concentration, the concentration of the reducing agent and pH of the reaction mixture on the yield of perrhenate reduction were studied to find a possibility to decrease the stannous chloride concentration in the reaction mixture without negative changes on the yield of perrhenate reduction. Britton-Robinson buffer solutions were selected as the background electrolytes because of their buffering capacity in a wide pH interval. The highest degree of perrhenate reduction was obtained at pH 2 at perrhenate concentrations ranging from 10(-4) to 10(-3) mol/L. The stability of reduced rhenium against pH change from 2 to 5.5 and against dilution of rhenium in the reaction mixture to the concentration suitable for the application in radiotherapy were studied as well. The results obtained by capillary electrophoresis and by thin-layer chromatography with radiometric detection were compared.

Labeling peptides with rhenium-188

A direct labeling technique via EHDP for the preparation of 188Re-somatostatin analogue peptide β-(2-naphthyl)-D-Ala–Cys–Tyr-D-Trp–Lys–Val–Cys–Thr–amide complex was developed. The influence of reaction conditions such as pH, temperature, weak ligand concentration and stannous chloride concentration were investigated. Methods of analysis were also established permitting identification of radiochemical impurities which may be present in the radiopharmaceutical solution. Results showed that under the procedure reported herein 188Re–peptide complex can be prepared with a radiochemical purity of 90% and a specific activity up to 1.8 GBq mg −1 without radiolytic degradation of the product.

99m-Technetium as a marker of liposomal deposition and clearance in the human lung

The clearance of pulmonary delivered 99mTc-labelled dipalmitoyl phosphatidylcholine (DPPC) liposomes has been studied in 4 healthy volunteers using the technique of gamma-scintigraphy. The labelling process was dependent on the method of separation of free and liposomally bound activity and on the concentration of stannous chloride (SnCl 2) used. Gel chromatography resulted in lower labelling efficiencies on increased SnCl 2 concentration due to the progressive failure of liposomes to elute from the column. Higher labelling efficiencies were achieved following treatment with an anionic exchange resin as a result of efficient recovery of the liposomes. Transmission electron microscopy and X-ray microanalysis showed that liposomes (1 ml containing 40 mg phospholipid) labelled with 20–25 MBq 99mTc in the presence of 0.3 mg SnCl 2 appeared uncontaminated with technetium-tin colloid, and were used in the in vivo studies. Pulmonary deposition of multi-lamellar and small unilamellar vesicles, delivered from an air jet nebulizer, was dependent on droplet size of the aerosol product. Short term clearance of both liposome populations was typical of muco-ciliary transport resulting in statistically equivalent retentions at 6 h. Subsequent retention data suggested that faster process(es) than those described for insoluble particulates were contributing to the clearance of alveolar deposited liposomes.

Technetium-99 m-labeled mouse-spleen leukocytes: Radiolabeling parameters

Bouse-spleen leukocytes were radiolabeled with 99m Tc under neutral pH conditions. A low concentration of stannous chloride was used to reduce the sodium pertechnetate to a cell-binding lower-valence state. Cell radiolabeling was measured by radioactivity retention on glass-fiber filters. This procedure is quick and allows the assay of small aliquots of the radiolabeling reaction mixture. A stable cell radiolabel of 24.4% ± 5.2% was obtained which remained attached to the cell up to 27.5 h as measured by in vitro incubation in tissue culture medium. The viability of the cells after 99m Tc-cell-labeling remains as high as the control. The radiolabeling efficiency of the cells with 99m Tc was dependent on the concentration of cells and stannous chloride, but was independent of Na 99m TcO 4 concentration.

The Radiation-Induced Oxidation of Stannous Chloride in Aqueous Hydrochloric Acid

Abstract The radiation-induced oxidation of stannous to stannic ion in aqueous hydrochloric acid has been studied and that this system is proposed as a chemical dosimeter for higher doses. The amount of oxidation is proportional to the energy absorbed and the yield of stannic ion is independent of dose rate and initial stannous chloride concentration over a wide range studied, but increases when stannic con-concentration is high or oxygen is present. Mechanism for this oxidation based on G-values is discussed in terms of the primary decomposition products of water radiolysis. The results can be interpreted to mean that the stannic ion is oxidized only by OH radical. This system could be used for a chemical dosimeter having 8% reproducibility.

THE EFFECT OF HYDROCHLORIC ACID ON THE OXIDATION OF STANNOUS CHLORIDE WITH AIR

Abstract 1. The oxidation velocity of stannous chloride in hydrochloric acid with air was studied. When the concentration of hydrochloric acid is smaller than about 0.25 normal, the reaction seems to be between first and zero order. When the concentration of hydrochloric acid is greater than about 0.25 normal, the velocity is independent of the concentration of stannous chloride. 2. The effect of temperature is small. 3. The dissolution velocity of oxygen into hydrochloric acid of various concentrations was obtained indirectly.

ON THE OXIDATION OF THE MIXTURE OF STANNOUS CHLORIDE AND SODIUM SULPHITE IN ALKALINE SOLUTION WITH AIR

Abstract 1. The oxidation velocity of the mixture of sodium sulphite and stannous chloride in alkaline solution with air was studied. 2. When the initial concentration of stannous chloride is not small, the oxidation velocity is independent of their concentrations and is smaller than that of each. 3. When the initial concentration of stannous chloride is small, the oxidation of the mixture takes place at a slow rate first, and increases with time.