Synthesis and Characterization of Nanoparticles as Potential Viral and Antiviral Agents
Devarajan Thangadurai, Saher Islam, Charles Oluwaseun Adetunji in Viral and Antiviral Nanomaterials, 2022
Sol-gel method, hydrothermal synthesis, microemulsion method, chemical vapour synthesis, polyol synthesis, etc. are some chemical methods of nanoparticle synthesis (Dhand et al. 2015). These chemical methods utilize the bottom-up approach of nanoparticle synthesis and involve the assembly of atoms or molecules to nanoscale structures. The mechanism of nanoparticle generation involves reducing metal ions by reducing agents or decomposition of metal precursors in the presence of a stabilizer with extra energy. The chemicals such as hydrazine, sodium borohydride, hydrogen, etc. are generally used as reducing agents (Khandel et al. 2018). Organic solvents, natural/synthetic polymers, surfactants, etc. are used as stabilizing agents to avoid agglomeration of metal nanoparticles. Even though nanoparticles of well-defined dimension, size, shape, and composition have resulted through chemical methods (Yu et al. 2008), major disadvantages such as environmental pollution, use of toxic and nonbiodegradable chemicals, lack of specificity in biomedical applications, etc. limit the use of chemical methods for the synthesis of metal nanoparticles. Some reports on chemical methods of metal nanoparticle synthesis are discussed here in short. Chen et al. (2013) reported the synthesis of silver nanoparticles by a chemical reduction method, which shows inhibitory effects against type 3 adenovirus (Figure 2.3). Lysenko et al. synthesized gold nanoparticles covered with silicon dioxide shells through the sol-gel method and used them as antiviral agents against adenoviruses.
Technetium-Labeled Compounds
Garimella V. S. Rayudu, Lelio G. Colombetti in Radiotracers for Medical Applications, 2019
As stated earlier, when technetium is bound to various agents of interest in nuclear medicine the reduced states Tc(V), Tc(IV), and Tc(III) predominate. A number of reducing agents, included in Table 5, have been utilized to accomplish this reduction, the most frequently used being stannous ion,9, 19 ferric chloride and ascorbic acid,8, 84, 85ferrous ion,86 concentrated HCl,87, 100-106 and sodium borohydride.88, 89, 98 Less frequently used reductants include cuprous ion,91 formamidine sulfinic acid,92dithionite,93 various sulfhydryl compounds (which sometimes serve the dual purpose of reducing as well as complexing the technetium), and other miscellaneous agents that reduce and complex the technetium at the same time. Electrolytic reduction of pertechnetate has also been used in a variety of situations.46,94-96 When zirconium or tin electrodes are used, the reduction actually proceeds via the formation of reducing species of these metal ions.48 When inert electrodes are employed,50-52 suitable number of electrons can be supplied by applying an appropriate voltage, and the technetium reduced to a known oxidation state. All reductions, whether using electrolytic or chemical methods, are generally carried out in the presence of a ligand that can stabilize the lower valence state of technetium and thus minimize or prevent subsequent hydrolytic and oxidation reactions.
The Design of Receptor-Binding Radiotracers
Lelio G. Colombetti in Principles of Radiopharmacology, 2019
All experiments assuming a similarity of chemical behavior between 99Tc and 99mTc have considered the concentration of technetium as the only variable in the reaction. Unfortunately, variations exist in other parameters, such as the quantity of reducing agent employed in chelate formation. The ratio of stannous and stannic ion to the amount of technetium has been considered responsible for reports of both 99mTc (III) and Tc (IV) in the chelate.76 The quantity of reducing agent used in compound formation is therefore crucial. These findings also strongly suggest that more than one valence state of technetium can bind to the same chelate, although it is uncertain what effect this has on the in vivo distribution of the compound. Another important consideration is the method used to determine the oxidation state of 99Tc at the millimolar level. As an example of this, iodine titration could theoretically yield misleading information concerning the oxidation state of technetium if the iodine oxidizes not only the excess reducing agent, but also the reduced technetium itself. Many pitfalls are evident.
The effect of radiolabeled nanostructured lipid carrier systems containing imatinib mesylate on NIH-3T3 and CRL-1739 cells
Published in Drug Delivery, 2020
Evren Atlihan Gundogdu, Emine Selin Demir, Meliha Ekinci, Emre Ozgenc, Derya Ilem Ozdemir, Zeynep Senyigit, Makbule Asikoglu
Five groups (n = 6) were obtained to investigate the effect of reducing agent. Ten milligrams of F1-IMT, F2-IMT, and F3-IMT was dissolved in 1 mL of saline. Reduction of 99mTc was performed with different amount of stannous chloride in 0.01 N HCl (10, 50, 250, 500, and 1000 µg). Stannous chloride solution was added to the formulations, under an atmosphere of bubbling nitrogen. Radiolabeling was made with 1 mCi/0.1 mL of 99mTc in saline. The radiolabeled formulations were mixed for one minute in vortex mixer and incubated for 15 minutes at room temperature. The 50 µL of samples were taken from each formulations during 6 h and radiochemical purity of samples was analyzed with RTLC. The contents of the formulations to examine the effect of reducing agent on radiolabeling process are shown in Table 1.
Antioxidant, antimicrobial and cytotoxic potential of silver nanoparticles synthesized using flavonoid rich alcoholic leaves extract of Reinwardtia indica
Published in Drug and Chemical Toxicology, 2019
Prabhat Upadhyay, Sunil K. Mishra, Suresh Purohit, G. P. Dubey, Brijesh Singh Chauhan, S. Srikrishna
Nanoparticles (NPs), which are defined as particles having at least one dimension of 100 nm or less, are used to produce novel materials with unique physicochemical properties. Their small size high surface area per unit mass, chemical composition and surface property effects may be important factors in NP-induced toxicity, and nonspecific oxidative damage is one of the greatest concerns. To overcome the complication of toxicity in the synthesis and biological applications, plants or plant extracts have been established to have a leading role in the AgNPs biosynthesis process (Khan et al. 2017). Silver nanoparticles can be synthesized using a variety of chemicals and physical methods, involving chemical reduction, photochemical reduction, electrochemical reduction and heat vaporization. These processes involve several toxic chemicals as reducing agents. Because of using noble metal nanoparticles in areas of human contact, there is an emergent need to develop eco-friendly biosynthesis processes that hinder the use of toxic chemicals. The use of silver nanoparticles both as an antimicrobial agent and as a potential drug carrier in the treatment of cancer has recently gained considerable attention (Iravani et al. 2014).
Preparation and characterization of dicarboxylic acids salt of aripiprazole with enhanced physicochemical properties
Published in Pharmaceutical Development and Technology, 2021
Afrooz Hamideh, Ziyaur Rahman, Sathish Dharani, Tahir Khuroo, Eman M. Mohamed, Mohammad T. H. Nutan, Indra K. Reddy, Mansoor A. Khan
The prepared salts were characterized and confirmed for improvement of physicochemical properties of APZ. The formation of new phase was confirmed by vibration spectroscopic, X-ray powder diffraction and thermal methods. The melting point of the salts were different from individual components, which was either higher than or in between the components. X-ray powder diffraction and infrared data of the salts showed unique refraction peaks or vibration bands, which were not present in individual components or their physical mixture. Solubility of the salts was significantly higher than the drug at all studied pH. The pH of maximum solubility did not change for the salts of MA and SA while it shifted to 6 for the salt of MAL. Thus, prepared salt has improved the solubility and dissolution with comparable solid and liquid stabilities. Oral bioavailability parameters of salts may not be impacted or have minimal impact when co-administered with acid reducing agent since they have higher solubility at higher pH value compared to APZ. This will be confirmed in future works.
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