PDF Publication Title:
Text from PDF Page: 009
GREEN CHEMISTRY LETTERS AND REVIEWS 481 Figure 7. Synthesis of Ag NPs after deprotonation of curcumin. level of terpenoids which make it an excellent reducing agent for the synthesis of metallic nanoparticles. There- fore, the enolic tautomer form of curcumin can interact easily with the acceptor orbital and be bound to the core of the Ag+ ions. Curcumin in its enolic form will act as a potent reducing agent where Ag+ will be reduced to Ag0, leading to the formation of Ag nuclei and finally to saturated Ag NPs. Another explanation was adopted by Khan et al. (74) to evaluate the role of curcumin as a reducing agent to produce Ag NPs. Briefly, Khan et al. have dissolved a specific amount of curcumin in NaOH. According to the authors when adding NaOH to curcumin, curcumin oxide is formed. Hence, in the first place when adding curcumin to Ag NO3, a complex is formed (equation 1). This complex reacted with curcumin oxide in order to produce Ag0 (equation 2). Ag+ + Cur [Ag(Cur)]+ (1) [Ag(Cur)]+ + R-COH [Ag(Cur)]+R-COOH (2) Similarly, Shameli et al. have adopted the same concept (75,76). According to Shameli et al., [Ag(Cur)]+ reacted with an aldehyde group presented in the metha- nolic group of curcumin (curcumin oxide) to form curcu- min reduced and stabilized Ag NPs. The reduction of Ag+ is in the first case due to the oxidation of the aldehyde group into the carboxylic acid group. Al Namil et al. (77,78) were able to synthesize Ag NPs through green solid-state reaction, using curcumin and silver nitrate. In this case, the authors have mixed Ag NO3 plus curcumin and ground them for about one hour until homogeneous powder is obtained. The color changed from yellow to dark orange. Then, a specific volume of ethanol was added and the growth of the Ag NPs was studied for 16 h. Despite the reduction of Ag+ to Ag0, the method involved by Al Namil et al. has increased its role as a stabilizing agent. After complete reduction, the surface charge of curcumin plays a major role as a stabilizing agent, inducing the stabiliz- ation and the formation of uniform Ag NPs. Hence, this is due to the C=O group in the enol form of curcumin and/or to the biding of silver nanoparticles with the hydroxyl group in curcumin. El Khoury et al. (79) in their experiment have also verified the interaction of Ag with the C=O group in curcumin to assure a complete reduction. Hence, to increase the stability of the formed Ag NPs, the authors have added glycerol to the mixture during synthesis. In this case, monodisperse Ag NPs were obtained. The addition of glycerol did not alter the formation of Ag NPs in its absence. Yet, glycerol has been disposed on the curcumin’s surface, inducing the stability enhancement of the produced Ag NPs. Abdulwahab et al. (61) have compared the prep- aration of Ag NPs using curcumin or citrate. It was found that using curcumin as a reducing agent smaller particles were formed. Hence, Abdulwahab et al. have confirmed the preparation of Ag NPs under continuous stirring without adjustment of pH. According to the authors and under continuous stirring, curcumin can act as a reducing agent without changing pH, since under basic media, curcumin can be degraded. Another study was done by Yang et al. (80) to verify the difference between the use of curcumin and citric acid as a reducing agent. According to Yang et al., the curcumin-stabilized AgNPs were more stable in a physio- logical environment. Hence, they possess higher and better antiviral properties. To finish up, Ag NPs can be applied in different ways and different fields. Hence, Al Namil et al. (77) and Verma et al.(70) have used their Ag NPs as catalysis agents to enhance the catalytic reduction reaction of 4-nitro- phenol. Moreover, Al Namil et al. (78) have investigated the role of Ag NPs as nanoprobe to detect human serum albumin, in addition to El Khoury et al. (79) that were also able to detect nucleic acid using Ag NPs synthesized in their way. Furthermore, Alsammarraie et al. (72), Sathish- kumar et al. (73), and El Khoury et al. (79) have elabo- rated the role of Ag NPs as an antibacterial against different microorganisms. In addition, the antioxidant and anticancer activity was also established by Selvan et al. (71) and Yang et al. (80), respectively. 2.3. Synthesis of mixed nanoparticles (Au/Ag) Abdelghani et al. were the first to synthesize mixed met- allic nanoparticles using curcumin as a reducing and sta- bilizing agent (81). In this case, curcumin was mixed withPDF Image | Curcumin as a novel agent for metallic nanoparticles
PDF Search Title:
Curcumin as a novel agent for metallic nanoparticlesOriginal File Name Searched:
Curcumin-nanoparticles.pdfDIY PDF Search: Google It | Yahoo | Bing
CO2 Organic Rankine Cycle Experimenter Platform The supercritical CO2 phase change system is both a heat pump and organic rankine cycle which can be used for those purposes and as a supercritical extractor for advanced subcritical and supercritical extraction technology. Uses include producing nanoparticles, precious metal CO2 extraction, lithium battery recycling, and other applications... More Info
Heat Pumps CO2 ORC Heat Pump System Platform More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)