Effect of poly-α, γ, L-glutamic acid as a capping agent on morphology and oxidative stress-dependent toxicity of silver nanoparticles

Abstract

Highly stable dispersions of nanosized silver particles were synthesized using a straightforward, cost-effective, and ecofriendly method. Nontoxic glucose was utilized as a reducing agent and poly-α, γ, L-glutamic acid (PGA), a naturally occurring anionic polymer, was used as a capping agent to protect the silver nanoparticles from agglomeration and render them biocompatible. Use of ammonia during synthesis was avoided. Our study clearly demonstrates how the concentration of the capping agent plays a major role in determining the dimensions, morphology, and stability, as well as toxicity of a silver colloidal solution. Hence, proper optimization is necessary to develop silver colloids of narrow size distribution. The samples were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, and zeta potential measurement. MTT assay results indicated good biocompatibility of the PGA-capped silver nanoparticles. Formation of intracellular reactive oxygen species was measured spectrophotometrically using 2,7-dichlorofluorescein diacetate as a fluorescent probe, and it was shown that the PGA-capped silver nanoparticles did not induce intracellular formation of reactive oxygen species.

Biogenic synthesis of antimicrobial silver nanoparticles capped with l-cysteine

“…Depending on the properties of this capping agent, the characteristics (geometry and solubility) of the nanoparticles can be controlled. The choice of capping agent must be directed by the characteristics and application of the intended nanoparticles; for biological applications, polypeptides (gluthatione) [21,45,46], tiopronin [10,33] and aminoacids have been previously employed [31,45]. The common feature of these compounds is the presence of sulphur whose strong affinity for Ag results in coverage of the nanoparticles and provides stability during nanoparticles ripening.…”

“…citrates [22,28], oleic acid [26], poly(acrylic acid) [29], starch [30] and glutamic acid [31] or prepared with a capping agent that allows binding of other compounds to the nanoparticles such glutathione [32] or tiopronin [33]. Silver nanoparticles of very different geometrical (size and shape) characteristics can be obtained modifying the reaction conditions.…”

Multifunctional PLGA particles containing poly(l-glutamic acid)-capped silver nanoparticles and ascorbic acid with simultaneous antioxidative and prolonged antimicrobial activity

“…Pure PGA showed the main peaks contributed by the functional groups of the molecule such as: the O-H stretching band at 3375 cm À1 ; the amide I band at 1654 cm À1 ; the C@O symmetric absorption band at 1410 cm À1 ; the N-H(d) in-plane bending or scissoring at 1305 cm À1 ; the C-N stretching at 1050 cm À1 and the N-H(x) out-of-plane bending or wagging at 762 cm À1 [35].…”

A novel bone cement impregnated with silver–tiopronin nanoparticles: its antimicrobial, cytotoxic, and mechanical properties

“…31 Many different synthetic routes have been proposed to prepare silver nanoparticles; in general, ionic silver (Ag + ) contained in a salt, generally AgNO 3 , is reduced to metal silver (Ag 0 ) through a reducing agent such as HNO 3 /citrate, 32 Al-alkoxide, 33 NaBH 4 , 34 N,N-dimethyl formamide, 35 or sugars. 36,37 The nanoparticles can also be stabilized using chelating substances such as citrates, 38 oleic acid, 37 and glutamic acid 39 or prepared with a capping agent that allows binding of other compounds to the nanoparticles; for example, glutathione 40 or tiopronin. 41 Silver nanoparticles of very different geometric (size and shape) characteristics can be obtained by modifying the reaction conditions.…”