In vitro removal of toxic heavy metals by poly(γ-glutamic acid)-coated superparamagnetic nanoparticles

Abstract

Background: Chelation therapy involving organic chelators for treatment of heavy metal intoxication can cause cardiac arrest, kidney overload, mineral deficiency, and anemia. Methods: In this study, superparamagnetic iron oxide nanoparticles (SPIONs) modified with an edible biopolymer poly(γ-glutamic acid) (PGA) were synthesized by coprecipitation method, characterized and evaluated for their removal efficiency of heavy metals from a metal solution, and simulated gastrointestinal fluid (SGIF). Results: Instrumental characterization of bare-and PGA-SPIONs revealed 7% coating of PGA on SPIONs with a spherical shape and an iron oxide spinel structure belonging to magnetite. The particle sizes as determined from transmission electron microscopy images were 8.5 and 11.7 nm for bare-and PGA-SPIONs, respectively, while the magnetization values were 70.3 and 61.5 emu/g. Upon coating with PGA, the zeta potentials were shifted from positive to negative at most of the environmental pH (3-8) and biological pH (1-8), implying good dispersion in aqueous suspension and favorable conditions for heavy metal removal. Batch studies showed rapid removal of lead and cadmium with the kinetic rates estimated by pseudo-second-order model being 0.212 and 0.424 g/mg⋅min, respectively. A maximum removal occurred in the pH range 4-8 in deionized water and 5-8 in SGIF corresponding to most gastrointestinal pH except for the stomach. Addition of different ionic strengths (0.001-1 M sodium acetate) and essential metals (Cu, Fe, Zn, Mg, Ca, and K) did not show any marked influence on lead removal by PGASPIONs, but significantly reduced the binding of cadmium. Compared to deionized water, the lead removal from SGIF was high at all pH with the Langmuir monolayer removal capacity being 98.70 mg/g for the former and 147.71 mg/g for the latter. However, a lower cadmium removal capacity was shown for SGIF (23.15 mg/g) than for deionized water (31.13 mg/g). Conclusion: These results suggest that PGA-SPIONs could be used as a metal chelator for clinical treatment of metal poisoning.

Utilization of chitosan-coated superparamagnetic iron oxide nanoparticles for chromium removal

“…In FTIR, the presence of strong absorption bands at around 569 and 575 cm −1 showed the formation of magnetic nanoparticles (Fe-O stretching vibration of tetrahedral sites of spinel structure) ( Fig. 2a, b) (Inbaraj and Chen 2012). The peak at 2920 cm −1 , 1627 cm −1 , 1416 cm −1 and 1069 cm −1 was the stretching vibrations of -CH, N-H, C-N vibration of amino group and C-O in the ether group of chitosan, respectively (Fig.…”

Increased Production of the Value-Added Biopolymers Poly(R-3-Hydroxyalkanoate) and Poly(γ-Glutamic Acid) From Hydrolyzed Paper Recycling Waste Fines

“…PGA is biosynthesized naturally by a variety of Bacillus species, and is an edible, water-soluble, biodegradable, and anionic biopolymer (Bajaj and Singhal, 2011;Ogunleye et al, 2015). These properties make PGA suited for a variety of applications, including metal-ion binding and flocculation for wastewater treatment, composite materials for tissue engineering and drug delivery, and as a medicinal metal chelator for heavy metal removal (Yokoi et al, 1996;Shih et al, 2001;Ye et al, 2006;Siao et al, 2009;Inbaraj and Chen, 2012). Current research into improving PGA production for human use is focused on the metabolic engineering of various Bacillus species; notably, wild-type B. licheniformis WX-02 is capable of producing large amounts of PGA from glucose and glutamate and has been successfully engineered for enhanced biosynthesis (Cai et al, 2017(Cai et al, , 2018.…”

SPIONs Prepared in Air through Improved Synthesis Methodology: The Influence of γ-Fe2O3/Fe3O4 Ratio and Coating Composition on Magnetic Properties

“…Superparamagnetic iron oxide nanoparticles (SPIONs), the only clinically approved metal oxide nanoparticles (NPs) [1], emerge as medically interesting nanoparticles (NPs), being able to integrate multifunctional platforms and to perform multiple objectives such as imaging and therapy, (theranostics) or to perform a single advanced function through the incorporation of multiple functional units [2,3,4,5,6,7,8,9]. Concerning biomedical applications, SPIONs may be externally magnetically triggered, endowing a wide variety of purposes, namely: (i) site-specific magnetic targeting [10], (ii) target drug delivery of drugs and genes [11,12], (iii) negative contrast agents in magnetic resonance imaging (MRI) [13,14], (iv) hyperthermia treatment under alternating magnetic fields [15,16], (v) magnetic transfections [17], (vi) iron detection [18], (vii) chelation therapy [19], (viii) tissue engineering [20], (ix) stem cell tracking [21] and (x) cell separation and isolation [22].…”