Gold nanoparticles capped with L-glycine, L-cystine, and L-tyrosine: toxicity profiling and antioxidant potential

Abstract

Biomolecules-based surface modifications of nanomaterials may yield effective and biocompatible nanoconjugates. This study was designed to evaluate gold nanoconjugates (AuNCs) for their altered antioxidant potential. Gold nanoparticles (AuNPs) and their conjugates gave SPR peaks in the ranges of 512-525 nm, with red or blueshift for different conjugates. Cys-AuNCs demonstrated enhanced (p < 0.05) and Gly-AuNCs (p > 0.05) displayed reduced DPPH activity. Gly-AuNCs and Tyr-AuNCs displayed enhanced ferric-reducing power and hydrogen peroxide scavenging activity, respectively. Cadmium-intoxicated mice were exposed to gold nanomaterials, and the level of various endogenous parameters, i.e., CAT, GST, SOD, GSH, and MTs, was evaluated. GSH and MTs in liver tissues of the cadmium-exposed group (G2) were elevated (p < 0.05), while other groups showed nonsignificance deviations than the control group. It is concluded that these nanoconjugates might provide effective nanomaterials for biomedical applications. However, more detailed studies for their safety profiling are needed before their practical applications.

Figure 1

Optimization of amino acids-capped gold nanoparticles at different concentrations of amino acids a Cys-AuNCs, b Gly-AuNCs, c Tyr-AuNCs; inset graphs displaying focused area of SPR change

Figure 2

Characterization of gold NMs; a UV–visible spectroscopy of AuNPs and their nanoconjugates, b Zeta potential, for each sample, n = 3, c TEM micrograph, scale bar = 50 nm, d size distribution map

Figure 3

Scanning electron microscopy of; a C-AuNPs, b Tyr-AuNCs, c Gly-AuNCs, and d Cys-AuNCs; scale bar on all SEM images shown is 200 nm

Figure 4

Size distribution maps of; a C-AuNPs, b Tyr-AuNCs, c Gly-AuNCs, d Cys-AuNCs

Figure 5

Fourier transform infrared spectroscopy of; a L-cystine, b Cys-AuNCs, c L-glycine, d Gly-AuNCs, e L-tyrosine, f Tyr-AuNCs

Figure 6

UV–visible spectroscopy-based stability study of: a C-AuNPs, b Cys-AuNCs, c Gly-AuNCs, d Tyr-AuNCs

Figure 7

In vitro antioxidant activity of NMs; a DPPH scavenging activity of different conjugates compared to the ascorbic acid as a standard antioxidant, b gold NMs, the data have shown are Mean ± SD value with n = 6. A statistically significant difference in DPPH scavenging activity was found among different NMs at different concentrations where ^“*^” represent p < 0.05 and ^“**^” represent p < 0.01, two-way ANOVA with post hoc Tukey test was used. c Hydrogen peroxide (HP) scavenging % of gold NMs and ascorbic acid, d HP scavenging % of gold NMs, the data have shown are Mean ± SD values with n = 3. For homogeneity of data, p > 0.05, the difference was found with different concentrations of nanoconjugates in HP scavenging activity

Figure 8

In vitro antioxidant activity of NMs; Ferric reducing power assay of Gold NMs, the data shown are Mean ± SD values with n = 3. For homogeneity of data p > 0.05, different nanoconjugates displayed a difference in FRP (df _{8, 30}; mean square = 0.01; F = 27.1; partial η² = 0.88 and p < 0.05); Two-way ANOVA with Tukey test as post hoc was used to the evaluated difference, where ^“*^” denote p < 0.05

Figure 9

In vivo animal trial; a Animal body weight, b CAT-activity in liver tissues and serum samples, the data shown are Mean ± SE values in (liver tissues n = 5, serum samples n = 3), for both types of samples homogeneity of data was p > 0.05, so one-way ANOVA with Tukey test as post hoc was applied, where ^“*^” represent p < 0.05 when compared with control, c SOD Activity, the data shown are Mean ± SE values in (liver tissues n = 5, serum samples n = 3), for homogeneity of data (p > 0.05), one-way ANOVA with post hoc Tukey test was applied, where ^“*^” indicates p < 0.05 when compared with control, d For GST activity, the data shown are Mean ± SE values in (liver tissues n = 5, serum samples n = 3); for homogeneity of data (p > 0.05), one-way ANOVA with Tukey test was used, there was no statistically significant difference was found in GST level

Figure 10

a GSH levels in kidney and liver tissues, the data shown are Mean ± SE values, n = 5; for homogeneity of data (p > 0.05), a significant difference was found in liver GSH and not found in kidney GSH. One-way ANOVA with post hoc Tukey test was performed, where ^“*^” represents p < 0.05 when compared with control, b For MTs in kidneys and liver tissues, the data shown are Mean ± SE values, n = 5; for homogeneity of data (p > 0.05), a statistically significant difference was found in MTs in kidneys and liver tissues. One-way ANOVA with post hoc Tukey test was used, where ^“*^” indicate p < 0.05 when compared with control

Figure 11

Synthesis of amino acids functionalized-gold nanoparticles