Hydrophilic gold nanospheres: influence of alendronate, memantine, and tobramycin on morphostructural features

Abstract

Turkevich gold nanospheres are the original nanospheres that have been modified over time. Its combination with targeting medications such as alendronate, memantine, and tobramycin will provide additional benefits in targeting specific areas in the bone, brain, and microorganisms, respectively. Hence, The reactivity and stability of nanospheres with various drug concentrations (milli-,micro-, and nano-levels) have been studied. With alendronate, the absorbance spectra of nanospheres at [Formula: see text] 520 nm were always stable and no redshifts occurred. In contrast, the spectra with memantine and tobramycin were stable at the nano-level and redshifts occurred at the milli- and micro-levels. HRTEM and DLS revealed that the core diameter was relatively stable in all cases, whereas the hydrodynamic diameter and zeta potential varied with varying drug concentrations. Increasing concentration increased hydrodynamic diameter slightly with memantine (from 64.99 to 98.41 nm), dramatically with tobramycin (from 135.3 to 332.16 nm), and almost negligibly with alendronate (from 52.08 to 58.94 nm ). Zeta Potential, conversely, is reduced as concentration increases. Memantine had the greatest reduction in negativity, followed by tobramycin, but alendronate had a slight increase in negativity. Benefits from this research would be in targeted drug delivery, where stability and reactivity of gold nanospheres are critical.

Keywords: Alendronate; Biocompatibility; Drug targeting; Gold nanospheres; Memantine; Stability; Tobramycin.

Fig. 1

High resolution transmission electron microscope (HRTEM) images of gold nanospheres, alone (a), with tobramycin nano-concentration (b), with alendronate micro-concentration (c), with memantine micro-concentration (d), with tobramycin micro-concentration (e)

Fig. 2

Linearity curve and correlation coefficient of gold nanospheres loaded by: a alendronate milli-concentration within range of (0.11–1.48 E−02 mM). b Memantine nano-concentration within range of (33.46–334.63 nM). c Tobramycin nano-concentration within range of (4.28–128.34 nM)

Fig. 3

spectrophotomertic and spectrofluorimetric characterization of AuNSs at ${\mathrm{\lambda }}_{\mathit{max}}$ 520 nm & ${\mathrm{\lambda }}_{\mathit{ex}}$ 520 nm

Fig. 4

Absorbance spectra of gold nanospheres with Memantine nano-concentration within range of (33.46–334.63 nM) (a), Tobramycin nano-concentration within range of (4.28–128.34 nM) (b), Alendronate milli-concentration within range of (0.11–1.48 E–02 mM) (c)

Fig. 5

Twenty minutes stability of gold nanospheres with Memantine at nano-range (33.46–334.63 nM) (a), Tobramycin at nano-range (4.28–128.34 nM) (b), Alendronate at milli- range (0.11–1.48 E–02 mM) (c)

Fig. 6

Redshifts in absorbance spectra of gold nanospheres loaded by memantine (micro-level) (a), and tobramycin (micro-level) (b)

Fig. 7

Chemical structures of alendronate, memantine, and tobramycin molecules

Fig. 8

Average hydrodynamic diameter of gold nanospheres alone and with the various concentrations of alendronate, memantine, and tobramycin

Fig. 9

A graphical diagram shows how the colors change along with the hydrodynamic diameter and core diameter change

Fig. 10

Illustrative diagram of proposed arrangement and aggregation of alendronate, memantine, and tobramycin toward gold nanospheres

Fig. 11

FTIR of gold nanospheres in absence and presence of alendronate

Fig. 12

FTIR of gold nanospheres in presence of memantine and tobramycin