Many applications
using gold nanoparticles (AuNPs) require (i)
their functionalization with a biopolymer to increase their stability
and (ii) their transformation into an easy-to-handle material, which
provide them with specific properties. In this research, a portable
tablet platform is presented based on dextran-encapsulated gold nanoparticles
(AuNPs-dTab) by a ligand exchange reaction between citrate-capped
gold nanoparticles (AuNPs-Cit) and dextran. These newly fabricated
tablets were characterized utilizing ultraviolet–visible spectroscopy
(UV–vis), Fourier transform infrared spectroscopy–attenuated
total reflectance (FTIR–ATR), transmission electron microscopy
(TEM), dynamic light scattering (DLS), X-ray diffraction spectroscopy
(XRD), differential scanning calorimetry (DSC), and atomic force microscopy
(AFM) techniques. The results showed that dextran-capped gold nanoparticles
in a tablet platform (AuNPs-dTab) were well-dispersed and highly stable
for at least a year at room temperature. In addition to particle and
surface characterization of AuNPs-dTab, the tablet morphology in terms
of thickness, diameter, density, and opacity was also measured using
6 and 10% dextran with 2, 4 and 8 nM AuNPs-Cit. We further investigated
the pH-responsive behavior of AuNPs-dTab in the presence and absence
of sodium chloride. Results showed that neutral and alkaline environments
were suitable to render AuNPs dispersed in a tablet, while an acidic
condition controls the aggregation rate of AuNPs as confirmed by concentration-dependent
aggregation phenomena. Besides the easy fabrication, these tablets
were portable and low-cost (approx. 1.22 CAD per 100 tablets of a
100 μL solution of dextran-capped gold nanoparticles (AuNPs-dSol)).
The biocompatible nature of dextran along with the acidic medium trigger
nature of AuNPs makes our proposed tablet a potential candidate for
cancer therapy due to the acidic surrounding of tumor tissues as compared
to normal cells. Also, our proposed tablet approach paves the way
for the fabrication of portable and easy-to-use optical sensors based
on the AuNPs embedded in a natural polymeric architecture that would
serve as a colorimetric recognition indicator for detecting analytes
of interest.