B. Rezaei, M. Shahshahanipour, Ali A. Ensafi

In the present research, a sensitive biosensingmethodwas proposed for the detection of trace amounts of ascorbic
acid (AA). Herein, colloidal silver nanoparticles (SNPs)were successfully in-situ produced by chemical reduction
of silver ion in the presence of AA, as a reducing agent. The one-pot in-situ produced silver nanoparticles
were characterized by UV–vis, dynamic light scattering (DLS), zeta potential and transmission electron microscopic
(TEM). SNPs act as a strong fluorescence quencher for the CdTe quantum dots via an inner filter effect
(IFE). Since the absorption band of SNPs entirely covered both emission and excitation bands of QDs. Therefore,
the decreasing in the fluorescence signal depends on the AA concentration in the linear range of 0.2–
88.0 ng mL−1 and with a detection limit of 0.02 ng mL−1. Relative standard deviations of 2.3% and 2.8% (n =
5) were achieved for the determination of 1.8 and 8.8 ng mL−1 AA, respectively. This novel QDs nanosensor
based on IFE could provide noticeable advantages of simplicity, convenience, cost-effectiveness, and sensitivity.
This method was successfully applied for the detection of ascorbic acid in human real samples serums.

Ascorbic acid
Silver nanoparticles
CdTe quantum dot
Inner filter effect
In situ production