Related Experiment Video
Updated: Mar 4, 2026
Synthesis of Near-Infrared Emitting Gold Nanoclusters for Biological Applications
Published on: March 22, 2020
DNA-hybridization on gold nanospheres: a dual-fluorescence investigation of surface loading and strand length effects
Daria Stoia1,2, Ana-Maria Craciun1, Gabriela Chereches3
1Babes-Bolyai University, Interdisciplinary Research Institute in Bio-Nano-Sciences, Nanobiophotonics and Laser Microspectroscopy Center, Cluj-Napoca, Romania.
Significance:
Gold nanospheres (AuNSs) functionalized with DNA are powerful tools for studying nanoscale biomolecular interactions through fluorescence modulation. Understanding how DNA conformation influences fluorescence is essential for advancing biosensor design.
Aim:
We examine how DNA strand length and surface loading govern the fluorescence behavior of Cy5-labeled single-stranded DNA (polyA-Cy5) bound to AuNSs and how these properties change upon hybridization with complementary polyT strands.
Approach:
PolyA-Cy5 strands of different bases were conjugated to AuNSs and analyzed using steady-state and time-resolved fluorescence spectroscopy before and after polyT hybridization.
Results:
Surface attachment induced strong fluorescence quenching, with intensity varying with strand length due to differences in DNA conformation. Short strands remained rigid and upright, whereas longer strands adopted more flexible geometries. Upon hybridization, longer duplexes exhibited fluorescence enhancement attributed to increased fluorophore-metal spacing as dsDNA becomes more upright. Lifetime measurements supported these conformational changes and suggest a Förster resonance energy transfer (FRET)-based quenching mechanism. Experiments in fetal bovine serum (FBS) confirmed that hybridization-induced enhancement persists in biologically relevant media.
Conclusions:
The results reveal strand-length and density-dependent conformational dynamics of DNA on AuNSs and establish a robust fluorescence-based method for probing nanoscale assembly. The nanosystem can also be tracked intracellularly, as demonstrated by its detectable signal in fluorescence imaging.
