We report a fluorescent probe for mRNA detection. It consists of a gold nanorod (GNR) functionalized with fluorophore-labeled hairpin oligonucleotides (hpDNA) that are complementary to the mRNA of a target gene. This nanoprobe was found to be sensitive to a complementary oligonucleotide, as indicated by significant changes in both fluorescence intensity and lifetime. The influence of the surface density of hpDNA on the performance of this nanoprobe was investigated, suggesting that high hybridization efficiency could be achieved at a relatively low surface loading density of hpDNA. However, steady-state fluorescence spectroscopy revealed better overall performance, in terms of sensitivity and detection range, for nanoprobes with higher hairpin coverage. Time-resolved fluorescence lifetime spectroscopy revealed significant lifetime changes of the fluorophore upon hybridization of hpDNA with targets, providing further insight on the hybridization kinetics of the probe as well as the quenching efficiency of GNRs.
Two-Photon luminescence (TPL) from gold nanorods shows considerable potential in biological imaging for high
resolution, low photo-damage, tunable near infra-red (NIR) longitudinal band, polarization dependence, ability to
conjugate to bio-molecules and low toxicity. Here we demonstrate the application of gold nanorods as TPL imaging
agents by studying the gold nanorods taken up by Madin-Darby canine kidney (MDCK) cells using both confocal
imaging and fluorescence lifetime imaging microscopy (FLIM). The characteristic luminescence lifetime of gold
nanorods is found to be less than 100 ps, which can be used to distinguish gold nanorods from other fluorescent labels
and endogenous fluorophores in lifetime imaging.
Two-photon luminescence (TPL) from gold nanorods shows considerable potential in biological imaging. We study the imaging of gold nanorods in Madin-Darby canine kidney (MDCK) cells using fluorescence lifetime imaging microscopy (FLIM). FLIM provides images with better contrast and sensitivity than intensity imaging. The characteristic fluorescence lifetime of gold nanorods is found to be less than 100 ps, which can be used to distinguish gold nanorods from other fluorescent labels and endogenous fluorophores in lifetime imaging.
The unique optical properties associated with nanostructured materials that support the excitation of surface plasmons
offer many new opportunities for the enhanced optical investigation of biological materials that pose a security threat. In
particular, ricin is considered a significant bioterrorism risk due to its high toxicity combined with its ready availability
as a byproduct in castor oil production. Therefore, the development of optical techniques capable of rapid on-site toxin
detection with high molecular specificity and sensitivity continues to be of significant importance. Furthermore,
understanding of the ricin cell entry and intracellular pathways remains poor due to a lack of suitable bioanalytical
techniques. Initial work aimed at simultaneously tackling both these issues is described where different approaches for
the nanoparticle labeling of ricin are investigated along with changes in ricin toxicity associated with the labeling