Photothermal detection of individual gold nanoparticles: perspectives for high-throughput screening.
We use photothermal microscopy to detect and image individual gold nanoparticles that are either embedded in a polymer film or immobilized in an aqueous environment. Reducing the numerical aperture of the detection optics allows us to achieve a 200-fold-enlarged detection volume while still retaining sufficient detectivity. We characterize the capabilities of this approach for the detection of gold colloids with a diameter of 20 nm, with emphasis on practical aspects that are important for high-throughput-screening applications. The extended detection volume in combination with the stability of the photothermal signal are major advantages compared to fluorescence-based approaches, which are limited by photoblinking and photobleaching. Careful consideration is given to the trade-off between the maximum increase in local temperature that can be tolerated by a biological specimen and the minimum integration time needed to reliably determine whether a given volume contains a target species. We find that our approach has the potential to increase the detection-limited flow rate (i.e. the limit given by the detection volume divided by the minimum detection time) by two to three orders of magnitude.
Kulzer
Florian
F
Institute of Biology, Leiden University, P.O. Box 9505, 2300 RA Leiden, The Netherlands.
Laurens
Niels
N
Besser
Jaya
J
Schmidt
Thomas
T
Orrit
Michel
M
Spaink
Herman P
HP
D005456:Fluorescent Dyes / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010777:Photochemistry; D013696:Temperature; D013997:Time Factors
D005456:Fluorescent Dyes; D006046:Gold