Plasmonic Photothermal Fluorescence Modulation for Homogeneous Biosensing

Abstract

Fluorescence readout is uniquely powerful for biological assays and imaging because it combines the detection of specific biotargets with high spatial and temporal resolution. Recently, several strategies for the modulation in time of fluorescence emission have been proven useful to separate the target signal from constant background contributions. Here, we investigate the emission modulation of organic fluorophores located in the nanometric vicinity of plasmonically heated gold nanorods and apply it to a novel, all-optical homogeneous biosensing scheme. The combination of plasmonic heating and temperature sensitive molecular fluorescence enables the robust quantification of surface reactions.

Plasmonic Photothermal Nanoparticles for Biomedical Applications

“…[90] However, there remains a critical need for new technologies to address current limitations of this technology, such as long procedural time, heavy [82] Copyright 2012, Wiley-VCH. [89] Copyright 2016, American Chemical Society. The steps in the photothermal time trace data show real-time single-molecule binding and unbinding events.…”

“…Each data point corresponds to the average of five replications by multiple on/off cycles of the NIR laser (inset). Reproduced with permission . Copyright 2016, American Chemical Society.…”

“…Fluorescence labeling and detection has been a powerful method in various biomedical applications due to many analytical advantages . Pellegrotti et al reported a novel method of fluorescence quenching with plasmonic photothermal effect used for bioassay (Figure c) . They demonstrated that the fluorescence emission of organic dyes can be significantly reduced near nanoparticles by light‐induced thermal energy, which is different from the well‐known fluorescence suppression by metallic nanoparticles in close proximity due to direct energy transfer of the dyes to particles.…”

Spectroscopy and Biosensing with Optically Resonant Dielectric Nanostructures

“…These nanostructures can significantly enhance the interactions between quantum emitters (e.g., quantum dots, defect centers in crystals, molecules) and their surrounding photonic environment, leading to giant luminescence enhancement, ultrafast emission in the picosecond range, strong coupling, surface‐enhanced Raman scattering (SERS), optical interconnections, and control of emission patterns . Because of these advantages, plasmonic nanostructures are broadly used in many applications, including near‐field microscopy, biosensors, photovoltaics, photodetection, and medicine . However, the typical plasmonic materials, gold and silver, have finite conductivities at optical frequencies, leading to inherent dissipation of the electromagnetic energy.…”

Efficiency and Bond Selectivity in Plasmon‐Induced Photochemistry

“…Highly‐confined heat can also vaporize the surrounding media of the NP, affect stability of emitters or molecules nearby, or even create strong repulsive forces between nano‐objects . In recent years several applications, such as photothermal cancer therapy, photothermal imaging, and photothermal biosensing, among many others, have been proposed in order to take advantage of this highly‐localized heat generated in metallic‐based plasmonic nanoantennas. Although heat‐dissipation strategies may help to mitigate temperature increase in metal plasmonic NPs, real‐world applications so far have been strongly limited due to these drawbacks…”