Turning Plasmonic Antennas on the Right Side: Template Stripping Maximizes Single Molecule Fluorescence Enhancement
Plasmonics is looking for nanogap antennas featuring narrow gap sizes, full accessibility to the plasmonic hotspot and high fabrication throughput. However, the current fabrication methods remain limited to gaps typically around 15-20 nm. Importantly, the plasmonic hotspot is often buried into the structure and not directly accessible for sensing at the antenna surface, thereby limiting the antenna optical performance when it comes to probing molecules.
In a recent Nano Letter article “In-plane plasmonic antenna arrays with surface nanogaps for giant fluorescence enhancement”, we present large arrays of nanoantennas, fabricated by a new approach combining electron beam lithography with planarization, etch back and template stripping. The flat arrays of nanoantennas feature 10 nm gaps with sharp edges and direct surface accessibility of the plasmonic hotspot. This improved nanoantenna fabrication and full access of the hotspot opens up the possibility of fully exploiting the physical properties of plasmonic antennas for a broad range of applications, such as biosensing at membranes or in nanofluidic channels, light harvesting, photocatalysis…
- We demonstrate the superior performance of these surface antennas by probing single fluorescent molecules, and reach huge fluorescence enhancement factors up to 15,000-fold, outperforming previous plasmonic realizations.
- Compared to the previous methods, the combination of back etching with template stripping drastically improves the optical performance of plasmonic nanoantennas by more than one order of magnitude, as we show in a direct comparison with focused ion beam milling.
- Our fabrication approach is fully scalable, with excellent reproducibility, and can be applied to virtually any antenna design.
PSA detection in protein buffer solution, here's the match:
On the left side: PhOCCS, single mixing step, no washing, 60 min incubation, single readout, 20 pg/mL limit of detection
On the right side: ELISA, three washing and rinsing steps, >3h total process duration, >100 pg/mL limit of detection
Let the figure speak by themselves. Simple sensing. No headache. No complex analysis tricks.
Label-free molecular biosensors featuring a high sensitivity together a simple manipulation and low operation costs remain a major technological challenge. We introduce a novel technique for high sensitivity specific DNA sensing in a single step homogeneous solution phase in our recent open access article Single-Step DNA Detection Assay Monitoring Dual Color Light Scattering from Individual Metal Nanoparticles Aggregates. Our groundbreaking technology features several distinctive advantages: it is fast, simple and accurate.
- The dual-color scattering analysis allows to reach a sub picomolar sensitivity and is 10x more sensitive than a single-color counterpart. It also enables to maintain a concentration of probe nanoparticles high enough to reach fast read-out kinetics in a single mixing step.
- Our technique is demonstrated to be sensitive and specific enough to detect single nucleotide deletion and mismatch, even for recognition sequences that are twice longer than typically used in this field.
Good period to take some distance from our daily routine and think about ourselves. But who are we by the way? True individuals or mirrors of somebody else? Think of it, and til next time, live like a nanopirate!
Warning: the video below is giving the hard truth, and it may hit hard. Sensitive readers, fasten your seatbelts.