Detection of Single Nanoparticles and Lentiviruses Using Microcavity Resonance Broadening

Adv. Mater. 2013, 25, 5616–5620 In the above Communication, the discussion on the detection limit (page. 5619) requires minor corrections. In addition, the Supporting Information file has been updated as well. These amendments do not affect the original experiments and conclusions of the article. The first sentence below Equation 1 on page 5619 should read: For the single nanoparticles (R = 70 nm) and lentiviruses we used, the resonance linewidth broadening (Γ/2π) of the cavity mode caused by a Rayleigh nanoparticle is described by Γ/2π≌(1/2π)(αωc/Vc)(1+αωc3/(6πν3)) f2(r). Here α denotes the polarizability of the nanoparticle determined by its physical properties, ωc and Vc are resonant frequency and mode volume of the probe mode, f(r) represents the normalized mode distribution at the position r of the particle, and ν stands for the speed of light in its surroundings. The paragraph before the summary should read: From the experimental results in Figure 3a, the measured uncertainties are approximately σ≌(0.0132Δω+0.0527) MHz, and the detection limit can be derived from Γ/2π=σ. Thus, the required Q factor can be one order of magnitude smaller than in mode splitting detection schemes where the splitting signal should be larger than the mode linewidth (see Supporting Information). When the Q factor of the cavity mode is smaller, e.g., 107 which is suitable for real applications, the detection limit for mode broadening remains about 23 nm, which is still better than that for mode splitting (27 nm) with a Q factor of 108. Furthermore, with adequately high Q factors, e.g., exceeding 4 × 108, the smallest detectable nanoparticle is estimated to be smaller than 10 nm. Considering the intrinsic absorption of nanoparticles, the detection limit can be even smaller. The authors apologize for any inconvenience. The authors thank Professor Stephen Arnold for helpful discussions.