Coherent anti-Stokes Raman scattering microscopy of single nanodiamonds

Abstract

Nanoparticles have attracted enormous attention for biomedical applications as optical labels, drug delivery vehicles, and contrast agents in vivo. In the quest for superior photostability and bio-compatibility, nanodiamonds (NDs) are considered one of the best choices due to their unique structural, chemical, mechanical, and optical properties. So far, mainly fluorescent NDs have been utilized for cell imaging. However, their use is limited by the efficiency and costs in reliably producing fluorescent defect centers with stable optical properties. Here, we show that single non-fluorescing NDs exhibit strong coherent anti-Stokes Raman scattering (CARS) at the sp3 vibrational resonance of diamond. Using correlative light and electron microscopy, the relationship between CARS signal strength and ND size is quantified. The calibrated CARS signal in turn enables the analysis of the number and size of NDs internalized in living cells in situ, which opens the exciting prospect of following complex cellular trafficking pathways quantitatively.

Revisiting the classification of NIR-absorbing/emitting nanomaterials for in vivo bioapplications

“…For non-fluorescent nanodiamond, researchers have already exploited the intrinsically strong C-C sp3 vibrational resonance at 1332 cm − 1 to demonstrate the coherent anti-Stokes Raman scattering microscopy on a single diamond NP. 224 Because the signal level is proportional to the volume of the NP, the feasible crystal size is approximately 150-300 nm.…”

Light- and pH-activated intracellular drug release from polymeric mesoporous silica nanoparticles

“…Thus CARS provided label-free visualization of cell structures with sub-micron resolution in situ. [37][38][39] Two-photon excited fluorescence (TPEF) is a standard technique in modern microscopy. Due to lower scattering, enhanced skin penetration, and reduced photodamage, TPEF offered an ideal tool for examining the intracellular localization of nanoparticles.…”

Anomalous Nonlinear Optical Response of Graphene Near Phonon Resonances

“…Different non-linear optical phenomena like second-, third-harmonic generation and four wave mixing (FWM) [5][6][7] can be quite strong in these materials [8][9][10][11][12][13][14][15]. However, the interpretation of the nonlinear optical response is strongly affected by electronic and phonon resonances [16][17][18][19], therefore the knowledge of the interplay between these resonances is desirable.Here we measured the third order optical emission by the degenerated four wave mixing emission of graphene, h-BN and their heterostructure near phonon resonances. We show that while the FWM signal in h-BN shows the expected enhancement, in graphene the signal is decreased exactly at the phonon resonance.…”

“…The so-called coherent anti-Stokes Raman spectroscopy (CARS) is a special case of FWM when the energy difference between ω 1 and ω 2 matches a phonon energy ( ω ph ), then ω 4 corresponds exactly to the anti-Stokes frequency in Raman scattering. In general, when the energy condition ω 1 − ω 2 = ω ph is satisfied, the ω 4 amplitude is enhanced [16][17][18][19].In order to study the CARS phenomenon in graphene and h-BN, flakes were prepared by micromechanical cleavage of natural graphite or bulk h-BN in transparent quartz substrates (SPI Inc.). Monolayer graphene were located in the substrates by an optical microscope followed by Raman characterization, where the 2D Raman band in monolayer graphene was characterized by a single Lorentzian [24].…”