Tweezing and manipulating micro- and nanoparticles by optical nonlinear endoscopy

Abstract

The precise control and manipulation of micro-and nanoparticles using an optical endoscope are potentially important in biomedical studies, bedside diagnosis and treatment in an aquatic internal organ environment, but they have not yet been achieved. Here, for the first time, we demonstrate optical nonlinear endoscopic tweezers (ONETs) for directly controlling and manipulating aquatic micro-and nanobeads as well as gold nanorods. It is found that two-photon absorption can enhance the trapping force on fluorescent nanobeads by up to four orders of magnitude compared with dielectric nanobeads of the same size. More importantly, two-photon excitation leads to a plasmon-mediated optothermal attracting force on nanorods, which can extend far beyond the focal spot. This new phenomenon facilitates a snowball effect that allows the fast uploading of nanorods to a targeted cell followed by thermal treatment within 1 min. As two-photon absorption allows an operation wavelength at the center of the transmission window of human tissue, our work demonstrates that ONET is potentially an unprecedented tool for precisely specifying the location and dosage of drug particles and for rapidly uploading metallic nanoparticles to individual cancer cells for treatment.

Self-assisted optothermal trapping of gold nanorods under two-photon excitation

“…Our observation confirms that this process is convective flow assisted; (2) Although the heat was dissipating during the 2 s laser scanning, the convective flow is still enough to attract more GNRs to the center; (3) The trapping process can be quantified by the average intensities over time as shown in figure 2(D) (excluding the big clusters due to the fact particles were aggregated before entering the FOV). A rapid increase of intensity over time implies a positive feedback loop as described earlier by Gu et al [22]. Trapping with less frequent laser scanning, i.e.…”

“…When more heat is generated with accumulation of GNRs at the focus, the trapping range is extended due to the convective flow (figure 1(B)). It has been reported that this effect was observable as the concentration increases to 10 3 per nanoliter [22]. In following measurements, we used the stock concentration of GNR, i.e.…”

Breaking the diffraction-limited resolution barrier in fiber-optical two-photon fluorescence endoscopy by an azimuthally-polarized beam

“…2a)63334. To maximize the excitation efficiency, a pair of gratings is used as pre-chirp unit in the dispersion compensation module (DCM) (see Methods).…”

Femtosecond‐Laser Direct Writing of Metallic Micro/Nanostructures: From Fabrication Strategies to Future Applications

“…By exploiting the optical-trapping effect, [116][117][118][119][120][121][122] FsLDW also enables the direct assembly of metallic nanoparticles into desired microstructures through the "femtosecond-laser photodynamic assembly (FsL-PDA)" process (depicted in Figure 1c). Using metal nanoparticles as nano-building-blocks, Sun and co-workers first achieved the FsL-PDA of metallic microstructures.…”