Spatiotemporally controlled nano-sized third harmonic generation agents

Abstract

Here, we present a new class of third harmonic generation (THG) imaging probes that can be activated with precise spatiotemporal control using non-linear excitation. These probes consist of lipid-coated perfluorocarbon nanodroplets with embedded visible chromophores. The droplets undergo phase transition from liquid to gas upon heating mediated by two-photon absorption of NIR light by the embedded dyes. Resulting microbubbles provide a sharp, local refractive index mismatch, which makes an excellent source of THG signal. Potential applications of these probes include activatable THG agents for biological imaging and "on-demand" delivery of various compounds under THG monitoring.

Effect of perfluorocarbon composition on activation of phase‐changing ultrasound contrast agents

“…Five PNCA formulations with different PFC cores (100% C5 [C6‐0]; 75% C5 and 25% C6 [C6‐25]; 50% C5 and C6 [C6‐50]; 25% C5 and 75% C6 [C6‐75]; and 100% C6 [C6‐100]) were prepared according to previous work, 15–18 with PFC mixtures being mixed on a per‐particle level. Briefly, a lipid cake composed of 18.0 mg 1,2‐distearoyl‐sn‐glycero‐3‐phosphocholine (DSPC, 94.3% by molarity), 1.7 mg 1,2‐distearoyl‐sn‐glycero‐3‐phosphoethanolamine‐N‐methoxy‐polyethyleneglycol‐2000 (DSPE‐PEG‐2000, 2.5%), and 0.3 mg cholesterol (3.2%; all from Avanti Polar Lipids, Inc., Alabaster, AL) was formed and then rehydrated in 2 ml deionized (DI) water for each of these preparations.…”

“…A DelsaNano C dynamic light scattering system (Beckman Coulter, Inc., Brea, CA) was used to measure the mean size and polydispersity index (PDI) of nanodroplets in triplicate approximately 1 and 8 weeks after fabrication (i.e., before and after all US characterization). The relative amount of PFC in stock nanodroplet preparations was measured using 19 F nuclear magnetic resonance (NMR), as previously described 15 . Briefly, NMR scans were carried out using a 500‐MHz NMR spectrometer (Bruker Corporation, Billerica, MA), and 19 F concentrations were determined by integrating C5 and/or C6 NMR peaks with normalization by the integrated peak of the known trifluoroacetic acid standard.…”

“…The relative amount of PFC in stock nanodroplet preparations was measured using 19 F nuclear magnetic resonance (NMR), as previously described. 15 Briefly, NMR scans were carried out using a 500-MHz NMR spectrometer (Bruker Corporation, Billerica, MA), and 19 F concentrations were determined by integrating C5 and/or C6 NMR peaks with normalization by the integrated peak of the known trifluoroacetic acid standard. Aqueous PNCA stock preparations were stored in sealed glass vials at 4 • C and mixed by gentle vortexing for 5-10 s before each use.…”

“…We address this problem by investigating high-frequency (i.e., 12.3 MHz) activation and imaging of PNCAs with varying HBP PFC cores and two distinct lipid shells to achieve a stable formulation that can be reliably activated and imaged with high contrast using diagnostic US. [15][16][17][18] with PFC mixtures being mixed on a perparticle level. Briefly, a lipid cake composed of 18.0 mg 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC, 94.3% by molarity), 1.7 mg 1,2-distearoyl-sn-glycero-3phosphoethanolamine-N-methoxy-polyethyleneglycol-2000 (DSPE-PEG-2000, 2.5%), and 0.3 mg cholesterol (3.2%; all from Avanti Polar Lipids, Inc., Alabaster, AL) was formed and then rehydrated in 2 ml deionized (DI) water for each of these preparations.…”

One-Pot, One-Step Synthesis of Drug-Loaded Magnetic Multimicelle Aggregates

“…For the synthesis of MaMAs, 1.97 mg of lipids and 0.4 mg of IONPs (based on the iron content measured by ICP-MS) were taken for a typical batch. The exact ratio of lipids is outlined in Table and consisted of PEGylated DSPE phospholipids that are commonly used in various biomedical applications − including clinical lipid formulations. − Specifically, 1,2-distearoyl- sn -glycero-3-phosphoethanolamine-N-[amino­(polyethylene glycol)-1000] (DSPE-PEG-1000), 1,2-distearoyl- sn -glycero-3-phosphoethanolamine-N-[amino­(polyethylene glycol)-2000] (DSPE-PEG-2000), and 1,2-distearoyl- sn -glycero-3-phosphoethanolamine-N-[azido­(polyethylene glycol)-2000] (DSPE-PEG-2k-Azide) were mixed at the molar ratios of 60%:20%:20%, respectively.…”