Near-Infrared Frequency Upconversion Luminescence Bioimaging Based on Cyanine Nanomicelles

Abstract

Upconversion optical imaging has great application prospects in biomedical imaging. However, research on molecular upconversion luminescence materials is very limited. In this study, a cyanine dye modified using polyethylene glycol is reported, which has frequency upconversion luminescence (FUCL) capability and can be applied for in vivo FUCL imaging after forming nanomicelles. The optical properties of PEGylated cyanine dye show that the light absorption property of cyanine does not be influenced and can still emit near-infrared fluorescence. However, under the condition that the illumination wavelength is larger than the maximal fluorescence wavelength, the FUCL of cyanine dye is generated at the same position as the down-converted luminescence. The nanomicelles exhibit good biocompatibility. When applied to in vivo imaging, the cyanine-based nanomicelles not only qualify for high-resolution subcutaneous blood vessel imaging but also exhibit good imaging ability for various organs and tumors. These results point out that cyanine-based nanomicelles with FUCL characteristics are expected to be further applied in the field of biomedicine, providing a basis for the construction of FUCL molecules.

Supramolecular Annihilator with DPA Parallelly Arranged by Multiple Hydrogen-Bonding Interactions for Enhanced Triplet–Triplet Annihilation Upconversion

“…There are several mechanisms to achieve UC emissions, such as multistep excitation of lanthanides ions [1], two-photon absorption [2], and second-harmonic generation [3], among which UC based on triplet-triplet annihilation (TTA) [4][5][6][7] is attracting continuous attention due to its unique advantages of tunable excitation wavelengths and high quantum efficiency. Thus, this has wide application potentials, ranging from photocatalysis [8,9], bio-imaging and bio-sensing [10][11][12][13], and drug release [14,15], to 3D printing [16,17]. The triplet sensitizer and annihilator are the essential components for TTA-UC, and a diagram illustrating the mechanism of TTA-UC is shown in Figure S1, in which the triplet-triplet energy transfer (TTET) process from the sensitizer to the annihilator and triplet-triplet annihilation (TTA) between the triplet annihilators are two pivotal processes for TTA-UC, both of which follow a Dexter mechanism.…”

Self-Assembled BODIPY Nanoparticles for Near-Infrared Fluorescence Bioimaging

“…In recent years, boron–dipyrromethene (BODIPY) dyes have been widely studied and applied as ideal fluorescent bioprobes [ 22 , 23 ] and exhibit excellent optical properties, such as high modifiability, excellent fluorescence quantum yield, small emission bandwidth, and satisfactory detection sensitivity [ 24 , 25 , 26 , 27 , 28 , 29 ]. To achieve the goal of NIR emission for detection or imaging, a common method is to extend the conjugation of the molecular structure.…”