Unveiling size‐fluorescence correlation of organic nanoparticles and its use in nanoparticle size determination

Abstract

Quantitatively establishing the correlation between nanoparticle size and fluorescence is essential for understanding the behavior and functionality of fluorescent nanoparticles (FNPs). However, such exploration focusing on organic FNPs has not been achieved to date. Herein, we employ the use of supramolecular polymeric FNPs prepared from tetraphenylethylene‐based bis‐ureidopyrimidinone monomers (bis‐UPys) to relate the size to the fluorescence of organic nanoparticles. At an equal concentration of bis‐UPys, a logarithmic relationship between them is built with a correlation coefficient higher than 0.96. Theoretical calculations indicate that variations in fluorescence intensity among FNPs of different sizes are attributed to the distinct molecular packing environments at the surface and within the interior of the nanoparticles. This leads to different nonradiative decay rates of the embedded and exposed bis‐UPys and thereby changes the overall fluorescence quantum yield of nanoparticles due to their different specific surface areas. The established fluorescence intensity‐size correlation possesses fine universality and reliability, and it is successfully utilized to estimate the sizes of other nanoparticles, including those in highly diluted dispersions of FNPs. This work paves a new way for the simple and real‐time determination of nanoparticle sizes and offers an attractive paradigm to optimize nanoparticle functionalities by the size effect.

Theoretical insights into the AIE mechanism of assembles

“…Since the proportion of embedded HPS molecules increases with the size increase of amorphous aggregates, and their FQE are independent on aggregate size, theoretically we predict the linear relationship between the fluorescence intensity and the size of amorphous HPS aggregates. Later, this theoretical prediction is successfully verified by fluorescence spectra experiments (Figure1d)[47,48]. Such a linear relationship provides a possibility of monitoring the aggregate size of amorphous AIEgens in situ in future experiments.…”

Precise molecular engineering for the preparation of pyridinium photosensitizers with efficient ROS generation and photothermal conversion

“…[1][2][3] In this system, fluorescence imaging with high sensitivity, high resolution and real-time response is widely accepted, while near-infrared imaging is preferred due to deeper tissue penetration and less light damage. 4,5 As a new treatment method, photodynamic therapy (PDT) and photothermal therapy (PTT) have the advantages of controllability and non-invasiveness, and can avoid the problem of drug resistance, and can be used as a powerful supplement to traditional treatment. 6,7 In addition, the heat generated during PTT is also a real-time imaging signal, 8,9 which can help improve the accuracy of diagnosis and treatment location.…”

Monophenyl luminescent material with dual-state emission and pH sensitivity for cell imaging

“…It is important to note that the size of aggregates has a signicant impact on their optical properties. [14][15][16] Before AIE probes can be used for cellular imaging, they are usually converted into nanoparticles in a tedious process. Therefore, attention has been focused on developing innovative uorescent probes that maintain optical properties and cellular imaging quality in complex cellular environments, with or without aggregation.…”