Fig. 6.

Multiple imaging methods and classic cases for Pdots of the π-conjugation chain. A). Pdots-related developments and applications are typically implemented on a nano- or microscale, including (i) preparation and spectrum, (ii) analysis and detection, (iii) biomedical imaging, and (iv) nanodrugs or therapeutic agents. The squares in the figure represent the main influencing factors in these practical applications. Source: Connected Papers (https://www.connectedpapers.com/). B). Typical representative of Pdots whose emission spectra lie in the visible range of light. And the challenges to be faced in the development of NIR Pdots nanoprobes. Absorption spectra - upper left, emission spectra - upper right, scattering coefficients of different biological tissues & intralipid - lower left, absorption spectra of oxyhaemoglobin (red), deoxyhaemoglobin (blue) and water (black) through a 1-mm-long path in human blood - lower right. Reprinted with permission from Refs. [297,298]. Copyright 2008 and 2015 American Chemical Society. C). Method for NIR NPs synthesis of visible light fluorescent materials - aggregation-induced emission (AIE). Absorption and fluorescence spectra of P1c, P2c, and P3c polymers in water & THF - upper right. Fluorescence intensity changes of P3a, P3b, and P3c in THF/water mixtures containing different water fractions (v/v % = THF/water %). In vivo NIR-II fluorescence imaging of mouse brain at designated time points after intravenous injection of P3c Pdots – lower right. Reprinted with permission from Ref. [51]. Copyright 2020 John Wiley and Sons Ltd. D). Applications of Pdots in the field of super-resolution imaging. Fluorescence images of microtubules in HeLa cells labeled with the AIE Pdots - left. And the same cells were incubated with both biotinylated anti-α-tubulin and PFBT–NH–PIMA Pdots-streptavidin - right. Reprinted with permission from Refs. [35,299]. Copyright 2012 and 2017 John Wiley and Sons Ltd. E). In vivo photoacoustic imaging of tumor (liver), bronchial lymph nodes (BLN), inguinal lymph nodes (ILN), supraclavicular lymph nodes (SLN) and lymph nodes (LN) (lower). Reprinted with permission from Ref. [300]. Copyright 2013 Springer Nature. & F). In vivo PA imaging and 3D images of tumor incubated with Pdots (SPN4) - left. Thermal image of the SPNs solutions after 808 nm laser irradiation for 4 min. Reprinted with permission from Ref. [301]. Copyright 2015 John Wiley and Sons Ltd.