Nanoparticle-based Cell Trackers for Biomedical Applications.

The continuous or real-time tracking of biological processes using biocompatible contrast agents over a certain period of time is vital for precise diagnosis and treatment, such as monitoring tissue regeneration after stem cell transplantation, understanding the genesis, development, invasion and metastasis of cancer and so on. The rationally designed nanoparticles, including aggregation-induced emission (AIE) dots, inorganic quantum dots (QDs), nanodiamonds, superparamagnetic iron oxide nanoparticles (SPIONs), and semiconducting polymer nanoparticles (SPNs), have been explored to meet this urgent need. In this review, the development and application of these nanoparticle-based cell trackers for a variety of imaging technologies, including fluorescence imaging, photoacoustic imaging, magnetic resonance imaging, magnetic particle imaging, positron emission tomography and single photon emission computing tomography are discussed in detail. Moreover, the further therapeutic treatments using multi-functional trackers endowed with photodynamic and photothermal modalities are also introduced to provide a comprehensive perspective in this promising research field

2<i>H</i>‑[1,2,3]Triazolo[4,5‑<i>c</i>]pyridine Cored Organic Dyes Achieving a High Efficiency: a Systematic Study of the Effect of Different Donors and π Spacers

New D–A−π–A-based isomeric sensitizers, <b>PTN<i>n</i></b> (<i>n</i> = 1–2) and <b>NPT<i>n</i></b> (<i>n</i> = 1–5), were synthesized using 2<i>H</i>-[1,2,3]­triazolo­[4,5-<i>c</i>]­pyridine (<b>PT</b>) as an auxiliary acceptor, triphenylamine or <i>N</i>,<i>N</i>-bis­[4-(hexyloxy)­phenyl]­aniline as the donor, furan, thiophene, phenyl, or 3-hexylthiophene as the conjugated spacer, and 2-cyanoacrylic acid as the acceptor and anchor as well. They were used as the sensitizers of dye-sensitized solar cells. The <b>NPT<i>n</i></b> dyes show better performance than the <b>PTN<i>n</i></b> dyes. Among them, the best efficiency of 7.92% (∼96%, <b>N719</b>) was obtained with the <b>NPT5</b> dye, indicating that the <b>PT</b> core could be used as a new building block for the design of high-performance sensitizers in the future. The negative Mulliken charge from the auxiliary acceptor was found to be useful as a semiempirical index for correlation of the molecular structure with the cell efficiency among structurally similar D–A−π–A-type congeners

Boosting Algal Bloom by Five-Fold with AIEgens: Towards the Development of Biofactory

Human population is now faced with grand challenges such as global warming, food shortage and energy sustainability, which could be partially solved by massively increasing the growth and yield of photosynthetic organisms which capture the light energy to convert carbon dioxide and water into usable chemical energy. Cyanobacteria and eukaryotic microalgae are considered as attractive targets to be exploited by the algal factory because of their fast growth, low cost cultivation, less arable land and the diversity of high-value chemical substances produced. Many optical approaches have been introduced to increase the efficiency in artificial culturing systems, such as adding a luminescent layer that absorbs ultraviolet light and emits photosynthetic active radiation for cyanobacteria. In this work, we introduced luminogens with aggregation-induced emission characteristics (AIEgens) into the growth medium of a marine cyanobacteria. These hydrophobic AIEgens formed highly emissive luminogenic aggregates in the aqueous medium and dispersed around the cyanobacteria. Remarkedly, the number of cyanobacteria incubated in the medium with AIE aggregates was 5-fold more than the control group after 14-day culturing. The increased photosynthetic active radiation and the change of cyanobacteria protein expression in photosynthesis and metabolism might be the reason. Our study is the first using organic luminogenic aggregates as optical engineering inside the growth medium to dramatically increase the growth of cyanobacteria and demonstrated that AIEgens is promising technologies in the development of algal factories

Centimeter-Deep NIR-II Fluorescence Imaging with Nontoxic AIE Probes in Nonhuman Primates

Fluorescence probes with aggregation-induced emission (AIE) characteristics are of great importance in biomedical imaging with superior spatial and temporal resolution. However, the lack of toxicity studies and deep tissue imaging in nonhuman primates hinders their clinical translation. Here, we report the blood chemistry and histological analysis in nonhuman primates treated with AIE probes over tenfold of an intravenous dose of clinically used indocyanine green (ICG) during a study period of 36 days to demonstrate AIE probes are nontoxic. Furthermore, through bright and nontoxic AIE probes and fluorescence imaging in the second window (NIR-II, 1,000–1,700 nm), we achieve an unprecedented 1.5-centimeter-deep vascular imaging in nonhuman primates, breaking the current limitation of millimeter-deep NIR-II fluorescence imaging. Our important findings, i.e., nontoxic features of AIE probes and centimeter-deep NIR-II vascular imaging in nonhuman primates, may facilitate successful translation of AIE probes in clinical trials

Organic Photosensitizers Incorporating Rigidified Dithieno­[3,2‑<i>f</i>:2′,3′‑<i>h</i>]­quinoxaline Segment Tethered with Thiophene Substitutes for Dye-Sensitized Solar Cells

Metal-free D−π–RS−π–A type sensitizers, consisting of triphenylamine as the electron donor, 2,3-bis­(3-(2-ethyl­hexyl)-5-methyl­thiophen-2-yl)­dithieno­[3,2-<i>f</i>:2′,3′-<i>h</i>]­quinoxaline (<b>DTQT</b>) as the rigidified conjugation spacer (RS), thiophene as the π-spacer, and 2-cyanoacrylic acid as the acceptor/anchor, have broad absorption spectra ranging from 350 to 550 nm and a high molar extinction coefficient up to >46 200 M^–1 cm^–1. Under simulated AM 1.5 G illumination, the dye-sensitized solar cells (DSSCs) fabricated from the dyes exhibited light-to-electricity conversions in the range of 6.78% to 8.27%. The best efficiency is slightly higher than that of <b>N719</b>-based standard DSSC (7.92%). The efficiency can be further boosted to 8.51% by optimizing the concentration of LiI electrolyte

Naphtho[2,3‑<i>c</i>][1,2,5]thiadiazole and 2<i>H</i>‑Naphtho[2,3‑<i>d</i>][1,2,3]triazole-Containing D–A−π–A Conjugated Organic Dyes for Dye-Sensitized Solar Cells

Dipolar dyes comprising an arylamine as the electron donor, a cyanoacrylic acid as electron acceptor, and an electron deficient naphtho­[2,3-<i>c</i>]­[1,2,5]­thiadiazole (NTD) or naphtho­[2,3-<i>d</i>]­[1,2,3]­triazole (NTz) entity in the conjugated spacer, were developed and used as the sensitizers in dye-sensitized solar cells (DSSCs). The introduction of the NTD unit into the molecular frame distinctly narrows the HOMO/LUMO gap with electronic absorption extending to >650 nm. However, significant charge trapping and dye aggregation were found in these dyes. Under standard global AM 1.5 G illumination, the best cell photovoltaic performance achieved 6.37 and 7.53% (∼94% relative to N719-based standard cell) without and with chenodeoxycholic acid (CDCA) coadsorbent, respectively. Without CDCA, the NTz dyes have higher power conversion efficiency (7.23%) than NTD dyes due to less charge trapping, dye aggregation, and better dark current suppression