Xuehong Min

Real-Time, Quantitative Lighting-up Detection of Telomerase in Urines of Bladder Cancer Patients by AIEgens

As a biomarker for early cancer diagnosis, telomerase are one of the promising targets for cancer therapeutics. Inspired by the fluorescent emission principle of aggregation-induced emission fluorogens, we creatively designed an AIE-based turn-on method to detect telomerase activity from cell extracts. A positively charged fluorogen (TPE-Z) is not fluorescent when freely diffused in solution. The fluorescence of TPE-Z is enhanced with the elongation of the DNA strand which could light up telomere elongation process. By exploitation of it, we can detect telomerase activity from different cell lines (E-J, HeLa, MCF-7, and HLF) with high sensitivity and specificity. Moreover, our method is successfully employed to demonstrate the applications in bladder cancer diagnosis (41 urine specimens from bladder cancer patients and 15 urine specimens from normal people are detected). The AIE-based method provides a simple one-pot technique for quantification and monitoring of the telomerase activity and shows great potential for future use in clinical tests.

Biocompatible Green and Red Fluorescent Organic Dots with Remarkably Large Two-Photon Action Cross Sections for Targeted Cellular Imaging and Real-Time Intravital Blood Vascular Visualization.

Fluorescent organic dots are emerging as promising bioimaging reagents because of their high brightness, good photostability, excellent biocompatibility, and facile surface functionalization. Organic dots with large two-photon absorption (TPA) cross sections are highly desired for two-photon fluorescence microscopy. In this work, we report two biocompatible and photostable organic dots fabricated by encapsulating tetraphenylethene derivatives within DSPE-PEG matrix. The two organic dots show absorption maxima at 425 and 483 nm and emit green and red fluorescence at 560 and 645 nm, with high fluorescence quantum yields of 64% and 22%, respectively. Both organic dots exhibit excellent TPA property in the range of 800-960 nm, affording upon excitation at 820 nm remarkably large TPA cross sections of 1.2×10(6) and 2.5×10(6) GM on the basis of dot concentration. The bare fluorophores and their organic dots are biocompatible and have been used to stain living cells for one- and two-photon fluorescence bioimagings. The cRGD-modified organic dots can selectively target integrin αvβ3 overexpressing breast cancer cells for targeted imaging. The organic dots are also applied for real-time two-photon fluorescence in vivo visualization of the blood vasculature of mouse ear, providing the spatiotemporal information about the whole blood vascular network. These results demonstrate that the present fluorescent organic dots are promising candidates for living cell and tissue imaging.

Rational Designed Bipolar, Conjugated Polymer-DNA Composite Beacon for the Sensitive Detection of Proteins and Ions

Nature owns remarkable capabilities in sensing target molecules, while the artificial biosensor lags far behind nature. Inspired by nature, we devise a new sensing platform that can specifically bind the molecules and synchronously initiate a specific signal response. We rationally designed a type of bipolar probe that is comprised of a hydrophilic DNA part and a hydrophobic conjugated polymer (CP) unit. In aqueous solution, they can form micelles with a hydrophobic CP core and a hydrophilic DNA shell. The aggregation-caused quenching suppresses the fluorescence of CP. Adding telomerase, the hydropathical profile of the bipolar probes is drastically regulated that results in the collapse of micelles and liberates fluorescence simultaneously. The probe has been used in both mimic systems and real urine samples (38 samples). We achieve sensitive and specific detection of telomerase and obtain clearly classification for normal people and cancer patients. It can also be used in a signal off sensor that is used to detect mercury ions.

Lab in a Tube: Sensitive Detection of MicroRNAs in Urine Samples from Bladder Cancer Patients Using a Single-Label DNA Probe with AIEgens

We demonstrate an ultrasensitive microRNA detection method based on an extremely simple probe with only fluorogens but without quencher groups. It avoids complex and difficult steps to accurately design the relative distance between the fluorogens and quencher groups in the probes. Furthermore, the assay could accomplish various detection limits by tuning the reaction temperature due to the different activity of exonuclease III corresponding to the diverse temperature. Specifically, 1 pM miR-21 can be detected in 40 min at 37 °C, and 10 aM (about 300 molecules in 50 μL) miR-21 could be discriminated in 7 days at 4 °C. The great specificity of the assay guarantees that the real 21 urine samples from the bladder cancer patients are successfully detected by our method.

Protease-Responsive Prodrug with Aggregation-Induced Emission Probe for Controlled Drug Delivery and Drug Release Tracking in Living Cells

Controlled drug delivery and real-time tracking of drug release in cancer cells are essential for cancer therapy. Herein, we report a protease-responsive prodrug (DOX-FCPPs-PyTPE, DFP) with aggregation-induced emission (AIE) characteristics for controlled drug delivery and precise tracking of drug release in living cells. DFP consists of three components: AIE-active tetraphenylethene (TPE) derivative PyTPE, functionalized cell penetrating peptides (FCPPs) containing a cell penetrating peptide (CPP) and a short protease-responsive peptide (LGLAG) that can be selectively cleaved by a cancer-related enzyme matrix metalloproteinase-2 (MMP-2), and a therapeutic unit (doxorubicin, DOX). Without MMP-2, this prodrug cannot go inside the cells easily. In the presence of MMP-2, DFP can be cleaved into two parts. One is cell penetrating peptides (CPPs) linked DOX, which can easily interact with cell membrane and then go inside the cell with the help of CPPs. Another is the PyTPE modified peptide which will self-aggregate because of the hydrophobic interaction and turn on the yellow fluorescence of PyTPE. The appearance of the yellow fluorescence indicates the release of the therapeutic unit to the cells. The selective delivery of the drug to the MMP-2 positive cells was also confirmed by using the intrinsic red fluorescence of DOX. Our result suggests a new and promising method for controlled drug delivery and real-time tracking of drug release in MMP-2 overexpression cells.

A photostable AIE fluorogen for lysosome-targetable imaging of living cells

Disruptive variation in intracellular pH and its fluctuations in lysosomes have a close relationship with the more acidic lysosome lumen of cancer cells (pH 4.5-5.5). Traditional lysosome-targeted probes, such as LysoTracker Green DND-26 (LTG) and LysoTracker Red DND-99 (LTR), can fluoresce when the weak base units in the probes are removed after donating protons under the photoinduced electron-transfer (PET) effect. However they can only be used at low concentration to avoid the aggregation-caused quenching (ACQ) effect and are also easily photobleached under continuous excitation irradiation, displaying low photostability. Herein, a tetraphenylethylene (TPE)-based lysosome-targetable fluorescence probe, TPE-CA, was synthesized, which could selectively monitor the pH change in subcellular organelles and exhibited a strong blue emission under an acidic condition with pH = 4. Using crystallographic, NMR and HRMS analyses, the mechanism regarding the pH dependent fluorescent performance of TPE-CA has been illustrated at the molecular level. In addition, experimental results show that TPE-CA is cell-permeable and biocompatible with HeLa, MCF-7 and HLF cells. The punctate fluorescent spots in the co-staining experiment of TPE-CA with LTG and LTR proves that the blue fluorescence spots of TPE-CA are indeed localized in the most acidic lysosome organelles. In particular, TPE-CA also inherits the aggregation-induced emission (AIE) feature of TPE, showing better photostability under continuous UV illumination compared with the commercial dyes (LTG and LTR). These results show that TPE-CA would be beneficial for understanding the acid environment of lysosomes in related cells and organs with potential biological significance.

AIE-based superwettable microchips for evaporation and aggregation induced fluorescence enhancement biosensing

Superwettable microchips with superhydrophilic microwells on superhydrophobic substrate have attracted increasing attention in fluorescence-based biological and medical diagnostics. However, traditional fluorophores often suffer from the aggregation-caused quenching (ACQ) problem at high concentration or in aggregated state. Here, we developed an AIE-based superwettable microchip by combining the evaporation-induced enrichment of superwettable microchips and the aggregation-induced emission of AIEgens together into one chip. Benefitting from the synergistic effect of the above two mechanisms, the AIE molecules (TPE-Z, a tetraphenylethene salt) were enriched from the diluted solution via evaporation and aggregated within the superhydrophilic microwell and then realized the fluorescence enhancement. Based on the dual enhancement effect of the AIE-based superwettable microchip, microRNA-141 (miR-141) can be detected with excellent reproducibility, sensitivity and specificity. A low detection limit of 1 pM can be achieved with higher signal-to-noise ratio than the traditional fluorescent probes. The proposed AIE-based superwettable microchip will provide a simple fluorescence enhancement biosensing platform for rapid, multiplexed and high-throughput analysis of specific targets in environmental monitoring, food safety, medical diagnosis and related research areas.