Self-Enhanced Carbonized Polymer Dots for Selective Visualization of Lysosomes and Real-Time Apoptosis Monitoring.

Xiaohuan Zhao,Wenjing Wang,Shoujun Zhu,Jing Li,Dongning Liu,Mingxi Yang,Bai Yang

doi:10.1016/j.isci.2020.100982

Xiaohuan Zhao, Wenjing Wang + Show 5 more

Open Access

https://doi.org/10.1016/j.isci.2020.100982

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Abstract

SummaryProtons are highly related to cell viability during physiological and pathological processes. Developing new probes to monitor the pH variation could be extremely helpful to understand the viability of cells and the cell death study. Carbonized polymer dots (CPDs) are superior biocompatible and have been widely applied in bioimaging field. Herein, a new type of extreme-pH suitable CPDs was prepared from citric acid and o-phenylenediamine (CA/oPD-CPDs). Due to the co-existence of hydrophilic and hydrophobic groups, CA/oPD-CPDs tend to aggregate in neutral condition with a dramatic decrease of fluorescence, but disperse well in both acidic and alkaline conditions with brighter emission. This specialty enables them to selectively illuminate lysosomes in cells. Moreover, CA/oPD-CPDs in the cytoplasm could serve as a sustained probe to record intracellular pH variation during apoptosis. Furthermore, CA/oPD-CPDs present a continuous fluorescence increase upon 2-h laser irradiation in living cells, underscoring this imaging system for long-term biological recording.

Highlights

Protons play crucial roles in living cells during physiological and pathological processes, including intracellular protein degradation in lysosomes, homeostasis, and cell death (Gottlieb et al, 1995, 1996; Zanke et al, 1998)
A new type of extreme-pH suitable Carbonized polymer dots (CPDs) was prepared from citric acid and o-phenylenediamine (CA/oPD-CPDs)
CA/oPD-CPDs in the cytoplasm could serve as a sustained probe to record intracellular pH variation during apoptosis

Summary

Introduction

Protons play crucial roles in living cells during physiological and pathological processes, including intracellular protein degradation in lysosomes, homeostasis, and cell death (Gottlieb et al, 1995, 1996; Zanke et al, 1998). Acidification is an early feature of apoptosis and cell death. The sets of proteins-enzymes related to apoptosis exclusively operate at acidic pH values. Monitoring the acidification of living cells is a universal approach to identify cell viability and measure the efficiency of anti-cancer drugs. To satisfy this need, the materials need to be biocompatible and able to remain in the living cells without being digested within a long period. Some organic dyes are unable to function in acid circumstances and digested within hours in living cells. There is an ever-increasing demand for developing pH-responsive and extreme-pH-suitable fluorescence materials that are non-toxic and can be permanently preserved in living cells

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