Red fluorescent proteins (RFPs) have emerged as valuable biological markers for biomolecule imaging in living systems. Developing artificial fluorogenic systems that mimic RFPs remains an unmet challenge. Here, we describe the design and synthesis of six new chromophores analogous to the chromophores in RFPs. We demonstrate, for the first time, that encapsulating RFP chromophore analogues in canonical DNA G-quadruplexes (G4) can activate bright fluorescence spanning red and far-red spectral regions (Em = 583-668 nm) that nearly match the entire RFP palette. Theoretical calculations and molecular dynamics simulations reveal that DNA G4 greatly restricts radiationless deactivation of chromophores induced by a twisted intramolecular charge transfer (TICT). These DNA mimics of RFP exhibit attractive photophysical properties comparable or superior to natural RFPs, including high quantum yield, large Stokes shifts, excellent anti-photobleaching properties, and two-photon fluorescence. Moreover, these RFP chromophore analogues are a novel and distinctive type of topology-selective G4 probe specific to parallel G4 conformation. The DNA mimics of RFP have been further exploited for imaging of target proteins. Using cancer-specific cell membrane biomarkers as targets, long-term real-time monitoring in single live cell and two-photon fluorescence imaging in tissue sections have been achieved without the need for genetic coding.

The rapid advancement of thermal materials and fluorescence spectroscopy has extensively promoted the development of micro-scale fluorescence thermometry in recent years. Based on their advantages of fast response, high sensitivity, simple operation, high spatial resolution, and non-destructive detection, fluorescence thermometers have become powerful analysis tools used to sense temperature fluctuations through fluorescent signals, especially to accurately capture living cells via fluorescent signals and local temperature variations in living bodies, thus providing the most direct means for the in-depth understanding of biological processes in cells. Herein, we systematically categorize the currently reported fluorescence thermometers based on the aspects of fluorescence intensity and wavelength, reveal the intrinsic relationship between fluorescence (intensity and wavelength) and temperature response, expound the applications of fluorescence thermometers in the fields of chemical sensing and biomedicine, and analyze the challenges faced by current fluorescence thermometers based on fundamental problems and practical applications simultaneously, thus highlighting the future directions of fluorescence thermometers.

By revealing the intrinsic link between the inherent advantages of nanocellulose and hydrogels, we highlight the applications of nanocellulose hydrogels in medical treatment, electricity, sensor, environmental governance, food, and agriculture.