Sensing temperature at the subcellular level is of great importance for the understanding of miscellaneous biological processes. However, the development of sensitive and reliable organic fluorescent nanothermometers remains challenging. In this study, we report the fabrication of a novel organic fluorescent nanothermometer and study its application in temperature sensing. First of all, we synthesize a dual-responsive organic luminogen that can respond to the molecular state of aggregation and environmental polarity. Next, natural saturated fatty acids with sharp melting points as well as reversible and rapid phase transition are employed as the encapsulation matrix to correlate external heat information with the fluorescence properties of the luminogen. To apply the composite materials for biological application, we formulate them into colloidally dispersed nanoparticles by a technique that combines in situ surface polymerization and nanoprecipitation. As anticipated, the resultant zwitterionic nanothermometer exhibits sensitive, reversible, reliable, and multiparametric responses to temperature variation within a narrow range around the physiological temperature (i.e., 37 °C). Taking spectral position, fluorescence intensity, and fluorescence lifetime as the correlation parameters, the maximum relative thermal sensitivities are determined to be 2.15% °C−1 , 17.06% °C−1 , and 17.72% °C−1 , respectively, which are much higher than most fluorescent nanothermometers. Furthermore, we achieve the multimodal temperature sensing of bacterial biofilms using these three complementary fluorescence parameters. Besides, we also fabricate a cationic form of the nanothermometer to facilitate efficient cellular uptake, holding great promise for studying thermal behaviors in biological systems.

The maintenance of an intact membrane structure is of great importance for bacteria to execute various biological functions. However, chemical probes for monitoring the dynamic changes of bacterial membranes are barely reported. Herein, we, for the first time, report a novel polarity-sensitive probe for reflecting the packing degree of bacterial membrane lipids. Specifically, we synthesize a membrane-targeting fluorescent probe (TICT-lipid) that possesses both twist intramolecular charge transfer and aggregation-induced emission properties. TICT-lipid exhibits sensitive responses to the minute difference in the packing degree of membrane lipids, facilitating rapid differentiation of Gram-negative and Gram-positive bacteria. Interestingly, in the presence of membrane-disrupting antibiotics, the localization of TICT-lipid shifts from the outer membrane to the cell membrane by outputting blue-shifted and enhanced emission, making the mechanism of action of antibiotics clearly visible. TICT-lipid is a polarity-sensitive fluorescent probe, holding great promise in the study of membrane-related bacterial processes and antibiotic screening.

Naturally-occurring saturated fatty acids (NSFAs) have emerged as a class of promising biomaterials due to their low cost, chemical stability, well-defined melting points, large heat of fusion, reversible solid-liquid phase...

Photodynamic therapy (PDT) has attracted much attention in disease treatments. However, the exploration of a novel method for the construction of outstanding photosensitizers (PSs) with stimuli-responsiveness remains challenging. In this...

Antimicrobial susceptibility testing plays a pivotal role in the discovery of new antibiotics. However, the development of simple, sensitive, and rapid assessment approaches remains challenging. Herein, we report an activated alkyne-based cascade signal amplification strategy for ultrafast and high-throughput antibiotic screening. First of all, a novel water-soluble aggregation-induced emission (AIE) luminogen is synthesized, which contains an activated alkyne group to enable fluorescence turn-on and metal-free click bioconjugation under physiological conditions. Taking advantage of the in-house established method for bacterial lysis, a number of clickable biological substances (i.e., bacterial solutes and debris) are released from the bacterial bodies, which remarkably increases the quantity of analytes. By means of the activated alkyne-mediated turn-on click bioconjugation, the system fluorescence signal is significantly amplified due to the increased labeling sites as well as the AIE effect. Such a cascade signal amplification strategy efficiently improves the detection sensitivity and thus enables ultrafast antimicrobial susceptibility assessment. By integration with a microplate reader, this approach is further applied to high-throughput antibiotic screening.