Genetically Encoded Activators of Small Molecules for Imaging and Drug Delivery

Revealing the Optimization Route of Piezoelectric Sonosensitizers: From Mechanism to Engineering Methods

Piezoelectric catalysis is a novel catalytic technology that has developed rapidly in recent years and has attracted extensive interest among researchers in the field of tumor therapy for its acoustic-sensitizing properties. Nevertheless, researchers are still controversial about the key technical difficulties in the modulation of piezoelectric sonosensitizers for tumor therapy applications, which is undoubtedly a major obstacle to the performance modulation of piezoelectric sonosensitizers. Clarification of this challenge will be beneficial to the design and optimization of piezoelectric sonosensitizers in the future. Here, the authors start from the mechanism of piezoelectric catalysis and elaborate the mechanism and methods of defect engineering and phase engineering for the performance modulation of piezoelectric sonosensitizers based on the energy band theory. The combined therapeutic strategy of piezoelectric sonosensitizers with enzyme catalysis and immunotherapy is introduced. Finally, the challenges and prospects of piezoelectric sonosensitizers are highlighted. Hopefully, the explorations can guide researchers toward the optimization of piezoelectric sonosensitizers and can be applied in their own research.

An Effective Docking-Guided Strategy for Rational Tailoring of Fluorescent Aptamer Switches of Dimethylindole Red Analogue

The light-up aptamer-dimethylindole red (DIR) complexes have been applied in biochemistry analysis as promising signal transduction tools. However, the unfavorable repulsions between DIR and the long-sequence aptamer switch hinder the complex's further development, and it is urgent to engineer a feasible and efficient strategy for synchronously and rationally adjusting the DIR chemical structure and the DIR aptamer performance. Herein, we communicate a versatile docking-guided rational tailoring strategy to effectively upgrade a DNA aptamer which specifically turns on the fluorescence of a synthesized amino-functionalized DIR analogue (NH₂-DIR). After optimizing with three-level tailoring strategies including molecule docking-guided tailoring, coarse tailoring, and fine tailoring, the NH₂-DIR aptamer switch with higher binding affinity and specificity, considerable fluorescence-activation ability, and 40% shortened length was obtained. Integrating the experimental and docking results, the binding mechanism between NH₂-DIR and the tailored aptamer was deciphered via three types of interactions.

Multifunctional stimuli-responsive chemogenetic platform for conditional multicolor cell-selective labeling

Multicolor conditional labeling is a powerful tool that can simultaneously and selectively visualize multiple targets for bioimaging analysis of complex biological processes and cellular features. We herein report a multifunctional stimuli-responsive Fluorescence-Activating and absorption-Shifting Tag (srFAST) chemogenetic platform for multicolor cell-selective labeling. This platform comprises stimuli-responsive fluorogenic ligands and the organelle-localizable FAST. The physicochemical properties of the srFAST ligands can be tailored by modifying the optical-tunable hydroxyl group with diverse reactive groups, and their chemical decaging process caused by cell-specific stimuli induces a conditionally activatable fluorescent labeling upon binding with the FAST. Thus, the resulting switch-on srFASTs were designed for on-demand labeling of cells of interest by spatiotemporally precise photo-stimulation or unique cellular feature-dependent activation, including specific endogenous metabolites or enzyme profiles. Furthermore, diverse enzyme-activatable srFAST ligands with distinct colors were constructed and simultaneously exploited for multicolor cell-selective labeling, which allow discriminating and orthogonal labeling of three different cell types with the same protein tag. Our method provides a promising strategy for designing a stimuli-responsive chemogenetic labeling platform via facile molecular engineering of the synthetic ligands, which has great potential for conditional multicolor cell-selective labeling and cellular heterogeneity evaluation.

Comparison of the stimuli-responsive FAST platform (srFAST) proposed in this work with the reported original FAST system (O-FAST). The srFAST could achieve not only conditional selective labeling, but also multicolor selective labeling.

Activatable fluorescent probes for in situ imaging of enzymes

As the main biomarkers of most diseases, enzymes play fundamental but extremely critical roles in biosystems. High-resolution studies of enzymes using activatable in situ fluorescence imaging may help to better elucidate their dynamics in living systems. Currently, most activatable probes can realize changeable imaging of enzymes but inevitably tend to diffuse away from the original active site of the enzyme and even translocate out of cells, seriously impairing in situ high-resolution observation of the enzymes. In situ fluorescence imaging of enzymes can be realized by labelling probes or antibodies with always-on signals that fail to enable activatable imaging of enzymes. Thus, fluorescent probes with both "activatable" and "in situ" properties will enable high-resolution studies of enzymes in living systems. In this tutorial review, we summarize the existing methods ranging from design strategies to bioimaging applications that could be used to develop activatable fluorescent probes for in situ imaging of enzymes. It is expected that this tutorial review will promote the new methods generated to design such probes for better deciphering enzymes in complex biosystems and further extend the application of these methods to other fields of enzymes.

Genetically Encoded Activators of Small Molecules for Imaging and Drug Delivery

Chemical biologists have developed many tools based on genetically encoded macromolecules and small, synthetic compounds. The two different approaches are extremely useful, but they have inherent limitations. In this Minireview, we highlight examples of strategies that combine both concepts to tackle challenging problems in chemical biology. We discuss applications in imaging, with a focus on super-resolved techniques, and in probe and drug delivery. We propose future directions in this field, hoping to inspire chemical biologists to develop new combinations of synthetic and genetically encoded probes.