RESUMEN
The conformation of complementary determining region (CDR) is crucial in dictating its specificity and affinity for binding with an antigen, making it a focal point in artificial antibody engineering. Although desirable, programmable scaffolds that can regulate the conformation of individual CDRs with nanometer precision are still lacking. Here, we devise a strategy to program the CDR conformation by anchoring both ends of a free CDR loop to specific sites of a DNA framework structure. This method allows us to define the span of a single CDR loop with an â¼2 nm resolution. Using this approach, we create a series of DNA framework based artificial antibodies (DNFbodies) with varied CDR loop spans, leading to different antibody-antigen binding affinities. We find that an optimized single CDR loop (â¼2.3 nm span) exhibits â¼3-fold improved affinity relative to natural antibodies, confirming the critical role of the CDR conformation. This study may inspire the rational design of artificial antibodies.
RESUMEN
A new strategy is developed herein to improve the solid fluorescence of thiazolothiazole viologen by using the ZnCl42- cluster as a scaffold to hinder π-stacking. Importantly, the Cl···H bonds are formed in the solid state to sustain the framework and can be automatically dissociated when dissolved in H2O, thus having no impact on the strong emission in aqueous solution. As such, the first case of organic-inorganic viologen-zinc halide named 4PV·ZnCl4 was designed and synthesized, and a significant increase in photoluminescence quantum yield (ΦF) is realized from 4PV·2Br (ΦF = 0%) to 4PV·ZnCl4 (ΦF = 27.0%) in solid and from 97% to 98% in H2O. 4PV·ZnCl4 also displays pH stimuli-responsive naked-eye chromic behavior and photoluminescence with different coloring states and intensities. The multifunctional performance of 4PV·ZnCl4 provides a prerequisite for carrying different information, expanding their promising application in multilevel information encryption.