Biomimetic Recognition-Based Bioorthogonal Host-Guest Pairs for Cell Targeting and Tissue Imaging in Living Animals

Bioconjugation methods offer very important tools in studying biological systems.Synthetic host-guest pairs provide an alternative and complementary conjugation method to bioorthogonal reactions and biological association pairs.Nevertheless,macrocyclic hosts that can be used for in situ capture are limited and often rely on extremely high binding affinities.Herein,we report an alternative bioorthogonal host-guest pair that relies on highly selective molecular recognition in water.The host,namely amide naphthotube,possesses a biomimetic cavity with inward-directing hydrogen bonding sites and shows selective and strong binding to the guest(2-phenyl pyrimidine)even in biological media.Through anchoring the tetraphenyl ethylene-modi fied hosts to cell surfaces,the bioorthogonal host-guest pair can be applied in cell surface recognition,cell-cell interactions,and tissue imaging in mice.The bioorthogonality is originated from the high binding selectivity of the biomimetic macrocyclic host,which is different from other known host-guest pairs that have been applied in biological systems.This research provides a new noncovalent bioconjugation tool and a new concept for designing bioorthogonal host-guest pairs for biological applications.

Donor strategy for promoting nonradiative decay to achieve an efficient photothermal therapy for treating cancer

Photothermal therapy(PTT)is emerging as an effective treatment for superficial carcinoma.A key challenge to the effectiveness of PTT is to develop photosensitizers with high photothermal conversion efficiency.Aiming to address this challenge,we develop a series of multi-arylpyrrole derivatives with different donors that contain different multi-rotor structures to explore highly efficient PTT photosensitizers.Among these multi-arylpyrrole derivatives,MAP4-FE nanoparticles with a small size of their donor groups and better-donating ability exhibit a high photothermal conversion efficiency(up to 72%)when they are encapsulated by an amphiphilic polymer.As a result,the MAP4-FE nanoparticles have shown satisfactory PTTeffects on in vivo tumor eradication under the guidance of photoacoustic signals.The findings of this study provide significant insights for the development of high-efficiency PTT photosensitizers for cancer treatment by making full use of the nonradiative decay of small size donors as rotors.