Scheme 1. a) Synthesis of sp 2 -TPE-COF by Knoevenagel Condensation between ETBA and PDAN and following exfoliation treatment. b) The diagram of titration experiment for copper ion detection. c) Electron transfer process during copper ion sensing with sp 2 -TPE-COF NSs.

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Bacterial infections still cause many health problems for human beings. Silica aerogels with a three-dimensional (3D) porous structure and a large surficial area are promising candidates for drug delivery, but they have rarely been investigated for antibacterial agent delivery. Herein, we study mesoporous silica aerogels as carriers for delivery of three slightly soluble antibacterial agents including cinnamaldehyde (CA, liquid), salicylic acid (SAA, solid), and sorbic acid (SOA, solid) under supercritical fluid carbon dioxide. Notably, all three antibacterial agents form uniform nanocrystals in the mesopores of silica aerogels and the loading efficiency reaches 56 wt %, which assists in overcoming the obstacles of low bioavailability of slightly soluble antibacterial agents. Benefiting from nanocrystallized antibacterial agents, the agent-loaded aerogels exhibit an inhibition rate of 99.99% against Escherichia coli during the initial release; notably, they still have a 95% inhibition rate even after ∼90% of CA is released. Importantly, the agent-loaded silica aerogels demonstrate good biocompatibility in vitro. This work indicates that mesoporous silica aerogels are a promising platform for antibacterial agent delivery.

Mitochondria and nucleus targeted photodynamic therapy (PDT) to locally destruct organelles which play vital roles in physiologic processes holds great promise for PDT. Notably, the emerging polymeric photosensitizers with multiple...