Fig. 1.

Schematic diagrams showing three types of hybrid micro-/nanogel-based optical probes: (A) Type 1 where the antibody or specific targeting ligand acts as a chemical/biochemical signal receiver; (B) Type 2 where an optical moiety acts directly as the chemical/biochemical signal receiver; and (C) Type 3 where a responsive polymer gel network chain acts as the chemical/biochemical signal receiver, which will undergo a volume phase transition, change the physicochemical environment of the optical moieties, and convert the received signal into an optical signal.