Injectable
and sprayable hydrogels have attracted considerable attention for
application in the biomedical field owing to their high moldability
and efficiency in encapsulating therapeutics and cells. Herein, we
report the spontaneous assembly of injectable and sprayable hydrogels
via a one-step mixing of solutions of tannic acid (TA) and O-carboxymethyl chitosan (CMCS) without an external stimulus.
The presence of 1,4-benzenediboronic acid (BDBA) improves the mechanical
properties and reduces the gelation time of the resulting hydrogels.
The hydrogels assemble via hydrogen bonds between TA and CMCS as well
as via dynamic boronate ester bonds between TA and BDBA, as confirmed
by Fourier transform infrared spectroscopy. Balancing the interactions
between the three components (CMCS/TA/BDBA) is essential for the construction
of the hydrogels. The moduli of the CMCS–TA–BDBA hydrogels
initially increase as the amount of BDBA increases and decrease after
reaching a maximum value at a BDBA-to-TA molar ratio of 3:1. The CMCS–TA–BDBA
hydrogels with interconnected porous morphologies display rapid gelation
(∼10 s), biocompatibility, self-healing, injectable, and sprayable
abilities. In addition, the hydrogels can be used for hemostasis.
The extent of bleeding in mouse livers treated with the hydrogels
could be reduced extensively from 240 (nontreated mouse livers) to
55 mg (77% reduction). The reported hydrogels coupled with the combination
of functionality and biological activity make them promising hemostatic
materials for biomedical applications.