PH Responsive Polyrotaxane Hydrogel And Antibacterial Properties

Hydrogel is an ideal biological scaffold material,which can be loaded with drugs or biological macromolecules for tissue engineering repair or regeneration.However,the reported hydrogels usually do not combine the high drug activity,good thixotropic property,on-demand release of drugs and good biocompatibility,which have limited their application in the fields of tissue engineering and regenerative medicine to a certain extent.Therefore,the development of biocompatible hydrogels with releasing drugs on demand are highly needed.In this article,based on?-cyclodextrin??-CD?and polyethylene glycol?PEG?polypseudorotaxane supramolecular hydrogel,a novel supramolecular hydrogel that releases drugs on demand and has sol-gel reversible supramolecular hydrogels are mainly investigated.Based on the microenvironment generated by bacterial proliferation and metabolism,a new type of quaternary ammonium salt antibacterial hydrogel capable of real-time dectection of bacteria and release on demand is designed.A simple one-pot quaternization reaction was performed by?-CD,N,N-diethylethylenediamine?DEEDA?and tetraphenylethylene benzyl bromide?TPE-CH₂Br?to prepare a p H-responsive and antibacterial?-CD derivative??-CD-TPE?,which uses the intrinsic fluorescence of the TPE part and the antibacterial function of the quaternary ammonium unit can effectively integrate the function of“monitoring and killing bacteria”.This derivative was then added to the?-CD/PEG polypseudorotaxane supramolecular hydrogel to construct a new type of quaternary ammonium antimicrobial hydrogel capable of detecting bacteria in real time and releasing it on demand.The experimental results prove that the cumulative drug release amount under normal physiological conditions is less than the cumulative drug release amount under the conditions of simulated bacterial proliferation and metabolism microenvironment?p H 6.5?in the same time.In vitro antibacterial experiments proved that the gel kills and images Gram-positive bacteria?S.aureus?and Gram-negative bacteria?E.coli?,and has better antibacterial effect on Gram-positive bacteria.Cell experiment results show that the supramolecular hydrogel has good biocompatibility.The reversible sol-gel transition of the polypseudorotaxane?PPR?hydrogels is achieved through adding a CO₂-switchable guest molecule into the PPR hydrogel of poly?ethylene glycol??PEG?and?-cyclodextrins??-CDs?.Alternating treatments with CO₂ and heating drive such reversible transition due to the competitive complexation as evidenced by 2D NOESY ¹H NMR and isothermal titration calorimetry as well as X-ray diffraction.In addition,in vitro cell experiment results show that the stimulus responsive hydrogel has good biocompatibility.The present work describes a straightforward way to obtain switchable PPR hydrogels triggered by a compatible stimulus of CO₂.These stimuli-responsive PPR hydrogels have potential applications as biomaterials.