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The synthesis of dendritic hydrogels and inorganic nanoparticles and their application as antibacterial and imaging materials

Time: Tue 2021-06-15 10.00

Location:, (English)

Subject area: Fibre and Polymer Science

Doctoral student: Yanmiao Fan , Kemi, Ytbehandlingsteknik

Opponent: Professor Mauri Kostiainen, Aalto University

Supervisor: Professor Michael Malkoch, Fiber- och polymerteknologi, Polymerteknologi, Ytbehandlingsteknik; Professor Annelie Brauner, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet & Division of Clinical Microbiology, Karolinska University Hospital

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The overuse and misuse of conventional antibiotics has caused increased prevalence of drug-resistant bacteria, the infections of which cause high mortality and economic losses per year. It is therefore crucial to develop new technologies and treatments for infections caused by drug-resistant bacteria. Dendritic polymer-based hydrogels and nanomaterials have shown promise as alternatives to traditional small-molecule antibiotics.

Third generation (G3) allyl-functional hyperbranched dendritic-linear-dendritic copolymers (HBDLDs) based on polyethylene glycol (PEG) and 2,2-bis(hydroxymethyl) propionic acid (bis-MPA) were synthesized, and used to form hydrogels with a dithiol-functional PEG crosslinker using thiol-ene coupling (TEC). The hydrogels were used to co-deliver both hydrophilic and hydrophobic antibiotics with the aid of dendritic nanogels (DNGs). Antibacterial hydrogel band aids were also fabricated in a facile procedure.

Amino-functional HBDLDs based on PEG and bis-MPA were synthesized, and together with a di-N-hydroxysuccinimide-functional PEG as the crosslinker, amino-functional hydrogels with inherent antibacterial properties were fabricated. The cationic hydrogels are highly effective towards a wide range of wound-isolated bacteria, and can reduce inflammation and oxidative stress.

To minimize the cytotoxicity of amino-functional dendrimers, self-assembled hydrogels based on cationic dendrimers and cellulose nanofibrils were fabricated. Cationic dendrimers and their fragments can be released from the hydrogels to kill bacteria whilst showing insignificant cytotoxicity with human cells.

Bis-MPA dendrimers with both amino and allyl functionalities were also synthesized. Allyl groups can be used to form hydrogels with a dithiol-functional PEG crosslinker via TEC, and the amino groups provide the hydrogels with antibacterial properties.

Fluorescent silicon nanoparticles (SiNPs) were synthesized and their interaction with bacteria was investigated. SiNPs exhibited strong binding to Staphylococcus aureus (S. aureus), showing promise as a potential capturing and imaging agent for S. aureus.