Polydopamine Photothermal Hydrogels:Preparation And Its Application In Tumor Therapy

Physically/chemically crosslinked hydrogels feature three-dimensional networks with abundant water,becoming good candidates for a variety of bioapplications.Thanks to its good biocompatibility and excellent photothermal responsivity,polydopamine(PDA)has been extensively studied for the treatment of malignant tumors.In this thesis,PDA-based hydrogels were studied in terms of its mechanical strength,adhesion,and photothermal properties,etc.Furthermore,PDA-based hydrogels were shown to prevent tumor recurrence.In Chapter 2,hydrogels were synthesized by using acrylamide(AAm)and N-(3-aminopropyl)methacrylamide(APMA)as comonomers,and PDA nanoparticles(PDA NPs)as chemical crosslinkers.The concentration of APMA and PDA NPs significantly affected the mechanical properties and adhesion of the p(AAm-co-APMA)/PDA(or PAAD)hydrogels.It was found that the PAAD hydrogel achieved a maximum extension of 3400%and an excellent adhesive strength to pigskin(76.2 kPa ± 32.9 kPa).Both characters were much better than other previous reports.In addition,PDA NPs rendered PAAD hydrogels with good photothermal responsivity.The temperature of PAAD hydrogels increased by 30? when exposed to near-infrared(NIR)within 10 minutes.Such photothermal responsivity can be easily modulated multiple cycles.In Chapter 3,after careful evaluation of in vitro cytotoxicity,the PAAD hydrogels were used to treat 4T1 tumor-bearing mice.When the primary tumors were resected,the PAAD hydrogel patch well matched the irregular shapes of surgical wounds(due to its good stretchability and adhesive property),and kill the residual tumors under NIR irradiation for a short time(due to photothermal responsivity).In the end,the multifunctional hydrogel patch was peeled off,followed by a suture of the wound.The synergistic surgery-photothermal therapy enabled us to effectively kill solid tumors and prevent recurrence of cancer in mice(P<0.05),as evidenced by monitoring the recurrence of cancer,hematoxylin and eosin(H&E)and immunohistochemistry analysis of tumors,etc.In Chapter 4,hydrogels were synthesized by using N-isopropylacrylamide(NIPAm)and acrylic acid(AAc)as comonomers,and N,N'-bis(acryloyl)cystamine as chemical crosslinker.The concentration of AAc and PDA affected the mechanical properties of p(NIPAm-co-AAc)/PDA(or PNAD)hydrogels.In addition,PDA NPs rendered PNAD hydrogels with good photothermal responsivity.PNAD hydrogels showed temperature responsivity.