Functional Modification Of Textiles Based On Photothermal Performance Of Melanin-like Nanoparticles

Recently,photothermal textiles are widely used in the fields of photothermal therapy,photothermal sterilization and photothermal health care.Synthetic melanin（melanin-like）nanoparticles（SMNPs）have similar structures and properties to natural melanin nanoparticles（MNPs）,and their photothermal,UV-protection,adhesion and biocompatibility properties are extremely outstanding.Moreover,due to the chemical disorder of SMNPs,other compounds can be added during their synthesis to modulate the photothermal properties of SMNPs or add other functions.In this thesis,levodopa（L-DA）was used as the precursor of SMNPs with metal ions or thionin（Th）to form metal ion or thiocorrin-doped SMNPs by one-pot autoxidation polymerization,and these SMNPs were used to prepare photothermal textiles.The main research contents and results are as follows:（1）Rapid photothermal sterilization of cotton fabrics loaded with Ag NPs@Fe³⁺-SMNPsIn this part,Fe³⁺complexed SMNPs(Fe³⁺-SMNPs)were synthesized by adding Fe³⁺during the autoxidation of L-DA,and Fe³⁺-SMNPs loaded with Ag NPs(Ag NPs@Fe³⁺-SMNPs)were prepared by in situ reducing growth of nanosilver on the surface of Fe³⁺-SMNPs using the reduction property of phenolic hydroxyl group.The morphology and sizes of Ag NPs@Fe³⁺-SMNPs were analyzed by SEM and DLS,which were spherical in shape and around 500 nm.The chemical structure was analyzed by UV-Vis,FTIR spectroscopy and XRD energy spectrum,and the results confirmed the successful synthesis of Ag NPs@Fe³⁺-SMNPs.The photothermal properties of the dispersions were also investigated under xenon lamp（700 m W/cm²）irradiation,and the results confirmed that the photothermal properties were superior to those of the pristine SMNPs.A rapid photothermal sterilization cotton fabric(Ag NPs@Fe³⁺-SMNPs@Cotton)was constructed by deposition method using Ag NPs@Fe³⁺-SMNPs.The surface morphology,chemical structure,photothermal,photothermal sterilization,antibacterial and wearing properties of the modified cotton fabrics were investigated.The results showed that the surface of the modified cotton fabric was rough with a number of Ag NPs@Fe³⁺-SMNPs attached,and its surface temperature was around 109℃under xenon lamp irradiation and around 60℃under sunlight irradiation.The survival rates of E.coli and S.aureus on their surfaces were below 0.4%at 10 min under xenon lamp irradiation,and below 0.7%when the bacteria were in contact with the modified cotton fabric for 6 h without xenon lamp irradiation.After 20 times of washing and100 times of rubbing,the modified cotton fabric maintained excellent photothermal and sterilization properties with good fastness.（2）Anti-UV,photothermal and antibacterial cotton fabrics loaded with Ag-SMNPsIn this part,Ag-SMNPs was synthesized by adding Ag⁺during the autoxidation of L-DA,which contained both Ag NPs and complexed Ag⁺.The morphology and size of Ag-SMNPs were analyzed by SEM and DLS,and the results showed that Ag-SMNPs were spherical in shape and their particle size was around 500 nm.The chemical structures of Ag-SMNPs were analyzed by UV-Vis,FTIR,XPS and XRD,and the results confirmed the presence of both singlet Ag and complexed Ag⁺in Ag-SMNPs.The photothermal performance of Ag-SMNPs was also superior to that of SMNPs under xenon lamp irradiation.A multifunctional cotton fabric（Ag-SMNPs@Cotton）with UV protection,photothermal and antibacterial properties was constructed by deposition method using Ag-SMNPs.The surface morphology,chemical structure,UV protection,photothermal,photothermal sterilization,antibacterial and wear properties of the modified cotton fabrics were investigated.The results showed that the surface of the modified cotton fabric was rough with several Ag-SMNPs attached.The UPF value(UPF_AV)of the modified cotton fabric was 114.92,and its UVB and UVA transmittance(T（UVB）_AV and T（UVA）_AV)were less than 1.3.The surface temperatures of the modified cotton fabric were 113.8℃and 58.3℃under xenon lamp and sunlight irradiation,respectively.The survival rate of E.coli and S.aureus on the surface of the modified cotton fabric was below 6%when irradiated with xenon lamp for 10 min,and the survival rate of bacteria was below 3.4%when contacted with the modified cotton fabric for 6 h without xenon lamp.After20 washes,the properties of the modified cotton fabric did not decrease significantly and had good fastness.（3）Rapid photothermal/photodynamic sterilization of cotton fabrics loaded with Th-SMNPsIn this section,Th-SMNPs-1,2,3（1,2 and 3 represent the Th/L-DA molar ratios of 1:10,1:7and 1:5,respectively）were prepared by adding different masses of Th during the autoxidation of L-DA.The morphology and dimensions of Th-SMNPs-1,2,and 3 were analyzed by SEM and DLS,and the results showed that they were all spherical in shape,and the higher the Th content,the larger the particle size,with the particle size of Th-SMNPs-3 being around 300 nm.The chemical structures of Th-SMNPs-1,2,3 was analyzed by XPS,and the results confirmed the Michael addition and Schiff base reactions of Th with SMNPs.The molecular weight of the crude reaction solution of Th-SMNPs-3 was analyzed with the possible molecular structure of Th-SMNPs-3 using MALDI–TOF spectrometry.The photothermal properties of Th-SMNPs-1,2 and3 were tested under 808 nm laser（2.0 W/cm²）irradiation,among which Th-SMNPs-3 showed the strongest photothermal properties.And the molar extinction coefficientε808 value of Th-SMNPs-3 was calculated to be 4.7×109 M^-1 cm^-1,and its total photothermal efficiency（η*）value was 34.49%,which was 60%higher than that of SMNPs.The mechanism of the photothermal enhancement of Th-SMNPs-1,2,3 was analyzed by DFT theoretical calculations and EPR spectroscopy.Th formed a D-A structure with L-DA oxidation monomer,and the LUMO-HOMO energy band gap within the molecule of Th-SMNPs-1,2,3 was reduced,which promoted the light absorption and conversion.The doping of Th increased the content of semiquinone radicals and suppressed the non-thermal radiative leap.Rapid photothermal/photodynamic sterilization of cotton fabric（Th-SMNPs-1,2,3@Cotton）were constructed by deposition method using Th-SMNPs-1,2,3.The surface morphology,chemical structure,photothermal,monoclinic oxygen（¹O₂）generation,photothermal/photo-dynamic sterilization,and the wearing properties of the modified cotton fabrics were investigated.The results showed that the surface of the modified cotton fabric was rough and the higher the Th content,the rougher the modified cotton fabric was.The photothermal properties of the modified cotton fabrics were tested under 808 nm laser（0.05-0.5 W/cm²）irradiation,and the results showed that the Th-SMNPs-3@Cotton had the strongest photothermal properties up to100℃.The ability of Th-SMNPs-3@Cotton to generate ¹O₂ was the strongest under 660 nm laser（0.05 W/cm²）irradiation.The survival rate of E.coli and S.aureus on the surface of Th-SMNPs-3@Cotton was around 10%under both 808 nm（0.1 W/cm²）and 660 nm dual laser irradiation.Moreover,Th-SMNPs-3@Cotton could be used as a wound healing dressing.