Properties Of Traditional Composite Textiles Loaded With Photodynamic Antibacterial Agents

In recent years,increased attention has been paid to the development and application of surface self-cleaning functional materials which are economical,safe,durable and effective against bacteria.Especially in the medical textile industry,the choice of antibacterial materials can effectively lower the risk of direct or indirect transmission and infection among the hospital environment,patients and medical workers.At present,problems such as the inefficiency against drug resistant strains,certain toxicity against environment,high costs and lack of scalability are still the main obstacles of antimicrobial application research,therefore,the development of photodynamic antimicrobial functional materials which are nonspecific,robust,and cost-effective?scalable?have become the focus in the field.However,current research on photodynamic antimicrobial materials mostly focus on new types of polymer-based material systems,the practical studies of photosensitizer on the traditional textile are relatively restricted,in the meanwhile,the majority of them prepare textiles with single colors due to the use of photosensitizer alone,which limits the promotion of practical production application.Basing on the principle of photodynamic inactivation,the functional textile with photodynamic antibacterial effect was obtained by loading photosensitizer on the two-component traditional textile while its color was diversified by adding common dyes.Firstly,effective photodynamic fabrics were prepared by using cationic dyeable polyester fabric(T^?+?)and polyester/cotton interwoven fabric(T^?+?/C with the content ratio of 1:1)as substrate and methylene blue?MB?as photosensitizer.Dye-uptake and apparent K/S values as a function of MB concentration?%o.w.f?were determined,and were found to correlate.Photooxidation studies employing the model substrate 1,5-dihydroxynaphthalene?1,5-DHN?revealed that the MB-polyester fabrics were able to generate singlet oxygen in an illumination time-dependent manner.As the best result in the evaluation of the antibacterial effect against Staphylococcus aureus ATCC-29213,the antibacterial reduction caused by MB-T^?+?with the initial concentration of MB as 3%reached 99.89%after 30 min of illumination at 65 mW/cm².The striped polyester/cotton interwoven fabric was then designed,in which the cationic dyeable polyester yarn and cotton yarn were loaded with 3%MB and 1%direct dyes respectively,the substrate oxidation experiment results showed that the resulted fabric has the ability to produce singlet oxygen for photooxidation.However,considering that the diffusion range of singlet oxygen is very limited?<250 nm?,it is difficult to eliminate the bacteria on the cotton yarns that are without photosensitizer loading,which directly limits the photodynamic antibacterial efficiency of the fabric.Secondly,effective photodynamic fabrics were prepared using polyester/cotton blended fabric?T/C,40/60?as the substrate and thionin acetate?TA?as the photosensitizer.According to K/S and CIELab test,the color depths of fabrics increase with the rise of initial dye concentration of TA.The inactivation rate?%?of bacteria grew along the increase of photosensitizer TA in a certain concentration range?added concentration<0.5 mmol/g fabric?,beyond this range,the increase of photosensitizer will inhibit the photodynamic antibacterial effect of the fabric.Among them,under the illumination of 30 min,80 mW/cm²,3%TA loaded T/C caused inactivation of gram positive Methicillin-resistant Staphylococcus aureus ATCC-44 to 99.9998%,however,the photodynamic inactivation rate against gram negative strains as Multi-drug resistant Acinetobacter baumannii ATCC-1605 and Klebsiella pneumoniae ATCC-2146 were 94.1%and 45.3%,respectively.In addition,the results showed that the illumination conditions had a significant effect on the antibacterial?against Methicillin-resistant Staphylococcus aureus ATCC-44?results,which were significantly improved while the illumination time increased within 30 min,little changes were observed after 30 min.However,the antibacterial efficiency was 99.93%and 99.9998%when the light intensities were?60 mW/cm² and?70 mW/cm²,respectively?with an illumination time of 30min?,indicating that small differences in light intensity around the critical region?60-70mW/cm²?may lead to significant differences in the antibacterial results.Finally,photodynamic antibacterial fabrics were prepared with wool/acrylic blended fabric?W/A,32/2?as substrate and rose bengal?RB?as photosensitizer,where RB was loaded on wool fibers and acrylic fibers were dyed with common cationic dyes of different concentrations,colors and types.The resultant photodynamic materials were characterized by physical?SEM,DSC,TGA,tensile strength?,spectroscopic?fluorescence?,colorimetric?K/S and CIELab values?,and color fastness?against rubbing,washing?and photodynamic?photooxidation of the substrate potassium iodide,photoinactivation against different spices?studies.After illumination of 60 min,the bacterial inactivation of RB-W/A against gram positive Staphylococcus aureus ATCC-6538 and Bacillus subtilis CMCC?B?63501 were99.98%and 99.993%,respectively.The results showed that the dyeing sequence between photosensitizer RB and traditional cationic dyes had minor effect on the photodynamic oxidative and antibacterial activities of the fabric,but cationic dyes with different concentrations inhibited the antibacterial efficiency of photosensitizer RB to different degrees,where the W/A added with 1%o.w.f cationic yellow achieved an inactivation of 99.3%against Staphylococcus aureus.It indicates that the preparation of two-component photodynamic antibacterial materials is independent from the dyeing sequence,while the introduction of traditional dyes will exhibit certain limitation to the activity of photosensitizers.The results of this study confirmed the feasibility of preparing photosensitizer loaded blended fabrics through a low cost and scalable method used in this paper as well as achieving the adjustment of their apparent colors by adding common dyes,which revealed the potential of these photodynamic materials in further developments and applications.