Structural Regulation And Performance Evaluation Of Ag/Zn-Based Antibacterial Agents

Inorganic nano antibacterial agents exhibit broad-spectrum,long-lasting and efficient antibacterial effect,and featuring high safety and biocompatibility,high temperature resistance,and no microbial resistance.Therefore,they have received numerous attentions in application and research as medical materials,food packaging materials,textile antibacterial finishing,antibacterial coatings and other fields.Ag⁺-loaded inorganic powder and nano-Zn O are most widely used commercial inorganic antibacterial agents so far.However,the controlled release of Ag⁺to achieve both durable and efficient antibacterial activity and ideal biosafety are still big challenges in fields such as dental materials,bone repair materials and biodegradable food packaging materials.Nano-Zn O has also been widely used in cosmetics,feed additives,textiles and so on due to its low cost non-toxicity,UV-shielding and odor-removing effects.Nevertheless,enhancing the antibacterial activity and washing resistance of Zn O still requires improvement for application as feed antibacterial additives and textile antibacterial finishing.To solve above-mentioned problems and further improving the performance of the Ag⁺-loaded type and nano-Zn O antibacterial agents,the research of following:（1）The silver-loaded hydroxyapatite（Ca?（PO?）?（OH）,HA）microspheres（Ag-HA）with controllable Ag⁺distribution were prepared,realizing the controllability of Ag⁺release behavior.Multiple functional amino and carboxylic groups on S.aureus surfaces provide numerous sites to chelate Ag⁺and Ca²⁺.The coordination chemistry of Ag⁺and Ca²⁺,inorganic precipitation reaction,precipitation transformation reaction and altering the addition sequence of Ag⁺and Ca²⁺were comprehensively utilized on the surface of S.aureus bacteria which serve as hard-templates.The prepared Ag-HA composite nanospheres feature uniform size,controllable spatial distribution of Ag.The formation,structure and release behavior of Ag⁺were systematically characterized and studied with X-ray powder diffractometer（XRD）,Scanning electron microscope（SEM）,Spectral scan（EDS-mapping）,Transmission electron microscope（TEM）,X-ray photoelectron spectroscopy（XPS）,Fourier transform infrared spectroscopy（FT-IR）,Zeta-potentiometer,atomic absorption spectroscopy（AAS）.The antibacterial activity of the samples was evaluated by microbiological several experimental techniques such as the zone of inhibition and minimum inhibitory concentration（MIC）tests.The results indicate that the Ag-HA hybrid,with uniform size,has exhibited customized spatial distribution and release of Ag⁺for antibacterial requirement.（2）A“two-step dip rolling”strategy was used to improve the application performance of nano-Zn O in the field of textile antibacterial finishing.Based on the traditional padding process,commercial water-based polyacrylic acid binder and nano-Zn O dispersion are used.The strong chemical bonding between Zn O and binder makes nano-Zn O anchored on the surface of fabric fibers by a two-step dip rolling method.SEM,EDS-Mapping,FT-IR,Gb test for water Resistance of Textiles（GB/T 20944.3-2008）,bacteriostatic zone method,bacteriostatic rate method and other technical means were used to track and evaluate the microstructure,chemical interaction and antibacterial property of the samples after antibacterial and washing tests.The agglomeration nano-Zn O in the binder is thus avoided,which are always a problem arisen from the traditional one-step dip rolling process and results in the non-ideal antibacterial activity.Plus,our product through the two-step dip rolling strategy exhibits much improved washing resistance.The results have shown that after 50 standard washings,our cotton fabrics（with Zn O）still have ideal antibacterial properties against Staphylococcus aureus and Escherichia coli.（3）Screening of powdery nano-Zn O with high antibacterial activity by tailoring the structure of Zn O nano-aggregates.As many as 12 Zn O nano-aggregates with different structures and morphologies were prepared by inorganic precipitation reaction.The aggregated structure and antibacterial properties of those sample particles were evaluated by XRD,SEM and inhibition zone test,and the structure-activity relationship was preliminarily discussed.By comparison,single crystal nanorod-shaped Zn O has the weakest antibacterial activity,while rod-shaped aggregates assembly by Zn O nanoparticle is better than other samples.The differences in antibacterial properties may be mainly attributed to the different crystal faces of the nano-aggregate particles.This paved the way for the further development of Zn O antibacterial materials with high antibacterial activity.