Preparation Of Raspberry-like Particles And Their Antibacterial Properties

Due to the high price of silver based antibacterial agents,three kinds of low-cost cooper based antibacterial agents were prepared.The prepared particles have excellent antibacterial and hydrophobic properties.After introducing n-dodecylmercaptan?NDM?,the hydrophobic and antibacterial properties of particles had both been improved.?1?In this paper,raspberry-like polydopamine/copper nanoparticles?PDA-Cu NPs?were prepared.Polydopamine was used as the carrier to load copper nanoparticles.The micro structure and antibacterial properties of the nanoparticles were studied.The results showed that PDA-Cu NPs had good dispersion stability in water and the average diameter was around 500nm.The as-formed PDA-Cu NPs exhibited a well-developed nanostructure hierarchical roughness.The water contact angle was 102.2°,showing good hydrophobic properties.With increasing copper nitrate?Cu?NO₃?₂·3H₂O?,better antibacterial properties could be observed.When the mass ratio of Cu?NO₃?₂·3H₂O/PDA was fixed at 6,PDA-Cu NPs showed good antibacterial properties.The MIC and MBC values of PDA-Cu NPs-1/6 for E.coli were 48.7?g/mL and 195.0?g/mL and the MIC and MBC values for S.epidermidis were 39.0?g/mL and97.5?g/mL,respectively.The antibacterial performance against S.epidermidis was better than that of E.coli.?2?Melamine-catechol microspheres?MF-CA?were prepared by using low-cost catechol and melamine as raw materials.The as prepared MF-CA was used as the carrier to load copper nanoparticles.The chemical structure,microstructure and antibacterial properties of the composite particles were studied.The results showed that if further increasing the molar ratio of formaldehyde and melamine,the microspheres would show better morphology.Under this condition,the surface of the prepared MF-CA microspheres was smooth and the dispersion was relatively good.The average size of the particles was about 3?m.The particle size of copper nanoparticles increased with the temperature.With increasing copper nitrate?Cu?NO₃?₂·3H₂O?,better antibacterial properties could be observed.MF-CA-Cu NPs-1/4 had good antibacterial properties,which can kill both bacteria completely within 30 min.The MIC and MBC values of MF-CA-Cu NPs-1/4 for E.coli were 193.8?g/mL and 387.5?g/mL and the MIC and MBC values for S.epidermidis were 48.4?g/mL and 193.8?g/mL,respectively.?3?The above two raspberry-like antibacterial particles were further modified with n-dodecylmercaptan?NDM?.Two different hydrophobic antibacterial particles?PDA-Cu NPs-NDM,MF-CA-Cu NPs-NDM?were prepared.The chemical structure,microstructure and hydrophobic properties of the two particles were studied.The results showed that the NDM modified particles had good hydrophobicity.The water contact angle could reach up to 128.8°.After coating with n-dodecylmercaptan,the CFU values of PDA-NDM decreased significantly.And the clear decrease in the number of live bacteria found on the PDA-Cu NPs surface indicated a higher bactericidal efficiency of copper nanoparticles.Compared with PDA-NDM or PDA-Cu NPs,the PDA-Cu NPs-NDM with multiple antibacterial properties showed better antibacterial efficiency,indicating the synergetic antibacterial activity of copper nanoparticles and n-dodecylmercaptan.For MF-CA-Cu NPs,the CFU values for both bacteria were greatly reduced.The n-dodecylmercaptan modified particles had excellent hydrophobicity.The water contact angle increasing from 46.9°to 142.1°.The sterilization rate of MF-CA-Cu NPs-NDM was about 99.9%,showing the synergistic antibacterial activity of n-dodecylmercaptan and copper nanoparticles.