Research Highlights
The hollow nano silica (HSN) modified by γ - glycidyl ether oxypropyl trimethoxysilane (KH560) was synthesized in one step by fine emulsion method. The surface epoxy hollow nano silica (epoxy HSN) was grafted onto the surface of HSN by the ring opening reaction of amino group and epoxy group, and the antibacterial agent hsn-phmg was prepared Bacteria have excellent performance and good water dispersibility.
Research background
Infection control is of great significance in various fields. Therefore, antibacterial materials which can effectively inhibit the growth of microorganisms and have low cytotoxicity have attracted extensive research interest. Phmg is a highly effective and broad-spectrum antibacterial agent with good biocompatibility and moderate cost, which has great potential in the preparation of antibacterial materials. However, phmg is water-soluble and difficult to recover, resulting in secondary pollution. Hollow nanoscale silica (HSN), as a new functional material, is also a good carrier of antimicrobial agents. The one-step synthesis of HSN by miniemulsion has the advantages of simple operation, low cost, high yield, easy modification and large amount of synthesis.
Content details
Using TEOS, KH560, methyl silicone oil and CTAB as the main raw materials, Epoxy-HSN was synthesized by miniemulsion method, and then PHMG was grafted onto the surface to produce HSN-PHMG. The composition diagram is shown in Figure 1.
Figure 1 composition diagram of hsn-phmg
Phmg grafting can improve the water dispersion of HSN. Figure 2 shows the water dispersion comparison between epoxy-hsn and hsn-phmg. Phmg on the surface of hsn-phmg ionizes a large number of cations in water, resulting in electrostatic repulsion force between hsn-phmg particles, thus avoiding the agglomeration and sedimentation of hsn-phmg.
Fig. 2 pictures of epoxy-hsn (a) and hsn-phmg (b) dispersion solution standing for 4 days after ultrasonic dispersion and standing for 12 hours after redispersion (concentration of 0.5 mg / ml)
The structure, morphology and content of epoxy HSN and hsn-phmg were studied by means of infrared, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetry. The infrared spectra of phmg and hsn-phmg show the stretching vibration peak of C = n in guanidine group at 1650 cm-1, which indicates the successful synthesis of phmg and hsn-phmg; the C 1s spectrum in XPS spectrum of epoxy-hsn (Fig. 3b) shows the peak of C-O-C in epoxy group, and the C in XPS spectrum of hsn-phmg The peak of C-O-C in the epoxide group disappeared in the 1s spectrum, and the peaks of C = n and C-N in guanidine group appeared, indicating the ring opening reaction between epoxy group and amino group. TEM results showed that both epoxy-hsn and hsn-phmg had good hollow structure, and their morphology was basically the same, indicating that the grafting of phmg had no effect on the shape of HSN. The mass fraction of phmg in hsn-phmg was about 9.5% by heat loss re estimation.
Fig. 3 infrared spectra of phmg, HSN, epoxy HSN and hsn-phmg (a); C 1s spectra of XPS spectra of epoxy HSN (b) and hsn-phmg (c); TEM spectra of epoxy HSN (d) and hsn-phmg (E); thermogravimetric curves of epoxy HSN and hsn-phmg (f)
The antimicrobial activity of hsn-phmg was characterized by mic and biocidal kinetic experiments. The results showed that the MIC of hsn-phmg to E. coil and S. aureus was 32mg / L, and HSN and phmg had synergistic antibacterial effect; the kinetic experiment of biological killing showed that when the concentration of hsn-phmg was twice of MIC, E.coli was all killed after 2H; if the concentration was 4 times of MIC, the time was reduced to 1H (Fig. 4).
Fig. 4 antibacterial kinetics experiment of different concentration of hsn-phmg on E.coli (a); bacterial colony diagram of different concentration of hsn-phmg in different time contacting with E.coli suspension (b)
Conclusion
The Epoxy-HSN was synthesized by miniemulsion, and the antibacterial agent HSN-PHMG was prepared by grafting with PHMG. Hsn-phmg showed good water dispersion, TEM characterized the hollow structure of epoxy-hsn, phmg grafting had no effect on its morphology; FTIR and XPS characterized the successful grafting of phmg; the mass fraction of phmg in hsn-phmg was estimated to be about 9.5% based on TGA; antibacterial experiment showed that the MIC of hsn-phmg to E. coil and s. aureus was 32 mg / L, and the water dispersion of hsn-phmg of 64 mg / l could be used in 2 Kill E. coil completely within H. As a new antibacterial agent, hsn-phmg has the advantages of strong antibacterial activity, low preparation cost, simple preparation and so on. It has a broad application prospect in the fields of health care, environmental engineering and so on.
From:
Study on Preparation of new antibacterial agent by functionalized hollow nano silica with polyhexamethylene guanidine hydrochloride
Zhang Ziwen, Zhang Kangmin, Yang Jianjun, Wu Qingyun, Wu Mingyuan, Zhang Jian'an, Liu Jiuyi
Materials engineering, 2020, 48 (3): 40-46
DOI: 10.11868/j.issn.1001-4381.2019.000015
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