Synthesis Of Silver Nanoparticle-supported Mesoporous Silica Material With Radial Wrinkle-structure And Its Antibacterial Performance

Ag nanoparticles(Ag NPs) possesses diverse advantageous such as good adsorbability, high surface energy and strong activity, and is wildly utilized as antibacterial agent in the past decades. However, nano-scale Ag NP,in the form of colloids, often encounter practical problems(poor dispersion, quick release, inferior storage stability), which strictly limited their application. Considering the above-mentioned situation, attaching Ag NP to inorganic material with excellent stability may successfully solved the problem. Mesoporous silica materials, which have merits such as large specific surface area, large pore volume, good biocompatibility, high chemical stability and easy surface modification, have been used in various applications. Herein we attempt to load Ag NPs onto the inside and outside surface of mesoporous silica with typical radial wrinkle structure(RMSs). This novel silica nanoparticle with radial pores is supposed to possess additional advantages such as carrying capacity, modificability and accessibility than the traditional MCMs or SBAs only with uniform mesopores. First, center-radial open pores have more accessibility for various sized molecules to enter into the internal surface of the particles, which is in favor of the loading and the high dispersion stability of Ag NPs. Meanwhile, spherical Si O2 shell will protect Ag NPs embedded in pores from deterioration, and reduce their consumption rate, which can extend its life. Finally, the synergistic combination of multiple-scale pores will harmonize the diffusion of guest molecules with different sizes through the porous matrices.Using sulfhydryl, amine and carboxyl groups-modified RMSs as carrier, Ag-supported RMSs were obtained through in-situ reduction of silver atoms adsorbed by three mentioned functional groups. The antibacterial capacity was then investigated in detail. The current work contains the following three parts:(1) Synthesis and characterization of mesoporous silica material with radial wrinkle-structure. In alkaline environment, RMSs were prepared through sol-gel method at room temperature by using cetyltrimethylammonium(CTAB) as template, tetraethoxysilane(TEOS) and(3-Mercaptopropyl)trimethoxysilane(MPS) as silica source, diethyl ether as solubilizer. Series of RMSs with different morphology and sizes were obtained by changing the concentration of MPS. When volume ratio of MPS to TEOS was 0.08, sample has better morphology regularity with uniform sizes of about 100 nm and high surface area of 696.59 m2/g;(2) Synthesis and characterization of silver-supported RMSs modified with sulfhydryl groups. After sulphonation reaction of the obtained RMSs, Ag atoms were dispersedly locked up on its inside and outside surface by electrostatic adsorption and then reduced through in-situ reduction method. Then the silver-supported RMSs were obtained. It turns out that Ag NPs carried on RMSs have dense distribution without agglomeration, small particle size of only 3-5 nm and outstanding antibacterial performance to either Escherichia coli(E.coli) or Staphylococcus aureus(S.aureus) with minimal inhibitory concentration(MIC) of 36.55 mg/L and 73.10 mg/L and minimal bactericidal concentration(MBC) of 48.55 mg/L and 48.55 mg/L respectively.(3) Synthesis and characterization of silver-supported RMSs modified with amine and carboxyl groups. Similarly, the silver-supported RMS-NH2 and RMS-COOH were prepared using adsorption and in-situ reduction method above. Test results indicate that Ag NPs in Ag NP@Si O2-NH2 have smaller size(7-10 nm) than in Ag NP@Si O2-COOH(20-30 nm), and have much better antibacterial ability against with either E.coli or S.aureus for its dense distribution and smaller particle size.