Fabrication of silver nanoparticles doped in the zeolite framework and antibacterial activity

Figures & data

Table 1 Physical properties of silver nanoparticles (Ag NPs) in Ag/zeolite synthesized at different AgNO₃ concentrations: A1 0.5%, A2 1.0%, A3 1.5%, A4 2.0%, and A5 5.0%

Samples	Reaction volume (L)	λmaxa	Absorbanceb	Approximated efficiency (%)	Ag NPs particle sizec (nm)
A1	0.50	394	0.33	95.36 ± 1.21	2.10 ± 0.26
A2	1.00	401	0.54	92.88 ± 1.88	2.12 ± 0.37
A3	1.50	399	0.62	90.79 ± 2.76	2.44 ± 0.53
A4	2.00	395	0.76	87.48 ± 3.13	2.95 ± 0.65
A5	5.00	394	1.27	80.96 ± 6.56	3.11 ± 0.88

Notes:

a The experiments were repeated three times and were averaged to give the data in Table 1;

b The data were obtained by multiplying the absorbance of the corresponding diluted solutions by their dilution factors when diluted solutions were used for the data;

c The size of Ag NPs was determined by measuring diameters of about >100 nanoparticles in transmission electron microscopy image and by averaging them.

Table 2 Average inhibition zone and standard deviation for zeolite, AgNO₃/zeolite (A0,) and Ag/zeolite at different AgNO₃ concentrations: A2 1.0%, A4 2.0%, and A5 5.0%

Bacteria	Inhibition zone (mm)				Control negative (mm) zeolite (10 mg/ml)	Control positive (mm)
	A0	A2	A4	A5		CTX	C
E. coli	12.52 ± 0.14	7.87 ± 0.22	6.44 ± 0.08	7.40 ± 0.16	NA	21.80	16.71
S. dysentriae	9.03 ± 0.05	7.52 ± 0.18	6.48 ± 0.19	6.95 ± 0.32	NA	23.22	19.41
S. aureus	12.08 ± 0.30	7.40 ± 0.05	6.53 ± 0.47	6.13 ± 0.22	NA	23.60	16.43
MRSA	9.43 ± 0.19	8.16 ± 0.09	6.92 ± 0.14	7.04 ± 0.25	NA	18.89	15.48

Abbreviations: C, chloramphenicol; CTX, cefotaxime; E. coli, Escherichia coli; MRSA, methicillin-resistant Staphylococcus aureus; NA, not appearing; S. aureus, Staphylococcus aureus; S. dysentriae, Shigella dysentriae.

Figure 1 Schematic illustration of the synthesis of the silver nanoparticles into the zeolite framework by strong chemical reduction.

Figure 2 Photograph of AgNO₃/zeolite (A0) and Ag/zeolite nanocomposites at different AgNO₃ concentrations: A1 0.5%, A2 1.0%, A3 1.5%, A4 2.0%, and A5 5.0%.

Figure 3 Ulraviolet-visible absorption spectra of silver/zeolite nanocomposites for different AgNO₃ concentrations: A1 0.5%, A2 1.0%, A3 1.5%, A4 2.0%, A5 5%, and A0 AgNO₃/zeolite in the absence of NaBH₄.

Figure 4 Powder X-ray diffraction patterns of zeolite and silver/zeolite nanocomposites for determination of nanosilver crystals at different AgNO₃ concentrations (0.5, 1.0, 1.5, 2.0, and 5.0% [A1–A5]).

Figure 5 Transmission electron microscopy images of A) zeolite and B) zeolite after impregnation with aqueous AgNO₃ (AgNO₃/zeolite [A0]).

Figure 6 Transmission electron microscopy images and corresponding particle size distribution of silver/zeolite nanocomposites at different AgNO₃ concentrations (A2 1.0% [A, B], A4 2.0% [C, D], and A5 5.0% [E, F]).

Figure 7 Scanning electron microscopy micrographs and energy dispersive X-ray fluorescence spectrometer spectra, respectively, for the zeolite (A, B) and silver/zeolite nanocomposites (A2 1.0% [C, D], A4 2.0% [E, F], and A5 5.0% [G, H]).

Figure 8 Fourier transform infrared spectra of zeolite and silver/zeolite nanocomposites (A2 1.0%, A4 2.0%, and A5 5.0%).

Figure 9 Comparison of the inhibition zone test between Gram-negative and Gram-positive bacteria (ie, E. coli [A], S. dysentriae [B], S. aureus [C], and MRSA [D]) form zeolite, A0, A1, A2, and A5 (1–5), respectively.

Abbreviations: E. coli, Escherichia coli; MRSA, methicillin-resistant Staphylococcus aureus; S. dysentriae, Shigella dysentriae.