L. Liu et al. / Inorganica Chimica Acta 435 (2015) 66–72
67
coordinative activity and can be used as inorganic carriers for Ag
NPs. Compounds that can bridge inorganic and organic materials,
such as silver carried zirconium alkyl-N,N-dimethylenephospho-
nate (ZRDP) agents bound to various functional moieties, are
available.
samples were placed on round brass stubs and sputter coated with
gold and then scanned at an accelerating voltage of 20 kV.
2.2. Synthesis of Ag NPs
Based on above ideas, in this work we have designed and pre-
pared some novel zirconium phosphate derivatives, Zirconium
In a typical process [24], Ag NPs were synthesized via ascorbic
acid reduction of silver nitrate using ethanol as a solvent in the
presence of poly (N-vinyl-2-pyrrolidone) (PVP). AgNO3 (0.2 g)
and PVP (0.5 g) were dissolved in 40 mL ethanol, and then added
methyl-N,N-dimethylenephosphonate (Zr[(O
conium ethyl-N,N-dimethylenephosphonate (Zr[(O
ZEDP), zirconium propyl-N,N-dimethylenephosphonate
Zr[(O NC ], ZPDP), zirconium n-butyl-N,N-
dimethylenephosphonate (Zr[(O PCH NC ], ZBDP), zirconium
n-hexyl-N,N-dimethylenephosphonate (Zr[(O PCH NC
ZHDP), zirconium n-octyl-N,N-dimethylenephosphonate
PCH NC 17], ZODP), possessing the following advantages:
a) n-[bis(phosphonomethyl)amino]-alkyl (R-N(CH PO , RDP)
3
PCH
2
)
2
NCH
3
], ZMDP), zir-
3
2
PCH )
2 2 5
NC H ],
ꢀ1
(
3
PCH
2
)
2
3
H
7
drop wise 10 mL of ethanol solution containing 0.1 mol L
L
-ascor-
3
2
)
2
H
4 9
bic acid with vigorous stirring at room temperature, resulting in a
colloidal solution of silver nanoparticles.
3
2
)
2
6
H13],
(
(
Zr[(O
3
2
)
2
8
H
2
3
2
H )
2
2.3. Preparation of RDP, ZRDP and Ag-ZRDP
is a bactericide; (b) synergetic antibacterial activity (when two or
more kinds of antibacterial materials are combined together, and
the antibacterial properties are better than any single material)
can be obtained when mixing n-[bis(phosphonomethyl)amino]-
alkyl and Ag NPs; (c) drug resistance of organic bactericide can be
resolved during usage; (d) the aggregation of Ag NPs can be inhib-
ited; (e) the problem of free Ag NPs which are cytotoxic to mam-
malian cells can be solved. The antibacterial activity of Ag-ZRDP
was tested against Escherichia coli (E. coli) and Staphylococcus aureus
2.3.1. RDP
n-[Bis(phosphonomethyl)amino]-alkyl (R-N(CH PO H ) , RDP)
was synthesized by the Mannich-type reaction according to litera-
ture [25]. H PO (0.2 mol) and alkylammonium (0.1 mol) were
2
3
2 2
3
3
mixed in a 250 mL three-necked flask then concentrated HCl aque-
ous solution (10 mL) was slowly added with stirring. Then, the
temperature of mixture was brought to 110 °C followed by adding
drop wise a 100% excess of 37% aqueous formaldehyde solution
(15 mL) during 1–2 h and refluxing for another 2–3 h.
Subsequently, the mixture was stored at room temperature over-
night with stirring, resulting in a crystallized product. The NMR
of RDP was presented in the Supporting information (S1).
(S. aureus). The toxic effect of Ag-ZRDP on A549 cells was deter-
mined by using the Cell Counting Kit-8 (CCK-8) assay [23]. The
structure and properties of Ag-ZRDP were characterized using a
variety of methods: Fourier transform infrared spectroscopy
(
FTIR), X-ray diffraction (XRD) and transmission electron micro-
scopy (TEM), and scanning electron microscopy (SEM) was utilized
to observe the morphology of the bacteria.
2.3.2. ZRDP
A solution of RDP (0.01 mol) in 100 mL water was added into
ZrOCl
2
ꢁ8H
2
O (3.23 g, 0.01 mol) in 100 mL water with vigorous stir-
2
. Experimental
ring at 60–70 °C for 6 h. Subsequently, the mixture was filtered and
washed with deionized water until the pH of solution was near 5–
2.1. Materials and methods
6
. Dry ZRDP was obtained at 60 °C for 48 h under vacuum. The
chemical equations for the synthesis of ZRDP are shown in
Scheme 1.
All the analytical grade reagents were commercially available
and were used without further purification. Methylamine, ethy-
lamine, propylamine, n-butylamine, n-hexylamine and n-octy-
lamine were purchased from Aladdin Company (Shanghai,
2.3.3. Ag-ZRDP
China). NaCl,
D
-glucose, ZrOCl
2
ꢁ8H
2 3
O, AgNO and other reagents
ZRDP was dispersed in deionized water to obtain a suspension
were bought from Chengdu Kelong Chemical Reagent Company.
Biological reagent Muellor Hinton agar, peptone, beef extract was
provided by Beijing Aoboxing Bio-Tech Co., Ltd. Deionized water
was used for preparation of all solutions. All H and P NMR mea-
surements were recorded on a Bruker AVANCE III 600 MHz spec-
of 10.0 mass% and transferred to a 1 L reaction kettle followed by
adding different amounts of AgNO (final concentration from
.05 to 1.6 mass%) with stirring. Then, the temperature was main-
3
0
1
31
tained at 60 °C for 3 h. Subsequently, the mixture was filtered and
washed with deionized water resulting in the Ag-ZRDP sample. The
sample was obtained at 45 °C for 12 h under vacuum.
2
trometer using TMS as an internal standard for a D O solution
and reported in parts per million (ppm). The Fourier Transform
infrared (FT-IR) spectra of the nanocomposites were recorded in
KBr discs using a Nicolet (Madison, WI, USA) 170SX FTIR spectrom-
ꢀ1
eter in the range of 4000–600 cm , in the attenuated total reflec-
tion mode. X-ray diffraction was performed on a XRD-3D, Puxi,
(
Beijing, China) X-ray diffractometer under the following condi-
tions: Nickel filtered Cu K radiation (k = 0.15406 nm) at a current
a
ꢀ1
of 20 mA and a voltage of 36 kV. The scanning rate was 4° min in
the angular range of 3–40° (2h). The concentration of silver ions
was measured by ICP single channel scanning spectrometer, Puxi,
(
Beijing, China) TPS-7000. The specific surface area was measured
by Quantachrome Instruments (USA) QUA211007. The micromor-
phologies of all the samples were investigated by transmission
electron microscope (TEM) using a JEM-2010 (Japan) at an acceler-
ating voltage of 200 kV. The surface morphologies of bacteria of the
control and treated with Ag-ZRDP were observed by scanning elec-
tron microscope (SEM) using a HITACHI S-4800, Japan. All the
Scheme 1. The chemical equations for the synthesis of ZRDP.