58
V. Demchenko et al.
pouring onto PTFE plates and drying up to constant masses at the same temperature.
Dry IPEC films were washed in distilled water up to neutrality and dried repeatedly
at 20 ◦ ´ up to constant masses. The resulting films were 100 μm thick.
IMC samples were prepared via immersion of IPEC films into an aqueous
solution of AgNO 3 with a concentration of 0.1 mol/L at T = 20 ± 2 ◦ ´ for 24 h.
The colorless IPEC films became dark red. The absorption capacities of IMC films
£ = 5.0 mmol/g.
The chemical reduction of Ag + ions in the IMCs was conducted with NaBH 4 (a
molar ratio of [BH 4
− ]:[Ag + ] ≥ 1.0) in an alkaline medium (pH 10.8) in a solvent
mixture of water–isopropanol (4:1 vol %) at µ = 20 ± 2 ◦ ´ for 3 h (until the
release of gaseous bubbles ceased). The concentration of NaBH 4 in the aqueous
alcohol solution was 0.1 mol/L.
Thermal reduction of Ag + ions in the IMC’s volume was performed by heating
of films to 100–160 ◦ C within 30 min. Specimens were heated in the oven using
precise thermal regulator VRT-3. Temperature regulation precision was ±0.5 ◦ ´.
As a result of the reduction, IMC films changed color from red to metallic.
The features of the structuring of the IPEC (pectin–PEI), the IMC (pectin–
Ag + –PEI), and nanocomposites of IPEC–Ag were studied by wide-angle X-ray
diffraction on a DRON-4-07 diffractometer, whose X-ray optical scheme was used
to “pass” primary-beam radiation through samples. X-ray diffraction studies were
performed at µ = 20 ± 2 ◦ ´ in Cu- α radiation monochromated with a Ni filter.
The antimicrobial activity of IPEC–Ag nanocomposites, prepared by chemical
and thermal reduction of Ag + ions in IMC, was investigated using reference strains
of opportunistic bacteria Staphylococcus aureus ATCC 6538 and Escherichia coli
ATCC 35218 (as model gram-positive and gram-negative bacteriÃ).
Investigations were carried out by agar diffusion method on a solid LB (LuriaBertani) nutrient medium [23]. The nanocomposite films (size 10 × 10 mm) were
placed on the surface of nutrient agar, which had been previously inoculated with
10 μL of bacterial suspension of S. aureus and E. coli at the rate of 2 × 10 5 CFU/ml.
The plates were incubated at 37 ◦ ´ for 24 h.
Clear zones, which has no bacterià around the film of composite, containing Ag
were the indicator of antimicrobial activity. All experiments were repeated three
times. The IPEC film was applied as a control sample.
The analysis of wide-angle X-ray diffractograms has shown that IPEC formed of
pectin and PEI is characterized by short-range ordering during translation of fragments of oppositely charged polyelectrolyte macromolecular chains in space. This
circumstance is indicated by the appearance of one diffuse diffraction maximum
with 2θ m ∼ 20.8 ◦ on the X-ray diffractogram of the IPEC sample (see Fig. 3.6,
curve 1). The average value of the period of short-range ordering of fragments of
complementary macromolecular chains of oppositely charged polyelectrolytes in
the IPEC (the Bragg distance between the macromolecule chains of anionic and
cationic polyelectrolytes in the IPEC) is 4.3 Å, i.e., slightly less than that in the
cationic polyelectrolyte.
However, the sorption of AgNO 3 by the IPEC sample and formation of the IPEC–
Ag + IMC is accompanied by a change in the diffractogram. This result is proved by
V. Demchenko et al.
pouring onto PTFE plates and drying up to constant masses at the same temperature.
Dry IPEC films were washed in distilled water up to neutrality and dried repeatedly
at 20 ◦ ´ up to constant masses. The resulting films were 100 μm thick.
IMC samples were prepared via immersion of IPEC films into an aqueous
solution of AgNO 3 with a concentration of 0.1 mol/L at T = 20 ± 2 ◦ ´ for 24 h.
The colorless IPEC films became dark red. The absorption capacities of IMC films
£ = 5.0 mmol/g.
The chemical reduction of Ag + ions in the IMCs was conducted with NaBH 4 (a
molar ratio of [BH 4
− ]:[Ag + ] ≥ 1.0) in an alkaline medium (pH 10.8) in a solvent
mixture of water–isopropanol (4:1 vol %) at µ = 20 ± 2 ◦ ´ for 3 h (until the
release of gaseous bubbles ceased). The concentration of NaBH 4 in the aqueous
alcohol solution was 0.1 mol/L.
Thermal reduction of Ag + ions in the IMC’s volume was performed by heating
of films to 100–160 ◦ C within 30 min. Specimens were heated in the oven using
precise thermal regulator VRT-3. Temperature regulation precision was ±0.5 ◦ ´.
As a result of the reduction, IMC films changed color from red to metallic.
The features of the structuring of the IPEC (pectin–PEI), the IMC (pectin–
Ag + –PEI), and nanocomposites of IPEC–Ag were studied by wide-angle X-ray
diffraction on a DRON-4-07 diffractometer, whose X-ray optical scheme was used
to “pass” primary-beam radiation through samples. X-ray diffraction studies were
performed at µ = 20 ± 2 ◦ ´ in Cu- α radiation monochromated with a Ni filter.
The antimicrobial activity of IPEC–Ag nanocomposites, prepared by chemical
and thermal reduction of Ag + ions in IMC, was investigated using reference strains
of opportunistic bacteria Staphylococcus aureus ATCC 6538 and Escherichia coli
ATCC 35218 (as model gram-positive and gram-negative bacteriÃ).
Investigations were carried out by agar diffusion method on a solid LB (LuriaBertani) nutrient medium [23]. The nanocomposite films (size 10 × 10 mm) were
placed on the surface of nutrient agar, which had been previously inoculated with
10 μL of bacterial suspension of S. aureus and E. coli at the rate of 2 × 10 5 CFU/ml.
The plates were incubated at 37 ◦ ´ for 24 h.
Clear zones, which has no bacterià around the film of composite, containing Ag
were the indicator of antimicrobial activity. All experiments were repeated three
times. The IPEC film was applied as a control sample.
The analysis of wide-angle X-ray diffractograms has shown that IPEC formed of
pectin and PEI is characterized by short-range ordering during translation of fragments of oppositely charged polyelectrolyte macromolecular chains in space. This
circumstance is indicated by the appearance of one diffuse diffraction maximum
with 2θ m ∼ 20.8 ◦ on the X-ray diffractogram of the IPEC sample (see Fig. 3.6,
curve 1). The average value of the period of short-range ordering of fragments of
complementary macromolecular chains of oppositely charged polyelectrolytes in
the IPEC (the Bragg distance between the macromolecule chains of anionic and
cationic polyelectrolytes in the IPEC) is 4.3 Å, i.e., slightly less than that in the
cationic polyelectrolyte.
However, the sorption of AgNO 3 by the IPEC sample and formation of the IPEC–
Ag + IMC is accompanied by a change in the diffractogram. This result is proved by