Antimicrobial activity of silver nanoparticles supported by magnetite

Abstract

Antibacterial and antifungal ability of silver nanoparticles (Ag NPs) supported by functionalized magnetite (Fe 3 O 4 ) with 5aminosalicylic acid (5-ASA) was tested against Gram-negative bacteria Escherichia coli, Gram-positive bacteria Staphylococcus aureus and yeast Candida albicans. Characterization of materials including transmission electron microscopy, X-ray diffraction analysis, and inductively coupled plasma optic emission spectroscopy technique followed each step during the course of nanocomposite preparation. The synthesized powder consists of 30-50 nm in size silver particles surrounded by clusters of smaller (∼ 10 nm) Fe 3 O 4 particles. The content of silver in the nanocomposite powder was found to be slightly above 40 wt.-%. Concentration-dependent and time-dependent bacterial reduction measurements in dark indicated that use of Ag NPs leads to the complete reduction of E. coli and S. aureus even at the concentration level of silver as low as 40 μg/mL. However, the negligible antifungal ability of synthesized nanocomposite was found against yeast C. albicans in the entire investigated concentration range (0.1-2.0 mg/mL of the nanocomposite, i. e., 40-800 μg/mL of silver). Complete inactivation of E. coli and S. aureus was achieved in five repeated cycles indicated that synthesized nanocomposite can perform under long-run working conditions. From the technological point of view, magnetic separation is the additional advantage of synthesized nanocomposite for potential use as an antibacterial agent.

Antimicrobial activity of amino-modified cellulose nanofibrils decorated with silver nanoparticles

“…The high content of free amino groups, estimated to be around 5.0 mM/g, is a signi cant feature of NH 2 − CNFs. The amino groups are reactive and capable of reducing silver ions to metallic silver, free [23,24], or attached to inorganic [28,29] or organic [25][26][27] supports. So, in the second synthetic step (Scheme 1), Ag NPs were in-situ prepared by the electron transfer reaction from the amino groups and their transformation into imino groups, and thus conjugated to CNFs over the lone electron pairs of the N atoms from amino groups [24,28,29].…”

“…On one side, amino-functionalized cellulose nano brils (NH 2 − CNFs) display antimicrobial activity due to the electrostatic interaction between positively charged amino groups and negatively charged cell walls that enhanced their contact with microorganisms [20][21][22]. On the other side, the free amino groups are capable of reducing Ag + ions to their metallic form, providing the possibility to prepare free-standing colloidal Ag NPs [23,24] or Ag NPs linked to different types of supports, polymer [25][26][27] and inorganic [28,29], with high antimicrobial activity. Besides the antimicrobial activity of Ag NPs on support, when they are easily accessible to microbial species in the surrounding medium, Ag NPs dispersed within a polymer matrix also have antimicrobial activity.…”

Photocatalytic ability of visible-light-responsive hybrid ZrO2 particles

“…Since the ICT complex formation occurs by a condensation reaction between hydroxyl groups from ZrO 2 and 5-ASA, we used the reducing ability of free amino groups to reduce silver ions to metallic silver. 37,38 0.5 g of ZrO 2 /5-ASA was dispersed in 100 mL of water containing 25.0 mg of AgNO 3 and kept under reux overnight at 60 °C. The washing procedure for prepared ZrO 2 /5-ASA/Ag was the same as that for ZrO 2 /5-ASA.…”

“…The weight percentage of Zr in ZrO 2 /5-ASA and ZrO 2 /5-ASA/Ag is practically the same, indicating that the content of 5-ASA is negligible, most likely ∼1 wt%, as we observed previously for similar hybrids. 37,38,46 XRD patterns of the as-prepared ZrO 2 and hybrid ZrO 2 /5-ASA/ Ag are shown in Fig. 1A.…”

Plasma-liquid synthesis of silver nanoparticles and their antibacterial and antifungal applications

“…Silver nanoparticles have been reported to be functional due to their various applications including antiviral activity [13], antibacterial activity [14], antifungal activity [15], catalytic applications [16], plasmon resonance [17][18][19], remedial applications [20,21], diagnostic [22,23] and conductive applications [24,25]. Different research groups implemented a wide range of methods for the synthesis of silver nanoparticles, including physical [26,27], chemical [28,29], and biological methods [30,31].…”