Different cellulosic polymers for synthesizing silver nanoparticles with antioxidant and antibacterial activities

Abstract

The use of cellulosic polymers as efficient reducing, coating agents, and stabilizers in the formulation of silver nanoparticles (AgNPs) with antioxidant and antibacterial activity was investigated. AgNPs were synthesized using different cellulosic polymers, polyethylene glycol, and without polymers using tri-sodium citrate, for comparison. The yield, morphology, size, charge, in vitro release of silver ion, and physical stability of the resulting AgNPs were evaluated. Their antioxidant activity was measured as a scavenging percentage compared with ascorbic acid, while their antibacterial activity was evaluated against different strains of bacteria. The amount of AgNPs inside bacterial cells was quantified using an ICP-OES spectrometer, and morphological examination of the bacteria was performed after AgNPs internalization. Cellulosic polymers generated physically stable AgNPs without any aggregation, which remained physically stable for 3 months at 25.0 ± 0.5 and 4.0 ± 0.5 °C. AgNPs formulated using ethylcellulose (EC) and hydroxypropyl methylcellulose (HPMC) had significant (p ≤ 0.05; ANOVA/Tukey) antibacterial activities and lower values of MIC compared to methylcellulose (MC), PEG, and AgNPs without a polymeric stabilizer. Significantly (p ≤ 0.05; ANOVA/Tukey) more AgNPs-EC and AgNPs-HPMC were internalized in Escherichia coli cells compared to other formulations. Thus, cellulosic polymers show promise as polymers for the formulation of AgNPs with antioxidant and antibacterial activities.

Silver Nanoparticle-Coated Ethyl Cellulose Inhibits Tumor Necrosis Factor-α of Breast Cancer Cells

“…AgNPs with EC stabilization were prepared using the previously reported method by Abdellatif et al [26][27][28] Simply, EC standard 1% solution was prepared in distilled water, and AgNO 3 aqueous solution 1 mM was also prepared and adjusted for its pH (8.0) and ionic strength using 1 mL/mol NaOH. The prepared AgNO 3 solution was heated to boiling over a hot plate and kept stirring after addition of 2 mL of the prepared EC solution.…”

“…47,48 Previous work has shown in our group the prolonged release of silver cations from AgNPs-EC compared with other AgNPs prepared using MC, HPMC, and PEG. 26 It is also interesting to note the slow initial release of silver cations related to the shielding effect of polymer around NPs, affecting water ingress into the NP core. 32 In other words, the cellulose fiber chains probably acted as a physical barrier to impede the silver cations release as demonstrated before.…”

“…(Malvern Instruments GmbH, Herrenberg, Germany). 26 Data were presented as the average of three different measurements of the same NP batch.…”

“…Silver ions released from the prepared AgNPs-EC were carried out, as mentioned before by our research group. 26 , 32 In vitro release was performed in double distilled water of about 100 mL for 48 h. The amounts of silver cations released at different time points were calculated using inductively coupled plasma spectroscopy (ICP-OES, iCAP 6000, Thermo Scientific, USA) with an emission detector against a blank silver metal standard solution. Data were presented as the mean of three additional readings.…”

“…30,38,39 The prepared AgNPs-EC was prepared using silver nitrate reduction via ethyl cellulose which acts as a reducing agent and stabilizing compound for efficient AgNP preparation with little aggregation, as investigated before by different researchers. 26,40 This cellulosic derivative containing reducing groups and hydroxyl groups could offer the reducing properties for silver nitrate to produce silver NPs. The negatively charged EC facilitates the attraction of the positively charged silver cations to the polymeric chains followed by reduction with the exciting reducing groups.…”