Alginate coated biogenic silver nanoparticles for the treatment of Pseudomonas infections in rainbow trout

Pseudomonas species are among the main pathogens causing rainbow trout infections. The present study provides a simple, green, sustainable, and rapid technique to synthesize of biogenic alginate-capped silver nanoparticles (Alg-Ag NPs) suitable for the treatment of Pseudomonas infections. It has been shown that the mechanism (aggregative or autocatalytic) of Alg-Ag NPs formation depended on Alg concentration and the heating approach used. The rate constants and activation energy were calculated. Alg-Ag NPs were characterized by UV-Vis, FTIR, XRD, TEM, AFM, XPS, and DLS. The optimal conditions for the fabrication of spherically-shaped (17-19 nm) and negatively-charged (zeta-potential <-50 mV) Alg-Ag NPs, which are stable during 9 months, included hot-plate assisted synthesis at 100 °C in diluted (1 mg/mL) Alg solutions. In vitro studies showed that Alg-Ag NPs exhibited prominent antimicrobial activity against collection Pseudomonas strains (inhibition zones ranged from 9.0 ± 1.0 to 19.0 ± 1.0 mm), with no significant loss of antibacterial efficacy after 9 months of storage. AFM analysis confirmed that the antibacterial effect of Alg-Ag NPs dealt with the direct nanomechanical disrupting of bacterial cells. The ability of Alg-Ag NPs to inhibit the growth of virulent P.aeruginosa, P.fluorescens and P. putida strains isolated from infected rainbow trout was evaluated. All tested strains were susceptible to Alg(10)-Ag NPs, while Alg(1)-Ag NPs demonstrated a limited strain-specific antibacterial effect. The obtained data displayed the prospects for the application of biogenic Alg-Ag NPs to create novel delivery systems for combating Pseudomonas infections in rainbow trout.

Green synthesis of metallic nanoparticles using pectin as a reducing agent: a systematic review of the biological activities

CONTEXT

Pectin is a plant heteropolysaccharide that is biocompatible and biodegradable, enabling it to be an excellent reducing agent (green synthesis) for metallic nanoparticles (MNPs). Nevertheless, in the biological industry, pectin has been left behind in synthesising MNPs, for no known reason.

OBJECTIVE

To systematically review the biological activities of pectin synthesised MNPs (Pe-MNPs).

METHODS

The databases Springer Link, Scopus, ScienceDirect, Google Scholar, PubMed, Mendeley, and ResearchGate were systematically searched from the date of their inception until 10^th February 2020. Pectin, green synthesis, metallic nanoparticles, reducing agent and biological activities were among the key terms searched. The data extraction was focussed on the biological activities of Pe-MNPs and reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations for systematic reviews.

RESULTS

A total of 15 studies outlined 7 biological activities of Pe-MNPs in the only three metals that have been explored, namely silver (Ag), gold (Au) and cerium oxide (CeO₂). The activities reported from the in vitro and in vivo studies were antimicrobial (9 studies), anticancer (2 studies), drug carrier (3 studies), non-toxic (4 studies), antioxidant (2 studies), wound healing (1 study) and anti-inflammation (1 study).

CONCLUSIONS

This systematic review demonstrates the current state of the art of Pe-MNPs biological activities, suggesting that Ag and Au have potent antibacterial and anticancer/chemotherapeutic drug carrier activity, respectively. Further in vitro, in vivo, and clinical research is crucial for a better understanding of the pharmacological potential of pectin synthesised MNPs.

Physicochemical aspects of design of ultrathin films based on chitosan, pectin, and their silver nanocomposites with antiadhesive and bactericidal potential

Implant-related infection is one of the serious problems in regenerative medicine. Promising approach to overcome the problems caused by bacterial growth on the medical implants is their modification by bioactive coatings. A versatile technique for designing multilayer films with tailored characteristics at the nanometer scale is layer-by-layer assembly. In this study, multilayer films based on biopolymers (pectin and chitosan) and their nanocomposites with silver nanoparticles have been prepared and evaluated. The buildup of multilayers was monitored using the quartz crystal microbalance with dissipation technique. The morphology of the obtained films was investigated by atomic force microscopy. We have demonstrated that pectin-Ag-containing films were characterized by the linear growth and smooth defect-free surface. When pectin-Ag was substituted for the pectin in the multilayer systems, the properties of the formed coatings were significantly changed: the film rigidity and surface roughness increased, as well as the film growth acquired the parabolic character. All prepared multilayer films have shown antibacterial activity against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. The significant decrease in the number of the adhered E. coli on the multilayer surface has been determined; moreover, many of the cells were misshapen with cytoplasm leaking. The prepared multilayer films showed a mild activity against S. aureus predominantly due to the antiadhesive effect. Our results indicate that antibacterial activity of biopolymer multilayers is determined by the film composition and physicochemical characteristics and can be associated with their antiadhesive and bactericidal behaviors.

Noble Metal Nanoparticles in Pectin Matrix. Preparation, Film Formation, Property Analysis, and Application in Electrocatalysis

Stable polymeric materials with embedded nano-objects, retaining their specific properties, are indispensable for the development of nanotechnology. Here, a method to obtain Pt, Pd, Au, and Ag nanoparticles (ca. 10 nm, independent of the metal) by the reduction of their ions in pectin, in the absence of additional reducing agents, is described. Specific interactions between the pectin functional groups and nanoparticles were detected, and they depend on the metal. Bundles and protruding nanoparticles are present on the surface of nanoparticles/pectin films. These films, deposited on the electrode surface, exhibit electrochemical response, characteristic for a given metal. Their electrocatalytic activity toward the oxidation of a few exemplary organic molecules was demonstrated. In particular, a synergetic effect of simultaneously prepared Au and Pt nanoparticles in pectin films on glucose electro-oxidation was found.

New pectin-induced green fabrication of Ag@AgCl/ZnO nanocomposites for visible-light triggered antibacterial activity

The pectin (CEP) was used as matrix material to prepare Ag@AgCl/ZnO nanocomposites with a green method for photocatalytic antibacterial activity in visible-light. Briefly, Ag@AgCl plasmonic hybrids were prepared in the CEP macromolecule matrix with size control, which was attributed to the stability of carboxyl and hydroxyl groups on the CEP. Subsequently, an effective and green two-steps approach was explored for the fabrication of CEP-Ag@AgCl/ZnO nanocomposites with resource saving and environment friendly. Interestingly, more Ag⁺ was converted into metallic Ag in the CEP-Ag@AgCl/ZnO than that in the CEP-Ag@AgCl. This phenomenon was attributed that the reducibility of free hemiacetal hydroxyl groups on CEP was realized with the help of NaOH in the preparation of CEP-ZnO. In addition, the CEP chains were not obviously destroyed except for the change in the crystallinity after the preparation of the CEP-Ag@AgCl/ZnO nanocomposites, indicating that the method was non-destructive. Moreover, the pH triggered release of Zn²⁺ and low release of Ag⁺ in CEP-Ag@AgCl/ZnO nanocomposites with excellent photocatalytic antibacterial activity were confirmed in this work. The proposed green process provides a new idea for the large-scale production of antibacterial pectin-based nanocomposites in industry with a low-cost.

Application of bioderadable materials based on alginate and pectin to prevent the formation of peritoneal adhesions

Treatment of peritoneal adhesions are still of great importance today. One of the prophylactic measures is biodegradable gels and membranes. The objective of the investigation was to develop and to experimentally assess new materials based on pectin and alginate. Alginate hydrogel was prepared with 4.0, 7.0 and 10.0 weight per cent. The pectin sols were synthesized by the “green chemistry” method. To make flms and porous membranes the solution casting method and the freeze-drying technique were used accordingly. The materials were studied in vitro and in vivo. Their physical properties, biocompatibility, biodegradability, adhesion, the prevention effect, the possibility of using as a matrix for mesenchymal stem cell transplantation were assessed. Alginate hydrogel of 7.0 weight per cent didn’t cause postoperative complications and led to low adhesions incidence – in 10 % of cases (in the comparison group – 85.7 %). Pectin flms obtained by the solution casting method became deformed already in the physiological solution. Biodegradation of the flms was absent in the experiment, abscesses and infltrates in the abdominal cavity were noted. Mesenchymal stem cells didn’t attach to such flms. Porous pectin matrices synthetized by the freeze-drying technique became partially decomposed already in the physiological solution. In the experiment, these membranes were biodegraded in half animals with the formation of mild adhesions only in 25 %. Mesenchymal stem cells showed a good attachment to their surface. The developed materials based on alginate gel and porous pectin membranes showed a high biodegradation, good biocompatibility, adhesion the prevention effect and the possibility of using as a matrix for stem cells transplantation.

PREPARATION AND PROPERTIES OF KANAMYCIN-CONTAINING HYDROGELS BASED ON PECTIN-Ag NANOCOMPOSITE

The hydrogels based on nanocomposite pectin-Ag exhibiting the antibacterial activity (MIСAg = 0.02–0.81 mM) were obtained by ionotropic gelation. It was shown that the synthesized hydrogels had a high capacity for kanamycin (up to 70 wt. %). The obtained hydrogels provided a prolonged release of kanamycin in 0.9 % NaCl and enhanced its antibacterial activity (MIC decreased 10–20 times) due to the synergistic effect.