Influence of Polysaccharides' Molecular Structure on the Antibacterial Activity and Cytotoxicity of Green Synthesized Composites Based on Silver Nanoparticles and Carboxymethyl-Cellulose

Preparation of sodium alginate modified silver-metal organic framework and application in citric acid/PVA antimicrobial packaging

Silver-metal organic framework (Ag@MOF) has exhibited outstanding antimicrobial activity in antimicrobial applications, and reducing the biotoxicity associated with silver has become a research priority. In this study, Ag@MOF was initially modified with sodium alginate (SA) to form SA-Ag@MOF. The results showed that SA could control the release of Ag+, reducing the release by about 8% at 24 h, and the biotoxicity was significantly reduced. Finally, SA-Ag@MOF was applied as an antimicrobial agent in citric acid-modified PVA film to develop a novel composite antimicrobial film. When added at 2 MIC, the CA3-M2 film can effectively inhibit the growth of E. coli and S. aureus, and the inhibition rate has reached 98%. For white radish packaging applications, CA3-M2 film inhibited the growth of surface microorganisms, while ensuring moisture and tissue hardness to extend shelf-life up to 7 days. Overall, the strategy conceived here can be a theoretical basis for novel antimicrobial packaging.

Construction and antibacterial activities of walnut green husk polysaccharide based silver nanoparticles (AgNPs)

In this paper, the size-controllable nano‑silver particles (AgNPs) were synthesized from walnut green husk polysaccharide, and its cytotoxicity and antibacterial activity were evaluated. Firstly, acidic polysaccharide WGHP2 was extracted from walnut green husk, and then the silver ion in AgNO3 was reduced in WGHP2 aqueous solution using NaBH4, so as to synthesize the nano‑silver composite. The nano‑silver composite was characterized by transmission electron microscope, Fourier infrared spectroscopy, ultraviolet-visible spectrometer, scanning electron microscope, inductively coupled plasma mass spectrometry and X-ray photoelectron spectroscopy. The results show that AgNPs stabilized by WGHP2 are mainly regular spheres with an average particle size distribution of 15.04-19.23 nm. The particle size distribution and morphology of AgNPs changed with the concentration of silver precursor, which is related to the dispersion of silver precursor in polysaccharide aqueous solution and the formation of AgO coordination bond between silver precursor and polysaccharide molecules. These coordination bonds changed the ability of nanoparticles to produce and release Ag+, and thus regulated their antibacterial activity and cytotoxicity, as evidenced by the experimental result of the cytotoxicity of the nano‑silver particle against PC12 cells and the bacteriostatic effect on E.coli and S.aureus. Conclusively, WGHP2-Ag has good stability, antibacterial activity and low cytotoxicity.

Bioinspired phosphorus-free and halogen-free biomass coatings for durable flame retardant modification of regenerated cellulose fibers

Inspired by mussel adhesion and intrinsic flame retardant alginate fibers, a biomass flame retardant (PPCA) containing adhesive catechol and sodium carboxylate structure (-COO-Na+) based on biomass amino acids and protocatechualdehyde was designed to prepare flame retardant Lyocell fibers (Lyocell@PPCA@Na). Furthermore, through the substitution and chelation of metal ions by PPCA in the cellulose molecular chain, flame retardant Lyocell fibers chelating copper and iron ions (Lyocell@PPCA@Cu, Lyocell@PPCA@Fe) were prepared. Compared with the original sample, the peak heat release rate (PHRR) and total heat release (THR) for modified Lyocell fibers were significantly reduced. In addition, the modified sample exhibited a certain flame retardant durability. TG-FTIR analysis showed that the release of flammable gaseous substances was inhibited. The introduction of Schiff bases and aromatic structures in PPCA, as well as the decomposition of carboxylic metal salts were beneficial for the formation of char residue containing metal carbonates and metal oxides to play the condensed phase flame retardant effect. This work develops a new idea for the preparation of eco-friendly flame retardant Lyocell fibers without the traditional flame retardant elements such as P, Cl, and Br.

Synthesis of Silver Nanocomposite Based on Carboxymethyl Cellulose: Antibacterial, Antifungal and Anticancer Activities

Traditional cancer treatments include surgery, radiation, and chemotherapy. According to medical sources, chemotherapy is still the primary method for curing or treating cancer today and has been a major contributor to the recent decline in cancer mortality. Nanocomposites based on polymers and metal nanoparticles have recently received the attention of researchers. In the current study, a nanocomposite was fabricated based on carboxymethyl cellulose and silver nanoparticles (CMC-AgNPs) and their antibacterial, antifungal, and anticancer activities were evaluated. The antibacterial results revealed that CMC-AgNPs have promising antibacterial activity against Gram-negative (Klebsiella oxytoca and Escherichia coli) and Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus). Moreover, CMC-AgNPs exhibited antifungal activity against filamentous fungi such as Aspergillus fumigatus, A. niger, and A. terreus. Concerning the HepG2 hepatocellular cancer cell line, the lowest IC₅₀ values (7.9 ± 0.41 µg/mL) were recorded for CMC-AgNPs, suggesting a strong cytotoxic effect on liver cancer cells. As a result, our findings suggest that the antitumor effect of these CMC-Ag nanoparticles is due to the induction of apoptosis and necrosis in hepatic cancer cells via increased caspase-8 and -9 activities and diminished levels of VEGFR-2. In conclusion, CMC-AgNPs exhibited antibacterial, antifungal, and anticancer activities, which can be used in the pharmaceutical and medical fields.

Multifarious global flora fabricated phytosynthesis of silver nanoparticles: a green nanoweapon for antiviral approach including SARS-CoV-2

The progressive research into the nanoscale level upgrades the higher end modernized evolution with every field of science, engineering, and technology. Silver nanoparticles and their broader range of application from nanoelectronics to nano-drug delivery systems drive the futuristic direction of nanoengineering and technology in contemporary days. In this review, the green synthesis of silver nanoparticles is the cornerstone of interest over physical and chemical methods owing to its remarkable biocompatibility and idiosyncratic property engineering. The abundant primary and secondary plant metabolites collectively as multifarious phytochemicals which are more peculiar in the composition from root hair to aerial apex through various interspecies and intraspecies, capable of reduction, and capping with the synthesis of silver nanoparticles. Furthermore, the process by which intracellular, extracellular biological macromolecules of the microbiota reduce with the synthesis of silver nanoparticles from the precursor molecule is also discussed. Viruses are one of the predominant infectious agents that gets faster resistance to the antiviral therapies of traditional generations of medicine. We discuss the various stages of virus targeting of cells and viral target through drugs. Antiviral potential of silver nanoparticles against different classes and families of the past and their considerable candidate for up-to-the-minute need of complete addressing of the fulminant and opportunistic global pandemic of this millennium SARS-CoV2, illustrated through recent silver-based formulations under development and approval for countering the pandemic situation.

Graphical abstract

Green and Facile Synthesis of Pullulan-Stabilized Silver and Gold Nanoparticles for the Inhibition of Quorum Sensing

Pullulan (Pull) decorated with monodisperse Ag and Au nanoparticles (NPs) was synthesized by a simple and green method. Samples were characterized by FTIR, UV–vis, NMR, XRD, TGA, SEM, XPS, DLS, and TEM. SEM images showed highly oriented microforms reported for the first time for Pull, because of the supramolecular self-assembling behavior of Pull chains. Antimicrobial and quorum sensing (QS) inhibition activities were tested against six pathogen bacteria and reporter and biomonitor strain. Pull decorated with NPs, in particular, Ag-modified ones, outperformed pristine Pull. The cell proliferation was tested with an MTT assay. NPs-decorated Pull was studied for the first time as an inhibitory agent against bacterial signal molecules and found to be a good candidate. The promising performance of AgNPs@Pull compared to the commercial antibiotic gentamicin showed that it has great potential as a therapeutic approach to overcome the bacterial resistance that has developed against conventional antibiotics.

Green Synthesis and Characterization of Carboxymethyl Cellulose Fabricated Silver-Based Nanocomposite for Various Therapeutic Applications

Purpose

The current study proposed the simple, eco-friendly and cost-effective synthesis of carboxymethyl cellulose (CMC) structured silver-based nanocomposite (CMC-AgNPs) using Syzygium aromaticum buds extract.

Methods

The CMC-AgNPs were characterized by ultraviolet (UV) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transmission infra-red (FTIR), energy-dispersive X-ray (EDX), and dynamic light scattering (DLS) techniques. The synthesized nanocomposites were evaluated for their bactericidal kinetics, in-vivo anti-inflammatory, anti-leishmaniasis, antioxidant and cytotoxic activities using different in-vitro and in-vivo models.

Results

The spherical shape nanocomposite of CMC-AgNPs was synthesized with the mean size range of 20–30 nm, and the average pore diameter is 18.2 nm while the mean zeta potential of −31.6 ± 3.64 mV. The highly significant (P < 0.005) antibacterial activity was found against six bacterial strains with the ZIs of 24.6 to 27.9 mm. More drop counts were observed in Gram-negative strains after 10 min exposure with CMC-AgNPs. Significant damage in bacterial cell membrane was also observed in atomic force microscopy (AFM) after treated with CMC-AgNPs. Nanocomposite showed highly significant anti-inflammatory activity in cotton pellet induced granuloma model (Phase I) in rats with the mean inhibitions of 43.13% and 48.68% at the doses of 0.025 and 0.05 mg/kg, respectively, when compared to control. Reduction in rat paw edema (Phase II) was also highly significant (0.025 mg/kg; 42.39%; 0.05 mg/kg, 47.82%). At dose of 0.05 mg/kg, CMC-AgNPs caused highly significant decrease in leukocyte counts (922 ± 83), levels of CRP (8.4 ± 0.73 mg/mL), IL-1 (177.4 ± 21.3 pg/mL), IL-2 (83.7 ± 11.5 pg/mL), IL-6 (83.7 ± 11.5 pg/mL) and TNF-α (18.3 ± 5.3 pg/mL) as compared to control group. CMC-AgNPs produced highly effective anti-leishmaniasis activity with the viable Leishmania major counts decreased up to 36.7% within 24 h, and the IC₅₀ was found to be 28.41 μg/mL. The potent DPPH radical scavenging potential was also observed for CMC-AgNPs with the IC₅₀ value of 112 μg/mL. Furthermore, the cytotoxicity was assessed using HeLa cell lines with the LC₅₀ of 108.2 μg/mL.

Conclusion

The current findings demonstrate positive attributes of CMC fabricated AgNPs as a promising antibacterial, anti-inflammatory, anti-leishmaniasis, and antioxidant agent with low cytotoxic potential.

Biological Synergy and Antimicrobial Mechanism of Hydroxypropyltrimethyl Ammonium Chloride Chitosan with Benzalkonium Chloride

Preservatives in eye drops have always been the focus of people's attention. Benzalkonium chloride (BAC) is one of the most frequently used bacteriostatic agents in eye drops, which has broad-spectrum and efficient bactericidal ability. However, the inappropriate dosage of BAC may lead to high cytotoxicity. Therefore, adding low-toxic hydroxypropyltrimethyl ammonium chloride chitosan (HACC) can not only achieve antimicrobial effect, but also have the advantages of moisturizing and biocompatibility. In this paper, the minimum inhibitory concentrations (MICs) of HACC and BAC were evaluated against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Diphtheroid bacillus and Candida albicans. Based on the MIC of each antimicrobial agent, an antimicrobial assay was performed to investigate the antimicrobial ability of disinfectant solution. Besides, cytotoxicity had also been assessed. When the HACC/BAC solution at weight ratio of 150/1 showed a highest antimicrobial efficiency and the cell proliferation rates were the highest in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. Furthermore, the cell leakage was examined by UV absorption, indicating the great synergistic antimicrobial effect between HACC and BAC. What is more, the results of micromorphology research suggested that as the result of repulsive force between the two molecules, the average particle size of HACC would decrease. Finally, the impedance experiment showed that with the addition of BAC, current density would increase significantly, suggesting that more positive charge group was exposed to aqueous solution, leading the the increase of antimicrobial ability. Based on these results, HACC-BAC combination solution might be a promising novel antimicrobial group for biomedical applications.

Construction of silver nanoparticles by the triple helical polysaccharide from black fungus and the antibacterial activities

Size controllable silver nanoparticles (AgNPs) were synthesized in situ on the polysaccharides-based nanotubes, which were formed by the triple-helix polysaccharide extracted from black fungus (AF1). The results of transmission electron microscope (TEM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) proved that AgNPs with the size from 10-25 nm were uniformly dispersed on the surface of AF1 dendritic nanotubes without affecting their tubular morphology. Moreover, due to the tubular structure, the loaded silver content of the composites (AgNPs and AF1 nanotube, AF1-Ag) could reach about 50% by thermogravimetric analysis (TG) evaluation. Thus, the smaller size of AgNPs and higher silver loading content suggest that the composites could be applied in the biomedical field. The antibacterial properties of AF1-Ag were evaluated as an example in the present work. As expected, the culture medium contained a few of AF1-Ag (10% ω%, c = 50 μg/mL) exhibited obvious antibacterial properties, and the effect of bacteriostasis increased with the increase of the amount of supported silver content. Taken together, the AF1-Ag with good antibacterial activity and good stability has the potential to be applied in the antibacterial field.

Preparation of silver nanoparticles by solid-state redox route from hydroxyethyl cellulose for antibacterial strain sensor hydrogel

As a smart wearable sensor device, the mildew of the biocompatible hydrogel limits its application. In this paper, silver nanoparticles were prepared by solid-state reduction of hydroxyethyl cellulose and compounded into a chemically cross-linked hydrogel as an antibacterial, flexible strain sensor. Because the high surface energy of silver nanoparticles can quench free radicals, we designed three initiators to synthesize hydrogels: ammonium persulfate (APS), 2,2'-Azobis(2-methylpropionitrile) (AIBN) and 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA). Impressively, silver nanoparticles composite hydrogel could only be successfully fabricated and triggered by the AIBN. The mechanical property of the composite hydrogel (0.12 MPa at 704.33 % strain) was significantly improved because of dynamic crosslinking point by HEC. Finally, the composite hydrogels are applied to the field of antibacterial strain sensor and the highest Gauge Factor (GF) reached 4.07. This article proposes a novel, green and simple strategy for preparing silver nanoparticles and compounding them into a hydrogel system for antibacterial strain sensor.

Synthesis of gold nanoparticles/polyaniline boronic acid/sodium alginate aqueous nanocomposite based on chemical oxidative polymerization for biological applications

Gold nanoparticles/polyaniline boronic acid/sodium alginate aqueous nanocomposite ((PABA-SAL)@AuNPs) was fabricated. Aniline boronic acid (ABA) served as reductant of gold salt, all within the SAL solution. While ABA reduced gold salt to its nanoparticles, the ABA monomer was also oxidized to its conducting polymeric form (PABA). The presence of PABA in the reaction mixture exerted solubility and stability challenge, thus SAL was used as stabilizer and solubilizer for PABA. The numerous cis-diol groups of SAL could bind to boronic acid groups of PABA to furnish PABA-SAL repeating polymer structure for AuNPs anchoring. Sparkling ruby red (PABA-SAL)@AuNPs have absorption peaks at 529 and 718 nm. Average particle sizes of nanocomposite were within 15-20 nm, with hydrodynamic diameter of 48.6 ± 0.9 nm, zeta potential of -32.5 ± 1.6 mV and conductivity value of 2015.3 ± 3.2 μS/cm. (PABA-SAL)@AuNPs possessed antibacterial activities against seafood associated bacterial isolates, with MIC and MBC ranging from 4 to 8 μg/mL. The moderate antioxidant capacity of (PABA-SAL)@AuNPs was observed, without any deleterious damages on human red blood cells. It also has good biocompatibility on Caco-2 and RAW 264.7, with cell viability not less than 70%. These results confirm the high prospect of (PABA-SAL)@AuNPs for possible biomedical applications.

Sensitive colorimetric detection of ascorbic acid based on seed mediated growth of sodium alginate reduced/stabilized gold nanoparticles

A sensitive detection strategy for ascorbic acid (AA), using sodium alginate reduced/stabilized gold nanoparticles (SA-AuNPs) as the optical probe, is reported. The SA-AuNPs were prepared by mixing gold salt and SA under stirring for 2 h at room temperature, without any further steps. The mixture was aged at 4 °C overnight, after which a faint-purple colloidal solution of SA-AuNPs was obtained. Characterization shows that the synthesis is incapable of reducing all Au³⁺ to Au°, but rather to mixture of Au°/Au⁺. The addition of AA to the SA-AuNPs probe reduced completely all Au⁺ to new AuNPs which were deposited on the pre-formed SA-AuNPs seed, leading to size increment and absorption spectra enhancement. The assay exhibited a good linearity between 12.5 and 150.0 μM AA and low limit of quantification of 11.2 μM. It was further used for AA quantitation in vitamin C injection and fruit juice with satisfactory accuracy and precision.

Recent Progress in Antimicrobial Nanomaterials

Bacterial infections are a well-known and serious problem in numerous areas of everyday life, causing death, pain, and huge added costs to healthcare worldwide [...].

Antimicrobial activity and inhibition of biofilm formation in vitro and on human dentine by silver nanoparticles/carboxymethyl-cellulose composites

OBJECTIVE

To evaluate the antimicrobial activity of a silver nanoparticles/carboxymethyl-cellulose (AgNPs/CMC) composite on in vitro and dentine disc heterogeneous biofilms.

DESIGN

AgNPs/CMC composite effect on normal human gingival fibroblast cells (HGF) viability was determined by the MTT reduction assay. In addition, we evaluated the antimicrobial effect of AgNPs/CMC composite on Candida albicans, Enterococcus faecalis, and Fusobacterium nucleatum growth in vitro and heterogeneous biofilms, as well as dentine disc biofilms.

RESULTS

Quasi-spherical AgNPs/CMC composites, with a mean 22.3 nm particle-size were synthesized. They were not toxic to HGF cells at concentrations tested that were antimicrobial, however they caused significant cytotoxicity (89 %, p <  0.05) at concentrations > 15 μg/mL. In vitro, they inhibited up to 67 %, 66 %, and 96 % C. albicans, E. faecalis, and F. nucleatum growth at concentrations ranging from 1.2 μg/mL to 9.6 μg/mL, as compared with untreated control. We also demonstrated significant (p <  0.05) 58 % biofilm reduction by 4.8 μg/mL AgNPs/CMC composite on human dentine discs.

CONCLUSION

AgNPs/CMC composite showed anti biofilm activity on monocultures, heterogenous cultures, and dentine discs, resulting a potentially effective alternative to prevent and eliminate infections after endodontic treatment.