Nanocomposites based on polylactide and silver nanoparticles and their antimicrobial and antiviral applications

Silver and gold nanoparticles: Eco-friendly synthesis, antibiofilm, antiviral, and anticancer bioactivities

For the first time in this study, silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) were green synthesized by the cost-effective and eco-friendly procedure using Cotton seed meal and Fodder yeast extracts. The biosynthesized NPs were characterized by UV-Vis spectroscopy, dynamic light scattering analysis (DLS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and fourier-transform infrared (FTIR) spectroscopy. Furthermore, the biosynthesized NPs were tested in vitro against biofilm formation by some pathogenic negative bacteria (Escherichia coli, Proteus mirabilis, Klebsiella sp., Salmonella sp., and Pseudomonas aeruginosa) and negative bacteria (staphylococcus aureus) as well as against human denovirus serotype 5 (HAdV-5) and anticancer activity using HepG2 hepatocarcinoma cells. UV-Vis absorption spectra of reaction mixture of AgNPs and AuNPs exhibited maximum absorbance at 440 nm and 540 nm, respectively. This finding was confirmed by DLS measurements that the highest intensity of the AgNPs and AuNPs were 84 nm and 73.9 nm, respectively. FTIR measurements identified some functional groups detected in Cotton seed meal and Fodder yeast extracts that could be responsible for reduction of silver and gold ions to metallic silver and gold. The morphologies and particle size of AgNPs and AuNPs were confirmed by the TEM and SAED pattern analysis. Biosynthesized AgNPs and AuNPs showed good inhibitory effects against biofilms produced by Escherichia coli, Proteus mirabilis, Klebsiella sp., Salmonella sp., Pseudomonas aeruginosa, and Staphylococcus aureus. In addition, they showed anticancer activities against hepatocellular carcinoma (HepG-2) and antiviral activity against human adenovirus serotype 5 infection in vitro. Finally, the results of this study is expected to be extremely helpful to nano-biotechnology, pharmaceutical, and food packing applications through developing antimicrobial and/or an anticancer drugs from ecofriendly and inexpensive nanoparticles with multi-potentiality.

Increasing the Service Life of Marine Transport Using Heat-Resistant Polymer Nanocomposites

This paper presents the technological aspects of increasing the thermal stability of polymers, with epoxy binder used to form the polymer materials. Polyethylene polyamine was used to crosslink the epoxy binder. To ensure the thermal stability of the polymer, nanodispersed condensed carbon with a dispersion of 10-16 nm was used. The research into nanocomposites under the influence of elevated temperatures was carried out using the "Thermoscan-2" derivatograph. Complex studies of thermophysical properties were carried out, according to the results of which the optimal content of nanofiller (0.050 pts.wt.) was determined. At the same time, this particular polymer was characterized by the following properties: temperature of the beginning of mass loss-T0 = 624.9 K; final temperature of mass loss-Tf = 718.7 K; relative mass loss-εm = 60.3%. Research into the activation energy of thermal destruction was performed to determine the resistance to the destruction of chemical bonds. It was proved that the maximum value of activation energy (170.1 kJ/mol) is characterized by nanocomposites with a content of nanodispersed condensed carbon of 0.050 pts.wt., which indicates the thermal stability of the polymer.

Nanogallium-poly(L-lactide) Composites with Contact Antibacterial Action

In diverse biomedical and other applications of polylactide (PLA), its bacterial contamination and colonization are unwanted. For this reason, this biodegradable polymer is often combined with antibacterial agents or fillers. Here, we present a new solution of this kind. Through the process of simple solvent casting, we developed homogeneous composite films from 28 ± 5 nm oleic-acid-capped gallium nanoparticles (Ga NPs) and poly(L-lactide) and characterized their detailed morphology, crystallinity, aqueous wettability, optical and thermal properties. The addition of Ga NPs decreased the ultraviolet transparency of the films, increased their hydrophobicity, and enhanced the PLA structural ordering during solvent casting. Albeit, above the glass transition, there is an interplay of heterogeneous nucleation and retarded chain mobility through interfacial interactions. The gallium content varied from 0.08 to 2.4 weight %, and films with at least 0.8% Ga inhibited the growth of Pseudomonas aeruginosa PAO1 in contact, while 2.4% Ga enhanced the effect of the films to be bactericidal. This contact action was a result of unwrapping the top film layer under biological conditions and the consequent bacterial contact with the exposed Ga NPs on the surface. All the tested films showed good cytocompatibility with human HaCaT keratinocytes and enabled the adhesion and growth of these skin cells on their surfaces when coated with poly(L-lysine). These properties make the nanogallium-polyl(L-lactide) composite a promising new polymer-based material worthy of further investigation and development for biomedical and pharmaceutical applications.

Recent Advancements in Sensing of Silver ions by Different Host Molecules: An Overview (2018-2023)

The chemosensors act as powerful tool in the detection of metal ions due to their simplicity, high sensitivity, low cost, low detection limit, rapid photophysical response, and application to the environmental and medical fields. This review article presents an overview for the chemosensing of Ag+ ions based on Calix, MOF, Nanoparticle, COF, Calix, Electrochemical chemosensor published from 2018 to 2023. Here, we have reviewed the sensing of Ag+ ions and summarised the binding response, mechanism, LOD, colorimetric response, adsorption capacity, technique used. The purpose of this review article to provide a detailed summary of the performance of different host chemosensors that are helpful for providing future direction to researchers on Ag+ ion detection and provides path to design effective chemsosensor (simple to synthesize, cost effective, high sensitivity, with more practical application). While studying the related article literature, we came across some challenges and that has been discussed lastly and provided solutions for them.

Preliminary Study of the Bactericide Properties of Biodegradable Polymers (PLA) with Metal Additives for 3D Printing Applications

Plastic is a highly used material in various sectors. Due to its plentiful availability in the environment, microorganism surface contamination is a risk. The aim of this work is to achieve bactericidal capacity in plastics that reduces the microorganism’s colonization risk and, consequently, reduces the chances of having an infection with E. coli and Listeria monocytogenes bacteria. Using polylactic acid (PLA) as the polymeric matrix, mixtures in concentrations of metal additive of ions of silver (Ag) R148 and S254 in 1% and 2% have been studied and manufactured. The materials are developed on an industrial scale through a process that proceeds as follows: (I) a mixture of polymer and additive in a double-screw compounder to obtain the compound in different concentrations, (II) the manufacture of filaments with a single-screw extruder, (III) 3D printing parts. Therefore, materials are evaluated in the form of powder, pellets and printed pieces to ensure their antibacterial effectiveness throughout the manufacturing process. The results of the research show antibacterial effectiveness for E. coli and Listeria monocytogenes of metal additives and polymeric compounds for all manufacturing phases on an industrial scale, with the effectiveness for additive R148 predominating at a concentration of 2%, demonstrating its microbial efficacy on surfaces with potential application in medicine.

Recent Advances in the Investigation of Poly(lactic acid) (PLA) Nanocomposites: Incorporation of Various Nanofillers and their Properties and Applications

Poly(lactic acid) (PLA) is considered the most promising biobased substitute for fossil-derived polymers due to its compostability, biocompatibility, renewability, and good thermomechanical properties. However, PLA suffers from several shortcomings, such as low heat distortion temperature, thermal resistance, and rate of crystallization, whereas some other specific properties, i.e., flame retardancy, anti-UV, antibacterial or barrier properties, antistatic to conductive electrical characteristics, etc., are required by different end-use sectors. The addition of different nanofillers represents an attractive way to develop and enhance the properties of neat PLA. Numerous nanofillers with different architectures and properties have been investigated, with satisfactory achievements, in the design of PLA nanocomposites. This review paper overviews the current advances in the synthetic routes of PLA nanocomposites, the imparted properties of each nano-additive, as well as the numerous applications of PLA nanocomposites in various industrial fields.

Polylactide-Based Films Incorporated with Berberine-Physicochemical and Antibacterial Properties

A series of new polymeric materials consisting of polylactide (PLA), polyethylene glycol (PEG) and berberine chloride (B) was evaluated. PEG was incorporated into the polymer matrix with the aim of obtaining a plasticizing effect, while berberine was added in order to obtain antibacterial properties in formed packaging materials. Materials were formed using the solvent-casting procedure. Fourier transform infrared spectroscopy and scanning electron microscopy were used so as to establish the structural changes resulting from the introduction of berberine. Thermogravimetry and differential scanning calorimetry were applied to study the thermal properties. Further, mechanical properties and differences in colour and transparency between the control sample and films containing berberine were also studied. The recorded data indicates that berberine formed a network on the surface of the PLA-based materials. Introduction of an active compound significantly improved thermal stability and greatly affected the Young's modulus values of the studied polymeric films. Moreover, it should be stressed that the addition of the studied active compound leads to an improvement of the antibacterial properties, resulting in a significant decrease in growth of E. coli and the S. aureus bacteria cultures.

Isothermic and Kinetic Study on Removal of Methylene Blue Dye Using Anisomeles malabarica Silver Nanoparticles: An Efficient Adsorbent to Purify Dye-Contaminated Wastewater

Remediation of industrial discharged dyes to the water bodies is much needed in the current scenario. Here in this, we prepared silver nanoparticles using Anisomeles malabarica. The synthesized nanoparticles were characterized by Fourier transform infrared study, scanning electron microscopy, dynamic scanning calorimetry, and thermogravimetric analysis. All the characterization studies suggested that the formation of silver nanoparticles was successful. The synthesized silver nanoparticles were used as an adsorbent to adsorb the methylene blue. To achieve this, optimum pH of the adsorbent to adsorb the dye was studied, and it was found to be pH 7. The adsorbent dose to adsorb the dye was found to be 0.1 g/L. From the isotherm theoretical studies, it was found that the adsorption isotherm follows Langmuir adsorption, and the $q_{\max }$ was found to be 97.08. From the kinetic study, the rate of the reaction follows the pseudosecond-order kinetics with $\text{regression}>0.9$ . From the study, it was inferred the nanoparticles synthesized can act as a good adsorbent and can be used to purify the wastewater contaminated with methylene blue.

Antimicrobial Activity of Biogenic Silver Nanoparticles from Syzygium aromaticum against the Five Most Common Microorganisms in the Oral Cavity

Syzygium aromaticum (clove) has been used as a dental analgesic, an anesthetic, and a bioreducing and capping agent in the formation of metallic nanoparticles. The main objective of this study was to evaluate the antimicrobial effect in oral microorganisms of biogenic silver nanoparticles (AgNPs) formed with aqueous extract of clove through an ecofriendly method “green synthesis”. The obtained AgNPs were characterized by UV-Vis (ultraviolet-visible spectroscopy), SEM-EDS (scanning electron microscopy–energy dispersive X-ray spectroscopy), TEM (transmission electron microscopy), and ζ potential, while its antimicrobial effect was corroborated against oral Gram-positive and Gram-negative microorganisms, as well as yeast that is commonly present in the oral cavity. The AgNPs showed absorption at 400–500 nm in the UV-Vis spectrum, had an average size of 4–16 nm as observed by the high-resolution transmission electron microscopy (HR-TEM), and were of a crystalline nature and quasi-spherical form. The antimicrobial susceptibility test showed inhibition zones of 2–4 mm in diameter. Our results suggest that AgNPs synthesized with clove can be used as effective growth inhibitors in several oral microorganisms.

Structure-Morphology-Antimicrobial and Antiviral Activity Relationship in Silver-Containing Nanocomposites Based on Polylactide

Green synthesis of silver-containing nanocomposites based on polylactide (PLA) was carried out in two ways. With the use of green tea extract, Ag⁺ ions were reduced to silver nanoparticles with their subsequent introduction into the PLA (mechanical method) and Ag⁺ ions were reduced in the polymer matrix of PLA-AgPalmitate (PLA-AgPalm) (in situ method). Structure, morphology and thermophysical properties of nanocomposites PLA-Ag were studied by FTIR spectroscopy, wide-angle X-ray scattering (WAXS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) methods. The antimicrobial, antiviral, and cytotoxic properties were studied as well. It was found that the mechanical method provides the average size of silver nanoparticles in the PLA of about 16 nm, while in the formation of samples by the in situ method their average size was 3.7 nm. The strong influence of smaller silver nanoparticles (3.7 nm) on the properties of nanocomposites was revealed, as with increasing nanosilver concentration the heat resistance and glass transition temperature of the samples decreases, while the influence of larger particles (16 nm) on these parameters was not detected. It was shown that silver-containing nanocomposites formed in situ demonstrate antimicrobial activity against gram-positive bacterium S. aureus, gram-negative bacteria E. coli, P. aeruginosa, and the fungal pathogen of C. albicans, and the activity of the samples increases with increasing nanoparticle concentration. Silver-containing nanocomposites formed by the mechanical method have not shown antimicrobial activity. The relative antiviral activity of nanocomposites obtained by two methods against influenza A virus, and adenovirus serotype 2 was also revealed. The obtained nanocomposites were not-cytotoxic, and they did not inhibit the viability of MDCK or Hep-2 cell cultures.

Preparation, Characterization, and Antimicrobial and Antiviral Properties of Silver-Containing Nanocomposites Based on Polylactic Acid-Chitosan

Antimicrobial and antiviral nanocomposites based on polylactic acid (PLA) and chitosan were synthesized by a thermochemical reduction method of Ag⁺ ions in the PLA-Ag⁺-chitosan polymer films. Features of the structural, morphological, thermophysical, antimicrobial, antiviral, and cytotoxic properties of PLA-Ag-chitosan nanocomposites were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and antiviral, antimicrobial, and cytotoxic studies. The effects of temperature and the duration of reduction of Ag⁺ ions on the structure of PLA-Ag-chitosan nanocomposites were established. During the thermochemical reduction (T = 160 °C, t = 5 min) of silver palmitate ions in PLA-Ag⁺-chitosan polymer films, Ag nanoparticles with an average size of 4.2 nm were formed. PLA-Ag-chitosan polymer nanocomposites have strong antimicrobial activity against S. aureus and E. coli strains. In particular, for PLA-chitosan samples containing 4% Ag, the diameters of the S. aureus and E. coli growth inhibition zones were 25.8 and 25.0 mm, respectively. The antiviral activity of the nanocomposites against influenza A virus, herpes simplex virus type 1, and adenovirus serotype 2 was also revealed. The PLA-4%Ag-chitosan nanocomposites completely inhibited the cytopathic effect (CPE) of herpes virus type 1 by 5.12 log₁₀TCID₅₀/mL (high antiviral activity) and the development of the CPE of influenza virus and adenovirus by 0.60 and 1.07 log₁₀TCID₅₀/mL (relative antiviral activity). The obtained nanocomposites were not cytotoxic; they did not inhibit the viability of MDCK, BHK-21, and Hep-2 cell cultures.

Application of Metal Nanoparticles for Production of Self-Sterilizing Coatings

Metal nanoparticles (NPs) are increasingly being used in many areas, e.g., industry, pharmacy, and biomedical engineering. NPs can be obtained through chemical and biological synthesis or using physical methods. AgNPs, AuNPs, CuNPs, FeNPs, MgNPs, SnO2NPs, TiO2NPs, and ZnONPs are the most commonly synthesized metal nanoparticles. Many of them have anti-microbial properties and documented activity supported by many tests against some species of pathogenic bacteria, viruses, and fungi. AgNPs, which are used for the production of commercial self-sterilizing packages, are one of the best-explored nanoparticles. Moreover, the EFSA has approved the use of small doses of silver nanoparticles (0.05 mg Ag·kg−1) to food products. Recent studies have shown that metal NPs can be used for the production of coatings to prevent the spread of the SARS-CoV-2 virus, which has caused the global pandemic. Some nanoparticles (e.g., ZnONPs and MgONPs) have the Generally Recognized As Safe (GRAS) status, i.e., they are considered safe for consumption and can be used for the production of edible coatings, protecting food against spoilage. Promising results have been obtained in research on the use of more than one type of nanometals, which prevents the development of pathogen resistance through various mechanisms of inactivation thereof.

Special Features of Polyester-Based Materials for Medical Applications

This article presents current possibilities of using polyester-based materials in hard and soft tissue engineering, wound dressings, surgical implants, vascular reconstructive surgery, ophthalmology, and other medical applications. The review summarizes the recent literature on the key features of processing methods and potential suitable combinations of polyester-based materials with improved physicochemical and biological properties that meet the specific requirements for selected medical fields. The polyester materials used in multiresistant infection prevention, including during the COVID-19 pandemic, as well as aspects covering environmental concerns, current risks and limitations, and potential future directions are also addressed. Depending on the different features of polyester types, as well as their specific medical applications, it can be generally estimated that 25–50% polyesters are used in the medical field, while an increase of at least 20% has been achieved since the COVID-19 pandemic started. The remaining percentage is provided by other types of natural or synthetic polymers; i.e., 25% polyolefins in personal protection equipment (PPE).

The Influence of the Gradient Infill of PLA Samples Produced with the FDM Technique on Their Mechanical Properties

Three-dimensional printing is a dynamically developing field of industry. Its main advantage is the small amount of waste, no need to use specialized tools, and easy control of the mechanical properties of the printed model. One of the most popular techniques of 3D printing is FDM. The main factor influencing the mechanical properties of 3D-printed materials is the filling density. The aim of this study was to determine the mechanical properties of porous structures with a porosity gradient of PLA samples printed using the FDM technique. The accuracy of mapping the structures by computed tomography was assessed, and then a static compression test was performed. It has been shown that the strength properties increased with the increase in the filling density. The highest value of compression strength, amounting to 41.2 MPa, was observed for samples made of PLA with an 80% filling degree, whereas the lowest value of compression strength was found in PLA-T samples with a filling degree of 10%, reaching only 0.6 MPa. It was found that not only the core filling density, but also the outer layers, influences the mechanical properties. The assessment of spatial architecture allowed for a qualitative and quantitative assessment. The obtained images from the computed tomograph showed that the designed sample models were correctly reproduced in the entire volume.