Bioactive and Physico-Chemical Assessment of Innovative Poly(lactic acid)-Based Biocomposites Containing Sage, Coconut Oil, and Modified Nanoclay.

The bioactivity of the versatile biodegradable biopolymer poly(lactic acid) (PLA) can be obtained by combining it with natural or synthetic compounds. This paper deals with the preparation of bioactive formulations involving the melt processing of PLA loaded with a medicinal plant (sage) and an edible oil (coconut oil), together with an organomodifed montmorillonite nanoclay, and an assessment of the resulting structural, surface, morphological, mechanical, and biological properties of the biocomposites. By modulating the components, the prepared biocomposites show flexibility, both antioxidant and antimicrobial activity, as well as a high degree of cytocompatibility, being capable to induce the cell adherence and proliferation on their surface. Overall, the obtained results suggest that the developed PLA-based biocomposites could potentially be used as bioactive materials in medical applications.

Weathering and degradation of polylactic acid masks in a simulated environment in the context of the COVID-19 pandemic and their effects on the growth of winter grazing ryegrass.

The COVID-19 pandemic has led to explosive growth in the production and consumption of disposable medical masks, which has caused new global environmental problems due to the improper disposal of these masks and lack of effective mask recycling methods. To reduce the environmental load caused by the inability of synthetic plastics to degrade, polylactic acid (PLA) masks, as a biodegradable environmentally friendly plastic, may become a solution. This study simulated the actual degradation process of new PLA masks in different environments by soaking them in various solutions for 4 weeks and explored the influence of the treated PLA fabric fibers on the growth of winter ryegrass. The results show that the weathering degradation of PLA fibers in water mainly occurs through the hydrolysis of ester bonds, and weathering leads to cheese-like and gully-like erosion on the surface of the PLA fiber fabric layer and finally to fiber fracture and the release of microplastics (MPs). The average number of MPs released within 4 weeks is 149.5 items/piece, the particle size is 20-500 µm (44%), and 63.57% of the MPs are transparent fibers. The outer, middle, and inner layers of weathered PLA masks tend to be hydrophilic and have lower mechanical strength. PLA fibers after different treatment methods affect the growth of winter ryegrass. PLA masks are undoubtedly a greener choice than ordinary commercial masks, but in order to confirm this, the entire degradation process, the final products, and the impact on the environment need to be further studied. In the future, masks may be developed to be made from more environmentally friendly biodegradable materials that can have good protecting effects and also solve the problem of end-of-life recycling. A SYNOPSIS: Simulation of the actual degradation process of PLA masks and exploration of the influence of mask degradation on the growth of winter ryegrass.

Microfluidic preparation of antimicrobial microparticles composed of l-lactide/1,3-dioxolane (co)polymers loaded with quercetin.

The resistance of microorganisms against commonly used antibiotics is becoming an increasingly important problem in the food and pharmaceutical industries. Therefore, the development of novel bactericidal agents, as well as the design of drug delivery systems based on materials composed of biocompatible and biodegradable building blocks, has attracted increasing attention. To address this challenge, microparticles composed of l-lactide homopolymer and l-lactide/1,3-dioxolane (co)polymers loaded with quercetin (Q) were fabricated by using a microfluidic technique. This method enables the preparation of homogeneous particles with sizes ranging from 60 to 80 µm, composed of degradable semicrystalline or amorphous (co)polyesters. The microencapsulation of Q in a (co)polymeric matrix enables prolonged release of the antimicrobial agent. The antibacterial properties of the obtained biocompatible microparticles are confirmed by the agar diffusion plate method for various bacterial strains. Therefore, Q-loaded microparticles can have important applications in food preservation as a novel antimicrobial system.

Biodegradable Nanohybrid Materials as Candidates for Self-Sanitizing Filters Aimed at Protection from SARS-CoV-2 in Public Areas.

The COVID-19 pandemic has raised the problem of efficient, low-cost materials enabling the effective protection of people from viruses transmitted through the air or via surfaces. Nanofibers can be a great candidate for efficient air filtration due to their structure, although they cannot protect from viruses. In this work, we prepared a wide range of nanofibrous biodegradable samples containing Ag (up to 0.6 at.%) and Cu (up to 20.4 at.%) exhibiting various wettability. By adjusting the magnetron current (0.3 A) and implanter voltage (5 kV), the deposition of TiO2 and Ag+ implantation into PCL/PEO nanofibers was optimized in order to achieve implantation of Ag+ without damaging the nanofibrous structure of the PCL/PEO. The optimal conditions to implant silver were achieved for the PCL-Ti0.3-Ag-5kV sample. The coating of PCL nanofibers by a Cu layer was successfully realized by magnetron sputtering. The antiviral activity evaluated by widely used methodology involving the cultivation of VeroE6 cells was the highest for PCL-Cu and PCL-COOH, where the VeroE6 viability was 73.1 and 68.1%, respectively, which is significantly higher compared to SARS-CoV-2 samples without self-sanitizing (42.8%). Interestingly, the samples with implanted silver and TiO2 exhibited no antiviral effect. This difference between Cu and Ag containing nanofibers might be related to the different concentrations of ions released from the samples: 80 µg/L/day for Cu2+ versus 15 µg/L/day for Ag+. The high antiviral activity of PCL-Cu opens up an exciting opportunity to prepare low-cost self-sanitizing surfaces for anti-SARS-CoV-2 protection and can be essential for air filtration application and facemasks. The rough cost estimation for the production of a biodegradable nanohybrid PCL-Cu facemask revealed ~$0.28/piece, and the business case for the production of these facemasks would be highly positive, with an Internal Rate of Return of 34%.

Characterization of Materials Used as Face Coverings for Respiratory Protection.

Use of masks is a primary tool to prevent the spread of the novel COVID-19 virus resulting from unintentional close contact with infected individuals. However, detailed characterization of the chemical properties and physical structure of common mask materials is lacking in the current literature. In this study, a series of commercial masks and potential mask materials, including 3M Particulate Respirator 8210 N95, a material provided by Oak Ridge National Laboratory Carbon Fiber Technology Facility (ORNL/CFTF), and a Filti Face Mask Material, were characterized by a suite of techniques, including scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Wetting properties of the mask materials were quantified by measurements of contact angle with a saliva substitute. Mask pass-through experiments were performed using a dispersed metal oxide nanoparticle suspension to model the SARS-CoV-2 virus, with quantification via spatially resolved X-ray fluorescence mapping. Notably, all mask materials tested provided a strong barrier against respiratory droplet breakthrough. The comparisons and characterizations provided in this study provide useful information when evaluating mask materials for respiratory protection.

Effective Oxidation-Responsive Polyester Nanocarriers for Anti-Inflammatory Drug Delivery.

BACKGROUND: High levels of oxidants, such as reactive oxygen species (ROS) and reactive nitrogen species (RNS), are typical characteristics of an inflammatory microenvironment and are closely associated with a various inflammatory pathologies, eg, cancer, diabetes, atherosclerosis, and neurodegenerative diseases. Therefore, the delivery of anti-inflammatory drugs by oxidation-responsive smart systems would be an efficient anti-inflammatory strategy that benefits from the selective drug release in an inflammatory site, a lower treatment dose, and minimizes side effects. PURPOSE: In this study, we present the feasibility of an oxidation-sensitive PEGylated alternating polyester, methoxyl poly(ethylene glycol)-block-poly(phthalic anhydride-alter-glycidyl propargyl ether) (mPEG-b-P(PA-alt-GPBAe)), as novel nanocarrier for curcumin (CUR), and explore the application in anti-inflammatory therapy. METHODS: The copolymers used were obtained by combining a click reaction and a ring-opening-polymerization method. CUR was loaded by self-assembly. The in vitro drug release, cytotoxicity toward RAW 264.7 cells and cellular uptake were investigated. Furthermore, the anti-inflammatory effects of CUR-loaded polymeric nanoparticles (NPs-CUR) were investigated in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages and tested in a murine model of ankle inflammation. RESULTS: Fast drug release from NPs-CUR was observed in trigger of 1 mM H2O2 in PBS. Compared with NPs and free drugs, the significant anti-inflammatory potential of NPs-CUR was proven in activated RAW 264.7 cells by inhibiting the production of TNF-α, IL-1ß, and IL-6 and increasing the level of an anti-inflammatory cytokine IL-10. Finally, a local injection of NPs-CUR at a dose of 0.25 mg/kg suppressed the acute ankle inflammatory response in mice by histological observation and further reduced the expression of pro-inflammatory cytokines in the affected ankle joints compared to that of free CUR. CONCLUSION: Both the significant in vitro and in vivo anti-inflammatory results indicated that our oxidation responsive polymeric nanoparticles are promising drug delivery systems for anti-inflammatory therapy.

Study of the use of a personalized peripheral sealing device on surgical face masks in high-risk situations against COVID-19.

A significant number of health care professionals subjected to high-risk situations have been infected by Covid-19 due to the lack of adequate protection equipment or the deficient safety margins that these present. The aim of this study was to investigate whether the use of a personal peripheral sealing device (PSD) on surgical face masks (SM) allows them to achieve double mask properties, by providing two-way protection to professionals or users. The proposed device is a thermoplastic resin ring composed of a reusable and biodegradable polylactic acid (PLA) designed to be used in a healthcare setting. Since it is a thermoplastic device, it can be molded and adapted to each individual, becoming personalized and ensuring a correct adjustment to the user's face. First, a qualitative fit test was performed using a saccharin solution (SS) to evaluate respiratory protective equipment in recruited professionals exposed to high-risk situations of infection by Covid-19. Individuals were divided into an intervention group, who used SM with the PSD, and a control group, who used SM without the PSD. In addition, a quantitative inward air leakage fit test was performed using a 2% sodium chloride (NaCl) aerosol in a sealed cabinet with probes sensitive to this substance, in order to validate the SM with the PSD as a Face Filtering Mask (FFP). Only 5% of the individuals who performed the qualitative fit test with the PSD perceived the sweet taste of the SS, while 100% of the individuals who performed the test without the PSD sensed it (p = 0.0001). In the quantitative fit test, the percentage of air leakage of 2% NaCl aerosol into the SM with the PSD was 6.5%, achieving the same range of air leakage as a FFP mask. Thus, the use of a personalized PLA thermoplastic PSD, together with an inexpensive and widely available SM, could have a significant impact in terms of preventive safety by providing bi-directional protection to its user.

Polylactic acid production from biotechnological routes: A review.

Polylactic acid (PLA) has been highlighted as an important polymer due to its high potential for applicability in various areas, such as in the chemical, medical, pharmaceutical or biotechnology field. Very recently, studies have reported its use as a basic component for the production of personal protective equipment (PPE) required for the prevention of Sars-Cov-2 contamination, responsible for the cause of coronavirus disease, which is currently a major worldwide sanitary and social problem. PLA is considered a non-toxic, biodegradable and compostable plastic with interesting characteristics from the industrial point of view, and it emerges as a promising product under the concept of "green plastic", since most of the polymers produced currently are petroleum-based, a non-renewable raw material. Biotechnology routes have been mentioned as potential methodologies for the production of this polymer, especially by enzymatic routes, in particular by use of lipases enzymes. The availability of pure lactic acid isomers is a fundamental aspect of the manufacture of PLA with more interesting mechanical and thermal properties. Due to the technological importance that PLA-based polymers are acquiring, as well as their characteristics and applicability in several fields, especially medical, pharmaceutical and biotechnology, this review article sought to gather very recent information regarding the development of research in this area. The main highlight of this study is that it was carried out from a biotechnological point of view, aiming at a totally green bioplastic production, since the obtaining of lactic acid, which will be used as raw material for the PLA synthesis, until the degradation of the polymer obtained by biological routes.

Synthesis of the Bacteriostatic Poly(l-Lactide) by Using Zinc (II)[(acac)(L)H2O] (L = Aminoacid-Based Chelate Ligands) as an Effective ROP Initiator.

The paper presents a synthesis of poly(l-lactide) with bacteriostatic properties. This polymer was obtained by ring-opening polymerization of the lactide initiated by selected low-toxic zinc complexes, Zn[(acac)(L)H2O], where L represents N-(pyridin-4-ylmethylene) tryptophan or N-(2-pyridin-4-ylethylidene) phenylalanine. These complexes were obtained by reaction of Zn[(acac)2 H2O] and Schiff bases, the products of the condensation of amino acids and 4-pyridinecarboxaldehyde. The composition, structure, and geometry of the synthesized complexes were determined by NMR and FTIR spectroscopy, elemental analysis, and molecular modeling. Both complexes showed the geometry of a distorted trigonal bipyramid. The antibacterial and antifungal activities of both complexes were found to be much stronger than those of the primary Schiff bases. The present study showed a higher efficiency of polymerization when initiated by the obtained zinc complexes than when initiated by the zinc(II) acetylacetonate complex. The synthesized polylactide showed antibacterial properties, especially the product obtained by polymerization initiated by a zinc(II) complex with a ligand based on l-phenylalanine. The polylactide showed a particularly strong antimicrobial effect against Pseudomonas aeruginosa, Staphylococcus aureus, and Aspergillus brasiliensis. At the same time, this polymer does not exhibit fibroblast cytotoxicity.