Bioinspired Antimicrobial PLA with Nanocones on the Surface for Rapid Deactivation of Omicron SARS-CoV-2.

Bioinspired bactericidal surfaces are artificial surfaces that mimic the nanotopography of insect wings and are capable of inhibiting microbial growth by a physicomechanical mechanism. The scientific community has considered them an alternative method to design polymers with surfaces that inhibit bacterial biofilm formation, suitable for self-disinfectant medical devices. In this contribution, poly(lactic acid) (PLA) with nanocone patterns was successfully produced by a novel two-step procedure involving copper plasma deposition followed by argon plasma etching. According to reverse transcription-quantitative polymerase chain reaction tests, the bioinspired PLA nanostructures display antiviral performance to inactivate infectious Omicron severe acute respiratory syndrome coronavirus 2 particles, reducing the amount of the viral genome to less than 4% in just 15 min due to a possible combined effect of mechanical and oxidative stress. The bioinspired antiviral PLA can be suitable for designing personal protection equipment to prevent the transmission of contagious viral diseases, such as Coronavirus Disease 2019.

Omicron SARS-CoV-2 antiviral on poly(lactic acid) with nanostructured copper coating: Wear effects.

Surface modification corresponds to a set of viable technological approaches to introduce antimicrobial properties in materials that do not have such characteristics. Antimicrobial materials are important to prevent the proliferation of microorganisms and minimize the transmission of diseases caused by pathogens. Herein, poly(lactic acid) (PLA) was decorated with nanocones through copper sputtering followed by a plasma etching. Antiviral assays by Quantitative Reverse Transcription-Polymerase Chain Reaction (RT-qPCR) show that nanostructured Cu-coated PLA has high antiviral activity against Omicron SARS-CoV-2, showing a relative reduction in the amplified RNA (78.8 ± 3.9 %). Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS), and wear-resistance tests show that 20 wear cycles disrupt the surface nanocone patterns and significantly reduce the Cu content at the surface of the nanostructured Cu-coated PLA, leading to total loss of the antiviral properties of nanostructured PLA against Omicron SARS-CoV-2.

Divalent metal ion removal from simulated water using sustainable starch aerogels: Effect of crosslinking agent concentration and sorption conditions.

This paper evaluates corn starch aerogels, studying different crosslinking agent (trisodium citrate) concentrations (1:1, 1:1.5, and 1:2) and sorption conditions (contact time, adsorbent weight, and initial concentration) regarding the potentially toxic elements (PTEs) [Cd(II) or Zn(II)] adsorption of the aqueous systems. Besides, other properties of aerogels, such as structural properties, specific surface area, and mechanical performance, were evaluated. For adsorption results, better values were observed in adsorption capacity and efficiency for the initial concentration of 100 ppm. In addition, an adsorption time of 12 h and an adsorbent weight of 3.0 g obtained better results due to the possible balance in this time and the high specific surface area available for Cd(II) adsorption. As for the type of adsorbent, the Aero 1:1.5 sample (intermediate crosslinking agent concentration) obtained better results, possibly due to the high porosity, smaller pore sizes, high pore density, and high specific surface area (198 m2·g-1). In addition, hydroxyl groups in the starch aerogel removed Cd(II) ions with 30 % adsorption efficiency. Lastly, Aero 1:1.5 obtained a high mechanical strength at compression and a satisfactory compressive modulus. In contrast, starch aerogels did not absorb the Zn(II) ion.

Antibacterial resin-based composite containing chlorhexidine for dental applications.

OBJETICVE: The aim of this study was to develop a composite material with antibacterial activity using MMT loaded with clorhexidine (CHX). For that it was used a BisGMA/TEGDMA matrix and added low concentration of MMT/CHX. The aim was to evaluate the drug release capacity of MMT, and not to provide reinforcement. METHODS: Six experimental composites were made with organic matrix of BisGMA/TEGDMA in equal proportions by weight. The composites received organophlizated montmorillonite with or without CHX. The concentrations were 2,5; 5 or 10% by weight. Degree of conversion (DC) was evaluated using FTIR (peak 6165 cm-1; n=5). Specimens for flexural properties (10×2×1mm) were immediate tested (24h). Elastic modulus(E) and flexural strength (FS) was measured using the three point bending test (n=10). Inibition halo was used to test the antibacterial activity against Staphylococcus aureus, Streptococcus mutans, and Porphyromonas gingivalis (n=5 for each bacteria). The inhibition of biofilm formation (BF) was evaluated by inserting polymerized disc of composite in to a culture media colonized with Streptococcus mutans (n=10). The release of CHX was measured using ultraviolet (255nm) for 10 days (n=5). The data of degree of conversion was analysed using Kruskal-Wallis/ Mann-Whitney, and the other variables using two-way ANOVA/Tukey, always considering a global level of significance of 5%. RESULTS: DC ranged from 71% to 74%. E ranged from 5.7 to 8.1GPa. FS ranged from 61.4 to 74.7MPa. There were no statistical differences among the groups for all the variables. For the three bacteria tested the composites with CHX loaded presented inhibition of growth for all concentration, except for 2,5% that did not inihibited the growth of P. gingivalis. BF was lower for the groups with 10% MMT/CHX, all groups presented BF, even those without CHX loaded. All concentrations presented release off CHX during all the 28 days analyzed. CONCLUSIONS: Within the limitation of this study it can be concluded that: all concentrations tested presented release of CHX and reduced BF. All concentration presented antibacterial activity for the three bacteria tested, except for 2,5% that did not inhibit the growth of P. gingivalis. The presence of MMT with CHX loaded did not interfere in the properties evaluated.

Effect of lyophilization on the structure and phase changes of PEGylated-bovine serum albumin.

Poly (ethylene glycol) (PEG) conjugation masks the protein's surface and increases the molecular size of the polypeptide, thus preventing the approach of antibodies or antigen processing cells and reducing the degradation by proteolytic enzymes. Proteins are readily denatured by numerous stresses arising in solution (e.g., heating, agitation, freezing and pH changes) or by chemical reactions (e.g., hydrolysis and deamidation), many of which are mediated by water. Lyophilization is most commonly used to prepare dehydrated proteins, which, theoretically, should have the desired long-term stability at ambient temperatures. Through Raman spectroscopy, differential scanning calorimetry (DSC) associated with the determination of water content by Karl Fisher titration, it was observed that after the modification of BSA-PEG in a ratio of 1:0.25 showed lower degree of structural alterations and consequently lower variation on the physical-chemical characteristics when it was compared to BSA-PEG (1:0.5). Moreover, the BSA-PEG (1:0.25) optimizes the conditions during the lyophilization process and storage of the protein.